prediction of earthquake damage to urban water distribution systems: a case study for denizli,...

ORIGINAL PAPER

Prediction of earthquake damage to urban water distributionsystems: a case study for Denizli, Turkey

Selcuk Toprak Æ Filiz Taskin Æ A. Cem Koc

Received: 27 June 2008 / Accepted: 27 July 2009 / Published online: 14 August 2009

� Springer-Verlag 2009

Abstract Prediction of damage to water supply lines

during an earthquake is a critical part of seismic planning.

This study evaluates the performance of the water supply

system in Denizli, Turkey, in the event of an M6, M6.3,

M6.5 and M7 earthquake associated with the Pamukkale

and Karakova-Akhan Faults. The relative effects of tran-

sient ground deformations and permanent ground defor-

mations based on maps of liquefiable soil and zones of

predicted lateral ground displacements are compared. The

relative effects of the different magnitude earthquakes and

pipeline damage relationships on the pipeline performance

following a seismic event are assessed.

Keywords Earthquake hazards � Ground shaking �Lateral spreading � Liquefaction � Pipeline damage, Denizli

Introduction

The devastating 1999 M7.4 Kocaeli and M7.2 Duzce,

earthquakes were a turning point in Turkey’s approach to

earthquake preparedness as they caused substantial damage

to the water services and in some areas the supply could not

be restored until many months after the earthquake. As a

consequence, many new laws were enacted in an attempt to

reduce the effect of any future earthquake on structures and

communities. Municipalities took actions (e.g., PAU 2002)

and some cities created ‘‘disaster masterplans’’ (KOERI

2000). However, such essential services as water and gas

distribution systems were given less attention and to date,

very few municipalities and companies have evaluated the

performance of their pipelines and structures against future

earthquakes.

Earthquake damage to buried pipelines can be attributed

to transient ground deformation (TGD) or to permanent

ground deformation (PGD) or both. TGD occurs as a result

of wave propagation or ground shaking effects while PGD

occurs as a result of surface faulting, liquefaction, land-

slides and differential settlement from consolidation of

cohesionless soils. The relative magnitudes of TGD and

PGD determine which will have the predominant influence

on pipeline response.

The paper first describes the changes in water supply

distribution systems in urban areas of Turkey including the

shift from brittle pipelines such as asbestos cement (AC)

and cast iron (CI) to more ductile pipelines such as poly-

ethylene (PE) and ductile cast iron (DI), and then assesses

the potential damage to the water pipelines of Denizli City,

Turkey, during future earthquakes both from the TGD and

liquefaction induced PGD.

Eight earthquake scenarios with four different earth-

quake magnitudes (M6, M6.3, M6.5 and M7) caused by

two different fault ruptures (Pamukkale and Karakova-

Akhan faults) were studied. The Pamukkale and Karakova-

Akhan faults are historically active faults and located to the

northwest of Denizli city (Fig. 1). Previous studies (e.g.,

Celik 2003) indicate that the Pamukkale and Karakova-

Akhan faults produce higher shaking intensities in Denizli

than some other active faults in the area (e.g., Honaz fault).

S. Toprak (&) � A. C. Koc

Civil Engineering Department, Pamukkale University,

Kinikli Campus, 20070 Denizli, Turkey

e-mail: [email protected]

A. C. Koc


F. Taskin

Turkiye Sinai Kalkinma Bank (TSKB), Appraisal Section,

Izmir, Turkey


123

Bull Eng Geol Environ (2009) 68:499–510

DOI 10.1007/s10064-009-0230-1

In order to analyze TGD and PGD effects on the pipelines,

peak horizontal ground velocity (PGV) and liquefaction

induced lateral ground displacement maps of the area were

prepared for each scenario earthquake.

Denizli has a population of more than 300,000 and is the

second largest city in the Aegean region of Turkey (Fig. 1).

It is an important centre for industry, tourism and exports.

The water distribution system was initially commissioned

in 1953 and has been progressively enlarged as the popu-

lation increased from 48,925 in the 1960s to 275,480 in the

2000s. As part of this study, the water pipelines of the city

were digitized and analyzed using Geographical Informa-

tion Systems (ArcGIS program, ESRI 2001).

