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BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
1
Impact of Extreme Urbanization on Water Resources and Flood Risk
in Sazlıdere Watershed, Istanbul
Sezar GÜLBAZ
1
Cevza Melek KAZEZYILMAZ-ALHAN
2
1,2
Department of Civil Engineering, Istanbul University, Istanbul, Turkey
E-mail: meleka@istanbul.edu.tr
Abstract
Water resources are vital elements of nature and protecting these sources plays an important role in
terms of meeting future drinking water demand and preventing flood events. Thus, exploring and
evaluating the results of human activities, that have a direct influence on water resources and flood
events, is of common interest to researchers in the hydrology area. Especially in drinking watersheds,
new developments interfere with the quantity of drinking water and flood as these strongly depend on
the increase in population which causes an increase in residential areas. Increase in residential areas
results in the alteration of time of concentration, water quantity, and flow rate. Therefore, the impact of
urbanization on water resources and flood should be investigated to avoid present and future
problems such as floods, droughts and pollution.
In this study, Sazlıdere Watershed located in Istanbul, Turkey is selected as the study site, which
provides an average of 55 million m3 of water per year to the city. Sazlıdere Watershed has 165 km2
of drainage area and the surface runoff, which develops on the watershed, flows into Sazlıdere Dam
Lake. The area is composed of high residential, low residential, industrial, agricultural and mostly
forest regions. However, there is a great potential of population growth and therefore a tendency of
increase in the residential area. Sazlıdere Watershed has experienced a rapid land use/cover change
especially during the last two decades and these changes are expected to continue in the future due
to tremendous population increase in this area.
The aim of this study is to investigate the impact of extreme urbanization on surface runoff and flood in
Sazlıdere Watershed by employing a calibrated hydrodynamic model according to various land use
scenarios. For this purpose, first, a calibrated hydrodynamic model was developed for the Sazlıdere
Watershed by using Environmental Protection Agency Storm Water Management Model (EPA
SWMM) which is a dynamic simulation model for the surface runoff that develops on a watershed
during a rainfall event. For model calibration and validation, we set up a rain gauge and a flow meter in
the field and read rainfall and flow rate data. Next, we simulated the flow developed on the watershed
under typical rainfall event measured from the rain gauge with the calibrated hydrodynamic model.
Finally, we investigated the model under different extreme urbanization scenarios by using typical and
extreme rainfall event to observe the possible effects of human activities on overflow and flood risk in
Sazlıdere Watershed. We found that even under typical storms, floods develop on the watershed and
finally several stream restoration options are suggested to prevent flood risk and water loss.
Keywords: Flood risk, impact of urbanization, hydrodynamic watershed model, calibration, EPA
SWMM.
Introduction
Because of the increasing negative effect of global warming and ascending population, protection of
the water resources becomes more important day by day. Rapid urban development and therefore the
effect of increase in water demand on water resources are pointed out by Almeida et al. (1).
Scrutinizing the behavior of water resources system is required to control and improve water supply
and quality. Water resources gradually become insufficient due to extreme usage of water with
increasing population, rapid urbanization and developing industrial and agricultural facilities.
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
2
Therefore, in order to overcome these emergent problems, it is crucial to protect and use water
resources effectively. In this respect, water resources management related issues are widely studied
in the literature. Additionally in many studies, flood control and water quality are analyzed in order to
meet society’s needs and plan natural resources in the watershed (2, 3, 4). Among these studies are
observation of hydrologic events having impact on the surface and ground water within the watershed,
measuring the hydraulic and hydrological data in a systematic way, and developing numerical models
to simulate the hydrology and hydraulics of the watershed. Particularly, mathematical and computer
models in water resources and watershed management are commonly used as a result of rapidly
developing information technologies.
In the literature, many studies exist on water quantity and quality modeling for both urban and rural
areas (5, 6, 7). One of the watershed modeling software program is Environmental Protection Agency
Storm Water Management Model (EPA SWMM). EPA SWMM is commonly used in many studies to
model the water quantity and quality modeling in the literature. As an example, two industrial parks in
Taiwan are modeled in order to correlate the relationship between pollutant mass and the runoff
volume by Chang et al. (8). Gülbaz and Kazezyılmaz-Alhan (9) used EPA SWMM in their study to
model part of the Çoruh River Watershed in Turkey. Another implementation of EPA SWMM is
modeling two best management practices of rain gardens and rain barrels by Aad et al. (10).
