Prediction and Mitigation of Flash Floods in Egypt

Abstract

Egypt is located in a semi-arid region and the annual average precipitation is 12 mm/year which ranges from 0 mm/year in the desert areas to 200 mm/year in the coastal areas. Countries located in semi-arid regions such as Egypt have alluvial (wadi) systems that formed during the fluvial time of the Tertiary and Quaternary Periods. These wadis suffer from a flash flood, consequent to heavy precipitations. Two major factors are responsible for flood generation and impart specific features to it. The first is the physical process, which generates the change of position between the lithosphere, atmosphere, and hydrosphere. Second, the flooded area, depth of inundation, and its duration depend on the geographic situation of the region where flood takes place. Due to the great variety in operation of the natural processes and the endless variation in the condition of the geographic arena where they act, many different kinds and scales of floods can be distinguished. There are at least 18 major types of floods of natural origin. Growing human influence has become evident from the increasing frequency of floods of anthropogenic origin. The main purpose of this chapter is to identify the general system of floods in terms of types, causes, problems caused by flood, and how to determine the amount of floodwater and prevention with application to the areal case study. Wadi Sudr, Sinai, Egypt is used as a real case study. The description of this wadi is defined. Recorded rainfall depths are studied and analyzed, and the IDF curve is generated. Runoff hydrograph of the wadi is estimated, and locations of protection measures using a number of dams and open channels have been selected and designed to protect the area from flood hazards.