Embed Size (px)
Citation preview
2/18/2014
1
Flash Floods Risk
Assessment in The Eastern
Desert
By
Eng. Mona M. Mohamed
Faculty of Engineering, Ain Shams University
Cairo, Egypt
1 2
Contents
Introduction.
The main goal.
Algorithm
Literature Review.
Methodology.
Results.
Conclusion .
References .
3
Introduction
Flash floods events
Eastern desert
Risk map
Mitigation of study
Literature Review
Methodology
Results
Conclusion
References
The flash floods events in Egypt and its effect. (1969,1980,1984,1985,1994)
INTRODUCTION
Heavy rainfall has caused floods across Egypt
including Al Arish 2010
4 4
Introduction
Flash floods events
Eastern desert
Risk map
Mitigation of study
Literature Review
Methodology
Results
Conclusion
References
Eastern Desert as a semi arid region is the
study area.
INTRODUCTION
2/18/2014
2
5 5 5
Introduction
Flash floods events
Eastern desert
Risk map
Mitigation of study
Literature Review
Methodology
Results
Conclusion
References
INTRODUCTION
1-The Red Sea Coastal Plain
2-The Red Sea Mountain
6 6
Introduction
Flash floods events
Eastern desert
Risk map
Mitigation of study
Literature Review
Methodology
Results
Conclusion
References
yet no risk map for the whole Eastern
Desert region was established .
INTRODUCTION
7
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
The Main Goal
A flood risk map with prioritization
for the locations subjected to
flooding in the Eastern Desert
towards the red sea coast using
morphological parameters.
8
By get the response of All watersheds
to the Same pseudo storm.
The Main Goal
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
2/18/2014
3
9
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
Algorithm
1-GIS Get
morphological
parameters
2-MCA Calculate
SRF
3-HEC
Get Q & Tp
4-Excell -Correlation bet. Q & Tp
Vs SRF
-get WSRF
MITIGATION of STUDY
10
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
- Definition :
“Sharp and unexpected "are the two best words
to use to characterize a flash flood and its
hydrograph.
- Properties of flash floods :
The hydrograph of a flash
flood has very specific
characteristics:
It generally has -a single
very high peak
discharge, -the flood
volume is not
necessarily important,
-the duration of the
entire flood event is
short, and -the time to
peak is within six hours.
11
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
- Definition :
Although there is no agreement among hydrologic experts on the
distinct classification of arid and semi-arid regions based on their
annual rainfall, the following categories may be generally identified
(Soliman 2010):
1. Areas where the annual total rainfall is less than 70
millimeters per year and evaporation exceeds the yearly
rainfall may be classified as extreme desert areas. Two-thirds
of the Middle East region can be classified as desert.
2. Areas where annual total rainfall is between 70 and 200
millimeters per year with sparse vegetation are called arid
regions.
3. Areas where total annual rainfall is between 200 and 450
millimeters are classified as semi-arid regions. The Mediterranean
Sea coast is classified as a Mediterranean zone with rainy and
moderately warm winters and dry summers and can be considered
to be between arid and semi-arid regions.”
12 12
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
- Definition :
“the terms arid and semi-arid zone are applied to
those areas where rainfall will not be sufficient for
regular rain-fed farming” (FAO, 1981; Walton, 1969)
UNESCO has taken the ratio of precipitation to
potential evapotranspiration (ET) as an aridity index:
P/PET<0.03 hyper arid zone
0.03<P/PET<0.2 arid zone
0.2<P/PET<0.5 semi-arid zone
2/18/2014
4
13
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
- Climate and natural characteristics :
The natural geography of the arid and semi-arid zones is complex
and differs from site to site.
infrequent
rainfall
low cover
ratio
serious soil
loss and
erosion
Poor
vegetation
cover
Drought
Parts of the arid and semi-arid regions of Egypt are located in Sinai
and Red Sea Governorate. This is distinguished by the scarcity of
rain and relative high moisture content. The average rainfall
received by the Eastern Desert annually ranges between 2.75 and
>50mm annually. Precipitation is most concentrated between
September and October, with storms of short duration and limited
area.
14
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
- Example of arid zones :
It is located at the western
side of the Gulf of Suez,
Eastern Desert, Egypt. Wadi
Ghoweibba represents one
of the largest basins in the
Eastern Desert of Egypt. It
covers an area of 3043 km2
with 70 km length and basin
perimeter of 298 km.
15
- Example of arid zones :
Receives small amounts
of rainfall (25.0 mm/year)
mainly in autumn and
winter (El-Rakaiby, 1989).
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
16
- Definition :
A watershed can be defined as
the area of land that catches
water from precipitation and
snowmelt. The water then
drains to a common waterway,
such as, a stream. Each stream
has its own watershed.
Watershed geomorphology
refers to the physical
characteristics of the
watershed.
