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

20M. A. AzabFig. (2) Topography of the study area (based on Egyptian MilitarySurvey topographic map 1986 at scale (1 : 250000).Geomorphic Characteristics of the Plio-Quaternary Alluvial Fans:From north to south, there are six major fans in the study area: Samadi, Nakari, Khalilate EIBahri, Rimarim, Khashir and Ras Banas. They range in area between 10km 2 (Khalilate EIBahri) and 190km 2 (Khashir), and their altitudes range between 79m a.s.l (Khalilate El Bahri)and 172m a.s.l (Nakari). The lower limit of the studied fans varies from 6.0 m a.s.1 (WadiSamadi) to 10.0m a.s.l (Wadi Rimarim). The apex of fan area are arranged adjacent to alongthe main faulted boundary extending at the mountain front has relatively higher slope. Itvaries from 5° (Wadi Rimarim) to 16° (Wadi Nakari). The middle fan areas one of gentleinclination, and varies from 3° at Wadi Gemal and Ras Banas to 8° at Khalilate EI Bahri. Thelower fan has a slope of less than 2°.These fans are drained by number of channels originating from the high relief mountain.These channels are generally parallel at the lower and middle parts of the fan zone. They arehigher dissected and have deep gullies in their lower parts. Most extensive terraces withdifferent levels are developed around the channels of these fans.Drainage CharacteristicsThe study area represents a part of the Red Sea drainage submegabasin (El Shazly et al.1991). The water divide follows the high peaks of the Red Sea Mountains. It is crooked andtrends roughly in a NNW direction parallel to the regional trend of the Red Sea. The finalshaping of the drainage network is an outcome of the last fluvial periods. The present dryvalleys and tributaries were already engraved during these fluvial periods. They are now filledwith surficial deposits of gravels, sands and clays. Twenty three drainage basins with outletsto the Red Sea were defined and sorted out, area-wise into three distinct categories (large>