حوض الدندر وحوض الرهد : دراسة جيومورفولوجية

Abstract

Abstract The study of watersheds is one of the important geomorphological studies, especially in Arid Zones. Thus, this study aims at identifying the morphometric and morphological characteristics of AL-Dinder and AL-Rahad basin, As well as exploring the extent of the similarities and differences between the two basins. The study has adopted, the analytic, quantitative, survey and the descriptive approach. For data analysis, the morphometric analysis to data of digital elevations model (STRM (by using the Geographic Information System and making application on the appropriate program: GIS 9.1 with Arc Info by Arc Hydro tool. Besides, the morphology analysis which is based on the tool of maps reading for topographic maps at the scale 1:100000, and the statistical analysis (means and correlation). The study revealed the following results: Each of the target two basins has different characteristics from the other such as: the large area and perimeter of Dinder basin than its counterpart Rahad basin, this indicated the size of drainage in the forme. Moreover, the hypsometric coefficient indicated that Dinder and Rahad basins has completed 76.5%, 65.5% of their erosion cycles respectively. Concerning the drainage net, it’s a higher stream order for Dinder basin (eighth) compared with Rahad basin (seventh). The bifurcation ratio is 3.54 in Dinder basin and 3.76 in Rahad basin . The drainage density is very low in both basins. This indicates that the land is of high permeability and gentle slope .The morphological analysis reveals that: the water divides zones in the high basins are characterized with many meanders, because of the vertical erosion, but in the middle and lower basins they are straight. This indicates clearly the weakness of lateral erosion .Furthermore, Dinder basin branches descend parallel to the main channel, while the branches of Rahad descend at acute angles. Among the most important geomorphological phenomena in the tow target basins is the meandering of the main channel , spread of flood plains and oxbow lakes .The study recommends giving more interest to the geomorphological studies, because of their significant role in the various areas of planning