Flood hazard assessment and mitigation using a multi-criteria approach in the Sinai Peninsula, Egypt

The Sinai Peninsula in Egypt is highly vulnerable to flash flooding due to its huge variation in relief and erratic rainfall. However, assessing flood risk in the Sinai is a difficult challenge due to the almost complete lack of accurate flood observations and relevant drainage basin characteristics. Therefore, this study evaluates the flood hazard in the Sinai Peninsula through multi-criteria analysis of morphometric characteristics of the drainage patterns, which can be easily inferred from readily available remote sensing data and geographical analysis tools. From a digital elevation model with a spatial resolution of 30 m, 112 catchments are identified, each characterized by twenty morphometric parameters, grouped into three categories: geometry, drainage network and relief. The importance of the morphometric parameters on flooding is assessed with the analytical hierarchy process. Normalized weights for each parameter and category, obtained from pairwise comparison matrices, allow to derive a flood sensitivity index and create a map showing different degrees of flash flood hazard. The results show that basins characterized as highly sensitive to flooding generally have high values for all three morphometric parameter categories: geometry, flow network and relief. About 17% of the Sinai appears to be very highly sensitive to flooding, 39% highly sensitive and 34% moderately sensitive. The very highly flood-prone basins are all located in the southern Sinai mountain ranges, while the highly flood-prone basins are mainly found along the outer edges of the southern Sinai mountain ranges and in some sub-basins of wadi El-Aris. Comparison with case studies reported in other publications and the media shows a strong agreement, indicating that the proposed methodology is reliable and accurate. Based on the obtained flash flood sensitivity map, management plans are proposed to reduce the risk of flash flooding and to protect major cities and roads by installing side channels and culverts to collect and drain the excess water from areas most affected prone to flooding.