Application of EPA SWMM to Devil’s Icebox–Connor’s Cave System in Central Missouri, USA was
done by Peterson and Wicks (11).
The study area Sazlıdere Watershed is among the most vital drinking watersheds in Istanbul
Metropolitan Area and provides an average of 55 million m
3
of water per year to the city. Despite the
rural areas within the watershed, rapid urbanization caused by the ascending population threatens
water resources to a great extent. Therefore, Sazlıdere Watershed is studied through hydrological
models and water quality analyses in order to highlight this problem and many solution options are
suggested in these studies (12, 13, 14). However, there is not a calibrated and detailed hydrodynamic
model available for Sazlıdere Watershed among the studies mentioned above. Establishing a
calibrated hydrodynamic model for Sazlıdere Watershed located in Istanbul, Turkey, analyzing
extreme events, and suggesting measures in order to protect water resources within the area is aimed
in this study. In order to serve this goal, EPA SWMM is used in order to model Sazlıdere Watershed
by using data related to watershed characteristics. Then, rainfall and flow rate measurements on the
field site are made to calibrate the model. Finally, the calibrated model is used to simulate surface
runoff and potential floods under typical rainfall event and extreme cases, namely rapid urbanization
and rainfall event with high return period and solution options are suggested.
Governing Equations
EPA SWMM is a dynamic simulation model for the surface runoff developing on a watershed during a
storm (15, 16). The quantity and quality of surface runoff on each subcatchment; the flow rate, the
depth, and the concentration in each conduit and junction can be calculated by EPA SWMM. Input
data for the watershed profile is composed of width, slope, area, and percent perviousness-
imperviousness for each subcatchment; length, cross section, height, and slope for each conduit; and
elevation for each junction. The outputs from the program are change of flow rate (hydrograph) and
change of concentration (pollutograph) through time, while the change of the rainfall intensity through
time (hyetograph) is given as input to the program. In order to calculate flow rate, EPA SWMM solves
the continuity and momentum equations for flood routing. One can select kinematic, diffusion, or
dynamic wave options according to the characteristics of the considered catchment. The most general
form of the flood routing equations is the dynamic wave equations which describe unsteady non-
uniform flow. Kinematic wave equations can be derived from the dynamic wave equations by
neglecting both inertial and pressure terms in the momentum equation, whereas diffusion wave
equations are obtained by ignoring only the inertial terms. The dynamic wave equations for flow
routing in conduits are given as follows (17):
0
x
Q
t
A
(1)
0
11
0
2
f
SSg
x
y
g
A
Q
x
Q
At
Q
A
(2)
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
3
where Q is the flow rate (L
3
/T), A is the cross-sectional area (L
2
), y is the water depth (L), S
f
is the
friction slope (L/L), S
0
is the bed slope (L/L), g is the gravitational acceleration (L/T
2
), t is the time (T),
and x is the distance (L).
The kinematic and diffusion waves are obtained from the dynamic wave equations as follows (18):
0
0
x
A
t
A
AQ
x
Q
t
A
m
m
(3)
where α and m are given according to the flow rate-friction slope relationship.
0
2
2
0
2
0
BS
Q
KmVc
x
Q
K
x
Q
c
t
Q
x
y
SS
x
Q
t
A
f
(4)
where, c is the diffusion wave celerity (L/T), K is the hydraulic diffusivity (L
2
/T), and B is the width (L).
In order to calculate infiltration, EPA SWMM uses three methods, namely the Green-Ampt Method, the
Integrated Horton Method and the SCS Curve Number Method. The equations for each method are
given as follows:
Green-Ampt Method (16):
.calculatednot is if
1/
if
for
ss
s
u
ss
s
FKi
Ki
MS
FKi
i f :FF
(5)
F
MS
KfffFF
u
spps
1 and : for
(6)
where F is the cumulative infiltration (L), F
s
is the cumulative infiltration of saturated soil (L), i is the
rainfall intensity (L/T), K
s
is the hydraulic conductivity for saturated soil (L/T), S
u
is the suction head (L),
M is the initial moisture deficit (L/L), f is the infiltration rate (L/T), and f
p
is the infiltration capacity (L/T).
Integrated Horton Method (16):
-
t-
0
efftff
p
)](),([min)( titftf
p
t
dftF
0
)()(
(7)
where f
∞
is the minimum infiltration capacity (L/T), f
0
is the infiltration capacity for dry soil (L/T), and α is
a constant (1/T).
