environmental design of coastal defence in lido di dante, italy

wwwelseviercomlocatecoastaleng

Coastal Engineering 52

Environmental design of coastal defence in Lido di Dante Italy

Barbara Zanuttigh a Luca Martinelli a Alberto Lamberti a Paula Moschella b

Stephen Hawkins b Silva Marzetti c Victor Ugo Ceccherelli d

a Distart Idraulica Universita di Bologna Viale Risorgimento 2 40136 Bologna Italyb The Marine Biological Association The Laboratory Citadel Hill Plymouth United Kingdom

c DSE Universita di Bologna Piazza Scaravilli 2 40126 Bologna Italyd CIRSA Universita di Bologna via S Alberto 163 48100 Ravenna Italy

Available online 2 November 2005

Abstract

The aim of the paper is to present an integrated design of a coastal defence by applying the knowledge gained within

DELOS (EVK3-CT-2000-00041 wwwdelosuniboit) to an existing prototype case For such purposes Lido di Dante

(Ravenna Italy) was selected being a well-documented site that suffers from severe erosion

The design method proposed follows the Design Guidelines for low-crested structures delivered by DELOS After a

preliminary analysis of the environmental context and constraints different design alternatives were proposed and then

modelled with the 2DH model suite MIKE 21 for representative hydrodynamics and meteorological conditions Engineering

ecological and social effects of each alternative are then assessed based on the results of numerical simulations and experience

in the area A global judgement of the alternatives is given including consideration of both construction and maintenance costs

The preferred scheme is then optimised through more detailed design and verified by numerical modelling The need for such

an integrated approach is finally discussed including limitations

D 2005 Elsevier BV All rights reserved

Keywords Beach Design Erosion Environment Hydrodynamics Habitat Biodiversity Contingent valuation method Beach value Social

preference

1 Introduction

Low-Crested coastal defence Structures (LCSs) are

usually designed by transposing at lower scale techni-

0378-3839$ - see front matter D 2005 Elsevier BV All rights reserved

doi101016jcoastaleng200509015

Corresponding author Tel +39 0512093754 fax +39

0516448346

E-mail address barbarazanuttighmailinguniboit

(B Zanuttigh)

ques and results mainly derived for breakwaters Little

attention has been paid to the fact that wave load

parameters and tidal range do not scale down In

particular these structures are low and hence are over-

topped at high tide or during storms and frequently

submerged modifying near-shore currents and deposi-

tional regimes As long as hydrodynamic morpho-

dynamic and ecological problems posed by LCSs are

not clarified unsuccessful designs have been frequent

(2005) 1089ndash1125

B Zanuttigh et al Coastal Engineering 52 (2005) 1089ndash11251090

leading to problems such as insufficient sand retention

erosion in gaps or at roundheads Both expected (eg

changes to surrounding soft-shore ecosystems) and

unexpected (eg habitat provision for non-native spe-

cies) ecological impacts can occur Conversely posi-

tive effects may be also overlooked (eg provision of

habitats for shellfish fish and other mobile fauna)

The DELOS project aimed at promoting effective

and environmentally compatible design of LCSs

through a multidisciplinary approach The project

team integrated research on hydrodynamics beach

morphology engineering design ecological studies

of structure and dynamics of coastal species associa-

tions cost-benefit analysis as well as assessment of

social consequences From the engineering point of

view the project provided physical (Kramer et al

2005mdashthis issue) numerical (Johnson et al 2005mdash

this issue) and field analyses (Lamberti et al 2005mdash

this issue) to achieve an accurate knowledge of LCSs

behaviour and effects From the ecological perspec-

tive the project drew attention to the modification of

habitats in coastal marine areas by deployment of

artificial structures such as port installations and

coastal defences (Chou 1997 Connell and Glasby

1999) To date the complex interactions between phy-

sical and biological processes on and around artificial

structures have been poorly identified (see Connell and

Glasby 1999 Bulleri et al 2000 Davis et al 2002

Chapman 2003) at the range of spatial and temporal

scales over which they occur (Miller 1999) As part of

DELOS ecological impacts of LCSs have been inves-

tigated on different coastal systems across Europe and

suggestions made for their construction in order to

minimise habitat changes (Airoldi et al 2005mdashthis

issue Martin et al 2005mdashthis issue Moschella et al

2005mdashthis issue) Mitigation measures to maximize if

desired biodiversity and bio-resources have also been

indicated (Moschella et al 2005mdashthis issue) within

the context of a broader perspective of the ecology of

the coastal zone (Airoldi et al 2005mdashthis issue)

From the socio-economical viewpoint DELOS pre-

pared an up-to-date inventory of coastal environment

valuation methods (eg Hanemann 1994 Hausman

1993) The analysis of the possibility of transferring

benefit quantification from one country to another

(Boyle and Bergstrom 1992) significantly extended

the base on which local quantifications can be made

Furthermore specific new coastal management pro-

jects have been evaluated by the Contingent Valuation

Method (Polome et al 2005mdashthis issue) Preferences

of visitors for different defence structures were also

analysed

This contribution is aimed at presenting an inte-

grated approach to design coastal defence based on

the application of DELOS Design Guidelines (Burch-

arth and Lamberti 2004) For this purpose a well-

documented DELOS study site which suffers from

severe erosion was selected Lido di Dante a small

seaside resort in the North Adriatic Sea 7 km far from

the town of Ravenna The use of the beach for recrea-

tional activities the extent of beach erosion and envir-

onmental problems common to the highly defended

littoral region of a eutrophic sea made this site an

interesting case study

The contribution is composed of five main parts

The first part describes the site looking at the factors

that mainly interact with the defence works namely

wave climate existing habitat and sediment transport

The second part identifies different possible design

alternatives and makes a preliminary selection of five

options based on the social and environmental con-

straints already outlined in the previous section

Numerical simulations with the 2DH model MIKE

21 have then been carried out in order to predict

waves currents and sediment transport induced by

each selected alternative Based on numerical results

maintenance plans are made and both building and

maintenance costs are estimated The third and fourth

parts comment respectively on the ecological and

socio-economic effects of design alternatives based

on output from numerical modelling The fifth part

combines the engineering performance the likely

ecological effects the social demand and the construc-

tion costs to make the final choice among the alter-

natives The chosen alternative is then optimised and a

detailed design finalized using the hydro-morpho-

dynamic verification of various alternatives through

numerical simulations Finally conclusions are drawn

on the importance of such an integrated approach for

improving the design of coastal defences

2 Preliminary investigation of constraints

Before planning an intervention political techno-

logical environmental and social constraints should

Table 1

European directives and nationalregional correspondent legislation to account for in coastal defence design in Lido di Dante

Code of directive Directiveconvention National andor regional legislation (modifications

are not quoted)

85337EEC 9711EC EIA (Environmental Impact Assessment) DPR 120496 (technical standards) DLgs

31051998 n 112 L 31102003 n 306 (application

of most recent directives) LR 18051999 n 9 LR

16112000 n 35 (for regional implications)

200142EC Sea (coastal works against erosion and works

that alter the coastline)

Regional law project under discussion

200060EC Water framework DLgs 11051999 n 152 DLgs 18082000 n 258

76160EEC 91692EEC Bathing water DPR 26071082 n 470 L 29122000 n 422

79409CEE 9243EEC Conservation of wild birds habitat LR 15021994 n 8 LR 21041999 n 3 LR

16022000 n6

91271EEC 91676EEC Waste water treatment pollution by nitrates LR 20112001 n 41 DLgs 11041999 n 152

90313EEC Access to environmental information DLgs 24021997 n 39

79923EEC Shellfish water directive DLgs 27011992 n131

Barcelona Convention

(1976 revised in 1995)

Protection of the marine environment and the

coastal region of the Mediterranean

L 25011979 n30 L 290599 n175

RAMSAR convention (1972) Wetlands of inter-national importance DPR 13031976 n 448

B Zanuttigh et al Coastal Engineering 52 (2005) 1089ndash1125 1091

be identified EU directives that are adopted in Italy

and form the standards at national and regional scale

are listed in Table 1 Moreover regional coastal

plans are available (IDROSER 1996 Preti et al

2002) including the description of the coast the

identification of critical points and the suggestion

of preliminary designs Suggestions for design of

emerged structures are reported in Tomasicchio et

al (1996) In the whole area surrounding Lido di

Dante natural rock is extensively used whereas no

artificial blocks are present and this was assumed as

a technological constraint Based on the results of a

socio-economic survey carried out in Lido di Dante

during Summer 2002 (Marzetti and Zanuttigh 2003)

Fig 1 Plan view of Lido

the use of fine yellow sand can be considered as a

social constraint

3 Analysis of the site

31 Environmental conditions

Lido di Dante (Fig 1) is a small seaside resort in

the Northern Adriatic Sea 7 km from the town of

Ravenna between the mouth of the rivers Fiumi Uniti

Northwards and Bevano Southwards The two rivers

drain basins of very different sizes and characteristics

the Fiumi Uniti basin is much wider and contains an

di Dante in 1993


important mountainous part contributing a significant

sediment load in the past the Bevano River is essen-

tially a natural drainage channel of the plain with little

sediment transport

The site is subjected to significant subsidence

which is mainly due to extractions of methane from

subsoil and can be estimated as 20 mmyear (CNR

1994) By assuming an average slope from the shore-

line until the closure depth of 1 100 this process is

responsible of 2 myear of shoreline retreat

The sandy beach of Lido di Dante has a concave

shape and is more than 2500 m long (Lamberti and

Zanuttigh 2005 Lamberti et al 2005mdashthis issue) It

can be divided into two parts the Northern beach

(almost 600 m long) has been subject to great erosion

and therefore it has been protected by groynes nour-

ishment and semi-submerged breakwater In contrast

the Southern beach has undergone slight erosion and

is in a very natural state

Present shoreline retreat is mainly caused by the

low sediment transport rates of the rivers in the last

decades and by the anthropogenic and natural sub-

sidence which justifies recent beach recession rate of

3 myear Erosion has disrupted the equilibrium of

the beach with major damage when storm surges are

coupled with high tides Littoral recession such as

erosion of dunes and land subsidence together with

building of tourism facilities has altered and par-

tially destroyed the maritime pinewoods behind the

dunes

Shore protection in Lido di Dante was the result

of several successive interventions to stop littoral

Fig 2 Plan view of Lido di Dante at 1993 including shoreline e

recession starting around 1960 (Fig 2) The first

work was carried out in 1978 when a single North-

ern groyne was constructed to retain sediment trans-

port due to littoral drift In 1983 another two

groynes were constructed to the South of the pre-

vious one forming two cells a beach nourishment of

70000 m3 protected by a submerged barrier made of

sandbags completed the intervention (many bags

were destroyed and found on the beach during the

following years)

The modelling and evaluation of designs to be

presented in the following sections use a scenario of

the site as it was in 1993 This was subject to great

erosion and protected only by small groynes (Figs 1

and 2) This approach enables investigation of several

realistic design alternatives

32 Climate and sediment transport

The climate data are derived from information and

measurements taken since 1983 and assume no major

shifts The meteorological climate of Lido di Dante

(Ravenna) is characterised by hot summers with occa-

sional heavy rain and persistent high pressure cold

winters with possibly some snow and thermal inver-

sion rainy springs and even more rainy autumns

characterised by low pressure (cyclonic circulations)

Meteorological and wave observations have been

made from the numerous gas platforms just in front

of Lido di Dante beach visual observations from the

PCB platform and KNMI ships were made in the

period 1971ndash1983 (IDROSER 1996) whereas mea-

volution in the period 1978ndash1993 (from IDROSER 1996)


surements from AGIP platforms were performed since

1992 (IDROSER 1996 Casadei et al 1998) More

recently two buoys were installed in Ancona-1999 at

50 m depth and in Punta della Maestra-2002 at 34 m

depth by the Hydro-Marine National Service and data

together with statistics are available on-line at (http

wwwidromarecom)

