Mitigation Strategies Based on Flash Floods Simulation Considering Water
Resources Management at Wadi El-Arish, Sinai Peninsula, Egypt
M. Saber

Geology Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt
msaber_75@yahoo.com

T. Hamaguchi & K. Tanaka

Water Resources Research Center, Disaster Prevention Research Institute, Kyoto University, Kyoto, JapanS. A. Kantoush

Civil Engineering Department, Faculty of Engineering and Material Science, The German University in Cairo – GUC, Cairo – Egypt

T. SumiWater Resources Research Center, Disaster Prevention Research Institute, Kyoto University, Japan

ABSTRACT:In arid regions, flash floods are the most devastating hazards in terms of loss of human lives and infrastructures. The main goal of thispaper is to simulate flash flood and to propose mitigation strategies in order to reduce the threat of flash floods and utilize its water inthe proper way at Wadi El-Arish, Egypt. Global Satellite Mapping of Precipitation (GSMaP) is integrated with Hydro-BEAM(Hydrological River Basin Environmental Assessment Model) for flash floods simulation. The simulation has been successfully carriedout to the flash flood event which hit Egypt on Jan. 18-20, 2010. The simulation results exhibit reasonable results coinciding with theactual situation. The contributed water of Wadi sub-catchments has been estimated and some mitigation strategies have been proposed
leading to future risk reduction in such regions. The developed methodology to forecast flash floods considering mitigation strategies
can be applied effectively at different arid regions.
Keywords: Flash flood simulation, GSMaP, flash flood mitigation, Wadi system, arid regions

1. INTRODUCTION
In many countries and regions of the world, flash floods
are the most deadly hazards in terms of both loss ofhuman lives and material damage (Fattorelli, et al.,1999). The main obstacle to study flash flood is clearly
the lack of reliable observations in most of the flash floodprone basins, thus, there is urgent necessity to develop a
new methodology to simulate and forecast flash flood inarid regions. The water demand in such areas increases
daily due to population growth, economic development,
and urbanization, thus, water management using all theavailable resources is becoming crucial. Furthermore, thedanger also comes from the rarity of the phenomenon,
which demands a new observation strategy, as well as
new forecasting methodology. Various problems
associated with forecasting flash floods caused byconvective storms over semi-arid basins have beenstudied by Michaud and Sorooshian, (1994). Rapidly
increasing availability of good quality weather radarobservations is greatly expanding our ability to measureand monitor rainfall distribution at the space and timescales which characterize the ﬂash-ﬂood events (Borga etal., 2007). Hydrological models of varying complexity
approaches are applied to provide detailed estimates offlow processes for ungauged regions (Sangati, et al.,2009; Bonnifait, et al., 2009; Bloschl et al., 2008; Reed etal., 2007; Bohorquez, et al., 2008). A method for
estimating flash flood peak discharge, hydrograph, andvolume has been presented by Aristeidis, and Ioannis(2010).
Ascribable to the aforementioned problems andcharacteristics of flash floods in arid regions, an efficient
integration of using remote sensing data and the
distributed hydrological model have been proposed forflash flood simulation in order to understand thecharacteristics and hydrological behaviors of flash
floods. Consequently, proposing the appropriate
strategies of mitigation in arid regions as well as flash
flood water management to overcome the scarcity ofwater resources in such regions.
Thus, the main objectives of this paper are: (i) Adoptingof an effective approach to simulate the flash floods at
wadi system with taking in our consideration the
distribution behaviors of flash floods (ii) Using remotesensing data after bias correction for a flash flood
simulation at wadi basins to overcome the challenge ofdata paucity in arid regions, (iii) Assessing andevaluating of contributed water flow of wadi basinsduring the flash flood events to be utilized as asignificant water resource, (iv) Determination of theprone areas for flash floods or vulnerability to thehazards and damage in the urbanized regions as trial toreduce the human being loss and damage of theirproperties, and (v) proposing mitigation strategies toreduce the threaten effect of flash floods.

model, the initial and transmission loss modeling isestimated by using SCS method (SCS, 1985) and
Walter’s equation (Walters, 1990), and groundwatermodeling based on the linear storage model ( Fig. 2).