Located on the western side of Turkey, Denizli is in the

seismic region affected by the NW–SE extending Gediz

Graben and E–W extending Menderes Graben as well as a

number of active faults (Saroglu et al. 1992). The Denizli

basin is situated close to the confluence of the two grabens

(Fig. 1i). The figure also shows the maximum intensity of

the historic earthquakes recorded prior to 1900 as well as

the earthquakes with a magnitude of [5 recorded between

1900 and 2004 (KOERI 2004). As shown in Fig. 1i, prior

to 1900 there were many earthquakes with intensities of IX

and X, some of which caused heavy damage and casualties

in the Denizli area. The magnitude-recurrence intervals

systems of Aydan et al. (2001a) suggests future earth-

quakes in the Denizli basin could have magnitudes of

between M6.0 and M7.2. In this paper, a M7.0 earthquake

is used to represent the maximum probable earthquake

while M6.3 is used as the most probable magnitude, based

on the study by Aydan et al. (2001b) which considered the

mean stress distributions in western Turkey.

Figure 1ii shows the general geology of the Denizli

basin consists of Neogene aged sedimentary rocks and

Quaternary deposits. Further information on the seismicity

and geology of the area can be found in Toprak and Taskin

(2007).

History of water distribution systems in Turkey

Primarily, the municipalities are the owners of the water

distribution networks in urban areas, and they control and

sell water to the consumers. However, the Bank of Prov-

inces (Iller Bankasi) in Turkey has historically had a con-

siderable influence, providing financial and technical

assistance to local authorities. According to the Bank of

Provinces statistics, some 175,000 km of pipelines was

constructed in Turkey with its support between 1969 and

2005 (Iller Bankasi, Bank of Provinces, 2008). Until the

mid 1990s, it was the Bank’s policy to use primarily AC

pipes for water supply systems, although in the following

years, the use of PVC pipes has increased, especially for

100–200 mm diameters. In recent years, however, PE and

DI pipes are being increasingly used. Figure 2 shows the

distribution of pipe materials in the water supply system of

five cities in Turkey. The water distribution system of

Istanbul is remarkably different from the others as ductile

cast iron is the principal pipe material used. Discussions

with experts from the Bank of Provinces indicated that the

water distribution system in Denizli is more representative

of other mid-size cities in Turkey.

Water supply system of Denizli

Water is supplied to Denizli from five main sources: the

Derindere spring (250 l/s), Gokpinar spring (700 l/s),

Kozlupinar spring (70 l/s), Benlipinar spring (20 l/s) and

numerous wells (400 l/s). Two springs are located to theFig. 1 Fault lines, past earthquakes, and geology around Denizli

(Modified after Toprak and Taskin 2007)

500 S. Toprak et al.

123

south of Denizli while the two higher capacity springs are

located to the southeast of the water service area (Fig. 3).

The wells are distributed both within and beyond the water

service area; the water from these sources being collected

in water storage tanks, treated and released to the distri-

bution system. Table 1 lists the tanks and information

about their elevations and capacities. Due to the topogra-

phy of the area, the water distribution system relies on

gravity flow. The distribution system is designed such that

the seven main pressure zones are independent and hence

in theory any damage can be contained in a particular zone.

The GIS database of the water supply system and its

details are provided in Toprak and Taskin (2007) but for

convenience, Fig. 4 shows the details of the water distri-

bution system in Denizli City and Fig. 5 the composition,

relative lengths and pipe diameters. It can be seen that the

total length of pipeline is about 1,745 km with some 95%

of the transmission and connection lines made of steel. The

main and distribution lines are asbestos cement (AC 54%),

polyvinyl chloride (PVC 44%) and cast iron (CI 2%). The

diameter of the distribution lines is between 65 and

200 mm whereas the main lines are between 100 and

600 mm in diameter. The CI pipelines are the oldest in the

system and primarily serve the more well-established parts

of Denizli which include important local business districts

with a high population density.