The tidal excursion in this area is low in the

average within the range F04 m with maximum

values around F085 m Most intense events are

associated with Bora (NE) and Scirocco (SE) winds

with similar intensity waves may reach 35 m every

year and rise to 6 m every 100 years Wind intensity is

stronger from the shorter fetch sector of Bora (NE)

where it frequently reaches 35 knots intensity

whereas from the long fetch sector of Scirocco (SE)

it seldom exceeds 30 knots

The representative wind and wave climate consist

of steep waves breaking far offshore caused by Bora

winds and milder slope waves caused by Scirocco

(see Table 2) Bora waves thus dominate the morpho-

dynamics of the offshore part of the littoral zone and

Scirocco waves dominate the near-shore part There-

fore in a coast where the Northward directed sedi-

ment transport is dominant almost everywhere the

study area is characterised by offshore sand transport

diverging from the Fiumi Uniti whereas Northwards

directed sand transport is prevalent close to the shore-

line In total the sediment transport in the area is still

directed north with a magnitude in the order of

100000 m3year (assessment based on wave climate

and valid for a free beach configuration IDROSER

1996) From comparison of cross-shore profiles taken

every 7 years cross-shore sediment transport appears

limited within the 8 m depth contour which is located

11 km from the shore

Table 2

Representative wave climate

Condition

no

Wave

direction

[8]

Hos

[m]

Tm

[s]

Wind

velocity

[ms]

Frequency

[]

1 45 15 50 12 474

2 45 40 80 20 053

3 90 15 50 12 586

4 90 35 80 18 081

5 135 15 50 12 480

6 135 35 80 18 047

7 120 03 30 5 4000

33 Water quality

The Adriatic Sea in this area is characterised by a

maximum depth around 50 m and generalized

eutrophic conditions caused by the Po river drainage

from the densely inhabited and cultivated Po plain The

Coast Project results (AEligrteberg et al 2002) on indica-

tors for monitoring the European coastline showed that

the North Adriatic in particular the Emilia Romagna

region is characterised by the highest sensitivity to

eutrophication in fact the Po river to the North with

its high nutrient loading determines a NorthndashSouth

gradient of most water quality parameters In winter

there is a general tendency to eutrophy extended 10 km

offshore which is usually rapidly removed by the water

recirculation induced by storms During summer the

eutrophic conditions are confined closer to the shore

and from the Po outlet to Ravenna Surveys carried

out by ARPA (Preti et al 2002) show that the

chlorophyll a concentration in the water column

averages below 10 Agl (data collected in the period

1992ndash2001 from Ravenna to Cesenatico)

Periodic monitoring of different indicators of

organic (coliphorm streptococcus) and factory pollu-

tion (pH phenol tensioactiv and mineral oils) oxy-

gen colour and transparency are carried out in Lido di

Dante by ARPA (Preti et al 2002) Based on the data

collected in the last ten years it can be deduced that

the values of dissolved oxygen exceed the limits fixed

by the DPR 47082 a few times per year Moreover

few cases of too high microbiological parameters are

usually identified during bathing season but did not

produce the bathing prohibition In both cases water

hyper-oxygenation is usually found together with

algae hyper-trophication

34 Ecosystems habitat and species

Data on ecosystems habitat and species are

derived from the field monitoring carried out in the

site during the DELOS project (Bacchiocchi and Air-

oldi 2003) Although no data are available on assem-

blages before the construction of the defence scheme

in Lido di Dante information is available about

macrobenthos inhabiting nearby non-impacted sedi-

ments so that data from the control site out of the

protected cell might be assumed to be representative

of the habitat at 1993


The site is part of a sandy flat coastal system

characterised by the presence of sedimentary habitats

and by the absence of hard-bottom substrata The

macrofauna of Lido di Dante is represented by a

relatively higher number of species (up to 106)

belonging to three main phyla Mollusca Annelida

Arthropoda and grouped into 17 major taxa In

particular the natural benthic assemblages inhabiting

the surf zone (from 0 to 4 m depth) at Lido di Dante

can be described as a typical Lentidium mediterra-

neum community which is common on the shallow

coastal environments of the Northern Adriatic Sea

The communities of Lido di Dante are relatively

poorly diversified only a few species are quantita-

tively dominant and characterise the spatial and sea-

sonal variation of the assemblage In particular the

high dominance of L mediterraneum determines low

diversity and marked fluctuations in abundances

across the year with low densities during the winter

and spring and a maximum in summer In general

this is a typical situation of physically controlled

environments where the main structuring factor is

the hydrodynamics

The ecological surveys performed on the barrier

revealed that mussels (Mytilus galloprovincialis) and

green macroalgae (Enteromorpha intestinalis) are pre-

sent both seaward and leeward in the structures but are

more abundant seaward whereas oysters (Ostrea edu-

lis and Crassostrea gigas) and biofilms are more

abundant leeward of the barrier oysters in particular

are practically absent seaward (around 5) It is likely

that mussels and green algae colonised also the three

existing groynes in 1993

4 Conceptual pre-design alternatives

41 Definition of technical environmental and socio-

economic objectives

The main objective of the design is the mainte-

nance of an adequate beach for recreational bathing

activity The achievement of this objective also pro-

vides a proper protection of land and infrastructures It

is indeed necessary to avoid possible flooding to

protect residential properties and streets and all the

human activities on which the economy and safety of

the village depend

Desired features for the resort include

Sufficient beach width (50 m is generally required

in the region)

Use of material which is typical of the surrounding

areas (yellow sand of medium grain size approx

02 mm and natural rock)

Appropriate swimming conditions (preserve swim-

mers from possible injuries or drowning)

Low visual impact (structure should not be such as

to obscure the horizon)

Fair water quality (avoid colonisation of the shel-

tered habitats by organisms such as floating green

macroalgae (Ulva sp) which drift to the beach

following storms)

It is also desired that the intervention

Minimise impacts on cultural heritage

Minimise impact on ecosystem habitat and spe-

cies and where possible

Enhance natural living resources for food and

recreation

42 Identification of design alternatives

The following interventions for beach defence can

be considered

Beach nourishment with sand

Nourishment with gravel or pebbles

Revetment

Submerged structure

Submerged structure made by sand filled geotextile

bags

Submerged multi-structure

Emerged structure

Emerged multi-structure

Groynes

It can be immediately seen that the use of pebbles

or gravel contrasts with one of the requirements

which is the use of fine sand Similarly the revetment

does not provide a beach for recreational use

Sand filled geotextile bags cannot be considered as a

possible solution due to the fact that they have already

been used in Lido di Dante and in similar sites along the

Emilia Romagna coast without success Sandbags are


definitely more expensive than rock and therefore

necessarily associated to a barrier with a narrow cross

section The bags reduce incident wave energy but

show a rapid decreasing efficiency due to the fact

that they tend to deteriorate fast Moreover they do

not favour in a particular way the colonisation of

organisms and where it happens it is also one of the

cause of bags disruption Finally pieces of geotextile

bags can be transported by the sea on the beach with

damage to the beach aspect and thus to the tourism

Finally a single or multiple high crested structure

will not be accepted by the local community for

aesthetic and ecological reasons

Based on these simple observations five design

alternatives can be selected from the list above

Beach nourishment with sand (referred in the fol-

lowing as Alternative 0)

Submerged single structure (Alternative 1)

Moderately emerged multi-structure (Alternative

2)

Prolongation of existent groynes (Alternative 3)

Composite intervention with submerged barrier

and connectors to existent groynes (Alternative 4)

All the alternatives include also nourishment with

sand for beach maintenance

The basic characteristics of the four Alternatives

are drawn in Fig 3 and can be summarised as follows

0) No hard-structure solution

1) Submerged continuous barrier 670 m long (Fig 3a)

with crest level 15 m The depth at the barrier is

35 m and the average distance from the shore is 185

m The single structure is meant to uniformly reduce

wave action and is most appropriate for low velocity

currents in the protected area

2) Moderately emerged barriers parallel to the coast

made of 4 units 150 m long and separated by 40 m

gaps (Fig 3b) The barrier crest level is +15 m

with a protection to the toe and to the gaps at 20

m The depth at the barrier (axis) is 30 m and the

mean distance from shore is 125 m This defence

type is usually adopted because of strong waves

associated with high tides

3) Northern and southern groyne extension of 80 and

40 m respectively (Fig 3c) This solution can be

appropriate in case of large long-shore sediment

transport and in case the reduction of transport

toward adjacent beaches is not critical

4) Submerged barrier 590 m long with crest level

15 m connected to the beach by submerged

groynes (Fig 3d) The configuration is similar to

no 1 except for the land connections from the

existing groynes to the barrier This structure is

suited to contrast strong long-shore currents

induced by overtopping and aims at reducing the

loss of material from the protected area

Only rock and stone materials are considered for

design as it is available widely used in the area and

environmentally acceptable In this preliminary phase

the rule of thumb (Dn50=03Hc) is used a more

precise investigation of stability being not computa-

tionally expensive but misleading as to the relevance

of the fundamental variables In practice in fact

many damages are registered due to toe collapse

even for the stability number Nsb1 which in shal-

low water corresponds to big stones (Dn50N037d)

note that where the foot is not firm bigger armour

stones are less stable

The design of cross sections is given in Fig 4

for the groyne roundhead characterised by a 1 3

slope the designed armour stone is slightly smaller

43 Analysis of waves currents and sediment trans-

port induced by each design alternative by means of

numerical 2DH simulations

431 Method and results

Numerical simulations presented here were per-

formed with MIKE 21 a 2DH numerical modelling

suite developed by DHI Water and Environment In

particular the Near-shore Spectral Waves (NSW) the

Parabolic Mild Slope (PMS) the Hydrodynamic (HD)

and the Quasi-3D Sediment Transport (ST-Q3) mod-

ules of MIKE 21 were applied

The NSW model is a wind-wave model which

describes the growth decay and transformation of

wind-generated waves and swell in near shore areas

Themodel is a stationary directionally decoupled para-

metric model and takes into account the effects of

refraction and shoaling local wind generation energy

dissipation due to bottom friction and wave breaking

wavendashcurrent interaction The basic equations in the

model are derived from the conservation equation for

Fig 3 Plan view of the four selected design Alternatives numbered with reference to the text (dashed line = submerged)