2. THE TARGET WADI BASIN
Wadi El-Arish is located in Sinai Peninsula, Egypt, itflows toward the Mediterranean Sea and its downstream
part is El-Arish City, as shown in Fig. 1. This wadi
infrequently receives flash flood water from much ofnorthern and central Sinai which make a great threat for
the human life and their properties of El-Arish City
residents. It is the largest ephemeral stream system of the
Sinai Peninsula. Its catchment area is calculated about
20,700 km2 throughout GIS processing of DEM. The
growing population and increasing industrial andagricultural activities create a large demand for water
resources for people need as well as a flash flood
protection warning system.
El-Arish area has the highest annual precipitation all overEgypt, where it receives about 300mm/year. Therefore,
the city depends on its fresh shallow groundwater that is
produced from Quaternary aquifers of delta Wadi
El-Arish (Dames and Moor, 1985). Wadi El-Arishmorphology is characterized by steep slopes in the upper
part of the basin, decreasing while approaching the sea as
investigated in the watershed model of the basin.
Average annual precipitation in the interior of the basin
is less than 30 mm as compared with the average annual
rainfall along the eastern Egyptian Mediterranean coastof about 90 mm (Smith, et al., 1997).

Figure 1. Location map of Wadi El-Arish, Sinai Peninsula,
Egypt
Precipitation

Evapo-transpiration

Recovery flow
Ａ layer

su
rfa
ce
run

Wa
ste

off

wa
ter

Riv

Ｂ layer

w
flo
er

ses
Initial losＣ layer
Ｄ layer

infiltration

GW runoff
Transmission losses

Wadi System

Modeled cell
(1km, 2km, …etc)

Figure 2. Conceptual model of Hydro-BEAM (Saber, 2010)

Point 1
Point 2

3. METHODOLOGY
A physical-based distributed hydrological model andremote sensing data as well as GIS technique have been
integrated to simulate flash floods in arid regions.
Hydro-BEAM (Hydrological River Basin Environmental
Assessment Model) which was first developed by Kojiri,
et al. (1998), and it was also adopted as
Hydro-BEAM-WaS(Hydrological
River
Basin
Environmental Assessment Model Incorporating Wadi
System) by Saber et al. (2010) and Saber (2010) to be
applicable at wadi system in arid regions. It is used asphysical-based
model
with
GSMaP
(http://sharaku.eorc.jaxa.jp/GSMaP_crest/) as remotesensing data which was calibrated with Global
Precipitation Climatology Center data (GPCC:
http://gpcc.dwd.de) in order to overcome the lack ofobservations in such areas.
Hydro-BEAM-WaS consists mainly of: watershed
modeling using GIS technique, surface runoff and stream
routing modeling based on using the kinematic wave

El-Rawafaa
Dam

Point 3
Point 4
Point 5
Point 6

Figure 3. Wadi El-Arish catchment, Sinai Peninsula, Egypt,
showing the target outlets for flash flood simulation as well as
the location of El-Rawafaa Dam

4. FLASH FLOOD SIMULATION
GSMaP data of precipitation has been used with
Hydro-BEAM for flash flood simulation at Wadi
El-Arish, Sinai Peninsula, Egypt. The simulation of flash
flood event of January 18-20, 2010 was discussed
because it has a big effect on residents and theirproperties at Wadi El-Arish as well as other regions at
the upstream of the Nile River. Six outlet points have

been selected based on the sub-catchments of the target
wadi for this simulation as depicted in Fig. 3. The resultsof simulation of this event show that flash flood
characteristics are highly variable from one outlet to theothers in terms of flow rate and time to reach the
maximum peak within the whole watershed (Fig. 4).
Furthermore, at the downstream outlet at theMediterranean Sea of Wadi El-Arish, the flow was very
severe; about 2864.84m3/s. At W. Abu-Tarifieh, one of
the sub-catchments of Wadi El-Arish, the discharge wascalculated about 240.52m3/s, and the discharge of all
sub-catchments was also calculated and listed in Table 1.
The time to peak and the flow duration in flash flood
simulations have been estimated (Table 1). Time to peak
0

1200

0

20
Rainfall40

Discharge

60
80
100

2000

120
1500

140
160

1000

1000

Discharge (m3 /s)

800

Rainfall40

Discharge

60
100

600

120
140

400

160

180

500

200

0

240

180
200

200

220
61

220
0

121 181 241 301 361 421 481 541 601 661 721

240
1

61

121 181 241 301 361 421 481 541 601 661 721

Time (hour)Time (hour)(a) Point 1(b) Point 2

800

1000

0

900

20

Rainfall40

Discharge

60
80
100

600

120
140

400

160

800

Discharge (m3 /s)

Discharge (m3 /s)

1000

0
20

Rainfall (mm)

1200

180
200

100

500

120

400

140

80

100

100

50
0

120
121 181 241 301 361 421 481 541 601 661 721

Time (hour)(e) Point 5250

Discharge (m3 /s)