SCS Curve Number Method (19):
a
r
IP
Q
S
F
(8)
FIQP
ar
(9)
where S is the potential retention (L), Q
r
is the actual runoff (L), P is the potential runoff (L), and I
a
is
the initial abstraction (L).
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
4
Research Area
Sazlıdere Watershed is located on European Continental side of Istanbul, Turkey and Sazlıdere Dam
is located at downstream point of the watershed. Sazlıdere Watershed has 165 km
2
of drainage area
and the surface runoff generated over Sazlıdere Watershed flows to Sazlıdere Dam Lake. In Figure 1,
Sazlıdere Watershed and Sazlıdere Dam Lake, which is built up in 1996, is given. Since Sazlıdere
Watershed supplies a major part of drinking water of Istanbul metropolitan area, the protection and
improvement of the watershed is important. The water capacity of the lake is 91,600,000 m
3
/year
according to the measurements of Istanbul Municipality Waterworks (ISKI). The altitude of the
watershed from the sea level in reservation areas is between 6-20 m and it reaches 170 m in the north
and south topographic boundaries (20, 13).
Figure 1. Location and boundary of Sazlıdere Watershed (Retrieved from Google Earth).
Model Setup and Data Collection
In this study, for the calibration and validation of the hydrodynamic model of Sazlıdere Watershed in
EPA SWMM, rainfall and flow rate need to be measured at the field site. In order to measure rainfall
data, a rain gauge was set up in the middle of the watershed. In addition to rain gauge, we set up a
flow meter near the downstream of Türkköse Stream in the watershed and we measured the velocity
and the corresponding water depth every half an hour during each rainfall event simultaneously with
rainfall data. In order to obtain the flow rate, the cross-sectional area of Türkköse Stream, at which the
flow meter is located, is also measured. The rainfall data is continuously collected by automatic data
logger from November 2009 to May 2010 and flow rate is measured during 5 rainfall events. Part of
the Sazlıdere watershed area, which feeds Türkköse Stream, is divided into 177 subcatchments by
using the topographical map of the modeled area to establish the hydrodynamic model accurately.
Then, using the topographical map, channels collecting the overland flow generated over the
subcatchments, are determined and introduced into the program as conduits. 173 conduits, which are
approximately 44 km long in total, are formed by defining length and cross-section of each conduit.
Each conduit is connected with junctions which are described by invert elevation and inflows. A total
number of 171 junctions are defined for the hydrodynamic model. In Figure 2, the hydrodynamic model
of Sazlıdere Watershed is shown. Here, the green lines represent the subcatcment borders and the
blue lines represent the conduits, i.e. open channels. The location of rain gauge and flow meter are
pointed with a red circle on the figure.
SAZLIDERE
DAM
BULGARIA
TURKEY
BLACK
SEA
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
5
Figure 2. Hydrodynamic model of Sazlıdere Watershed in EPA SWMM.
Calibration and Validation
The hydrodynamic model of Sazlıdere Watershed has been calibrated manually. In order to make
calibration and validation of the model, five storm events of the Sazlıdere Watershed were monitored,
and then the measurements were used to calibrate the model in EPA SWMM. Simulation of different
scenarios were made by using the verified model in order to examine the impact of ascending
population and extreme storm events on the amount of water and flood on the Sazlıdere Watershed.
Manning’s roughness coefficient (N) for pervious and impervious area, depth of depression storage (d)
on pervious and impervious area, Manning’s roughness coefficient (n) for conduits, hydraulic
conductivity (K), and parameters that define the soil type are selected initially according to their typical
values reported in the literature for the calibration of the hydrodynamic model (15, 16, 21). After that,
the values of these parameters are tuned until the flow rate simulated by the model matches the
measured flow rate. After calibration, simulated and measured flow rate results obtained for rainfall
event on February 14-17, 2010 are shown in Figure 3.
Figure 3. Measured and calculated flow rates for the calibration of the hydrodynamic model in EPA
SWMM during rainfall event on February 14-17, 2010 at downstream point of the watershed.
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
6
Discussion of Results
By using the calibrated model, we investigated effects of population growth, extreme urbanization, and
extreme storm event on surface runoff on Sazlıdere Watershed and flow in Türkköse Stream.
Moreover, we suggested several stream restoration options in order to prevent the flood events within
the area and simulations are repeated for the case after stream sections are restored.