Fig 4 Cross sections from up to down a) of the submerged barrier Alternative 1 b) of emerged barriers armour slope 1 2 Alternative 2 c) of

emerged groynes armour slope 1 3 Alternative 3 d) of submerged transverse connectors Alternative 4


the spectral wave action density and are solved using an

Eulerian finite difference technique

The PMS module is based on the parabolic approx-

imation to the mild-slope equation of Kirby (1986)

which assumes a predominant wave direction and

neglects wave diffraction and back-scattering in the

direction of wave propagation

The HD module solves the full time-dependent

non-linear equations of mass and momentum balance

The solution is obtained using an implicit ADI finite-

difference second-order accurate scheme see eg

Abbott et al (1973) for details

The ST-Q3 module calculates the rates of non-

cohesive sediment transport for both pure current

and combined waves and current situations on the

basis of the hydrodynamic conditions that correspond

to a given bathymetry

The weaknesses of the numerical results are mainly

related to limitations of the model in

The representation of near-shore wave propagationThe PMS wave module does not represent wave

reflection and diffraction along the direction of

wave propagation and may thus induce an under-


estimation of flow velocities and erosion in some

leeward areas moreover enhanced erosion at the

seaward side due to reflection is not accounted

for finally submerged structures benefit over the

emergent ones due to the lower reflection coeffi-

cient and the missing representation of transmis-

sion and overtopping when structure is emerged

The simulation of bathymetric changes The ST-Q3

model does not consider feedback from the bed

level change to the waves and the hydrodynamics

as in the case of a full morphological model exists

Hence the results provided by ST-Q3 can be used

to identify potential areas of erosion or deposition

and to get an indication of the initial rate at which

bed level changes will take place but not to deter-

mine an updated bathymetry at the end of the

simulation period

Offshore wave conditions in Table 2 were tested

for each design alternative In particular waves from

Fig 5 Alternative 0 a) bathymetry b) ave

1 to 6 reconstruct the typical wave attacks during

a year whereas Wave 7 is representative more or

less of calm periods with low waves coming from

the Scirocco that have been documented to induce

sediment transport close to the shore-line from

South to North Wave 7 was also chosen to look

in details at stagnant zone formation for ecological

purposes

Simulations account both for a sinusoidal tide var-

iation in the range F05 m and for wind as it is

reported in Table 2

Bottom bathymetry was reconstructed following

field observations and detailed multi-beam surveys

performed during DELOS Based on sediment sam-

ples collected within Lido di Dante monitoring bot-

tom Dn50 was assumed to be equal to 028 mm inshore

the structures and 022 mm offshore structure Dn50

was fixed as 08 m

NSW and PMS boundaries were assumed to be

dsymmetricalT (ie uniform conditions) whereas at

rage erosiondeposition trend per day

Fig 6 Simulations on Alternative 0 a) wave height Wave 6 b) current surface elevation and velocity Wave 6 c) wave height Wave 7

d) current speed Wave 7



HD boundaries fluxes and levels derived from radia-

tion stresses were imposed

Wave breaking was evaluated both in NSW and

PMS modules according to Battjes and Janssen 1978

model with default suggested values c1=10 (con-

trols steepness breaking) c2=08 (controls depth lim-

ited breaking) and a =10 (controls breaking

dissipation rate)

In the HD module eddy viscosity was imposed

to be constant with dissipation coefficient equal to

08

Figs 5ndash14 present for each design alternative the

following plots in the order

Bathymetry of the intervention see Figs 5a 7a 9a

11a 13a

Average bottom level variation per day (erosion

deposition intensity in bluered scale and sediment

fluxes denoted by vectors) The depositionerosion


trend is obtained by a weighted integration

(weights in Table 2) of all tested conditions see

Figs 5b 7b 9b 11b 13b

Wave field (wave height intensity in both colour

scale and vectors) for the most severe condition

identified by Wave 6 (waves breaking at the sub-

merged barrier highest wave height around 155 m

in front of the structure itself) see Figs 6a 8a 10a

12a 14a

Current field (set-up in colour scale current speed

intensity and direction as vectors) again for Wave

6 see Figs 6b 8b 10b 12b 14b


scale and vectors) for the lowest wave Wave 7 to

show the residual water agitation level inshore the

structures in the worst conditions see Figs 6c 8c

10c 12c 14c

Current field (speed intensity in both colour scale

and vectors) for the lowest wave Wave 7 to





Fig 9 Alternative 2 a) bathymetry b) average erosiondeposition trend per day


identify areas interested by worst circulation con-

ditions see Figs 6d 8d 10d 12d 14d

A summary of numerical results useful for ecolo-

gical purposes is reported in Table 3 which presents

extreme values of wave agitation and water residence

time inside the protected area These values are

obtained as average values of wave height and hydro-

dynamic flux balance to water volume ratio over the

protected area in correspondence of Waves 6 and 7

that represent the most dynamic and the most static

condition respectively These values can be regarded

as indicators of the intensity of residual agitation in

the protected area and water exchanges with the adja-

cent areas factors that can strongly affect the existing

habitat

Effects of the design alternatives on sediment

fluxes are summarised in the Table 4 which contains

long-shore and cross-shore average fluxes in corre-

spondence of the boundaries of the protected areas

and in the neighbouring beaches North and South of

the two extreme groynes Cross-shore fluxes are posi-

tive if directed inshore and long-shore fluxes are

positive if directed Southwards

432 Comments on numerical results

4321 Wave agitation Both in Alternative 0 and 3

waves propagate inshore undisturbed In the pro-

tected cell wave energy is reduced by approximately

50 by both Alternatives 1 and 4 In Alternative 2

wave agitation is almost null behind the barriers

whereas is still of importance at gaps (separated

values in Table 3) Reduction of incident wave

height on the shore is responsible for two opposite

effects one positive the reduction of offshore sand

transport from the emergent beach another negative

the landward reduction of wave agitation that inhibits

deposition of fine sediments

4322 Currents Current intensities induced by

the Alternatives are similar except for Alternative






2 where they are lower Current speeds landward

the structures are in the range 01ndash03 ms with

peaks of 05 ms at the shoreline for all the Alter-

natives except for Alternative 2 where the maxi-

mum is 03 ms Currents in correspondence of the

groyne roundheads are in the range 04ndash05 ms for

all alternatives except for Alternative 3 for which

are in the range 03ndash04 ms These currents are

directed offshore in Alternative 0 and this effect is

moved more offshore in Alternative 3 by the

groyne prolongation in Alternatives 1 4 and in a

more marked way in Alternative 2 they appear to

be redirected towards the beach In Alternative 1

vortexes are induced at the submerged barrier

roundheads

4323 Set-up Set-up at the beach compared to the

no-structure case (Alternative 0) increases with

increasing beach protection level in ascendant order

from Alternative 3 to 4 and 1 The only case for which

set-up decreases is in the presence of emerged barriers

(Alternative 2)

4324 Water mixing Considering the values of the

residence time tr in Table 3 all the interventions with

hard-structures imply the growth of tr with respect to

the existing situation Alternatives 1 and 4 are the only

designs that allow to maintain the range of tr very

close to the one computed for Alternative 0 tr for

lower waves (Wave 7) is nearly not affected at all

whereas for higher waves (Wave 6) is about 15 times

the tr for Alternative 0 In Alternative 3 the prolonga-

tion of the groynes breaks currents Northwards direc-

ted and induced a very calm area Alternative 2 is

likely to produce the strongest effects on water circu-

lation due to the very close environment produced by

the emerged barriers

4325 Sediment transport The design alternatives

produce different erosiondeposition trends as can be

derived by comparing Figs 5b 7b 9b 11b and

13b The erosion inside the protected cell which

is very high for the no-structure case (Alternative

0) is strongly reduced by the introduction of hard

structures






Alternative 1 shows a depositional tendency land-

ward of the submerged barrier with still some shore-

line erosion seaward the barrier there is in average a

deposition process whereas at the round heads erosion

takes place

In Alternative 2 deposition occurs in the pro-

tected area and in average at the shoreline

whereas gaps are eroded The mixture of erosion

and deposition patterns that seems to characterise

the protected cell has to be interpreted on the basis

of the more or less calm conditions produced by

Wave 7 that lasts the 40 of the year (Fig 7c) the

global tendency is an accumulation process that can

be responsible of salientstombolos as in other

places defended by breakwaters in Emilia Romagna

coast like Igea Marina or in Marche coast like

Gabicce The results of numerical simulation on

salient formation are in good agreement with the

formula by Herbich (2000) which was applied to

this design alternative

Both in Alternative 3 and 4 the depositional pro-

cesses are more marked near the shoreline and in the

Southern part than in the Northern part of the pro-

tected area In Alternative 4 deposition takes place

both landward and seaward the submerged barrier

whereas erosion occurs in correspondence of the

roundheads and of the submerged connectors

Erosion at the groyne roundheads is present in all

the alternatives Considering the effects on the adja-

cent beaches all the alternatives induce erosion in

particular at the Northern beach

Alternative 0 produces the highest erosion by

introducing hard structures the erosion process is

strongly reduced especially near the shore close to

the Southern groyne where some deposition takes

place for Alternatives 2 3 and 4 In Alternative 3

the sediment flux from the Northern beach is deviated

far offshore by the groyne prolongation

Quantitative comments can be derived from Table

4 Alternative 2 guarantees the highest entrapment of

Fig 14 Simulations on Alternative 4 a) wave height Wave 6 b) current surface elevation and velocity Wave 6 c) wave height Wave 7 d)

current speed Wave 7


Table 3

Extreme value of wave agitation Hs and residence time tr inside the

protected cell values are obtained as average over the cell in

correspondence of Waves 6 and 7 respectively

Alternative Wave agitation Hs Residence time tr

Wave 6 [m] Wave 7 [m] Wave 6 [s] Wave 7 [s]

0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4

Sediment transport for each design alternative

Alternative Protected area

Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

Long-shore flux is positive when North-directed and cross-shore

flux is positive when in-shore-directed


sediments inside the protected area followed in des-

cendent order by Alternative 1 4 and 3

Alternative 0 is the only one that produces a sand

loss as it is expected on the basis of historical data

This sand loss for the examined cell (600 m long5

m deep) is equivalent to 10 myear Data on shore-

line retreat collected from 1978 (construction of the

first groyne) to 1993 show an average recession of

about 35 m in the protected area Moreover the

nourishment performed in 1983 (after the shoreline

survey presented in Fig 2) should have produced a

shoreline advancement of 25 m Surveyed shorelines

in Fig 2 shows that shoreline retreat in the protected

area is about 12 m in the period 1978ndash1983 and 23

m in the period 1983ndash1993 to which the 25 m of

beach advancement have to be added This proves

that immediately after the nourishment the erosion

rate is higher and the shoreline recession can be

estimated as 5 myear corresponding to an offshore

flux of 15000 m3year The overestimation of about

twice in numerical simulations can be explained ndash

even if not completely justified ndash by two considera-

tions first simulations are carried out on a nourished

and advanced profile which was derived from a

detailed 2001 bathymetry of the area then other

nourishment of smaller entities a part from the

intervention in 1983 were perhaps performed but

not recorded In conclusion an overestimation of

about 50 should be considered when interpreting

values in Table 4

44 Construction costs

The building costs are evaluated in a simple way

considering a tentative unit cost for the supply and

placing of each part of the structure (armour 17H21

om3 dense filter 17 om3 geotextile 12 om2)

multiplied by the actual volumes Results are reported

in Table 5

A nourishment of 100 m3 per meter of beach (20 m

of beach advancement) for a total of 110000 m3 is

foreseen for all the five Alternatives The cost for this

initial nourishment assuming the sand cost to be 12

om3 is 1320000 o and exceeds the building costs

for all the alternatives

Maintenance is estimated over a period of 30 years

this being considered a long period for the usual

political horizon However this period is very short

in respect of maintenance required by the existing

structures in the Emilia Romagna Region Some of

these structures were built more than 90 years ago and

are still under periodic maintenance In order to

reduce maintenance frequency which also cause dis-

turbance the surrounding soft-bottoms (including

sediment characteristics and infaunal assemblages)

the renourishment is therefore planned every 3 years

Based on the historical information (Fig 2 and

surveys in the area) the protected cell within the

existing groynes requires nourishment of 15000

m3year whereas the adjacent beaches to the North-

ern and Southern groynes require approximately

9000 and 1000 m3year respectively This fixes the

maintenance plan for Alternative 0 nourishment of

75000 m33 years for the protected area and the

adjacent beaches

Numerical results and the experience on similar

sites allow formulation of specific nourishment plan

for all Alternatives In Table 6 maintenance is dis-

tributed in time in order to obtain an equivalent initial

cost and a proper interest rate of 4 (free from

devaluation) is applied

Table 5

Construction costs

Quantity Unit cost Total

Alternative 1

Structure (cross section Fig 4a) 641 m 123120 om 78919920 oRoundhead with radius increase of 4 m (r =145 m) 2185000 o 4370000 oTotal cost 83289920 o

