simulation on the efect of submerged breakwater to...

SIMULATION ON THE EFECT OF SUBMERGED BREAKWATER

TO THE WAVE TRANSMISSION AND RUN-UP

ZAHEDER BIN ABD AZIZ

A project report submitted in partial fulfillment

of the requirements for the award of the degree of

Master of Engineering (Civil - Hydraulics and Hydrology)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

JANUARY, 2013

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To My Beloved Mother and Father …

Thanks for all your pray, attention and spiritual support…

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ACKNOWLEDGEMENTS

In the duration of completing this thesis, first and foremost I would like to

give praise to Allah s.w.t on his blessing and gift of life in order for me to continue

with my studies.

It is with great pleasure I would like to give my heartiest gratitude to my

supervisor, Dr. Mohamad Hidayat bin Jamal on his tireless support and guidance.

His dedication and willingness to go the extra miles is very much appreciated and

will be my motivation for my future undertaking.

I would like to give thank also to my parents and family on their pray,

guidance and moral supports for me to complete this study.

Also I would like to give thanks to my colleague in UEM Builders Sdn Bhd

on their friendship and motivation for me to further my studies.

Last but not least, I would like to express my gratitude to my fellow

classmates of hydraulic and hydrology course session 2011/13 on their co-operation

and friendships. It has been a memorable one and half year. It has been great

pleasure in knowing every one of you.

Thank you…

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ABSTRACT

The construction of submerged breakwater is one of the methods to reduce the

effect of wave energy on the beach. Submerged breakwater has many advantages

compared to emerge breakwater such lower construction cost, a higher aesthetic

values and have a lower environmental impact to the surrounding areas. The aim of

this study is to simulate and investigate the effect of submerged breakwater to the

value of wave transmission coefficient, Kt and also the run-up value on the beach

slope. The initial data for wave period, wave height, water depth and beach slope was

taken from experimental dataset done by Saville, (1955). Several submerged

breakwater height will be tested in the numerical simulation which will follow the

experimental setup done by Chiranjeevi Rambabu and Mani (2005). The numerical

simulation will be based on the Non-Linear Shallow Water Equation (NLSWE). As

a results, the wave transmission coefficient, Kt value will decrease in relation to the

increase of submerged breakwater height. This will caused the increase energy

during breaking and also the velocity speed of the wave induced currents. The

increased of the current speed will resulted in a higher run-up value. The effective

submerged breakwater height is determined by its wave reduction capabilities which

influence the run-up values.

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ABSTRAK

Pembinaan tembol pemecah ombak tenggelam permukaan adalah salah satu cara

untuk mengurangkan kesan kuasa ombak ke atas permukaan pantai. Terdapat

banyak kelebihan tembok pemecah ombak tenggelam permukaan berbanding

pembinaan tembok pemecah ombak timbul permukaan diantaranya kos pembinaan

yang lebih rendah, nilai estatik yang lebih tinggi malah memberikan kesan

semulajadi yang lebih baik ke atas kawasan sekitarnya. Tujuan kajian ini adalah

untuk menilai kesan pembinaan pemecah ombak tenggelam permukaan ke atas nilai

koeffensi Kt dan nilai run-up diatas kecerunan pantai. Data utama seperti nilai masa

ombak, ketinggian ombak, kedalaman air dan kecerunan pantai diambil daripada data

ekperimen yang dilakukan oleh Saville (1955). Beberapa ketinggian tembok

pemecah ombak tenggelam permukaan telah dipilih untuk diujikaji didalam simulasi

komputer mengikut keadaan ekperimen yang dilakukan oleh Chiranjeevi Rambabu

dan Mani (2005). Simulasi adalah berdasarkan ‘Non-Linear Shallow Water

Equation’ (NLSWE). Keputusan simulasi menunjukkan nilai koeffensi Kt akan

berkurangan dengan peningkatan ketinggian tembok pemecah ombak tenggelam

permukaan. Ini akan mengakibatkan peningkatan tenaga semasa pemecahan ombak

dan juga peningkatan kelajuan arus ombak. Peningkatan kelajuan arus ombak ini

akan mengakibatkan peningkatan kadar run-up. Ketinggian tembok pemecah ombak

tenggelam permukaan yang effektif adalah bergantung kepada kebolehan struktur

untuk mengurangkan kuasa ombak yang boleh member kesan kepada nilai run-up.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION ii