Prediction of pipeline damage in Denizli

Pipeline damage is commonly expressed as repair rate,

which is the number of pipeline repairs in an area divided

by the length of the pipelines in the same area. Method-

ologies for estimating potential pipeline damage use rela-

tionships which may be referred to as ‘‘fragility curves’’,

‘‘damage functions’’, ‘‘vulnerability functions’’ or ‘‘damage

relationships’’. These relationships are primarily empirical

and obtained from past earthquakes. Following current

practice, this study uses the relationship between pipeline

damage and peak horizontal ground velocity (PGV) for

TGD effects (Toprak 1998; O’Rourke et al. 1998) and the

relationship between pipeline damage and amount of

ground movement or deformation for PGD effects.

Damage due to permanent ground deformation

Permanent ground deformations occur as a result of surface

faulting, liquefaction, landslides, and differential settle-

ment from consolidation of cohesionless soils. This study

focused primarily on pipeline damage resulting from liq-

uefaction-induced lateral spreads, as the major fault lines

are located either at the border or outside the city bound-

aries and the state of current knowledge about some minor

faults (activity or displacement capacity) in the city is not

sufficient to include damage from surface faulting in the

analyses.

Prediction of liquefiable areas

Following the 1999 Kocaeli and Duzce earthquakes, an

extensive investigation of the geological, geotechnical and

hydrogeological properties of the Denizli area was under-

taken (e.g., PAU 2002, 2003). In addition, other, more

limited, geological studies (e.g., PAU 2001) were also

taken into account. The data include primarily observation

digs (127 locations), standard penetration tests (SPT 120

locations), borings without SPT (61 locations) and labo-

ratory index tests. Groundwater level information was also

available from many of the investigation points.

Liquefaction analysis was performed using the ‘‘sim-

plified procedure’’. This methodology was first introduced

by Seed and Idriss (1971) and later modified by various

researchers. Youd et al. (2001) provide a state-of-the-art

summary of the consensus recommendations from 20

0%10%20%30%40%50%60%70%80%90%

100%

Izmit(4374 km)

Istanbul(14099 km)

Adana(4571 km)

Antalya(1625 km)

Denizli(1743 km)P

erce

ntag

e of

pip

e m

ater

ial i

n th

e sy

stem

PVC Cast Iron Ductile Iron Steel

Asbestos Cement Polietilen GRP Concrete

Fig. 2 Composition of the water distribution pipelines in selected

cities of Turkey

Fig. 3 Denizli City water supply system—location of springs and

water tanks/service areas

Prediction of earthquake damage to water supplies 501

123

experts in workshops held in 1996 and 1998. The method

requires SPT data and index test results. Only 77 of the

SPT results available from Denizli could be used as some

other information (such as fines content) was missing. The

depth range of the SPTs was between 5 and 15 m and the

energy ratio used for the calculation of (N1)60 values was

Table 1 Water storage tanks in Denizli City

No Water tank Elev. (m) Vol. (m3) Municip. No Water tank Elev. (m) Vol. (m3) Municip.