Alternative 2

Structure (cross section Fig 4b) 376 m 1644500 om 61833200 oGaps (no armour) 108 m 83600 om 9028800 oExternal roundhead (radius increase of 4 m) (r =130 m) 3317700 o 6635400 oRoundhead at gaps (radius increase of 4 m) no 6

(r =130 m)

1698900 ono 10193400 o

Total cost 87690800 o

Alternative 3

Structure (cross section Fig 4c) 87 m 205400 om 17869800 oAdditional foot protection 400 m3 1700 om3 680000 oRoundhead (radius increase of 4 m) (r =165 m) 5622200 o 11244400 oTotal cost 29794200 o

Alternative 4

Structure (cross section Fig 4a) 600 m 123120 om 73872000 oSubmerged groynes (cross section Fig 4d) 140 m 82320 om 11524800 oAdditional foot protection 400 m3 1700 om3 680000 oTotal cost 86076800 o


The maintenance to the rocky structure is supposed

to be rare (once every 10 years ie 3 times in the

considered period) although more frequent mainte-

nance is often carried out on the structures with dra-

matic effects on the epibiotic assemblages (eg loss of

mussel beds and enhancement of ephemeral green

macroalgae) Maintenance is quantified in a tentative

Table 6

Initial and maintenance costs over 30 years of project lifetime

Costs Alternative

0

Building costs [o] ndash

Initial nourishment volume [m3] 110000

Initial nourishment costs [o] 1320000

Initial costs [o] 1320000

Nourishment protected cell [m33 years] 40000

Nourishment adjacent beaches [m33 years] 30000

Structure maintenance [m39 years] ndash

Maintaining costs [o] 4394000

Total cost [o] 5714000

The interest rate is assumed to be 4 and nourishment cost is 12 om3

value of 10 m3 per meter of structure (for a cost of 20

om3) It is supposed that the value of the structure at

the end of the 30 years is null Indeed the building

cost is small compared to the total and it is difficult to

know whether at the end of the period the structures

are still efficient or whether it will be necessary to

remove them with additional costs

1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000


The periodic nourishment (planned every 3 years

ie 9 times in the considered period) is costly Cost for

damage to neighbouring beaches is not included and

is similar between Alternatives Note that the beaches

immediately adjacent to the protected area are

included in the simulation and their maintenance is

considered The costs for maintenance are quite sig-

nificant for Alternatives 0 and 3 which appear the

cheapest on the basis of the initial costs only

Table 7

Magnitude of environmental changes from the reference situation

(Alternative 0) induced by each design option

Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2

Residence time 2 4 4 2

Currents 3 2 2 3

Sediment processes 3 4 3 4

Environmental effects

Sediment infauna 2 4 3 4

Epibiota 2 4 1 2

Shellfish amp mobile fauna 3 4 2 2

Water quality 2 4 3 2

Both Wave 6 (winter conditions) and Wave 7 (summer conditions)

simulations were considered when scoring wave agitation residence

time and currents Scores represent degree of effects 1=minor

2=medium 3=marked and 4=very marked

5 Ecological comments to design alternatives

51 Preliminary considerations

Every type of LCS that is built on the coast will

change the surrounding environment Results from

DELOS have shown that the severity and extent of

the impacts on the habitats and associated biota depend

on the physical and biological features of the coastal

environment as well as the design of the LCS scheme

(Airoldi et al 2005mdashthis issue Martin et al 2005mdash

this issue Moschella et al 2005mdashthis issue)

In Lido di Dante the relatively shallow seabed the

eutrophic state of water and the considerable input of

organic material and sediments from the nearby rivers

make the area more sensitive to changes in the envir-

onmental conditions (Correggiari et al 1992) For

example under such conditions a reduction in water

circulation could indirectly facilitate the formation of

toxic algal blooms and anoxic bottom sediments via

nutrient retention on the lee of the structure

The proposed design alternatives will all produce

some modifications in the physical environment

These will in turn change the type of habitats present

in the area with likely consequences on species and

ecosystem function Biological responses to physical

changes in the coastal environment are not linear but

can vary in time and space Predicting ecological

impacts of design alternatives with high level of

confidence is therefore difficult It is possible to

forecast however in qualitative terms the relative

magnitude of impacts caused by each type of LCS

scheme on the water quality and various components

of the ecosystem (epibiota sediment infauna fish

and shellfish) These can be assessed on the basis

of the degree of changes in the physical conditions

predicted by the model results from DELOS and the

background knowledge on the ecology of sandy and

rocky shores

52 Forecast environmental impacts of structures

Scores indicating the magnitude of changes (from

1 being no changes to 4 being marked changes) in

water movement (waves residence time) currents and

sediment transport are assigned to each design alter-

native (Table 7) Changes are assessed using the

Alternative 0 as reference situation where no inter-

vention to hydrodynamic conditions was made

The ecological considerations of each design alter-

native described below are only indicative and should be

verified by studies and monitoring of real design appli-

cations It seems clear however that at local scale design

options can induce very different ecological effects

521 Alternative 2 mdash emerged barriers with gaps

This design option is likely to cause the strongest

changes to the surrounding environment particularly

on the landward side The reduction in hydrodynamics

on this side of the structures will markedly affect the

sediments and water quality which will in turn influ-

ence the abundance and diversity of the sediment

infauna

Water movement is considerably reduced during

most of the year leading to periods of stagnant water

in summer This will also result in deposition of very


fine sediments (siltclay) with likely increase in sedi-

ment organic matter contents and frequency of

decrease in oxygen depletion events These features

are not characteristic of an open beach but tend to be

alike to those of sheltered lagoon environments The

species assemblages could change accordingly In

contrast water circulation in the gaps between the

structures is not affected independently of wave con-

ditions (summer or winter situation) The landward

side is therefore characterised by areas of fine muddy

sediments with areas of coarser sand particularly in

proximity of the roundheads The resulting habitat

patchiness is likely to increase species diversity

although this effect would also depend on the tem-

poral stability and disturbance of these areas For

example erosion is higher in the gaps than in normal

open beach conditions resulting in higher disturbance

for infaunal species

The presence of emerged portions of the barriers

increases the diversity of rocky habitats Compared

with Alternatives 1 and 4 where only subtidal habitats

are created this design alternative include the inter-

tidal zone thus a higher number of species can colo-

nise the barriers including mussels and oysters Also

different types of epibiotic assemblages would colo-

nise the different areas of the barriers ranging from

species typical of exposed shore (seaward side ends)

to species of more sheltered habitats (landward side)

In a microtidal system such as the Adriatic coast

however the intertidal zone is very narrow thus the

increase in species diversity would be minimal The

increase in habitat diversity would also increase the

risk of invasion by non-native species which can

permanently change the identity of the native species

assemblages

The lack of water mixing will also affect water

quality since turbidity will increase as a consequence

of sediment suspension and trapping of organic mate-

rial More importantly the limited water circulation

would facilitate formation of algal blooms particu-

larly during summer when water temperature increase

considerably in presence of high nutrient concentra-

tions This in turn can cause anoxia in the water

columns with detrimental consequences for the soft-

bottom benthic fauna and flora

Potential mitigation effects of this design option

might include the increase of habitat and species

diversity (for appreciation of marine life) promotion

of natural resources such as mussels and oysters and

mobile fauna (for leisure food harvesting and fishing)

and easy accessibility to the structures by beach users

522 Alternative 4 mdash submerged barriers with

connectors

The semi-enclosed system created by this design

alternative (shore-parallel barrier with groynes)

