Use of radar data to unveil the paleolakes and the ancestral course of Wadi El-Arish, Sinai Peninsula, Egypt

Abstract

Aspects of the geomorphic evolution of Wadi El-Arish, the largest ephemeral drainage system in the Sinai Peninsula, are still ambiguous, and its paleochannels remain undefined. One of the obstacles that impede recognition of these paleodrainage features is the variation in topography from past to present. Some of this variation is attributable to the post Miocene tectonic activity in the region. This activity might have continued to the present, and led to developing an alternative course for the paleoriver. The folded Syrian Arc Belt in North Sinai had a significant influence on the shape and direction of Wadi El-Arish. Anticlinal ridges appear to have formed natural barriers that blocked the water flow across the main drainage course during humid periods, and forced Wadi El-Arish to deviate from its original course. In this research, we attempt to reconstruct the structural deformation and simulate the paleotopography to understand the evolution of the paleodrainage systems of the region. The unique perspective offered by space-borne radar data was used to define the structurally controlled paleolakes along Wadi El-Arish and to trace its former course. With a length of 109km, the former main channel course of Wadi El-Arish was depicted west of Gebel Halal. Three major paleolakes were defined within structurally controlled depressions. The largest lake occupied an area of at least 337km2 and contained approximately 10.7km3 of water when filled during pluvial phases. The simulation of the paleotopography was confirmed by field observations, and led to a concept for improved management of the renewable water resources in the study area. Thus, a 2km long canal with a depth of 6m is recommended to be established within the structural uplift. This canal would redirect the occasional runoff to a vast flat area west of Gebel Halal to provide water for approximately 1400km2 of fertile land for agricultural development. The flow redirection would also help to mitigate the negative effects of flash floods in El-Arish City and maximize the harvesting of rain water that would otherwise be lost to the sea.