1 Ak_DY3(2) 287 500 AKKALE 22 KUCUKPINAR 496 70 GOKPINAR

2 Ak_DY3(1) 336 1,500 AKKALE 23 G_CAMLIK 548 125 GOKPINAR

3 Ak_DY3(1) 336 1,000 AKKALE 24 DY6(4) 391 1,000 GUMUSLER

4 BAGBASI_2 514 1,000 BAGBASI 25 DY6(3) 430 1,500 GUMUSLER

5 BAGBASI_1 562 600 BAGBASI 26 DM6(5) 414 500 GUMUSLER

6 BAGBASI_3 465 1,500 BAGBASI 27 DM6(5) 420 200 GUMUSLER

7 CAMLIK 481 1,250 DENIZLI 28 DY6(2) 479 2,000 GUMUSLER

8 KURUCAY(ESKI) 481 4,000 DENIZLI 29 KAYHAN 398 80 KAYHAN

9 ESNAF SITESI 498 500 DENIZLI 30 KINIKLI_1 501 100 KINIKLI

10 KIREMITCI 460 5,000 DENIZLI 31 KINIKLI_ESKI 576 100 KINIKLI

11 SIRINKOY 675 800 DENIZLI 32 KINIKLI_2 488 150 KINIKLI

12 YENISEHIR 616 1,500 DENIZLI 33 KINIKLI_3 470 300 KINIKLI

13 HASTANE 467 5,500 DENIZLI 34 ASAGI 641 200 SERVERGAZI

14 KARSIYAKA 385 1,000 DENIZLI 35 YUKARI 671 200 SERVERGAZI

15 BAHCELIEVLER 561 800 DENIZLI 36 HACIEYUPLU 430 80 UCLER

16 BAHCELIEVLER 565 500 DENIZLI 37 DY6 401 500 UCLER

17 BAHCELIEVLER 561 3,000 DENIZLI 38 KARAHASANLI 516 80 UCLER

18 BEVLER(SUBEICI) 482 500 DENIZLI 39 DY3(1) 579 500 UCLER

19 ZEYTINKOY 463 30 DENIZLI 40 DY3(2) 579 500 UCLER

20 MERSINLIBUCAK 492 270 GOKPINAR 41 DY2 638 1,000 UCLER

21 GOKCEN 590 470 GOKPINAR 42 CAKMAK 626 150 UCLER

Fig. 4 Map of Denizli City water supply system

1

10

100

1000

10000

65 75 80 100

125

150

175

200

250

300

350

400

500

600

700

800

1000

1100

Pipe Diameter (mm)

Len

gth

(km

)

i) Length of pipelines with respect to pipe diameter

Asbestos cement 52%

Steel4% PVC 42 %

Cast iron 2 %

iii) Relative lengths of pipelines with respect to type

Transmission and connection lines 5%

Main lines 21 %

Distribution lines 74%

ii) Relative lengths of pipelines with respect to pipe composition

Fig. 5 Composition of pipelines in the Denizli City water supply

system (after Toprak and Taskin 2007)


123

45%. Correction factors for fines content, overburden

pressure, borehole diameter, rod length and sampling

method were used following Youd et al. (2001). The sub-

soil in the study area varies from clays to gravels; detailed

descriptions and discussions of the subsoil conditions are

available in PAU (2001, 2002, 2003).

Although previous PAU work (2001, 2003) includes

liquefaction analysis reports, they were not included in the

present study as they were based on an M6.3 earthquake

caused by various fault ruptures and attenuation relation-

ships based on Aydan et al. (2001a). In this study (related

to M6, M6.3, M6.5, and M7 earthquakes associated with

the Pamukkale and Karakova-Akhan Faults), Campbell and

Bozorgnia (2003) were followed as their attenuation rela-

tionship can be used to calculate both peak ground accel-

eration (PGA) and velocity (PGV). However, the results

from the two studies are comparable.

Both the PAU studies and the observations and mea-

surements undertaken indicate that the soils in the study

area, in general, would be classified as C (stiff soils) or D

(very dense soil and weak rock), with some weak layers,

according to FEMA-368. These would indicate shear wave

velocities of between 360–760 and 180–360 m/s, respec-

tively (FEMA-368 2000).

Factors of safety against liquefaction were computed at

each hole using the simplified procedure, i.e. dividing the

liquefaction cyclic resistance ratio (determined from the

SPT) by the cyclic shear ratio produced by the earthquake.

The lowest SPT value at each sounding was used. It is

appreciated that in a borehole, more than one layer may be

susceptible to liquefaction and there are indices which take

this into account (e.g., Toprak and Holzer 2003). However,

as the primary purpose of the liquefaction analysis was to

determine where lateral spread analysis should be under-

taken, the use of the lowest SPT value was sufficient. The

damage to pipelines was calculated using lateral displace-

ments in the liquefiable areas.

Figure 6 shows contours of factor of safety against liq-

uefaction for the M6.3 and M7 earthquake scenarios.

Based on the areas enclosed by the contours indicating

FS = 1, Fig. 7 shows the areas most likely to experience

liquefaction. If a more conservative approach is required,

Fig. 6 Factor of safety against

liquefaction contours for M6.3

and M7 earthquakes related to

the Pamukkale and Karakova-

Akhan Faults


123

the region between the FS contours of 1 and 1.3 can be

considered potentially liquefiable and hence the predicted

area shown in Fig. 7 would be expanded accordingly.

