Abstract
This study examines the morpho-tectonic settings of the drainage system in the northwestern Ethiopian plateau by focusing on the Tekeze River. The plateau is underlain by Precambrian crystalline rocks, overlain by EOCENE and Late Oligocene basalts. An attempt is made to study the underlying geology of Tekeze river basin and its significance in morphometry e.g., linear, relief and areal parameters. Further to analyze the influence of topography and geology on morphometry integrating Remote Sensing data and GIS techniques. The study used ArcGIS software for the computation, delineation of the boundary and morphometric analysis of the watershed using topographical maps and SRTM DEM data. Total area of watershed is 84738.55 Sq. Km. Total numbers of 18 rock types were mapped out in watershed and most of the area is covered by the Basalts (36.01%). The steep relief explained by complex geological history represented in major geological terrains starting from Archaen (about 40 billion years ago) till Quarternary period (about 11 thousand years ago) and marine sediments occurring in the western part. The Quantitative analysis of drainage network shows that the river is having the dendritic pattern. The drainage density is low which indicates the coarse drainage pattern. Drainage texture, stream frequency and the form factor of the watershed are 0.04, 0.12 and 0.69 respectively. The bifurcation ratio of the watershed ranges from 1.68 to 12 and the elongation ratio is 0.78 which refers to high relief of the study area. The mean bifurcation ratio of the whole watershed is 13.71 indicating that the drainage pattern is greatly influenced by geological structures.
Key Words: Morphometric Analysis, Watershed, Geology, GIS, Drainage Density, Tekeze River, Ethiopia
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