Integrating GIS and HEC-RAS to model Assiut plateau runoff

Abstract

In the mountainous area of Assiut plateau in southwestern Egypt, a proposed road is designed to pass through a flood path near Durunka village. A reliable and accurate information about natural hazards, could occur in this region especially flash floods, is required. Due to the lack of this information, a runoff model is built adopting the Soil Conservation Service method for an un-gauged watershed of Assiut plateau. The hydrologic characteristics and soil type and cover for the study area are estimated during a site visit. The watershed is delineated and the morphometric parameters are derived from analyzing the SRTM3 Digital Elevation Model (DEM) using Geographic Information System (GIS) to construct a hydrological model. This model provides a good estimate about the magnitude of flash floods including the water velocities and depths using HEC-RAS. Two rainfall events are used in this analysis, the first event is a storm with 50 years return period, and the second event is for highest precipitation value recorded in this area. The model showed that the maximum water depth could occur is 4.01 m and the highest water velocity is 11.75 m/s. The results of this study could help the decision makers in protecting the proposed road and to minimize the flood hazards.