Prediction of lateral spread displacements caused

by liquefaction

Liquefaction-induced lateral ground displacements cause

significant disruption to pipeline systems and a number of

authors have proposed equations for the prediction of lat-

eral spread displacements at liquefiable sites (e.g., Hamada

et al. 1986; Bartlett and Youd 1995). Youd et al. (2002)

used multilinear regression (MLR) of a large database and

suggested two equations; one for gently sloping ground

conditions and the other for relatively level ground con-

ditions with a ‘‘free face’’ towards which lateral displace-

ments may occur. As pipelines are generally located at

some distance from ‘‘free faces’’ and most sources of ‘‘free

faces’’ (such as channels) are covered in a city, only the

equation for gently sloping ground conditions was used in

this study, i.e:

logDH ¼ �16:213þ 1:532M � 1:406 log R� � 0:012R

þ 0:338 log Sþ 0:540 logT15

þ 3:413 log 100� F15ð Þ� 0:795 log D5015 þ 0:1 mmð Þ ð1Þ

where DH the estimated lateral ground displacement, in

metres; M the moment magnitude of the earthquake; R* a

modified source distance value and defined as R* =

R ? Ro, where Ro = a distance factor that is a function of

earthquake magnitude and defined as Ro = 10(0.89M-5.64);

R the nearest horizontal or map distance from the site to the

seismic energy source, in kilometres; T15 the cumulative

thickness of saturated granular layers with corrected blow

counts, (N1)60 of less than 15, in metres; F15 the average

fines content (fraction of sediment sample passing a No.

200 sieve-particles \0.075 mm) for granular materials

included within T15, in percent; D5015 the average mean

grain size for granular materials within T15, in millimetres,

S the ground slope, in percent.

Lateral displacements were calculated at each SPT

sounding location where liquefaction was predicted. Source

distance to each SPT sounding location was determined

using GIS and digital fault maps. Ground slope was deter-

mined using the digital elevation contour lines from

1/25,000 scale topographic maps, digitized by Kumsar et al.

(2004). As the ground slope in the liquefiable soil zones is

within the limit (\6%) discussed by Youd et al. (2002), the

equation proposed by these authors was used (Eq. 1). From

the calculated lateral displacements, first contours and then

zones of displacement were drawn using GIS (Fig. 8).

Displacements as high as about 3.15 m (for Karakova-

Akhan fault and M = 7 case) were predicted in the study area.

Comprehensive information regarding all parameters

used in the lateral spread calculations and resulting dis-

placements can be found in Taskin (2005). It should be noted

that the lateral displacements obtained from empirical

equations are not exact. For example, the general predictive

capability of the Youd et al. (2002) approach may be valid

only within a factor of about two for sites with similar soil

and other properties to those in the authors’ database and

with the constraints of that database. Cetin et al. (2004)

compared the predictive capability of methodologies pro-

posed by Hamada et al. (1986), Shamoto et al. (1998) and

Youd et al. (2002) based on the liquefaction-induced lateral

spreads which occurred at Izmit Bay during the Kocaeli

(_Izmit) Earthquake. The results illustrated that the empirical

method of Youd et al. (2002) tended to overestimate the

lateral ground displacements whereas the methods of

Hamada et al. (1986) and Shamoto et al. (1998) tended to

either underpredict or overpredict the observed lateral

ground displacements by large amounts. Based on Cetin

et al’s. (2004) evaluations, the displacements predicted in

this study are likely to be somewhat conservative.

Fig. 7 Predicted areas of soil liquefaction for M6.3 and M7

earthquakes related to the Pamukkale and Karakova-Akhan Faults,

using a factor of safety of 1


123

Pipeline damage

HAZUS (FEMA 1999) and American Lifelines Alliance

(ALA 2001) damage relationships for PGD were used to

predict the damage from lateral spread displacements in the

study area. HAZUS provides the following equation for

damage prediction of brittle pipelines:

RR ¼ 0:594 PGDð Þ 0;56 ð2Þ

where RR is repairs/km and PGD is in centimetre. To

predict the damage for ductile pipelines, Eq. 2 is multiplied

by 0.3.

The ALA (2001) equation is:

RR ¼ K2 � 2:582� PGD0;319 ð3Þ

where RR is repairs/km and PGD is in centimetres, K2 a

constant depending on the pipe type, e.g., K2 is equal to

0.15 for welded steel (ductile) pipes and 1 for cast iron

(brittle) pipes.