causes a reduction in wave transmission of almost

50 This design will create a fairly stable and

homogenous sedimentary habitat on the landward

side despite the structures being submerged Sedi-

ments on the landward side will have similar char-

acteristics to those already observed in Alternative 2

with fine muddy sediment accumulating behind the

barrier Under these conditions diversity is likely to

increase in comparison with unprotected sandy bea-

ches but species assemblages could also become

more similar to those of more sheltered habitats

Siltation will also increase and hence disturbance

to epibiotic species on the building blocks located

in proximity of the seabed

The submerged barriers will provide new rocky

habitats for colonisation by epibiotic species and in

particular shellfish for example mussels The bar-

riers will also attract fish and crustaceans by provid-

ing food resources and refuges in the cavities and

gaps between the rocks The reduction in water

depth on the landward side of the barriers due to

salient formation can however prevent fish moving

into this area

Water quality can be negatively affected by the lack

of water mixing on the landward side leading to

accumulation of nutrients pathogens and pollutants

The likely increase in fish and mobile fauna can be

seen as a positive effect for leisure fishing and food

harvesting However as the structures are only sub-

tidal appreciation of marine life would be possible

only by divers or snorkellers

523 Alternative 3 mdash extended groynes

Sediment processes appear markedly affected near

the northern groyne and the southern groyne Simi-

larly to the landward areas of shore-parallel barriers

the habitat behind the northern groyne will be char-

acterised by accumulation of fine grained and organic-

rich sediments At the southern groyne erosion of

sediment creates a more disturbed environment for


the infaunal assemblages The central sedimentary

area between the two main groynes seems less

affected as frontal waves are not stopped by offshore

barriers and wave energy is still high Similarly water

quality will be less affected than in Alternative 2 and

4 as water movement is mainly reduced in the shel-

tered areas behind the groynes

The impacts of this design option appear to be

more localised than in design Alternatives 2 and 4

In contrast erosion of the adjacent beaches outside the

protected coastal cell is considerably high This

defence scheme seems to produce more important

large-scale effects than the other design alternatives

The extended groynes also provide additional rocky

habitats that can be colonised by both subtidal and

intertidal epibiotic species crustaceans fish and birds

The habitat and species diversity and the easier access to

the structures by beach users particularly children

increases the recreational value of this defence scheme

524 Alternative 1 mdash submerged barrier

This design option seems to cause the least impacts

on the surrounding environment The ecological

effects although very similar to those of Alternative

4 are much reduced in magnitude The absence of

shore connectors makes the landward area a less

enclosed environment thus reducing problems of

water quality and sedimentation As a result differ-

ences in the infaunal assemblages between the land-

ward area and the adjacent beaches should be

relatively smaller

Similarly to Alternative 4 mitigation effects are

limited as the structure cannot be easily accessed by

people However the structures would still provide

new habitats for fish and mobile fauna thus promot-

ing natural living resources

Table 8

Evaluation rank of design alternatives including factors to be judged and

Alternative Beach protection Ecological effects

Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2

Partial weight 1 2 1 2 3 1

Global weight 1 1

53 Conclusive comments

The first a priori environmental consideration

should be to avoid any change from the original

natural conditions of the site This is however a

rather unrealistic option as several engineering inter-

ventions to prevent coastal erosion had already been

made in Lido di Dante since 1978 well before our

reference situation (Alternative 0) Therefore a more

appropriate approach for such modified environment

should be adopted identifying the LCS design alter-

native that represents the best trade-off between engi-

neering performance preservation of ecological

conditions and socio-economic value

The choice of an LCS scheme should include

design criteria that minimise and mitigate ecological

impacts Mitigation effects (eg LCS design promot-

ing shellfish resources) can be considered as bypro-

ducts of the construction of LCS and their importance

in the evaluation of design alternatives will depend on

the management goals Under the ecological perspec-

tive however minimisation of impacts should be

given the highest priority in the final choice of LCS

design (see Table 8) Furthermore any potential

impacts and mitigation effects of design alternatives

should be considered in a geographically broader

context rather than the single coastal cell where the

LCS is being built This is particularly important in

the Adriatic coast where local environmental impacts

are amplified at a regional scale due to the extensive

coastal defence protection (Colantoni et al 1997

Airoldi et al 2005mdashthis issue) Also mitigation

effects become negligible in comparison with the

cumulative impacts caused by the proliferation of

coastal defence structures thus overengineering

should always be avoided

weights

Social effects Total

costs

Global

marktion Recreational

use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1


All the design alternatives proposed here could be

improved by modifying selected design features as

shown in several ecological studies and experiments

carried out during DELOS These include

Making the structures more stable thus reducing

disturbance by frequent maintenance works On the

Adriatic coast this causes great disturbance to

epibiotic assemblages which are kept at an early

successional stage characterised by low diversity

and patchiness Reducing maintenance works

would therefore increase diversity of epibiotic

assemblages

Creating or increasing gaps between barriers to

facilitate hydrodynamics around the structures

Increasing porosity of the barriers perhaps by

reducing or eliminating the core This will reduce

water stagnation on the landward side

Increasing habitat and surface complexity for

example by creating pits and small holes or creat-

ing rock pools to maximise if desired habitat and

species diversity

Using local natural rock as building material

Limestone is particularly suitable as it is more

easily weathered than other types of rocks offering

therefore naturally complex surfaces that promote

settlement of epibiotic species including shellfish

such as mussels and oysters

6 Socio-economic considerations

Lido di Dante beach is characterised by a significant

development of tourism facilities due to the wide-

spread offer of rented accommodation and campsites

Data collected by the Tourism Office of Ravenna dur-

ing the period 1978ndash2001 show that the mean annual

night stay of tourists in the area is about 90000 with a

minimum of about 51000 recorded in 1989 The dras-

tic reduction in visitors observed in that year may be

related to the severe algal blooms which caused a

bmucillagineQ phenomenon that is complexly related

to water eutrophication (Drei 1996) For this reason

particular attention should be paid to the impact of

design alternatives on water quality and eutrophication

risk A survey based on the CVM and made up of 600

face-to-face interviews at the Lido di Dante beach was

carried out in AugustndashSeptember 2002 (Marzetti and

Zanuttigh 2003 Polome et al 2005mdashthis issue) Dur-

ing the survey design a questionnaire was prepared

adapting the site user questionnaire by Penning-Row-

sell et al (1992) to the specific conditions for Lido di

Dante beach The survey was designed to create a

hypothetical market with a contingent value for

hypothetical scenarios following beach erosion and

accretion that are likely to occur in ten years (see

photomontages 2ndash5 in Polome et al 2005mdashthis

issue) Interviewed people were requested to provide

monetary values representing enjoyment from recrea-

tional activities on the beach and its variation when the

beach advances or retreats

The mean daily use values of the Lido di Dante

beach in summer are the following

277 opersonday in the status quo

133 opersonday in the hypothetical situation of

erosion and


accretion

It must be noted that if the expected erosion of

Lido di Dante beach would take place then protection

is preferred to the do-nothing alternative and the

declared value of the eroded beach is much lower

than in the status quo In addition 164 of respon-

dents will never visit the eroded beach and 291 will

visit it less often than they do in the current state

Interviewed visitors expressed their preference on

the proposed design alternatives (see photomontage 2

in Marzetti and Lamberti 2003) justifying their

choice with the following reasons

325 of respondents prefer composite inter-

vention (submerged breakwaters groynes and

nourishment)

237 choose emerged parallel breakwaters

212 prefer groynes and

198 select nourishment

Aesthetic reasons mainly justify the preference for

the composite intervention while water quality and

suitability for children are the main reasons for respon-

dents preferring emerged breakwaters groynes are pre-

ferred because of suitability for recreational activities

andwater quality finally the preference for nourishment

is motivated by water quality and aesthetic reasons


The recreational usage of the beach is strictly

dependent on the main activities carried out on the

beach itself

475 of respondents sunbathe and relax

190 go walking

130 swim and

only 02 go fishing

Sunbathing and relaxing are also the second pre-

ferred activities of those who did not choose it as their

main one (242)

In conclusion all the Alternatives are djustifiedTfrom an economic point of view beach erosion

would in fact produce a considerable loss of beach

value at least 3 Moyear accounting for value

assigned by daily visitors residents registered and

non-registered tourists (at least 300000 presences

year in 2002) Since only 02 of visitors fish and

collect shellfish and organisms living on the barriers

it seems that these activities do not relevantly con-

tribute to the beach recreational value For this reason

the percentage of preferences for the different types of

coastal defences can be strictly considered the social

criterion for choosing among the five Alternatives so

that the list from the best to the worst is Alternative 4

and 1 2 3 and finally 0

7 Selection of the sustainable scheme

For the selection of the more sustainable design

alternative each aspect presented in the previous sec-

tion is accounted for and is evaluated with an appro-

priate weight (see Table 8) This kind of procedure is

detailed in DELOS Design Guidelines (Chapter 12 by

Zanuttigh et al 2006)

dBeach protectionT weight is equal to 2 (twice the

weigh for ecological and social effects) as this is the

main aim of the intervention Moreover dbeachprotectionT is divided into two tasks dShoreline main-

tenanceT refers to the results obtained with numerical

simulations on sediment transport fluxes inside the

protected cell dEffects on adjacent littoralsT includesthe erosion deposition effects induced in areas close to

the protected coastal cell this is based on both numer-

ical simulations and past experience on different types

of coastal defences which have been built along the

Emilia Romagna coast during the last 50 years In

particular the prolongation of harbour defences like

Porto Garibaldi Rimini and Cesenatico appeared to

produce strong negative downdrift effects

dEcological effectsT have weight equal to 1 and

ranking of the design alternatives is based on the

lowest ecological impact and highest mitigation

effects Ecological impacts refer to sediment bottom

infauna epibiota and water quality values in Table

8 increase with decreasing impact on present condi-

tions Mitigation effects refer to promotion of nat-

ural resources habitat and species diversity with

respect to the existing situation Alternative 0 In

the composite ranking different partial weights are

given to impact and mitigation effects (3 to 1

respectively)

Similar weight has been given to dSocial effectsTand include three aspects recreational use aesthetic

impact and swimming safety Recreational use and

aesthetic impact have been ranked in Table 7 on the

basis of the results of the socio-economic survey In

particular beach drecreational useT is mainly related to

sunbathing walking and swimming (in order of

importance) for this reason this rank is strictly

related to dbeach protectionT and dwater qualityTranks Alternatives 1 and 4 are considered as having

the same aesthetic impact and recreational use

dSwimming safetyT has been evaluated looking at

current intensities and directions (offshore or inshore)

close to the shoreline and in some critical points such

as the breakwaterbarriers trunks and roundheads

Finally dTotal costsT are again weighted 1

Although not listed in the project objectives some

economic optimisation is implicit in any significant

work Indeed no particular budget restriction was

indicated in the constraints and the weight of the

economical aspects avoids da prioriT exclusions

Moreover this aspect represents only building costs

maintenance costs are not considered as a separate

item because it would have rather been a duplication

of the dbeach protectionTThe sum of each weighted aspect in Table 8 sug-

gests that the scheme to be preferred is Alternative 1

The socio-economic effect due to the intervention

phase deserves a discussion but is not included in the

points to be evaluated in Table 8 since it is only a

temporary effect whereas the other aspects are char-

acterised by a mediumndashlong time scale


By assuming the same kind of good quality sand

for all the Alternatives the transportation of the sand

by land and the nourishment have the same modest

social and ecological impact (Benavente et al 2005)

By considering that works are always carried out in

a unique solution in the period OctoberndashApril the

social impact is null for rock transportation made by

sea as it can be adopted for the submerged (Alter-

natives 1 and 4) and emerged barriers (Alternative 2)

The construction of groynes which is necessarily

made from land exerts nevertheless a non-negligible

social impact due to the courtyard on the beach and to

rock transportation by land

Definitely the Alternatives can be listed in the

following descending order depending on their con-

struction impact mark in brackets Alternative 0 (5)

Alternative 1 (4) Alternative 2 (3 due to the greater

amount of rocks and work duration than Alternative

1) Alternative 4 (2 due to the fact that works are

closer to the shore than for Alternatives 1 and 2)

Alternative 3 (1)

Even assuming for absurd a weigh equal to 10 for

these construction effects the order list of preferred

alternatives in Table 8 will not change and thus also

the selected one (Alternative 1)

8 Optimised design

81 Identification of possible optimisations

The weak points of Alternative 1 that need special

care for optimisation are

Habitat complexity the structure lacks of design

features that enhance habitat and species diversity

Bathing safety eddies at the barrier roundheads

may be unsafe for swimmers and dangerous for

rescue boats

Recreational usage bathers cannot take advantage

of the structure as it is everywhere submerged

without special facilities for boats

Water quality water circulation close to the barrier

and the groynes can be improved to avoid stagna-

tion zones

Effects on adjacent beaches erosion in particular

at the south of the protected cell is enhanced by

the sediment flux paths

In order to answer to these disadvantages the

design is modified by

Extending the barrier at the roundheads with two

very low crest long aisles

Building two small emerged islands just in front of

the two external groynes roundheads

Enlarging the width of the existing groynes to

provide a walking path on them

The following improvements are expected with

reference to the above aspects

Both subtidal and intertidal epibiota can colonise

the structure

The presence of the emerged islands clearly marks

the presence of the submerged barrier and the

aisles thus increasing safety for swimmers

The two aisles become a secure passage for

navigation

Both islands and existing groynes can be used by

people for sunbathing and walking respectively

Diffraction induced by the islands should generate

long-shore fluxes in presence of small waves

Negative effects on adjacent beaches can be reducedusing sloping structures with submerged roundhead

Fig 15andashe present the final (as built) design of the

structure that accounts for a foreseen 30 cm settle-

ment A detached barrier 800 m long is placed at

185 m from the shoreline on a 35 m depth The

structure is symmetrical and formed by three differ-

ent cross sections a central submerged part with

height Hc=2 m crest level 12 m crest width

B =60 m length Lc=588 m two emerged islands

with heightHc=45 m crest level +13 m and diameter

equal to 6 m two side extensions with height Hc=2 m

crest level 23 m and length 100 m each armour

slope is 1 2 in all cases

82 Structural design

The aim of the present subsection is to design the

barrier and prove its stability In contrast to high

crested structures LCSs are often formed by just

two layers the armour which is approximately 60

of total height and a second layer with double func-

tion of filter and toe berm sufficiently wide to tolerate

Fig 15 a) Photomontage showing the expected aerial view of Lido di Dante after the construction of the optimised design b) plan view of the

optimised design c) longitudinal barrier section AndashA d) cross section of the small emerged island BndashB



some damage The two main failure mechanisms are

removal of outer stones from the armour and toe berm

by waves and settlement of the structure due to

removal of small particles from the bed transported

within the matrix of coarser stones (filter and toe

berm) in the internal part of the structure and at the

sedimentndashstructure interface

For the final design of armour more accurate tools

are used than the rule of thumb in order to evaluate

specific variables affecting the structure resistance and

the external load

The design load for the structure with return per-

iod 50 years is given by the most critical combination

of tide and waves In absence of a joint statistics the

analysed combinations are tentatively given by the

extreme value of the primary load (not defined a priori)

