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

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26M. A. AzaboI234567891011121314151617181920212223Table (3) Estimated rain fall and runoff quantities in the studied drainage basinsBasin name Area Annual Max. run off Max. run off in(Km 2 ) rainfallquantityin one day(l0m 3 )one day (l0m 3 ) Min. run off inone day (l0m 3 )W.SamadiW.Um TundibaW. AmboutW. NakariW. GhadirW. Khalilat El BahriW. Khalilat El QibliW. Sharm FaguriW. ErirW. El-GemalW. Sherm LuliW. Um DihesiW. Um AbbasW. Abu GhusunW. RangaW. QulanW. RadiW. Um RimarimW. KhashirW. LahmiW. Um GhazalW. HirtawyW. Sataiya63.2667.0790.4748.34554.2413.2811.5273.05261.321476.66337.97495.29309.6357.33156.7748.83464.01967.0816.4237.2139.0660.1524.121.11.171.570.849.640.230.21.274.5525.75.98.625.3912.730.858.0716.830.290.650.681.080.4298.784.054.295.793.0935.470.850.744.6816.7294.5121.6331.719.823.6710.033.1329.761.891.052.382.53.851.54363.082.662.823.82.0323.280.560.483.0710.9862.0214.1920.8132.416.582.0519.4940.620.691.561.642.531.01238.270.240.250.340.182.080.050.040.270.985.541.271.861.160.210.590.181.743.630.060.140.150.0230.0921.073Wadi Gemal Basin occupies a rather large area (about 1477 km 2 ) and its main trunk wadiassumes a seventh order. The drainage net is well developed, integrated, dense, oriented andhas variable angles of juncture (Fig. 7). The basin drains high mountains with steep slopesand elevations up to 1508 m. The significant large channels are mostly arranged in parallel tosubparallel patterns with dendritic to subdendritic tributaries. Trellis and subtrellis drainagepatterns are locally developed. The main wadi is oriented NNW in the upper part, EW in themiddle part and NE near its the mouth. Its large tributaries are mostly directed NW and NNE,mostly due to fault control. It is characterised by low (Rb), low drainage density and nearlycircle shape. Metamorphic rocks, metasediments and granites are the most widespreadlithologic units exposed in this basin. Neogene sedimentary rocks and Quaternary sedimentswith local fans are located at the mouth of the master wadi. The main trunk wadi at the lowerpart is narrow. This indicates a high potential for flood hazards at the upper reaches of thebasin and the downstream part of the trunk wadi. The basin mouth is crossed by a shortsegment of the Red Sea coastal road.
FLOOD HAZARD BETWEE MARSA ALAM - RAS BAAS 27Fig. (7) Drainage network of Wadi Gemal area (Ashmawy 2001).Wadi Um Abbas basin is of sixth order and has an area of about 338km.It is roughlyrectangular, well integrated, relatively dense, and has variable angles of juncture. Its pattern isdenderitic to subdenderitic in the upper part and parallel to subparallel in the middle part. Thetrunk wadi (Um Abbas) flows N, NE in the upper and lower parts to N, NW in its middle part.Its large tributaries are oriented N, NW, NNE, E-W to N. substantial segments of thesechannels are guided by faults. The lithology is dominated by basement (granitic rocks), whileoutcrops of Neogene and Quaternary sediments are exposed near the middle part and at themouth of the waid. The basin is characterized by middle drainage denisity, middle relief (upto 748 m high), high contribution for groundwater and classified as middle dangerous basin.Its shape is nearly circular and reflects the most favorable conditions for the short runoffdistance.Wadi Abu Ghusun Basin is fan shaped of sixth order and has an area of about 495km. Thebasin is characterized by rugged mountainous relief (up to 1468 m high) with very steepslopes particularly along and near the water divide. Wadi Abu Ghusun is the main channel,which flows NW to NE at the upper part and W-E, NW to NE at the lower part toward theRed sea. The long tributaries are clearly oriented and run NE and SE. The change of wadisegments in width, degree of channel incision and channel trends is generally due to thestructural control (mainly faults) and/ or to change in rock type. The large channels are mostlyarranged in parallel to subparallel patterns with dendritic to subdendritic arrangement for thesmaller tributaries. The lithology is dominated by basement rocks (granites and metavolcanicrocks) in the upper and middle parts. Towards the outlet, a few outcrops of Neogene andQuaternary sediments are exposed. This basin has low bifurcation ratio, nearly circular inshape. Ruggedness of relief and slope steepness are factors which tend to decrease the time of
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flood hazard betwee marsa alam - ras ba as, red sea, egypt abstract ...

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