Damage due to wave propagation

In order to predict pipeline damage due to ground shaking,

the distribution of PGV in the study area was first

determined using GIS. The mean PGV contours for eight

different fault ruptures (four on the Pamukkale Fault and

four on the Karakova-Akhan Fault) with magnitudes of M6,

M6.3, M6.5, M7 were developed by dividing the Denizli

map into a 1 9 1 km grid and determining the PGV at the

corners of each grid using the attenuation relationships of

Campbell (1997) and Campbell and Bozorgnia (2003).

Figure 9 shows the water supply system superimposed on

the PGV zones for Karakova-Akhan Fault, M6.3 earth-

quake scenario. Because the faults are located to the

northeast of Denizli, there is a repeated pattern of peak

ground velocity oriented from the northeast to the south-

west of Denizli. The length of pipelines in each zone was

calculated using GIS and the repair rates for each PGV

zone determined using various pipeline damage correla-

tions. The number of repairs was calculated for each PGV

zone by multiplying the corresponding repair rates and

length of pipelines. The repairs for each PGV zone were

determined for brittle and ductile pipelines separately. By

summing the repairs for each PGV, the total number of

repairs for a particular earthquake scenario was obtained. A

comprehensive treatment and discussion of various damage

correlations along with their evaluation using the Denizli

City water pipeline system is presented in Toprak and

Fig. 8 Predicted lateral ground

displacements for M6.3 and M7

earthquakes related to the

Pamukkale and Karakova-

Akhan Faults


123

Taskin (2007); only the results from Toprak (1998),

O’Rourke and Jeon (1999, 2000), ALA (2001) and the

O’Rourke and Deyoe (2004) damage relationship were

used in the present study.

Results and discussions

Table 2 presents the pipeline damage estimations for the

Denizli water supply system for different magnitude

earthquakes caused by a possible movement along the full

length of the Pamukkale and Karakova-Akhan Faults. The

number of likely repairs given in Table 2 is the sum of the

repairs for brittle and ductile pipelines including contri-

butions from permanent and transient ground deformations

(PGD ? TGD).

TGD generally induces much smaller levels of pipeline

strain and deformation than PGD. Nevertheless, because

TGD covers a broader area than PGD, the damage is

generally significant. Figure 10 shows the total number of

likely repairs summarized in Table 2 for each scenario

earthquake. It can be seen that the relative contribution of

PGD and TGD on the number of pipeline repairs depends

on the earthquake magnitude. For an M6 earthquake, TGD

related repairs are higher than PGD related repairs. For an

M6.3 earthquake, TGD and PGD related repairs are com-

parable and basically depend on the damage relationships

used in the analyses. As the intensity of the earthquake

increases, PGD related repairs become more pronounced

and the influence of the damage relationship used for the

TGD estimation reduces substantially.

In terms of impact on the population served by the water

supply system and the ability to fight post-earthquake fires,

system functionality (serviceability) is an important mea-

sure (Ballantyne and Crouse 1997). Existing correlations

between pipeline damage and system functionality use

average break rate, which is defined as the number of

pipeline breaks divided by the length of the pipelines in the

study area. The distinction between break and repair is

necessary, as a repair may be due to a leak in the pipeline

and not involve a break. Common practice is to assume that

for PGD, 80% of the repairs will be due to a break and 20%

to a leak, while for TGD, the opposite holds, i.e., 80% of

repairs are related to leaks and 20% to breaks (e.g., FEMA

1999).

Following this assumption, Table 2 shows the average

break rates for the earthquake scenarios used in this study.

The results show that M6 and M6.3 earthquakes associated

with the Pamukkale Fault may reduce the serviceability of

the Denizli water supply system by half whereas an M6.5

or M7 earthquake could bring the entire water supply

system to a halt. However, in the case of the Karakova-

Akhan Fault, which is closer to the city, even a M6.3

earthquake may bring the entire water supply system to a

complete halt.

Comparison of the serviceability index results in

Table 1 shows that PGD has more damage potential than

TGD for the pipeline system. This result is consistent with

that of O’Rourke (1999) who used a hypothetical location

and water distribution system with a limited number of

damage relationships. For the same earthquake scenario,

use of a different TGD damage relationship does not affect

the serviceability index significantly. This is primarily

because the variation in TGD relationships is relatively

small compared to the predominant effect of PGD damage.

