Quantitative geomorphological analysis of some watersheds on the eastern bank of the river Nile with relation to basin hydrogeology, Egypt

Geologically the study area is underlain by the Nubian Sandstone in the eastern part. and by younger Cretaceous to Paleocene units toward the River Nile in the western part. Eocene limestone plateau and Quaternary sediments outcrop on the surface in the northern part of the study area. The objective of this paper is to determine the main geomorphic parameters of the drainage basin in order to develop a regression equation to estimate the peak discharge of the catchment areas. Accordingly, drainage-basin analysis of fourteen watersheds east of the River Nile was carried out using the hydromorphometrical approach. The study revealed that the highest stream orders of the studied basins range between 5 and 6. The bifurcation ratio ranges between 2.45 and 3.09. indicating basins of more or less elongated shape where the runoff flows to the outlet over a relatively long time. The drainage density of the study basins ranges between 0.61) and 1.09 km-.indicating high values due to the low permeability of rock type and roughness. Generally. in the areas under investigation, 1 sq. mile area of the drainage basin contains a channel of 3.4 miles long. The runoff equations for the catchment areas were developed utilizing twenty-five physiographic parameters as the independent variables, alongwith the peak discharge (Qp) as the dependent variable. The results indicate that none of the topographic variables is unique, however, each reflects its influence on the other factors. It was found that the stream density and the steep land slope were generally associated with the steep channel slope. The application of the regression equations for the studied watersheds could be considered as highly satisfactory