DEDICATION iii

ACKNOWLEGMENT iv

ABSTRACT v

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiii

LIST OF APPENDICES xiv

1 INTRODUCTION

1.1 General 1

1.2 Background problem 2

1.3 Importance of study 3

1.4 Objective 4

1.5 Scope of study 5

2 LITERATURE REVIEW

2.1 General 6

2.2 Sea, tides, wave, currents and surges 6

2.3 Wave mechanics 8

2.4 Wave transformation 12

2.5 Wave set down, set up and run-up 18

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2.6 Wave transmission over breakwater 20

2.7 Previous studies on wave transmission 22

coefficient, Kt

2.8 Coastal management plan 25

2.9 Breakwater structure 26

2.9.1 Shore connected breakwater 28

2.9.2 Detached breakwater 29

2.9.3 Floating breakwater 30

2.9.4 Submerged breakwater 32

3 METODOLOGY

3.1 General 33

3.2 Foundation to numerical simulation 34

3.3 Data collection 35

3.4 Numerical simulation setup 37

3.5 Computer program introduction 38

3.6 Model calibration 40

4 RESULTS AND DISCUSSIONS

4.1 General 41

4.2 Model calibration results 41

4.3 Effect of friction factor on the run-up 44

4.4 Effect of different wave characteristic 45

on the run-up

4.5 Effect of submerged breakwater has on 47

wave transmission


the Kt value


the run-up

4.8 Discussion 55

5 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion 59

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5.2 Recommendation 60

REFERENCES 61

APPENDICES 63

x

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Common equation in coastal engineering 10

2.2 Tabulated Kd value by Weigel (1964) 14

2.3 Summary of breaker type 18

2.4 Summary of coastal protection structure 27

3.1 Converted run-up data from laboratory experiment 36

(Saville, 1955)

4.1 Run-up value of experiment and numerical simulation 42

4.2 Person’s R-square value for empirical equation 54

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Representation to the linear wave theory 9

2.2 Water particle displacement in deep, intermediate and 11

shallow water

2.3 Diffraction process due to barrier 13

2.4 Kd value by Weigel (1964) 14

2.5 Different form of breaking 17

2.6 Sketch definition of run-up, set up and set down 18

2.7 Tabulated figure for Kt estimation by Saville (1963) 22

2.8 Shows connected type breakwater 29

2.9 Shows detached type breakwater 30

2.10 Shows floating type breakwater 31

3.1 Graphical representation of NLSWE 34

3.2 Experiment dataset published by (Saville, 1955) 36

3.3 Numerical simulation setup 37

3.4 Example of variable used in FORTRAN program 38

3.5 Example of output file produced by FORTRAN program 39

3.6 Example of wave transmission profile using TECHPLOT 39

4.1 Percentage difference of run-up value for various friction 43

factors

4.2 Run-up value of different wave characteristic and 44

friction factor

4.3 Simulation run-up value for case with different wave period 45

4.4 Simulation run-up value for case with different wave height 45

xii

4.5 Simulation for case without submerged breakwater - T=6s, 47

H=2.4384m, d=5.334m, hs/d=0, B/d=0


H=2.4384m, d=5.334m, hs/d=0.625, B/d=1.25


H=2.4384m, d=5.334m, hs/d=0. 5, B/d=1.25


H=2.4384m, d=5.334m, hs/d=0. 375, B/d=1.25


H=2.4384m, d=5.334m, hs/d=0. 25, B/d=1.25


H=2.4384m, d=5.334m, hs/d=0. 25

4.11 Kt obtained from numerical simulation reference to submerged 52

breakwater height

4.12 Kt obtained from numerical simulation reference to submerged 52

breakwater crest width

4.13 Comparison of Kt value simulated and calculated 53

4.14 Comparison of run-up value for different test cases 55

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LIST OF SYMBOLS

Kt - Wave transmission coefficient

d - Water depth from the toe of submerged breakwater to SWL

ds - Water depth from top of the breakwater crest to SWL

hs - Submerged breakwater structure height from ocean bed

B - Submerged breakwater crest width

H - Wave height

E - Wave energy

T, t - Wave period

L - Wave length

g - Acceleration of gravity

d/gT2

- Dimensionless water depth

H/gT2 - Dimensionless wave steepness

hs/d - Structure height to water depth ratio

SWL - Still water level

Ir - Iribarren parameter

f - Friction factor

η - Deviation height from the SWL

ρ - Water density

α - Slope of breakwater structure on the seaward side

θ, β - Slope of beach profile

F - Freeboard - measured height of breakwater crest from SWL.