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
2/18/2014
5
17
- Watershed characteristics and its effect :
AREA Length
Q
Small Area
Large Area
Time Longer Length
Shorter Length
Q
Time
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
18
- Watershed characteristics and its effect :
Mild Slope
Steep Slope
Q
Time
Slope Shape
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
19
- Watershed characteristics and its effect :
Drainage
Density
Low Density
High Density
Q
Time
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
20
- Watershed characteristics and its effect :
Hydraulic
roughness
More Rough
Less Rough
Q
Time
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
2/18/2014
6
21
- El-Shamy ( 1992)
Class ‘A’ (high groundwater potentiality and low flooding)
Class ‘B’ (low groundwater potentiality and high flooding,)
Class ‘C’ (intermediate groundwater potentiality and flooding)
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
22
used a Weighted Normalized Risk Factor
(WNRF) for floods risk assessment.
The four parameters used are: AREA , SLOPE
, time of concentration and runoff volume
A weight coefficient (W) was assumed
constant for all factors and equal to 1/ (No. of
parameters)
It was noticed during the analysis for a case
study in the Eastern desert that the drainage
basin area has a great effect on the floods
generated at its outlet while other factors have
less effect than the drainage area such as the
slope and roughness.
- Elmoustafa (2012)
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
23
- RESOURCES TECHNOLOGY
This Study used 9 morphological
parameters
risk map for watersheds that affect on
Area from marsa alam to Ras Banas.
Morphological parameters was used :
1-Area of watershed (A) ,2-Slope ,3-Drainage
Density ,4-Drainage Frequency ,5-RB=Nw-1/Nw
6-Rt = Nw/p
7-Roughness factor Rn = R*D where ; R= heights
difference in km and D = Drainage Density
8-Shape factor =1.27A/P2 where ; A=watershed
Area and P =watershed perimeter
9-Heights Factor equal where ; R=maximum height
difference and LB distance between them
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Methodology
Results
Conclusion
References
24
- RESOURCES TECHNOLOGY
RISK VALUE=4*((X– X Min.
)/(X Max. –X Min.))+1
Then summation value of
risk was calculated and gets
risk for every watershed,
watersheds were classified
in to five categories:
most dangerous (5)
dangerous (4)
medium dangerous (3)
less dangerous (2)
not dangerous(1).
El-G em al
Lah m y
Gha dir
Ghso un
U rayar
R ing a
U m A bb as
Al Ad aya
N akry
Qul aan
Sam ada y
53
69
26
48
31
42
7
49
56
47
10
15
3
25
36
45
50
46
68
4
66
64
2
65
5
59
67
1
58
29
62
20
9
39
16
63
14
52
12
61
43
34
55
35
18
32
57
38
21
23
11
27
41
28
19
8
44
54
40 0 40 Kilometers
Study Area
Risk
most dangerous
dangerous
medium dangerous
less dangerous
not dangerous
N
EW
S
Introduction
The Main Goal
Algorithm
Literature Review
Basic concepts of
flash floods
Arid and semi arid
regions
Watershed
geomorphology
Catchment delineation
Previous Studies
Study Area & the
Problem Definition
Methodology
Results
Conclusion
References
2/18/2014
7
25
-The Digital Elevation Model (DEM) from NASA Shuttle Radar
Topographic Mission (SRTM) has provided digital elevation
data with a 90 m resolution.
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
26
Area (38-41000
km2)
Length.
Longest flow path.
Slope(0.002-0.064).
Streams number(1-
1216)
Streams Lengths
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
27
Drainage frequency (F)= Streams’ No./A
Drainage Density (D)= Streams’ Lengths/A
Surface flow length (Lo) = 1/2D
Shape factor (Ish) = 1.27(A/P^2)
Time of concentration (Tc)= (0.01944(L^0.77)/S^0.385)
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
28
Area Standardized Risk Factor
(ASRF) =( Area – Area Min. )/(Area Max. –Area
Min.)
The box plot technique was applied to avoid
extreme high values .
0
5.000
10.000
15.000
20.000
25.000
30.000
35.000
40.000
45.000
1 3 5 7 9 11 13 15 17 19 21 23 25 2729 31 33 35 3739 41 43454749 51 53 55 5759 61 636567
Watershed number
Area (km2)
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
2/18/2014
8
29
WSRF w1*ASRF
w2*SSRF
w3*FSRF
w4*DSRF
w5*LoSRF
w6*ISRF
w7*TcSRF
WSRF= Σ (Wi x SRFi)
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
30
Precipitation .
Loss method(SCS curve
number)
Transform method (The SCS
unit hydrograph).