and a likely value of the other (secondary) load

The extreme offshore wave load is Hos50 years=

60 m Ts=9 s and the actual wave incident on the

structure is evaluated by means of Goda (2000) for-

mulae for wave transformation The tide extremes for

the design return period are 093 and +109 m asl

A likely value of offshore wave load expected simul-

taneously to extreme tide is Ho=50 m Ts=85 s

whereas a likely value of tide expected simulta-

neously to the extreme wave lies in the range 065

mH+078 m asl

Both high and low tides are reported above since it

is not known a priori which water level determines the

lower structure stability In shallow waters the reduc-

tion of wave height by breaking on the structure

strongly depends on the tidal cycle greater waves

reach the structure at high tide A peculiar perfor-

mance of LCSs is that resistance is inversely related

to freeboard submergence being a stability factor

since the water shelters the armour from wave impact

High tide conditions associated to higher incident

loads and higher structure resistance are often not

critical for stability conversely low tide may result

critical In order to account for the effect of water

level all possible combinations of tide and waves

should be considered

A direct consequence of such peculiar performance

of LCS is that in case of expected settlement stability

must be assessed also in short term conditions A

bottom settlement of 30 cm is expected to be reached

in the first 1H2 years so that just after construction

the structure has higher freeboard than in final design

conditions and is therefore less resistant for the initial

period Stability is anyway proven for the first year(s)

against a wave load that is not the lifetime extreme

but has a return period of 5 years with a reasonable

failure probability

Table 9 presents the steps of the armour design

carried out according to the following equation (Kra-

mer and Burcharth 2003) valid for initiation of

damage conditions which is safer than Vidal et al

(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136

for 3 V Rc=Dn50 b 2 eth1THORN

Eq (1) shows the actual dependence of stability on

crest freeboard and therefore on tide The lower

stability is given by Rc6036 Hc the critical free-

board and consequently both greater or lower sub-

mergence determines safer conditions The central

part of the barrier has height Hc=20 m placed on

35 m of depth so that critical freeboard is 072 m

and critical low tide is 078 m asl Such value of

tide is rare but not extreme and possibly associated to

high but not extreme offshore conditions (Hos655 m

tentatively determines a joint 50 years return per-

iod) Another examined condition resulted slightly less

stable associated to the extreme wave (Hos50 years660 m) and a likely low tide (065 m asl) which is

the case reported in Table 9

For the design of the emerged island the most

severe load condition results to be the extreme wave

and a likely value of high tide (+078 m asl) similar

stability is found by assuming tide is the primary load

(+109 m asl) with likely high waves (Hos=50 m)

Stability computation in short term conditions (5

years return period) showed in slightly lower load and

resistance and verified stability

The designed armour is a combination of different

classes of stones available on the market As sug-

gested by Van der Meer et al (1996) final grading

has ratio D85 D15 lower than 2

In this example like in many other cases the crest

level is a design requirement an overdesign of the

armour stone determines a thicker armour layer

which added to the filter layer requires a bottom

excavation

Table 9

Design of armour layer

Cross section Island Side extensions

50 years return period loads

Hos [m] 60

zm [m asl] Highest extreme 109 lowest extreme 093

Critical load combination 50 years return period (incident waves)

Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185

Evaluation of stable armour

Dn50A (rule of thumb) [m] 060 135 030

Dn50A (Eq (1)) [m] 079 136 (Not applicable)

Design of armour

Dn50A (assumed value) [m] 08 135 035

W50A (correspondent to Dn50A) [t] 13 65 01

2 layers (40 05H1 t 60 1H3 t) 1 layer 3H6 t+2 layers 4H10 t 2 layers 50H500 kg

HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05


The filter layer and the toe berm consist of the

same material to simplify construction Some failure

mechanisms are specific namely the stability against

waves (for the toe berm) and compatibility with the

armour (for the filter) and some are common namely

the internal stability and the compatibility with the

bottom

The toe berm is 40 m wide consisting of several

stones in order to tolerate damage The stability cri-

terion for the toe berm is given by (Van der Meer et

al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09

028bHsi=db08 3bhb=Dn50b25 eth2THORN

For Nod=2 the obtained stone is Dn50=048 m

Awide toe is also useful to support possible stones

displaced from the armour Should this happen the

toe will retain displaced stones reducing the effective

slope of the armour layer which then becomes more

resistant At the roundheads the toe is designed 4 m

wider in order to ensure stability against scour and to

reduce currents

The filter must be compatible with the armour The

filter rule applied for the armourndashfilter interface

results in a condition which is less severe than Eq

(2) which then determines the median stone design

For the filterndashbottom interface the filter rule

(D15Fb4D85B D50B=02 mm) results in a condition

which is not internally stable In the following the toe

bermfilter compatibility with the underlying sand is

investigated

Design practice suggests that internal stability

condition is D60F D10Fb10 (with no further require-

ments) Actually the internal stability rule can be

obtained at least conceptually applying repeatedly

the filter rule if the amount of fine material in the

bedding layer is sufficiently controlled This is

recommended for instance in Pilarczyk (2000)

where for the internal stability it is suggested

4D05ND10 4D10ND20 4D20ND40 etc which can

produce a compact material with small pore size DP

(6D05 5 eg 1 mm) three orders of magnitude

smaller than the larger stones (D806250 D05N1 m)

in the conglomerate


A small advantage in the design of the filterndashfoun-

dation interface when the bottom is made of non-

cohesive fine material relies in the application of a

hydraulic stability condition The shear stress in the

fluid flowing in the filter layer is induced by hydraulic

gradient and its intensity is conditioned by the pore

diameter It is desired that such shear stress is not

sufficient to move the material of the foundation

possibly present in the pores (hydraulic filter condi-

tion for the bottom material) Such requirement deter-

mines the maximum pore diameter and is less strict

than the geometrical filter rule

Table 10 presents the design

Placement of geotexile is also planned for addi-

tional security against the loss of fine material through

the filterndashbottom interface because both the filter

mechanism and the geotextile are not entirely reliable

In fact during placement of the filter the fine material

may be washed out or may not be sufficiently mixed

to the coarser part conversely the geotextile may be

removed or folded by waves before being anchored to

the stones The geotextile is designed in HDPE (poly-

ethylene) non-woven (flexible and permeable resis-

tant to punctures) for O90=DB50=02 mm 600 gm2

It is placed rolling it down across the section in

Table 10

Design of filter layer

Armour and foundation geometry

Dn50A Table 9 [m]

D50B [mm]

Hydraulic condition for interface with bottom

wcr see for instance Pilarczyk 2000 [ndash]

Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []

DP =4wcrDD50B j [mm]

Design of filter (D50F is chosen in order to be stable and also as a toe be

D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]

presence of divers assuring a 50 cm overlapping

and anchoring it to the toe berm

83 Construction

The structure can be built by pontoon Bottom

should be preliminarily flattened in order to supply

sufficient depth to allow the placement of both armour

and filter As stability much depends on the proper

construction of the filter and a careful placement of

the geotextile a particular attention to this construc-

tion phase shall be paid considering at least the

following points

The material forming the toe berm and the filter

should be accurately mixed and in absence of

proper technology the bigger fraction (N100 mm)

should be placed separately in three layers on top

of the mix

During the placement of geotextile (by divers) and

of the first part of the filter layer waves should be

characterised by a Hrmsb010 m

Avoid possible overdimensioning of the armour

which reduces the overall stability if Dn50AN

4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance

A sand nourishment of 16500 m3 ndash equal to the

15 of the initial nourishment ndash is planned every 3

years Given the structure stability a very small

amount of structural maintenance is foreseen The

armour is very stable and the cost for its maintenance

is assumed to be similar to the toe maintenance

Considering that the toe is designed (Eq (2)) with

Dn50=05 m (with a volume of about 01 m3) and that

for 50 severe but not extreme storms occurring in 10

years a mean value of Nod=05 can be assumed the

maintenance is estimated as 25 m3Dn5010 years

which corresponds to 5 m3 per barrier meter (7400

m3) every 10 years

85 Verification of expected optimisations

The expected improvements already identified two

sections above have been verified through numerical

Fig 16 Optimised Alternative a) bathymetry b

simulations carried out with MIKE 21 as already done

previously for each design alternatives On the basis

of the results obtained for the optimised design (Figs

16 and 17) with simulations for Alternative 1 (Figs 7

and 8) it can be seen that in the optimised design

In this case only sediment fluxes produce diffuse

sedimentation close to the shoreline and a strong

reduction in erosion induced at the Northern beach

Erosion persists at the barrier and groyne round-

heads

Erosion is present also on the landward side of the

barrier and inside the protected cell far from the

shoreline

Wave agitation in the protected area is reduced

(Hs=02H08 m)

Eddies at the barrier roundheads in particular in

the presence of Wave 6 result in lower intensity

Currents inside the protected cell are characterised

by lower intensities especially close to the Southern

) average erosiondeposition trend per day

Fig 17 Simulations on Optimised Alternative a) wave height Wave 6 b) current surface elevation and velocity Wave 6 c) wave height Wave 7




groyne and to the shoreline Maximum values are

reached close to the groyne roundheads and rise up

to 04 ms whereas minimum values are around

005 ms

In conclusion numerical results confirm the impro-

vements desired and enhance an additional improve-

ment in deposition trends close to the shoreline

86 Monitoring plan

After structure construction the following monitor-

ing plan has to be carried out including

Evaluation of transmission piling up and rip cur-

rents during first significant storms This can be

achieved by a set (at least two movable) of Acous-

tic Doppler Current Profilers (ADCPs) measuring

simultaneously waves and currents at both sides of

the barrier and at the gaps

Continuous monitoring of direction and intensity

of waves again by means of ADCPs as the avail-

able wave buoys in the North Adriatic do not cover

the Emilia Romagna region and the closest are far

offshore

Shoreline evolution (4 times per year) by means of

a DGPS survey along the shellfish line

Annual bathymetry with investigation of structural

integrity Suited technology are the multi-beam

bathymetry or a net of bathymetric profiles spaced

20 m cross-shore and intersecting 5 long-shore

profiles one of which is in correspondence to the

barrier

Annual characterisation of sediment distribution

The collected information should provide a feed-

back to the maintenance programme Evaluation of

the annual loss in the protected area related to the

sediment distribution gives sufficient information for

the amount of required nourishment and for the mor-

phological behaviour of the defence structure also in

view of possible design modifications

9 Conclusions

In order to promote an integrated coastal zone

management in every day practice under the fra-

mework of DELOS design guidelines (in press by

Elsevier) have been prepared to be appropriate

throughout the European Union accounting for cur-

rent EC policies and directives

This contribution presented an application of

such integrated approach for selection of a sustain-

able coastal defence scheme in Lido di Dante

which at the hypothetical design stage was pro-

tected only by two groynes and was subject to great

erosion process thus justifying an intervention for

protecting the beach and all the associated coastal

activities

The preliminary considerations of European direc-

tives environmental constraints and site characteris-

tics allowed identification of five design alternatives

pure nourishment a submerged barrier emerged

barriers parallel to the shore prolongation of the

two external existing groynes and a submerged

barrier with submerged connectors to the existing

groynes

The inputs for the integrated design consisted of

available data on climate environmental conditions

habitat and species preferences of visitors tools

(derived from DELOS guidelines) for establishment

of design wave climate selection of structure type and

the lay-out and geometries tools for simulating waves

and currents induced by the structures and the con-

sequent morphological changes

Engineers would have selected emerged barriers

or submerged barrier with connectors as preferred

schemes for beach defence ecologists would have

preferred submerged barriers or the prolongation of

groynes to minimize ecological impacts and max-

imize target effects such as increasing habitat and

species diversity including natural living resources

socio-economists would have chosen submerged

structures mainly for aesthetic reasons but also

for water quality The global evaluation of design

alternatives brought to the selection of the sub-

merged barrier that was then optimised using gen-

eral multidisciplinary criteria suggested in DELOS

guidelines

The analysis performed and the results presented

for this site showed the close interactions among LCS

design habitat changes hydrodynamics beach ero-

sion water quality and beach value it is therefore

important to follow and to take into account all the

multiple effects of LCSs on the littoral environment


and thus promote an effectively sustainable coastal

defence scheme

List of symbols

Load parameters

Hos Offshore significant wave height

Hsi Incident significant wave height

Hrms Root mean square wave height

tr Water residence time in the protected area

Ts Significant wave period

Tm Mean wave period

zm Tide

j Head loss across structure

cb Parameter controlling the effect of steepness

on breaking (Battjes and Jansenn model)

c2 Parameter controlling effect of depth on

breaking (Battjes and Jansenn model)

a Parameter controlling breaking dissipation

rate (Battjes and Jansenn model)