The nature of the pipe material is very important in the

response of pipelines to earthquake forces, with brittle

pipelines more prone to damage than ductile pipes. Many

of the cast iron pipes were damaged during the 1976 M4.9

earthquake (Kaygin 2004, personal communication).

Asbestos cement pipes are more widespread and their use

should also be avoided, especially in and around PGD

zones as a high concentration of breaks and leaks can

impair the functionality of fire hydrants in a wide area, as

well as delay the restoration of a water service after the

earthquake. It is recommended that as part of mitigation

planning, a replacement programme should begin with CI

pipelines and progress to AC pipelines, especially in and

around high PGD zones. Such a programme could be

integrated into regular maintenance work in order to utilize

limited financial resources. Various methods (e.g., trench-

less technologies) are available to minimise the impact of

construction on residents, businesses and the environment

as far as possible (see Lund 2003).

Fig. 9 Water supply system superimposed on the peak ground

velocity (PGV) zones for an M6.3 earthquake associated with the

Karakova-Akhan Fault


123

This study has only considered the damage to pipelines

as a consequence of ground motion. It does not take

account of the effect of failure of other structures during an

earthquake, which may disrupt the connections between

distribution lines and the buildings and result in substantial

water loss such that the performance of the system as a

whole is significantly reduced. Similarly, water supply

restoration can be affected by the extensive building

Table 2 Predicted pipeline damage and performance of the system for the scenario earthquakes

Mw TGD methods Number of repairs Average break rate Serviceability index (%)

PGD methods PGD methods PGD methods

ALA HAZUS ALA HAZUS ALA HAZUS

Pamukkale fault rupture

6 Toprak (1998) 49 ? 43 15 ? 43 0.03 0.01 93 100

O’Rourke and Jeon (1999,

2000) diameter scaled PGV

49 ? 113 15 ? 113 0.04 0.02 85 98

ALA (2001) 49 ? 52 15 ? 52 0.03 0.01 93 100

O’Rourke ve Deyoe (2004) 49 ? 72 15 ? 72 0.03 0.02 93 100

6.3 Toprak (1998) 228 ? 64 79 ? 64 0.11 0.04 46 85



228 ? 151 79 ? 151 0.12 0.05 45 80

ALA (2001) 228 ? 76 79 ? 76 0.11 0.04 46 85

M.O’Rourke ve Deyoe (2004) 228 ? 91 79 ? 91 0.11 0.05 46 80

6.5 Toprak (1998) 738 ? 82 294 ? 82 0.35 0.14 6 34



738 ? 181 294 ? 181 0.36 0.16 6 34

ALA (2001) 738 ? 89 294 ? 89 0.35 0.14 6 34

M.O’Rourke ve Deyoe (2004) 738 ? 106 294 ? 106 0.35 0.15 6 34

7 Toprak (1998) 1,820 ? 131 1,007 ? 131 0.85 0.48 2 4



1,820 ? 255 1,007 ? 255 0.86 0.49 2 4

ALA (2001) 1,820 ? 119 1,007 ? 119 0.85 0.48 2 4

O’Rourke ve Deyoe (2004) 1,820 ? 138 1,007 ? 138 0.85 0.48 2 4

Karakova-akhan fault rupture

6 Toprak (1998) 339 ? 85 119 ? 85 0.17 0.06 26 75



339 ? 182 119? 182 0.18 0.08 26 60

ALA (2001) 339 ? 90 119 ? 90 0.17 0.06 26 75

O’Rourke ve Deyoe (2004) 339 ? 108 119 ? 108 0.17 0.07 26 65

6.3 Toprak (1998) 841 ? 113 366? 113 0.40 0.18 5 24



841 ? 225 366 ? 225 0.41 0.19 5 24

ALA (2001) 841 ? 108 366 ? 108 0.40 0.18 5 24

O’Rourke ve Deyoe (2004) 841 ? 127 366 ? 127 0.40 0.18 5 24

6.5 Toprak (1998) 1,364 ? 132 690 ? 132 0.64 0.33 3 6



1,364 ? 257 690? 257 0.65 0.35 3 6

ALA (2001) 1,364 ? 119 690 ? 119 0.64 0.33 3 6

M.O’Rourke ve Deyoe (2004) 1,364 ? 132 690 ? 132 0.64 0.33 3 6

7 Toprak (1998) 2,577 ? 174 1,796 ? 174 1.20 0.84 0 2



2,577 ? 319 1,796 ? 319 1.22 0.86 0 2

ALA (2001) 2,577 ? 142 1,796 ? 142 1.20 0.84 0 2

O’Rourke ve Deyoe (2004) 2,577 ? 163 1,796 ? 163 1.20 0.84 0 2


123

damage as in the case of Adapazari after the 1999 Kocaeli

earthquake.

