FLASH FLOOD RISK ASSESSMENT APPLYING MULTI-CRITERIA ANALYSIS FOR SOME NORTHWESTERN COASTAL BASINS, EGYPT

ater resources are increasingly a constraint on economic and social development in Egypt. Coping with the water scarcity in the North Western Coastal zone Basins (NWCB) requires good management for the flash floods. This requires an accurate estimation for the hazard degrees and flood risk. Multi Criteria Analysis (MCA) describes any structured approach used to determine overall preferences among alternative options, where the options accomplish certain or several objectives. The maximizing of water use in arid zones, like NWCB, is a highly important issue due to the damage, danger and other hazards associated to it to human life, properties, and environment. MCA techniques were tested and evaluated for the purpose of flash flood risk assessment, hydromorphological parameters for sample catchments in NWCB, were used in this analysis. Drainage network and watershed boundaries of NWCB shape file was created using TOPAZ (Topographic Parameterization) technique from the 90 m Digital Elevation Model (DEMs). These data are used in Watershed Modeling System (WMS) package to automatically delineate basin boundaries and define stream networks. Thirty four basins in NWCB were delineated for the study of the risk assessment of flash floods. Cluster analysis, depending on 10 estimated hydro-morphological parameters, classifies the NWCB into three groups. Ten chosen hydro-morphological parameters have their direct effect on flash flooding were used for estimating hazard scale depending on the MCA procedures. The proposed risk scale assumed category three for the high Weighted Standardized Risk Factor (WSRF) of five basins, while the category two (moderate WSRF) represents the middle sector of NWCB (19 basins). The class one represents 10 basins (low WSRF). Field measurements are highly recommended to verify the results of MCA procedure used in this paper.