1. Population Growth
The impact of population growth is predicted in this part of the study. Population growth causes an
increase in the impervious surfaces as the residential areas ascend. Thus, flooding risk emerges with
the surface runoff generated over the catchment. The flow under current population, which
corresponds to approximately 10% of the urbanized area, and the flow under estimated population for
the year 2035 (calculated with population projection method), which corresponds to 20% of the
urbanized area, are simulated and compared in order to examine the effect of population growth on
the flow. For the simulations, 20 independent rainfall data were recorded by rain gauge set into the
catchment during December 2009-March 2010 and 1 set of data is selected for the simulations of the
flow rate at downstream point of the watershed. The simulation results, which correspond to this single
storm event, are shown in Figure 4. The calculated flow rates at the outfall for the year 2010 and for
the year 2035 with the existing cross sections are labeled as “Q_2010_current” and “Q_2035_current”,
respectively. “Rainfall series I” was measured during January 22-23, 2010 on which the rainfall lasted
for 2 days and the flow generated over the catchment during this rainfall is predicted by the calibrated
the hydrodynamic model. Figure 4 shows the flow rate versus time at the outfall of the watershed for
the population of the year 2010 and 2035. As it can be seen from this figure, even for population of
year 2010, the conduits surcharge between the hours of 16-23 and 26-27, which means that a flood
event occurs even during this typical rainfall. When the population of year 2010 is considered, the total
amount of water generated on the watershed is calculated as 1,620,848 m
3
and 246,209 m
3
of this
amount overflows which corresponds to 15.1% of the total amount of water. When the population of
year 2035 is considered, the total amount of water generated on the watershed is calculated as
1,691,119 m
3
and 259,525 m
3
of this amount overflows which corresponds to 15.3% of the total
amount of water. Thus, the difference between the total water for the population of year 2010 and
2035, which develops on the Sazlıdere Watershed after the rainfall, is calculated as 70,271 m
3
. And
13,316 m
3
of this amount results in an increase in the amount of flood. Therefore, the increase in total
amount of water and flood expected on the watershed due to the population growth is 4.3 and 5.4%,
respectively. In addition, the increase in the total amount of water generated over the catchment due
to population growth is on the order of 10
5
m
3
under this recorded storm.
0
5
10
15
20
25
30
0 5 10 15 20 25 30 35 40 45 50
Time t (hr)
Flow Q (m
3
/s)
0
1
2
3
4
5
6
Rainfall intensity i (mm / hr)
Rainfall intensity Q_2010_current Q_2035_current
Figure 4. Rainfall intensity and predicted flow rate for the year 2010 and 2035 versus time at the
outfall of the Sazlıdere Watershed during rainfall event I with the current cross sections of the
channels.
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
7
2. Extreme Urbanization
In this part of the study, we simulated surface runoff and stream flow for 40%, and 80% of
imperviousness on the catchment under rainfall event I, in order to see the effect of extreme
urbanization. Extreme urbanization is greatly possible on the order of 40-80% in place like Istanbul
which is a big metropolitan city and is continuously growing. The calculated flow rates at the outfall for
year 2010, which correspond to 10% urbanization under current stream sections and under suggested
stream restoration, are labeled as “Q_2010_current” and “Q_2010_suggestion 1”, respectively.
Similarly, the calculated flow rates for 40% urbanization under current stream sections and under
suggested stream restoration are labeled as “Q_40%_current” and “Q_40%_ suggestion 1”,
respectively.
Figure 5 shows the hydrographs obtained at downstream of the watershed for 10% and 40% of
urbanization with stream restoration and with no stream restoration. According to the population of
year 2010, the amount of water that causes flood, was determined as 246,209 m
3
which corresponds
to 15.1% of the total amount of water generated over the catchment. When 40% of urbanization is
considered, the amount of water that causes flood, is determined as 289,171 m
3
which corresponds to
17% of the total amount of water generated over the catchment. Thus, in case of 40% of urbanization,
the flood that may occur in Türkköse Stream, will cause 17% of more water running over the
catchment. Therefore, we propose stream restoration in order to prevent flood events on the
catchment. For this purpose, we re-run the model by increasing the cross-sectional areas of the
Türkköse Stream 2.5 times (suggestion 1). When the restored stream sections are considered, we see
that the stream will be able to carry the expected rising flow rate and no flood will occur under extreme
urbanization with this suggested stream restoration. The same simulations are repeated for the case
of 80% of residential area and the results are presented in Figure 6 and summarized in Table 1. We
found that with the restored stream sections, the flood can be prevented and the stream can sustain all
the water generated over the catchment.