Geometrical parameters

Hc Structure height

Rc Crest freeboard

Lc Length of structure

HcA Thickness of armour layer

HcF Thickness of filter layer

Hs Significant wave height

hb Water depth at top of toe berm

d Depth at structure

B Width of structure at base

Material parameters

qs Density of stones

qw Density of water

D Relative buoyant density (qsqw) qw

W Weight

Dn Nominal diameter

DnA Nominal diameter of material forming the

armour W=qsDn3

DnF Nominal diameter of material forming the

filter

DF Diameter of material forming the filter (sieve

diameter)

DP Diameter pores within material (used with

reference to the filter layer)

DB Diameter of material forming the bottom

(sieve diameter)

WX Weight of mass given by X on mass dis-

tribution curve

DX Diameter of the sieve that allows passage of

X on mass distribution curve

OX Characteristic openings of the geotextile

(1X is passing)

Ns Stability number

Nod Number of displaced stones

wcr Critical Shield parameter (notation of Pilarc-

zyk 2000) it is frequently indicated with hcr

Acknowledgements

The support of the European Commission through

DELOS project contract EVK3-CT-2001-00041 is

gratefully acknowledged

A special acknowledgement is made to Dr Laura

Airoldi for availability of the ecological description of

Lido di Dante site Thanks to Dr Julio Zyserman for

the precious collaboration on MIKE 21

References

Abbott MB Damgaard A Rodenhuis GS 1973 System 21

jupiter A design system for two-dimensional nearly-horizontal

flows Journal of Hydraulic Research 1 1ndash28

AEligrteberg G Carstensen J Dahl K Hansen Rygg B Soslashren-

sen K Severinsen G Nygaard K Schrimpf W Schiller

Ch Druon J-N Casartelli S 2002 Eutrophication in Eur-

opean coastal waters Topic Report n 72001 EEA Copenha-

gen pp 1ndash86

Airoldi L Abbiati M Hawkins Jonsson PR Martin D

Moschella P Thompson R Aberg P 2005mdashthis issue

An ecological perspective on deployment and design of low

crested structures Coastal Engineering DELOS Special Issue


Bacchiocchi F Airoldi L 2003 Structure distribution and

dynamics of epibiota on different typologies of coastal

defence works Estuarine Coastal and Shelf Science 56

1157ndash1166

Battjes JA Janssen JPFM 1978 Energy loss and set-up due to

breaking of random waves Proc Int Conf Coastal Eng vol 16

ASCE New York pp 569ndash587

Benavente J Gracia FJ Anfuso G Lopez-Aguayo F 2005

Temporal assessment of sediment transport from beach nourish-

ments by using foraminifera as natural tracers Coastal Engi-

neering 52 (3) 205ndash219

Boyle KJ Bergstrom JC 1992 Benefit transfer studies myths

pragmatism and idealism Water Resources Research 28 (3)

657ndash663

Bulleri F Menconi M Cinelli F Benedetti-Cecchi L 2000

Grazing by two species of limpets on artificial reefs in the

northwest Mediterranean Journal of Experimental Marine Biol-

ogy and Ecology 255 (1) 1ndash19


Burcharth HF Lamberti A 2004 Design guidelines for low

crested structures Proc 29th Int Conf Coastal Eng vol 4

pp 4126ndash4138

Chapman MG 2003 Paucity of mobile species on constructed

seawalls effects of urbanization on biodiversity Marine Ecol-

ogy Progress Series 264 21ndash29

Chou LM 1997 Artificial reefs of Southeast Asia mdash do they

enhance or degrade the marine environment Environmental

Monitoring and Assessment 44 45ndash52

Casadei C Ceccaroni D Drei E Lamberti A 1998 Individua-

zione delle correnti nella zona protetta di Lido di Dante Atti del

XXVI Convegno Nazionale di Idraulica e Costruzioni Idrau-

liche in Italian pp 233ndash244

CNR Istituto di Geologia Marina 1994 Influenza della subsidenza

sul btrendQ evolutivo della fascia costiera Ravennate Bologna

publication for Comune di Ravenna

Colantoni P Gabbianelli G Mancini F Bertoni W 1997

Coastal defence by breakwaters and sea-level rise the case of

the Italian Northern Adriatic Sea Bulletin de lrsquoInstitut Oceano-

graphique Numero Special 18 133ndash150

Connell SD Glasby TM 1999 Do urban structures influence

the local abundance and diversity of subtidal epibiota A case

study from Sydney harbour Australia Marine Environmental

Research 47 373ndash387

Correggiari A Frascari F Miserocchi S Fontana D 1992 In

Vollenweider RA Marchetti R Viviani R (Eds) Break-

waters and Eutrophication Along the Emilia-Romagna Coast

pp 277ndash290

Davis JLD Levin LA Walther SM 2002 Artificial armored

shorelines sites for open-coast species in a southern California

bay Marine Biology 140 (6) 1249ndash1262

Drei E 1996 Analisi dellrsquointervento di ripascimento nella zona di

Lido di Dante e di alcuni dei suoi aspetti economici Degree

thesis University of Bologna in Italian 1ndash210

Goda Y 2000 Random seas and design of maritime structures

Advanced Series on Ocean Engineering 2nd edition vol 15

World Scientific pp 1ndash443

Hanemann WM 1994 Valuing the environment through contin-

gent valuation Journal of Economic Perspectives 8 19ndash43

Hausman JA (Ed) 1993 Contingent Valuation a Critical Assess-

ment North Holland Amsterdam

Herbich JB 2000 Handbook of Coastal Engineering

McGraw-Hill

IDROSER 1996 Progetto di Piano per la Difesa dal Mare e la

Riqualificazione Ambientale del Litorale della Regione Emilia-

Romagna publication for Regione Emilia-RomagnandashIdroser

Bologna

Kirby JT 1986 Rational approximations in the parabolic

equation method for water waves Coastal Engineering 10

355ndash378

Kramer M Burcharth HF 2003 Head and trunk stability of low-

crested breakwaters in short crested waves Proc Coastal Struc-

tures 2003 pp 137ndash149

Kramer M Zanuttigh B van der Meer J Gironella FX

2005mdashthis issue Laboratory experiments on low-crested

breakwaters Coastal Engineering DELOS Special Issue


Johnson HK Karambas Th Avgeris I Gonzalez-Marco D

Caceres I 2005mdashthis issue Modelling of waves and currents

around submerged breakwaters Coastal Engineering DELOS

Special Issue doi101016jcoastaleng200509011

Lamberti A Zanuttigh B 2005 An integrated approach for

coastal zone management in Lido di Dante Italy Estuarine

Coastal and Shelf Science 62 (3) 441ndash451

Lamberti A Archetti R Kramer M Paphitis D Mosso C Di

Risio M 2005mdashthis issue Prototype experience regarding

low-crested structures Coastal Engineering DELOS Special

Issue doi101016jcoastaleng200509010

Martin D Bertasi F Colangelo MA Frost M Hawkins

SJ Macpherson E Moschella PS Satta MP Thompson

RC deVries M Ceccherelli VU 2005mdashthis issue Eco-

logical impacts of low crested structures on soft bottoms and

mobile infauna how to evaluate and forecast the conse-

quences of an unavoidable modification of the native habitats

Coastal Engineering DELOS Special Issue doi101016

jcoastaleng200509006

Marzetti S Lamberti A 2003 Economic and social valuation of

the defence system of Venice and its lagoons (Italy) Proc

MEDCOAST 2003 vol 1 pp 307ndash318

Marzetti S Zanuttigh B 2003 Economic and social valuation of

beach protection in Lido di Dante (Italy) Proc MEDCOAST

2003 vol 1 pp 319ndash330

Miller MW 1999 Using bnaturalQ reef ecology in artificial

reef research advancing artificial reef goals through better

understanding of ecological processes Proc 7th CARAH

pp 37ndash44

Moschella P Abbiati M Aberg P Airoldi L Anderson JM

Bacchiocchi F Dinesen GE Gacia E Granhag L Jonsson

P Satta MP Sundelof A Thompson RC Hawkins SJ

2005mdashthis issue Low crested structures as artificial habitats for

marine life what grows where and why Coastal Engineering

DELOS Special Issue doi101016jcoastaleng200509014

Penning-Rowsell EC et al 1992 The Economics of Coastal

Management Belhaven Press London

Pilarczyk K 2000 Geosynthetics and Geosystems in Hydraulic

and Coastal Engineering Balkema pp 1ndash913

Polome P Marzetti S van der Veen A 2005mdashthis issue

Economic and social demands for coastal protection



Preti M Bonsignore F Guerrero M Martinelli L Grandi L

De Nigris N 2002 Stato del Litorale EmilianondashRomagnolo

Allrsquoanno 2000 I quaderni di ARPA Bologna pp 1ndash125

Tomasicchio U Adamo F Benassai E Boccotti P Colombo

P Lamberti A Matteotti G Noli A Jappelli R Franco

L 1996 Istruzioni Tecniche per la Progettazione delle Dighe

Marittime (Technical Instructions for Breakwater DesignCon-

siglio Superiore del Ministero dei lavori Pubblici and Con-

siglio Nazionale delle Ricerche Rome pp 1ndash117

Van der Meer JW drsquoAngremond K Gerding E 1995

Toe structure stability of rubble mound breakwaters Proc

of the Advances in Coastal Structures and Breakwater Confer-

ence Institution of Civil Engineers Thomas Telford Publishing

pp 308ndash321


Van der Meer JW Tutuarima WH Burger G 1996 Influ-

ence of rock shape and grading on stability of low crested

structures Proc 25th Int Conf on Coastal Engineering ASCE

pp 1957ndash1970

Vidal C Losada MA Mansard EPD 1995 Stability of

low crested rubble mound breakwater heads Journal of Water-

way Port Coastal and Ocean Engineering ASCE 121 (2)

114ndash121

Zanuttigh B Martinelli L Lamberti A Moschella P Marzetti S

2006 Example application to design guidelines Chapter 12

Guidelines for the Environmental Design of Low Crested Coastal

Defence Structures in press by Elsevier


Introduction

Preliminary investigation of constraints

Analysis of the site

Environmental conditions

Climate and sediment transport

Water quality

Ecosystems habitat and species

Conceptual pre-design alternatives

Definition of technical environmental and socio-economic objectives

Identification of design alternatives

Analysis of waves currents and sediment transport induced by each design alternative by means of numerical 2DH simulations

Method and results

Comments on numerical results

Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs

Ecological comments to design alternatives

Preliminary considerations

Forecast environmental impacts of structures

Alternative 2 - emerged barriers with gaps

Alternative 4 - submerged barriers with connectors

Alternative 3 - extended groynes

Alternative 1 - submerged barrier

Conclusive comments

Socio-economic considerations

Selection of the sustainable scheme

Optimised design

Identification of possible optimisations

Structural design

Construction

Maintenance

Verification of expected optimisations

Monitoring plan

Conclusions

Acknowledgements

References


leading to problems such as insufficient sand retention

erosion in gaps or at roundheads Both expected (eg

changes to surrounding soft-shore ecosystems) and

unexpected (eg habitat provision for non-native spe-

cies) ecological impacts can occur Conversely posi-

tive effects may be also overlooked (eg provision of

habitats for shellfish fish and other mobile fauna)