150

121 181 241 301 361 421 481 541 601 661 721

300

Rainfall (mm)

60

200

61

240
61

Time (hour)

40

250

1

220

(d) Point 4

20

Discharge

300

200

1

0

Rainfall

350

180

0

Time (hour)

450
400

160

300

121 181 241 301 361 421 481 541 601 661 721(c) Point 3

80

600

240
61

60

100

220
1

40

Discharge

200

200

0

700

RainfallRainfall (mm)1Discharge (m3 /s)

80

0
20

Rainfall
Discharge

200

40

150

60

100

80

50

100

0

Rainfall (mm)

2500

20

Rainfall (mm)3000

Discharge (m3 /s)

From the distribution maps of flash floods (Fig. 5) in thetarget wadi, the discontinuously flow is perfectly
depicted as one of the characteristics of ephemeral
streams, revealing that the proposed model can depict
these important surface flow behaviors in arid
environment.

Rainfall (mm)3500

is averaged between 8 hours at the upstream regions to17
hours at the downstream outlets, which means that thealarming time very short. In other words, evacuating thepeople is very difficult in such arid regions. In terms ofevaluation of sub-catchments water contribution towards
the Wadi El-Arish, the flow volume of water which canreach to the downstream point of each sub-basin havebeen calculated and listed in Table 1.

120
1

61

121 181 241 301 361 421 481 541 601 661 721

Time (hour)(f) Point 6

Figure 4. Simulation of flash flood event of (Jan.18-22, 2010) at several sub-catchment outlets of Wadi El-Arish: a) Point 1, b) Point2, c) Point 3, d) Point 4, e) Point 5, and f) Point 6

Table 1. Simulation results of event (Jan.18-22, 2010) at
Wadi El-Arish
Sub-catchmen
ts of Wadi
El-ArishOutlets

Locatio
n

Time
to
peak
(hr)

Peak
discharge(m3/s)

Flow
Volume(m3)

W. El-Arish(Point 1)

33.8E,
30.7N

172864.84

3.54 × 1008

W. El-Arish(Point 2)

33.8E,
30.4N

141080.38

1.26 × 1008

W.
Griha
(Point 3)

33.9E,
29.9N

13

1050.41

1.26 × 1008

W. Elbarok(Point 4)W.
Eqabah(Point 5)

33.7E,
29.8N
33.8E,
29.5N

10

885.389.9 × 10077

386.66

4.5 × 1007

W.
Abu-Tarifieh(Point 6)

33.7E,
29.4N

8

240.52

2.7 × 1007

El-Rawafaa Dam

Figure 5. Distribution maps of discharge of Jan. 2010 flash
flood event at Wadi El-Arish, Sinai Peninsula, Egypt, showing
discontinuous flow of discharge (red marks are the position of
sub-catchments outlets of simulation)