Summary and conclusions

The prediction of potential damage to services is a critical

part of seismic planning which includes hazard mitigation,

risk management and emergency response for future

earthquakes.

This study evaluates the serviceability of the water

distribution system in Denizli, Turkey, in the event of an

earthquake associated with the Pamukkale and Karakova-

Akhan Faults and compares the relative effects of transient

ground deformations (TGD) and permanent ground defor-

mations (PGD) on both brittle and ductile pipelines.

The analyses show that an M6 or M6.3 movement of the

Pamukkale Fault could reduce the efficiency of the Denizli

water supply system by half while a M6.5 or M7 earth-

quake would bring the entire water supply system to a halt.

In the case of the Karakova-Akhan Fault, even a M6.3

earthquake could totally disrupt the water supply system.

The study also showed that the relative contribution of

PGD and TGD on the number of pipeline repairs depends

on the earthquake magnitude. For an M6 earthquake, TGD

related repairs are higher than PGD related repairs. For an

M6.3 earthquake, the repairs are comparable; the variation

being associated with the damage relationships used in the

analyses. As the magnitude of the earthquake increases to

M7, PGD related repairs become more pronounced while

the effect of the damage relationship used with TGD is

substantially reduced.

It is recommended that to reduce pipeline damage in

urban areas, special emphasis should be given to the

replacement of brittle pipes with ductile materials, espe-

cially where permanent ground deformations are antici-

pated. In view of the similarity of the water supply systems

in many mid-size cities in Turkey, it is hoped that the

results of this study will also assist in other areas both in

Turkey and abroad.

Acknowledgments The research reported in this paper was sup-

ported by Scientific and Technological Research Council of Turkey

(TUBITAK) under Project No. 106M252 and Pamukkale University

Research Fund under Project No. 2003MHF006. The authors are very

Pamukkale Fault - ALA PGD

0

500

1000

1500

2000

2500

3000

6.0 6.3 6.5 7.0 6.0 6.3 6.5 7.0

Magnitude

Rep

air

Nu

mb

er

Toprak (1998)

O'Rourke & Jeon (1999,2000)

ALA (2001)

O'Rourke & Deyoe (2004)

Pamukkale Fault - HAZUS PGD

0

500

1000

1500

2000

2500

3000

Magnitude

Rep

air

Nu

mb

er

Toprak (1998)

O'Rourke & Jeon (1999,2000)

ALA (2001)

O'Rourke & Deyoe (2004)

Karakova-Akhan Fault - ALA PGD

0

500

1000

1500

2000

2500

3000

Magnitude

Rep

air

Nu

mb

er

Toprak (1998)O'Rourke & Jeon (1999,2000)

ALA (2001)O'Rourke & Deyoe (2004)

Karakova-Akhan Fault - HAZUS PGD

0

500

1000

1500

2000

2500

3000

Magnitude

Rep

air

Nu

mb

er

Toprak (1998)O'Rourke & Jeon (1999,2000)

ALA (2001)O'Rourke & Deyoe (2004)

6.0 6.3 6.5 7.0 6.0 6.3 6.5 7.0

Fig. 10 Number of repairs

predicted by various damage

relationships for the eight

earthquake scenarios studied


123

grateful to the Water Works staff of various municipalities for their

interest and assistance in assembling the water system data and in

particularly to Orhan Kaygin, Sule Vardar, Sibel Cukurluoglu and

Yusuf Ornek of Denizli Municipality Water Works Department for

their continuous support and discussions. Thanks are also extended to

Mehmet Genc of General Directorate of Disaster Affairs, Denizli

Branch, and the Geology Department of PAU, especially Prof. Halil

Kumsar for providing base maps for Denizli area and valuable

comments and discussions.

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