Flash floods impact on the construction of rainwater harvesting structures

Introduction. The lack of fresh water has become a serious problem. The main causes of the water crisis are population growth and climate change. Egypt is a very arid country which is facing water scarcity due to increasing demand and limited supply. Applying new approaches is required in this situation to deal with water scarcity. Wadi Watir in the Sinai Peninsula, chosen as the research area, is an important tourist and commercial watershed. It experiences water scarcity and the threat of flash floods. The residents are losing their crops and sheep. Roads are deserted, and their lives are in danger due to the periodic occurrence of flash floods. Materials and methods. For the first time, the current research investigates the impact of flash floods on the implementation of rainwater harvesting (RWH) systems. The flash flood risk and RWH structure maps were overlaid using GIS. Results. The results showed that five percolation tanks, five check dams, 11.15 km2 of area for on-ground percolation tanks, and 0.48 km2 of space for farm ponds are optimal for water harvesting during flash floods. Conclusions. The development of Wadi Watir was prioritized and divided into three phases. Therefore, the occurrence of flash floods clearly affects the development plans. The impact of flash floods should be considered during the calculation of the design capacity of the RWH structures.