5. FLASH FLOOD AS SIGNIFICANT WATERRESOURCE
Water resources management is crucial and important
issue in arid regions due to the shortage of rainfall, highevaporation and transmission losses, as well as
increasing population, coupled with limited water
resources and attendant increases in need for water.
However, flash floods are devastating and representing a
big threat for human life and arid environment, it can beutilized and managed in a proper way to be useful aswater resources. Thus, in this study, one of thesignificant targets is to evaluate the flash flood water as
additional water resources. The contribution of somewadi sub-basins into Wadi El-Arish is numericallyestimated during the simulated event as listed in Table 1.
The water contribution from sub-catchments towards
Wadi El-Arish during the flash flood has been recorded.
Also, it is noticed that the contributed water flow volume
at the downstream point of wadis is varying from one
wadi to the others depending mainly on the watershedcharacteristics, rainfall distribution, and hydrologicalconditions of these sub-catchments as depicted in the
distributed maps of discharge (Fig. 5). Throughout the
study of the effect of flash floods on the aquifer of Wadi
El-Arish Delta, it was found that there is deterioration in
the groundwater levels and increasing of water salinity
due to the exceeding of abstraction comparing with therecharge to the aquifer (Shawki, 2011). To this extend, itmeans that there are no reasonable strategies for how toutilize and manage the water of flash floods properly to
be useful in a conjunctive use of surface and subsurface
water to cover the water demands.
6. FLASH FLOOD MITIGATION
Simulation results of flash flooding at Wadi El-Arish in
Sinai Peninsula show how the extent of the threat of flash
floods in wadi basins. It was investigated that from the
distribution maps, flash floods are highly variable fromone wadi to the others, relying on the rainfall events inspatial and temporal distribution, and geomorphologic
and topographic conditions at wadi catchments. The
remarks of the spatial variability of flash flood
occurrence are illustrated in the flash flood event of Jan,2010 where the most affected regions at the middle of thecatchment and around EL-Rawaffa Dam as shown in Fig.
5.
In the real situation, the downstream area after
El-Rawafaa dam has been affected by this flash flood.
The government announced that more than 14 persons
were killed in Aswan and Sinai Peninsula as well as
thousands of people becoming homeless during thisevent. These results exhibit the extent of the performanceof the proposed model to predict flash floods in suchregions. It shows the most affected regions as depictedin the results of distribution maps Fig. 5 and Table 1.
Estimating of spatiotemporal flow volume of the flash
flood affecting the target regions have been estimatedand depicted, and consequently, the risk maps and theprone areas of flash flood can easily be illustrated.
El–Rawafaa Dam (Fig 6) was constructed on 1946 at
North Sinai peninsula, Egypt, for the purpose of flash
flood mitigation to protect the downstream regions fromthe flash flood and its storage capacity about 5.8
million m3. Its width is about 350 m and its height isabout 15m. Also, it is located about 40 km distance from
Al-Arish City along Wadi El-Arish. The current
simulation of flash flood of Jan, 2010, shows that thewater volume which can reach to El-Rawafaa Dam is
more than 100 million m3 that means it is very greaterthan the actual capacity of the dam, and hence, the big
damage was occurred in this region leaving human loss
and infrastructure damage.
Relying on the simulation results of this event, two
scenarios have been recommended, the first one is toconstruct five dams at the outlets of the sub-catchments(W. Griha (Point 3), W. Elbarok (Point 4), W. Eqabah(Point 5), and W. Abu-Tarifieh (Point 6)) as shown in
Fig. 3, in order to reduce the flow volume of flash flood
water which is expected to reach to the downstream
regions at El-Rawafaa Dam, by which, the water flowing
towards the Mediterranean Sea without utilization, could
be managed as a resource of recharge to the groundwateraquifer and the threat of flash floods will be alleviated inthis area.

(a)

(b)

Figure 6. El-Rawafaa Dam before the flash flood (a), andduring the flash flood event of Jan, 2010, showing how much of
the water is overflowing the dam

The second scenario is to construct a rechargeable dam
after El-Rawafaa dam while the accumulated water will
be used in two options, the first one as surface water for
agriculture purpose because the region after El-Rawafaa
dam is plain and it can be reclaimed for cultivation
purpose. The second option is to be recharged to thesubsurface aquifer of Wadi El-Arish Delta. Accordingly,
the problem of groundwater level decreasing and salt
water intrusion increasing will be solved at Wadi
El-Arish Delta and securing flash flood water to be
utilized properly as a means to overcome the problem ofwater scarcity in such regions.
7. CONCLUSION

An integration of using remote sensing data and the
distributed Hydrological model of Hydro-BEAM has
been proposed for flash flood simulation at Wadi
–El-Arish, Egypt. GSMaP product has been comparedwith the monitored data of GPCC, revealing that an
overestimated or underestimated systematic seasonal bias
is occurred. The simulation has been carried out to the
flash flood event of Jan. 2010. The simulated resultspresent remarkable characteristics such as time to peak isvery short resulting in a difficulty to evacuate the people
from the prone regions. Additionally, the distribution
maps of flash flood corresponding to rainfall data showthat there are high variability in occurrence of flash floodin space and time in terms of wadi characteristics and thetime of the flash flood event.
The findings and advantages of this study aresummarized as follows: i) Simulation of flash flood has
been successfully achieved at wadi sub-basins of Wadi
El-Arish, ii) GSMaP is calibrated and used to simulate
the flash floods to overcome the problem of data paucity

in arid regions, iii) A commendable contribution of wadi
sub-basins as water resources towards Wadi El-Arishduring flash floods has been recorded. and iv) Proposing
some mitigating strategies for flash flood risk reductionat Wadi El-Arish, the results exhibit that flow volume
which reach to El-Rawafaa dam is higher than its
capacity, resulting in failure of the dam, loss of human
lives, and infrastructure damage. In spite of the fact thatmitigating strategies for flash flood risk reduction are
difficult to be applied, strategies for flash flood
mitigation have been proposed. In conclusion, thedeveloped methodology to forecast flash floods
considering proposing mitigation strategies and water
resources management has been accomplished.
Consequently, taking the emergency actions forevacuating the people in advance can be done so that
their lives and properties may be saved and minimized.
Further studies concerning flash flood simulation andmitigation in arid regions, will be considered in our next
turn based on detailed field works and observations.
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