Negative value if structure is submerged

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LIST OF APPENDICES

APPENDIX TITLE PAGE

Table A.1 Run-up, Kt simulated, Kt calculated value for 63

case 1 (hs/d=0.625)


case 1 (hs/d=0.5)


case 1 (hs/d=0.375)


case 1 (hs/d=0.25)

Figure B.1 Simulation for case without submerged breakwater - T=4.5s, 65

H=1.2192m, d=5.334m, hs/d=0, B/d=0


H=1.2192m, d=5.334m, hs/d=0.25, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0.375, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0.5, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0.625, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0, B/d=0


H=1.2192m, d=5.334m, hs/d=0.25, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0.375, B/d=1.25

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H=1.2192m, d=5.334m, hs/d=0.5, B/d=1.25


H=1.2192m, d=5.334m, hs/d=0.625, B/d=1.25

CHAPTER 1

INTRODUCTION

1.1 General

Coastal area is a country natural treasure trove which is priceless not only due

to its diverse marine ecosystems but also crucial for the continuation of the country

economic progress. However this area is facing continues threat of destruction due

to action of natural forces such as wind and waves and also due to the interference of

human activities. The establishment of coastal protection system is an important step

in order to minimize the destruction and also to rehabilitate the damaged coastal area.

Countries with a large coastline area such as United State of America,

Australia and Japan are the pioneer in implementing coastal protection systems. This

system can be implemented in the form of soft or hard approached. Soft approached

dictates the coastal protection systems that does not require permanent protection

structure such as better conservation regulation, stricter law enforcement, giving

greater public awareness etc. The hard approached is the opposite where permanent

structures need to be constructed in order to protect the shoreline area. These

permanent structures such as jetties, sea wall, tide gate, emerged breakwater,

submerged breakwater etc.

2

1.2 Background problem

Wave and current forces is the source of many coastal engineering problems.

These natural forces not only cause damage the coastal area but also damage the

properties of the communities located along the coastal area. The need to provide

protection to the coastline area is crucial in order to avoid further devastation. The

construction of shoreline protection structure such as submerged breakwater is one of

the methods available in order to reduce this problem.

However in order to ensure the submerged breakwater structure effectiveness,

the determination of the submerged breakwater dimension need to consider many

factors such as the local wave parameters, material to be used for the submerged

breakwater, the location of the breakwater etc. All this parameter will influence the

submerged breakwater wave transmission coefficient which also can be the basis of

measuring the structure effectiveness. The purpose of this study is to investigate the

effect of different submerged breakwater geometry have on the wave transmission

and run-up values.

1.3 Importance of study

The main function of constructing submerged breakwater structure is as a

wave reduction structure. The submerged breakwater will act as an artificial barrier

which will reduce the energy of the propagating wave and currents. However the

effectiveness of the submerged breakwater structure depends very much on the

structure geometry such as breakwater height and crest width. This study is done in

order to investigate the effect of the structure geometry has on the submerged

breakwater wave reduction capabilities or wave transmission coefficient values.

3

Without the additional submerged breakwater structure acting as an artificial

barrier the coastal area will be subjected to the devastative impact of the high wave

and current forces. This energy of this wave will hit the beach surface with great

force, which will then dislodge the loose soil particle on the slope surface. The

repeating impact of the high wave on the slope of the beach will expedite the coastal

erosion problems. Apart from expediting the coastal erosion problems, the high

wave impacting the slope of the beach will also caused high run-up value. This high

run-up value will cause the excessive water to spill over on land and will caused

flesh flooding. The frequent flesh flooding in the coastal area will allow sea water

excess in order to infiltrate more easily into the ground water table. Due to the

salinity of the sea water, excessive amount of sea water infiltration will contaminate

the fresh ground water table in the coastal area.

1.4 Objective

The objective of this study will involve two different criteria or case study.

