Morphometric analysis and prioritization of sub‑watersheds for soil erosion using Geomatics technologies in Megech River catchment, Lake Tana Basin, North Western Ethiopia

Abstract

Soil erosion is one of the most critical environmental problems in the sustainable development of agriculture and natural resources. Ethiopia is facing severe soil erosion problems. The present study was carried out in the Megech River catchment, Lake Tana Basin, North Western Ethiopia. The present study aims to identify the sensitive soil erosion-prone sub-watersheds in the Megech River catchment. ASTER-DEM (Advanced Space-borne Thermal Emission and Reflection), a 30 m spatial resolution digital elevation model (DEM), was used to delineate the sub-watersheds and drainage networks through spatial Analyst and ArcHydro extension of ESRI ArcGIS v10.6.1 software. The cloud-free optical satellite data got from Landsat-8 Operational Land Imager (OLI) has been used to update the drainage network of the present study area. The study area was divided into four sub-watersheds: WS-1, WS-2, WS-3, and WS-4. The primary, linear, and areal drainage morphometric parameters were calculated by applying the standard formula. Furthermore, the ranks were allocated to each drainage morphometric parameter of the four sub-watersheds based on their soil erosion proneness. The compound factor value was calculated for the sub-watersheds. The lower value of the compound factor has a high possibility of soil erosion and vice versa. The compound factor of the present study area's sub-watersheds is 2.33 (WS-1), 2.88 (WS-2), 2.11(WS-3), and 2.67 (WS-4). Based on the compound factor value, the present study area's sub-watersheds 3,1,4 and 4 were classified into very high, high, medium, and low priority sub-watersheds, respectively. Through morphometric drainage analysis, the sub-watershed-3 has been identified as a very high-priority ranked watershed in the present study. It needs immediate soil conservation measures for efficient watershed planning and management. Further, the present study shows the effectiveness of the drainage morphometric analysis using the satellite image and GIS techniques in prioritizing the sub-watersheds for soil resource conservation and management in the Megech River catchment, Lake Tana Basin, North Western Ethiopia.