The DELOS project aimed at promoting effective

and environmentally compatible design of LCSs

through a multidisciplinary approach The project

team integrated research on hydrodynamics beach

morphology engineering design ecological studies

of structure and dynamics of coastal species associa-

tions cost-benefit analysis as well as assessment of

social consequences From the engineering point of

view the project provided physical (Kramer et al

2005mdashthis issue) numerical (Johnson et al 2005mdash

this issue) and field analyses (Lamberti et al 2005mdash

this issue) to achieve an accurate knowledge of LCSs

behaviour and effects From the ecological perspec-

tive the project drew attention to the modification of

habitats in coastal marine areas by deployment of

artificial structures such as port installations and

coastal defences (Chou 1997 Connell and Glasby

1999) To date the complex interactions between phy-

sical and biological processes on and around artificial

structures have been poorly identified (see Connell and

Glasby 1999 Bulleri et al 2000 Davis et al 2002

Chapman 2003) at the range of spatial and temporal

scales over which they occur (Miller 1999) As part of

DELOS ecological impacts of LCSs have been inves-

tigated on different coastal systems across Europe and

suggestions made for their construction in order to

minimise habitat changes (Airoldi et al 2005mdashthis

issue Martin et al 2005mdashthis issue Moschella et al

2005mdashthis issue) Mitigation measures to maximize if

desired biodiversity and bio-resources have also been

indicated (Moschella et al 2005mdashthis issue) within

the context of a broader perspective of the ecology of

the coastal zone (Airoldi et al 2005mdashthis issue)

From the socio-economical viewpoint DELOS pre-

pared an up-to-date inventory of coastal environment

valuation methods (eg Hanemann 1994 Hausman

1993) The analysis of the possibility of transferring

benefit quantification from one country to another

(Boyle and Bergstrom 1992) significantly extended

the base on which local quantifications can be made

Furthermore specific new coastal management pro-

jects have been evaluated by the Contingent Valuation

Method (Polome et al 2005mdashthis issue) Preferences

of visitors for different defence structures were also

analysed

This contribution is aimed at presenting an inte-

grated approach to design coastal defence based on

the application of DELOS Design Guidelines (Burch-

arth and Lamberti 2004) For this purpose a well-

documented DELOS study site which suffers from

severe erosion was selected Lido di Dante a small

seaside resort in the North Adriatic Sea 7 km far from

the town of Ravenna The use of the beach for recrea-

tional activities the extent of beach erosion and envir-

onmental problems common to the highly defended

littoral region of a eutrophic sea made this site an

interesting case study

The contribution is composed of five main parts

The first part describes the site looking at the factors

that mainly interact with the defence works namely

wave climate existing habitat and sediment transport

The second part identifies different possible design

alternatives and makes a preliminary selection of five

options based on the social and environmental con-

straints already outlined in the previous section

Numerical simulations with the 2DH model MIKE

21 have then been carried out in order to predict

waves currents and sediment transport induced by

each selected alternative Based on numerical results

maintenance plans are made and both building and

maintenance costs are estimated The third and fourth

parts comment respectively on the ecological and

socio-economic effects of design alternatives based

on output from numerical modelling The fifth part

combines the engineering performance the likely

ecological effects the social demand and the construc-

tion costs to make the final choice among the alter-

natives The chosen alternative is then optimised and a

detailed design finalized using the hydro-morpho-

dynamic verification of various alternatives through

numerical simulations Finally conclusions are drawn

on the importance of such an integrated approach for

improving the design of coastal defences

2 Preliminary investigation of constraints

Before planning an intervention political techno-

logical environmental and social constraints should

Table 1



are not quoted)


31051998 n 112 L 31102003 n 306 (application









16022000 n6








L 25011979 n30 L 290599 n175



















social constraint









di Dante in 1993





sediment transport


























dunes













following years)





























wwwidromarecom)






























Table 2


Condition

no

Wave

direction

[8]

Hos

[m]

Tm

[s]

Wind

velocity

[ms]

Frequency

[]

1 45 15 50 12 474

2 45 40 80 20 053

3 90 15 50 12 586

4 90 35 80 18 081

5 135 15 50 12 480

6 135 35 80 18 047

7 120 03 30 5 4000

33 Water quality




































































the hydrodynamics













economic objectives








the village depend



in the region)











following storms)






recreation



be considered



Revetment

Submerged structure


bags


Emerged structure


Groynes





























2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References

Table 1



are not quoted)


31051998 n 112 L 31102003 n 306 (application









16022000 n6








L 25011979 n30 L 290599 n175



















social constraint









di Dante in 1993





sediment transport


























dunes













following years)





























wwwidromarecom)






























Table 2


Condition

no

Wave

direction

[8]

Hos

[m]

Tm

[s]

Wind

velocity

[ms]

Frequency

[]

1 45 15 50 12 474

2 45 40 80 20 053

3 90 15 50 12 586

4 90 35 80 18 081

5 135 15 50 12 480

6 135 35 80 18 047

7 120 03 30 5 4000

33 Water quality




































































the hydrodynamics













economic objectives








the village depend



in the region)











following storms)






recreation



be considered



Revetment

Submerged structure


bags


Emerged structure


Groynes





























2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References





sediment transport


























dunes













following years)





























wwwidromarecom)






























Table 2


Condition

no

Wave

direction

[8]

Hos

[m]

Tm

[s]

Wind

velocity

[ms]

Frequency

[]

1 45 15 50 12 474

2 45 40 80 20 053

3 90 15 50 12 586

4 90 35 80 18 081

5 135 15 50 12 480

6 135 35 80 18 047

7 120 03 30 5 4000

33 Water quality




































































the hydrodynamics













economic objectives








the village depend



in the region)











following storms)






recreation



be considered



Revetment

Submerged structure


bags


Emerged structure


Groynes





























2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References








wwwidromarecom)






























Table 2


Condition

no

Wave

direction

[8]

Hos

[m]

Tm

[s]

Wind

velocity

[ms]

Frequency

[]

1 45 15 50 12 474

2 45 40 80 20 053

3 90 15 50 12 586

4 90 35 80 18 081

5 135 15 50 12 480

6 135 35 80 18 047

7 120 03 30 5 4000

33 Water quality




































































the hydrodynamics













economic objectives








the village depend



in the region)











following storms)






recreation



be considered



Revetment

Submerged structure


bags


Emerged structure


Groynes





























2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References
























the hydrodynamics













economic objectives








the village depend



in the region)











following storms)






recreation



be considered



Revetment

Submerged structure


bags


Emerged structure


Groynes





























2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References





















2)



















































































































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References













































simulation period











purposes



reported in Table 2







was fixed as 08 m















dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References












dissipation rate)



08




11a 13a













12a 14a








10c 12c 14c























habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




















habitat











































roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




















roundheads






(Alternative 2)





















structures










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References










takes place







































Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




Table 3






0 092 044 1043 5760

1 084 040 1438 5833

2 (gaps) 031 (130) 005 (040) 2667 9600

3 092 044 2143 9130

4 078 035 1667 5676

Table 4



Long-shore

flux [m3y]

Cross-shore

flux [m3y]

Inside the cell

[m3y]

0 +51856 82320 30464

1 +26896 +3284 +30180

2 +33527 +4960 +38487

3 +7283 +3985 +11268

4 +5285 +9180 +14465

































values in Table 4







in Table 5


























adjacent beaches







Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References

Table 5

Construction costs


Alternative 1


Alternative 2


(r =130 m)

1698900 ono 10193400 o


Alternative 3


Alternative 4










Table 6


Costs Alternative

0


















1 2 3 4

832899 911756 296898 860768

110000 110000 110000 110000

1320000 1320000 1320000 1320000

2153000 2197000 1618000 2181000

20000 10000 30000 15000

25000 35000 40000 25000

6700 5880 1200 7400

2883000 2876000 4405000 2575000

5036000 5073000 6023000 4756000











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References











Table 7



Alternative

1 2 3 4

Physical changes

Waves 2 4 1 2


Currents 3 2 2 3




Epibiota 2 4 1 2











































rocky shores





















infauna







































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




































assemblages


















connectors

























into this area















































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References































relatively smaller






Table 8



Shoreline

maintenance

Effects on

adjacent littoral

Ecological

impacts

Mitiga

effects

0 1 3 5 1

1 4 5 4 2

2 5 2 1 3

3 2 1 3 3

4 3 4 2 2


Global weight 1 1




































weights


costs

Global


use

Aesthetic

impact

Swimming

safety

3 4 1 2 1067

2 5 2 4 1500

4 2 5 3 1192

5 3 4 1 950

2 5 3 5 1383

1 3 1 3 1 3 ndash

1 1













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References













assemblages









species diversity









































erosion and


accretion














nourishment)














beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




beach itself


190 go walking

130 swim and

only 02 go fishing



main one (242)














































respectively)



















































Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References






















Alternative 3 (1)





8 Optimised design








rescue boats






tion zones















the structure





navigation







































the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References















the external load
















mH+078 m asl


























failure probability





(1995)

Hs

DDn50

frac14 006Rc

Dn50

2

023Rc

Dn50

thorn 136
































excavation

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References

Table 9




Hos [m] 60



Hsi (Goda 2000) [m] 208 284 208

zm [m asl] 065 +078 065

Structure geometry

d [m asl] 35

Hc [m] 20 45 10

Rc [m] 085 +022 185




Design of armour




HcA [m] 16 (=2d Dn50) 41 (=3d Dn50) 07 (=2d Dn50)

HcF [m] 07 07 05








bottom




al 1995)

Ns frac14Hs

DDn50

frac14 024hb

Dn50

thorn 16

N 015od 04bhb=db09









reduce currents









investigated













in the conglomerate



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References



























Table 10



Dn50A Table 9 [m]

D50B [mm]



Hso [m]

zm [m]

Hsi [m]

k t [m]

B [m]

j 6Hsi(1+k t) (2B) []

D =(qsqw) qs []



D50F D50FND50A 4 Eq (2) [mm]

D25F 6D50F 4 [mm]

D10F 6D25F 625 [mm]

D05F 6D10F 4 [mm]

DP 6D05F 5 [mm]



83 Construction








following points





of the mix






4Dn50F

080H13502

006

50

109

29

605

30

007

157

103

rm Eq (2))

480

120

20

5

1


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References


84 Maintenance













m3) every 10 years














heads



shoreline


(Hs=02H08 m)













005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References








005 ms




86 Monitoring plan













offshore








barrier









9 Conclusions














activities








groynes






















guidelines









defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References



defence scheme

List of symbols

Load parameters






Tm Mean wave period

zm Tide









Hc Structure height

Rc Crest freeboard








Material parameters


qw Density of water


W Weight

Dn Nominal diameter


armour W=qsDn3


filter


diameter)




(sieve diameter)


tribution curve




(1X is passing)

Ns Stability number




Acknowledgements








References








gen pp 1ndash86









1157ndash1166










657ndash663








pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References




pp 4126ndash4138

























pp 277ndash290















McGraw-Hill




Bologna



355ndash378




































pp 37ndash44




























pp 308ndash321





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References





pp 1957ndash1970




114ndash121






Introduction





Water quality






Method and results


Wave agitation

Currents

Set-up

Water mixing

Sediment transport

Construction costs








Conclusive comments



Optimised design


Structural design

Construction

Maintenance


Monitoring plan

Conclusions

Acknowledgements

References

environmental design of coastal defence in lido di dante, italy

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