Figure 5. Comparison of the hydrographs obtained for 10% and 40% of urbanization for the cases
with stream restoration and with no stream restoration.
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
8
Figure 6. Comparison of the hydrographs obtained for 10% and 80% of urbanization for the cases
with stream restoration and with no stream restoration.
Table 1. The amount of water and flood generated over the Sazlıdere Watershed for 40%, and 80% of
urbanization under current stream sections and rainfall event I.
40%
urbanization
80%
urbanization
Amount
of water
(m
3
)
%
Amount
of water
(m
3
)
%
Total amount of water
1,740,544
2,024,483
Amount of flood
289,171
17
413,040
20
Increase in amount of total water due to
urbanization
119,696
7
403,635
25
Increase in amount of flood due to urbanization
42,962
17
166,831
68
3. Extreme Storm Events
In this part of the study, we simulated the flow generated on Sazlıdere Watershed under an extreme
rainfall event recorded at Florya Meteorological Station in Istanbul, Turkey on July 03-05, 2005. It is
seen that the stream restoration proposed in the previous section (suggestion 1) is not adequate to
sustain the flow generated during this storm. Thus, this suggestion is still insufficient in order to
prevent flooding under extreme rainfall events. Therefore, the model was re-run by increasing the
cross-sectional areas of the Türkköse Stream further, namely increasing by 4 times the original cross-
sections (suggestion 2) and the results are presented under the same extreme rainfall event. We
observed that the second suggested restored stream can sustain the flow and therefore, the flood can
be prevented. Figure 7 shows the predicted flow rate versus time at downstream point of the Sazlıdere
Watershed occurred during the rainfall event on July 03-05, 2005. In this graph, the hydrograph
obtained by using the current stream sections and proposed stream sections under suggestion 1 and
suggestion 2 for the population of year 2010 are labeled as “current”, “suggestion 1”, and “suggestion
2”, respectively. As it can be seen from this figure that flooding occurs between hours 24-27 under
current stream sections. As a result of this rainfall event, the amount of water generated on the
catchment is calculated as 1,904,948 m
3
and 1,125,266 m
3
of this amount causes flooding which
corresponds to 59% of the total amount of water with current cross-sections. If the simulation is
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
9
repeated under the same storm by using the first suggested stream sections, we still observe flooding
for an amount of 573,002 m
3
which corresponds to 30% of the total water. Therefore, the stream
sections are further increased and the simulation is repeated again with the second suggested stream
sections after which no flooding is observed.
Figure 7. Flow rate and rainfall intensity versus time at the outfall of the watershed for July 03-05,
2005 storm event under the population for the year 2010 (10 % urbanization).
Conclusions
In this study, EPA SWMM is employed in order to develop a calibrated hydrodynamic model for
Sazlıdere Watershed in Istanbul, Turkey. Rainfall and flow rate at downstream of Türkköse Stream
have been measured by setting up a rain gauge and a flow meter into the field site. Calibration and
validation of the hydrodynamic model have been accomplished by making use of the measured data
set. Population effects on the amount of water and flood generated over the Sazlıdere Watershed are
predicted under typical rainfall event by using the measured data set on the site. Furthermore, effects
of extreme urbanization and extreme storm on water quantity are also investigated by using the
calibrated hydrodynamic model. Control strategies for any possible flood event on Sazlıdere
Watershed are discussed and several stream restoration options are suggested as a best
management practice (BMP). Following conclusions are reached based on the analyses carried out in
this study:
1) The current stream sections of Türkköse Stream are insufficient to carry the flow even under typical
rainfall events. Due to this fact, a notable increase in the amount of flooding is observed due to the
population increase in Sazlıdere Watershed.
2) Unbounded and unexpended extreme population increase and thus extreme urbanization result in
an extreme increase in water quantity and flood events. Stream restoration – increasing current cross
sections by 2.5 times in case of Türkköse Stream- may be a viable solution in preventing such
extreme flood events.
3) The current stream sections of Türkköse Stream are not large enough to route water downstream
generated over the watershed under extreme storm event and significant flooding occurs. No flooding
would occur only if the current cross-sectional areas are increased at least by 4 times as part of a
stream restoration solution.
