this presention is about calculation of area catchment

1. Presention about calculation of area
catchment
Presented by:
MOHAMMED MUTAHAR
I AM STUDENT IN UET PESHAWAR
SUBMITTED TO ASST.PROF.DR.MUJAHID KHAN

2. Introduction:
 A tropical storm that hit Yemen on October 24, 2008 (World
Bank 2008) led to a huge amount of rain for about 2 days with
a total volume of 91 mm on Wadi Hadramawt catchment area
of 2 million hectares. The catchment area collected around 2
billion cubic meters of water and formed severe flash floods in
different places and surged up to 10 m height (World Bank
and GFDRR 2010). Although in 1989 and 1996 this area was
subjected to floods, this particular flood is considered one of
the worst natural disasters to hit Yemen
 THIS IS PICTURE MAP OF Wadi Hadramawt,
Yemen :

4. Catchment delineation:
 Catchment delineation
The Wadi Hadramawt has a spatial heterogeneity which
makes it difficult to determine spatial data properties. In
order to analyze any watershed delineation, the WMS
computer software is considered to be an appropriate
solution
(Patel 2009; Kumar 2011). In this study, the WMS was
used to delineate the Wadi Hadramawt catchment using
its digital elevation model (DEM) ( U.S. Geological Survey,
2013) in order to determine the catchment properties.
Analyzing the catchment using the software showed

5. Catchment delineation:
 . that the catchment is better to be divided into eight sub-catch-ments. The output of this
step includes the area, maximum stream length, slope, lag time, and other properties of
each of the eight sub-catchments. Figure 6 shows the boundaries of each of the eight
sub-catchments. Table 5 shows the hydrological properties obtained from WMS in
addition to the curve number and soil impervious percentage from ArcGIS software for
each of the eight sub-catchments. The nature of the soil at the eight sub-catchments of
Wadi Hadramawt is similar. The rocky nature of most of the wadi governs the
imperviousness of the whole catchment. A low value of imperviousness of 10 % is
assumed to be suitable to the nature of Wadi Hadramawt.


6. of the eight sub-catchments. Figure 6 shows the boundaries
of each of the eight sub-catchments

7. Table 5 shows the
hydrological properties obtained from WMS in addition to
the curve number and soil impervious percentage from
ArcGIS software for each of the eight sub-catchments.
The nature of the soil at the eight sub-catchments of Wadi
Hadramawt is similar. The rocky nature of most of the
wadi governs the imperviousness of the whole catchment.
A low value of imperviousness of 10 % is assumed to be
suitable to the nature of Wadi Hadramawt.
As the runoff generated from each sub-catchment will
flow in channels till it reaches the catchment exit, channel
routing using the Muskingum Cung method will be used
hereafter. The channel routing parameters required for the wadi hadramaut.

8. Area (km2)
Initial
abstraction
(mm)
Curve no
Impervious
(%)
Lag time
(h)
A 1,647.87 9.66 84 10 9
8,612.61 9.66 84 10 18
B 755.88 10.38 83 10 4
C 8,704.45 7.58 87 10 12
D 2,561.32 8.94 85 10 7
E 176.02 11.9 81 10 3
F 6,931.13 6.92 88 10 11
G 807.58 11.14 82 10 6
H

9. Hydrological modelling:
 Hydrological modelling
By obtaining all the parameters needed for the estimation of
flood hydrograph, HEC-HMS (US Army Corps
of Engineers 2010) can be used to process these data
to give either the total hydrograph for the whole
catchment or for each of the eight sub-catchments