UC Berkeley

Desert environments are subject to flash floods in wadi floors, which may occur only once every decade or two in a given wadi (dry channels or valleys, except during rains). In areas of rapid growth, flood-prone areas can become urbanized in the time between floods. Being flat and constituted of sandy sediments, unlike the surrounding terrain, wadi floors are often used for construction, exposing the new settlements to flood risks. We present a case study of the town of El-Sheikh El-Shazli, in the Eastern Desert of Egypt, which has undergone increasingly rapid development over the past two decades. The town is named for an important 13th-century Sufi leader whose shrine receives thousands of visitors annually. We document the extent and effects of the last flash flood (1996) from interviews, field measurement of flood debris, and patterns in satellite imagery; these show the extent of new development in flood-prone wadi floors and the potential risks to residents and visitors in the absence of proper planning. We then recommend measures to reduce the future loss of life and damage from flooding.