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
31
Time to
peak
Peak
discharge
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Data collection
Morphological analysis
Sensitivity analysis
Results
Conclusion
References
32
00,10,20,30,40,50,60,70,80,9
1 0,93
0,21
0,85
0,14 0,21
0,02 0,02
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
2/18/2014
9
33
0,000,050,100,15
0,200,250,300,350,400,45
0,43
0,00
0,39
0,06 0,10
0,01 0,01
W= correlation value / Σ (correlations)
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
34
•Low Risk
•Low to moderate Risk
•Moderate Risk
•High Risk
•Very High Risk
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
35
-0,7
-0,6
-0,5
-0,4
-0,3
-0,2
-0,1
0
0,1
0,2
1/Area Slope 1/Tc 1/FShapefactor 1/Lo 1/D
-0,67 -0,57
-0,6
-0,2 -0,25
0,11
-0,17
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
36
0,00
0,05
0,10
0,15
0,20
0,25
0,30
1/Area Slope 1/Tc 1/FShape factor1/Lo 1/D
0,27
0,23 0,24
0,08 0,10
0,00
0,07
W= correlation value / Σ (correlations)
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
2/18/2014
10
37
•Low Risk
•Low to moderate Risk
•Moderate Risk
•High Risk
•Very High Risk
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
38
•Low to moderate Risk
•Moderate Risk
•High Risk
•Very High Risk
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
39
9%
13%
35%
43%
very high risk high risk moderate moderate to low
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Peak discharge risk
Time to peak risk
Overall risk
Conclusion
References
40
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
•The Egyptian eastern desert is having a long coast along the Red sea
of more than 1000 km length, Sixty eight main watersheds discharging
eastward into the red sea were studied, area of watersheds were found
to range between 38 km2 and 41,474 km2 and the slope were found to
range between 0.002 and 0.064 and the relation
•A new criterion was developed to evaluate the risk factor for the floods
resulting from watersheds generated within the Red Sea Mountains
and flowing to the Red Sea. These criteria could be used in other
places with similar characteristics.
•The box plot test represented a very useful, easy to use and quick tool
when trying to exclude extremely high parameter that may lead to
unrealistic risk factor.
2/18/2014
11
41
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
•Eastern Desert watersheds discharging into the Red Sea are
classified into four categories where 9% of watersheds have very high
risk, 13% has high risk, 35% has moderate risk and 43% has
moderate to low risk.
•The drainage basin area is the morphological parameter that has the
highest effects on the peak floods generated followed by time of
concentration and slope; other factors have less effect such as the
shape factor, drainage frequency, drainage density and surface runoff
length.
•The drainage basin slope is the morphological parameter that has the
highest effect on the time to peak followed by the shape factor.
42
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
For future studies,
•The Weighted Standardized Risk Factor (WSRF) obtained can be used
during the design of flood protection measurements and/or the
calculation of design peak flows for crossing structures. This may lead to
more economic design procedure that can be adopted in drainage
design guidelines and manuals. Studies should be carried out to
investigate how to implemented this in the design procedure
•It is recommended to study curve number as an important
morphological parameter in future assessment that affect on the
generated hydrograph realistic approach.
•The produced Risk map is helpful to know the locations that have high
flood risk in order to prevent loss of life and minimize damages to
property.
•This technique is to be investigated in other places that importance to
our future development plans such Sinai coast.
43
Introduction
The Main Goal
Algorithm
Literature Review
Methodology
Results
Conclusion
References
1. Ashraf M. Elmoustafa 2012, “Weighted Normalized Risk
Factor for Floods Risk Assessment” Ain Shams Engineering
Journal (ASEJ), April 2012.
2. El-Shamy, I. Z. 1992, “New approach for hydrological
assessment of hydrographic basins of recent recharge and
flooding possibilities”. 10th Symp. Quaternary and
Development, Egypt, Mansoura Univ., 18 April, p. 15.
3. Baptista et al. "Multi criteria evaluation for urban storm
drainage", First SWITCH scientific meeting University of
Birmingham, UK, 9-10 Jan 2007.
4. Horton, R. E., “Drainage basin characteristics, Trans. Am.
Geophysics. Union, vol. 13, pp. 350-361., 1932.
44
Thank you for your attention !
![INDEX [tubs.exceed-swindon.org]tubs.exceed-swindon.org/wp-content/uploads/2015/03/abstracts_ss... · 21 Evaluation of enviromental impacts from a municipal dump after ist deactivation](https://img.pdfslide.net/doc/110x75/5c497c9f93f3c31f4f7c1027/index-tubsexceed-tubsexceed-21-evaluation-of-enviromental-impacts-from.jpg)
![INDEX [tubs.exceed-swindon.org]tubs.exceed-swindon.org/wp-content/uploads/2016/11/ppt_ss_2016_… · CONSTRUCTED WETLAND FOCUSING ON ORGANIC MATTER AND NITROGEN REMOVAL Vitor Cano](https://img.pdfslide.net/doc/110x75/60065ac5f3687d4d706c6cbc/index-tubsexceed-tubsexceed-constructed-wetland-focusing-on-organic-matter.jpg)
![EMC-1 TM DIMENSIONS [inches (millimeters)]](https://img.pdfslide.net/doc/110x75/6250e6dd6328692d103d6323/emc-1-tm-dimensions-inches-millimeters.jpg)
