Drainage Morphometric Characterization of Megech River Watershed, North Western Ethiopia, Using Geospatial Tools

Abstract

Drainage morphometric characterization of a river catchment is important for appropriate preparation and administration of natural resources in sustainable growth. The main objective of this study was to extract and characterize the morphometric drainage parameters of the Megech River catchment, Northwestern Ethiopia. For this the Ethiopian mapping agency's 1:50,000 scale toposheets,  STER (Advanced Spaceborne Thermal Emission and Reflection), and Landsat-8 Operational Land Imager (OLI) satellite data were used. Drainage morphometric parameters of the watershed were assessed by computations of linear, areal, and relief aspects using the standard formula in the Geographic Information System (GIS) environment. The Megech River catchment is spreading over an area of 560 km2. The watershed is drained by a fifth-order river and shown a dendritic stream pattern, which is an indication of the homogeneousness in rock texture. The watershed's mean bifurcation ratio is 1.84, representing that the drainage pattern is not much affected by tectonic and structural disturbances. Lower and middle-order drainages typically control the basin with the drainage density value of 5.5 km/km2, which displays mild to sharp slope topography. The mean bifurcation value of the basin is 1.84, revealing drainage networks formed on regular bedrocks when the influences of geologic structures on the drainage network are insignificant. The drainage texture of the watershed is 7.4, and it falls under the category of very fine drainage texture (>8). Elongation and circularity ratios for the basin are 0.61 and 0.3, which shows that Megech watershed is elongated, having a steep to moderate slope.