1.4.1 Case without submerged breakwater

A) To investigate the effect of friction factor has on the value of run-up on the slope

of the beach

B) To investigate the effect of different wave characteristics has on the value of run-

up on the slope of the beach

4

1.4.2 Case with submerged breakwater

A) To simulate and investigate the effect of submerged breakwater with different

geometry has on wave transmission coefficient value, Kt

B) To evaluate the effect of submerged breakwater with different geometry has on

values of run up at the slope of beach

1.5 Scope of work

The purpose of this study is to investigate the effect of submerged breakwater

with different design geometry has on the wave transmission coefficient value Kt and

also the value of run-up at the beach slope. This study will be conducted by using

computer program in order to simulate and produced numerical calculation on the

wave transmission propagating above the submerged breakwater and also the run-up

value over the slope of the beach. The computer program will be using the Non-

linear Shallow Water equation NLSWE based model which was first developed by

Kobayashi, et al. (1987) and further developed by Pedrozo-Acuna (2005).

There are many factors that will influence the wave transmission coefficient

value Kt,. However for this study, the focus will be on the influence factors due to

the different wave characteristic and different submerged breakwater geometry. For

the factor involves the different wave characteristic the simulation data will be based

on the dataset produced by Saville (1955). A total six different wave characteristic

will be used in the numerical simulation. As for the different submerged breakwater

geometry focus will be on the submerged breakwater ratio comprises of structure

height to depth ratio hs/d and also breakwater crest width to depth ratio B/d which

will based on the work done by Chiranjevee Rambabu and Mani (2005). Other

5

influence factors for the submerged breakwater structure such as breakwater structure

slope, impermeability, structure orientation were not being considered.

61

REFERENCES

Chiranjeevi Rambabu, A and Mani, J.S. (2005). Numerical prediction of

performance of submerged breakwater, Ocean Engineering 32(2005) pp.1235-

1246

Coastal Engineering Manual (2002). US Army Coastal Engineering Research

Centre.,1, U.S Government Printing Office ,Washington D.C.

D’Angremond, K., Van der Meer, J.W., De Jong, R.J., 1996, Wave Transmission at

Low-crested Structures, Proceedings of the 25th Int. Conf. Coast.Engineering,

pp. 2418–2427.

Friebel, H. C., Harris, L. E., 1999, Re-evaluation of Wave Transmission Coeffcient

Formulae from Submerged Breakwater Physical Model, Florida.

Fuchs, R.A., Johnson, J.W. and Morison, J.R., "The Damping Action of Submerged

Breakwaters," Transactions of the American Geophysical Union, Vol. 32, No. 5,

1951, pp. 704-718.

Jeffreys, H., "Note on the Offshore Bar Problems and Reflection from a Bar," Wave

Report No. 3, Great Britain Ministry of Supply, 1944.

Kobayashi, N., Otta, A. K., and Roy, I. (1987). Wave reflection and run-up on rough

slopes, Journal of Waterway, Port, Coastal, Ocean Engineering, ASCE 113(3), pp

282–298.

Kobayashi, N and Wurjanto, A (1989), Wave transmission over submerged

breakwaters, Journal of Waterway, Port, Coastal and Ocean Engineering,

vol.115, ISSN 0733-0950x/89/0005-0662, pp.662-680

Pedrozo Acuna,A. (2011). Concerning swash on steep beaches. Ph.D Thesis.

University of Plymouth, United Kingdom

Saville, T.,Jr. (1955). Wave Runup on Shore Structures. Journal of the Waterways

and Harbor Division, Volume 82.

62

Saville, T.,Jr. (1956). Laboratory Data on wave Runup and Overtopping on Shore

Structures. Technical Memorandum No. 64. Beach Erosion Board.Corps of

Engineers.

Saville, T., Jr. (1963) Hydraulic Model Study of Transmission of Wave Energy by

Low-Crested Breakwater, Unpublished Memo for Record, U.S. Army,Corps of

Engineers, Beach Erosion Board, Washington, D.C.

Shore Protection Manual (1975). US Army Coastal Engineering Research Centre.,1,

U.S Government Printing Office ,Washington D.C

Sorensen, R. M. (2006). Basic Coastal Engineering, Springer Science, New York.

Svendsen, I.A. (2006). Introduction to Nearshore Hydrodynamics, World Scientific,

London

Van der Meer, J.W., Janssen, J.P.F.M., 1995.Wave run-up and wave over topping at

dikes. Wave Forces on Inclined and Vertical Structures ASCE — Task

Committee Reports, pp. 1–27.

Wiegel, R.L. (1962), ‘‘Diffraction of Waves by Semi-infinite Breakwater,’’ Journal,

Hydraulics Division, American Society of Civil Engineers, January, pp. 27–44.

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