ASSESSING FLASH FLOOD RISK IN THE EASTERN DESERT, EGYPT

Arid environments face a risk of flash flooding due to the lack of regular precipitation and the intensity of rainfall events. The Eastern Desert of Egypt is a hyper-arid environment, lying next to the Red Sea, which is periodically exposed to intense precipitation. The desert is made up of rugged mountains and a dense network of dry valleys (wadis) that drain rainfall from the mountains. Flash floods do not occur very frequently, causing people to develop a false sense of security, which compounds the potential hazard. There is also large uncertainty surrounding the process that leads to flash flooding, which can be attributed to the lack of hydrological and meteorological data. This creates the necessity for hydrological modeling to predict flood risk. Quseer, located in the outlet of the wadi, is a developing diving town and one of the largest towns along the coast. Wadi El-Ambagi covers ~1,540 km², making it one of the largest wadis in the Eastern Desert. This wadi is also home to one of the few road networks which cross the mountain range, connecting the Nile River valley to the Red Sea coast. Flood ravaged roads along this highway would halt transportation to and from the coast. With a growing population, and a history of rainfall events in the region, flash flood risk should be assessed for wadi El-Ambagi. This research aims to model the potential for flash flood risk in the wadi and suggest mitigation efforts to protect Quseer and its people from flood waters. This can be accomplished by understanding the behavior of surface runoff through generated hydrographs. The hydrologic model for the study area was developed using remotely sensed data: DEM obtained through the SRTM and ASTER GDEM2 topographic data. The geology and soil properties of the basin were then mapped from fused ASTER and PALSAR imagery to generate the curve number grid. Two hypothetical rainfall events were used to calculate flow rates for the wadi. The resulting hydrographs were characterized by sharp peaks indicating that wadi El-Ambagi could potentially experience a very high peak flow. High flow of this magnitude would be extremely destructive, proving catastrophic for anything in the path of flood waters. Quseer is at risk of flash flooding. The infrastructure, road networks, and citizens of this town are at risk and mitigation efforts should be made to protect Quseer.