flood hazard betwee marsa alam - ras ba as, red sea, egypt abstract ...

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22M. A. AzabFig. (4) Drainage net of the area between Wadi Samadi and Wadi Sherm LuliFig. (5) Drainage networks of the area between Wadi Um Abbas and Wadi Qulan
FLOOD HAZARD BETWEE MARSA ALAM - RAS BAAS 23Fig. (6) Drainage networks of the area between Wadi Radi and Ras Banas.Drainage Basin MorphometryQuantitative analysis of hydrographic basin can be achieved through measuring thegeomorphological parameters including stream order (U), bifurcation ratio (Rb), streamfrequency (F) and drainage density (D).Stream Orders (U) of the studied basins range between 7 (Wadi EI Gemal and Wadi Ghadir)and 4 (Wadi Samadi, Wadi Nakari Wadi Khalilate El Bahri, Wadi Khalilate EI Qibli, WadiUm Dahise, Wadi Urn Ghazal, Wadi Stayai, Wadi Kirah EI Hertawi and Wadi Um Rimarim).(Table 1).Bifurcation Ratio (Rb) defined as the ratio between the number of stream order (Nu) to thenumber of the next order (Nu+1)(Horton 1945). Basins with low Rb values tend to produce asharp peak flow while the high Rb reflects low extended peak flow. The estimated Rb valuesof the studied basins (Table 1) ranges between 2.82 and 4.85. Low values were recorded forWadi Satayia, Wadi Khalilate El Bahri, Wadi KhaIilate El QibIi, Wadi Sharm Luli, WadiGhadir and Wadi Um Abbas, and high values were recorded for Wadi Samadi, Wadi Nakari,Wadi Ranga, Wadi Radi, Wadi Um Rimarim, Wadi Kirah EI Hertawi, Wadi Lahmi and WadiQulan. The variation in Rb values reflects the difference in stages of geomorphic developmentand topographic variations. Basins of high bifurcation ratio are elongate in shape and permitthe passage of runoff over an extended period of time to feed the groundwater. Basins of lowbifurcation ratio are circular in shape and allow the runoff to pass in a short time (Saad et al.1980).Drainage Density (D) reflects the effectiveness of the surface water flow,as well as, theinfiltration capacity. It is a function of slope, rock resistance, rock' permeability, andvegetation cover. In the study area, the drainage density (1.4-5.02) is a direct expression ofrelief as the vegetation is not represented and the rocks are more or less impermeable andresistant. Drainage density is low in Wadi Samadi, Wadi Um Abbas, Wadi Abu Ghusun,Wadi Ranga, Wadi Khashir, Wadi Lahmi and Wadi Sataiya, and high in Wadi Khalilate El
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flood hazard betwee marsa alam - ras ba as, red sea, egypt abstract ...

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