BALWOIS 2012 - Ohrid, Republic of Macedonia - 28 May, 2 June 2012
10
Acknowledgements
This work was supported by Scientific Research Projects Coordination Unit of Istanbul University,
Project Number 4212. The authors would also like to thank General Directorate of State Hydraulics
Works (DSI), Turkish State Meteorological Service (DMI), Istanbul Metropolitan Municipality (IBB) and
Istanbul Municipality Waterworks (ISKI) for their support and valuable discussions in undertaking this
work.
References
(1) C.M.V.B. Almeida, D. Jr. Borges, S.H. Bonilla and B.F. Giannetti, Resources, Conservation and
Recycling, 54, 821-831 (2010).
(2) B. Yilmaz and N.B. Harmancioglu, Water Resources Management, 24, 4359-4379 (2010).
(3) I. Heinz, M. Pulido-Velazquez, J.R. Lund and J. Andreu, Water Resources Management, 21,1103-
1125 (2007).
(4) Y.P. Li, G.H. Huang and S.L. Nie, Advances in Water Resources, 29, 776-789 (2006).
(5) K.C. Abbaspour, J. Yang, I. Maximov, R. Siber, K. Bogner, J. Mieleitner, J. Zobrist and R.
Srinivasan, Journal of Hydrology, 333, 413-430 (2007).
(6) C.M. Kazezyılmaz-Alhan, M.A. Jr Medina and C.J. Richardson, Water Resources Research, 43,
Art. No. W04434 (2007).
(7) S. Jang, M. Cho, J. Yoon, Y. Yoon, S. Kim, G. Kim, L. Kim and H. Aksoy, Desalination, 212, 344–
356 (2007).
(8) C.H. Chang, C.G. Wen and C.S. Lee, Water Resources Management, 22, 1609–1623 (2008).
(9) S. Gülbaz and C.M. Kazezyılmaz-Alhan, River Flow Analysis by using Kinematic and Dynamic
Wave Models, Water and Energy Conference in Artvin, Turkey, 363-372 (2008).
(10) M.P.A. Aad, M.T. Suidan and W.D. Shuster, Journal of Hydrologic Engineering, 15, 434-443
(2010).
(11) E.W. Peterson and C.M. Wicks, Journal of Hydrology, 329, 294-305 (2006).
(12) A. Karaburun and A. Demirci, Fresenius Environmental Bulletin, 18, 2181-2191 (2009).
(13) A. Akça, Sazlıdere basin water quality, cost optimizations of waste water treatment and evaluation
of wetlands cost, M.S. thesis, Yıldız Technical University, Istanbul, Turkey (2005).
(14) H. Selcuk, Y. Vitosoglu, S. Ozaydin and M. Bekbolet, Desalination, 176, 211-217 (2005).
(15) L.A. Rossman, Storm Water Management Model, User’s Manual, Version 5, Water Supply and
Water Resources Division National Risk Management Research Laboratory, Cincinnati, Ohio, U.S.
Environmental Protection Agency, EPA/600/R-05/040 (2010).
(16) W.C. Huber and R.E. Dickinson, Storm Water Management Model, Version 4, User’s Manual,
Athens, GA. Environmental Research Laboratory, Office of Research and Development, U.S.
Environmental Protection Agency (EPA) (1988).
(17) V.T. Chow, D.R. Maidment and L.W. Mays, Applied Hydrology, McGraw-Hill Book Company,
USA, 0-07-010810-2 (1988).
(18) M.J. Lighthill and G.B. Whitham, On kinematic waves. I. Flood movement in long rivers,
Proceedings, Royal Society of London, London, England, Series A, 229, 281-316 (1955).
(19) V.M. Ponce and R.H. Hawkins, Journal of Hydrologic Engineering, 1, 11-19 (1996).
(20) M.E. Birpınar, N. Özkılıç, M.A. Aktürk, H. Mumcuoğlu, S. Pirim, S. Kurtuluş, S. Aykırı, M. Yaman,
A. Vardar, A. Kuzlu, B. Çakmak, B. Akdağ, F. Cihan, G.M. Selvi, İ. Şanlımeşhur, İ. Sadıkel, J.
Özdoğan, A. Karabulut, Ö. Akkaş Sezgin, R. Bukni, Ş. Tezcan, T. Erdoğan, Y. Karaaslan,
Environmental Report of Istanbul for year 2005, Istanbul Directorate of Environment and Forestry,
Turkey (2006).
(21) J. Temprano, O. Arango, J. Cagiao, J. Suarez and I. Tejero, Water SA., 32, 55-63 (2006).
