Watershed Prioritization for Land Management Decisions Using Morphometric Characteristics and Soil Erosion Risk in Ribb Sub-basin, Amhara Region, Ethiopia.
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Date
2025-06
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Addis Ababa University
Abstract
Land degradation, driven by human activities and climate change, presents a significant threat to Ethiopia's agricultural productivity and socio-economic stability. Despite decades of restoration efforts, the issue remains unescapable, necessitating a strategic framework to prioritize watersheds for targeted and effective interventions. Systematic approaches by using state of the art technologies in identifying key hydrological and bio-physical characteristics of landscapes helps to prioritize watersheds; planning units, based on their urgency for conservation. Such kind of studies or tools helps policy makers for appropriate decision making on resource allocation and practitioners for better intervention planning. Watershed prioritization needs to be seen as a critical approach in managing soil and water resources, particularly in data-limited regions where optimal resource allocation is vital. This study has prioritized watersheds using GIS-based methodologies by integrating morphometric parameters and soil erosion risk that could contribute to land degradation in one of the key tributaries of the Tana basin; the Ribb sub-basin, ultimately contributed to Blue Nile. Morphometric parameters considered in the study includes area, perimeter, stream frequency, bifurcation ratio, form factor, elongation ratio, and drainage density were generated from Digital Elevation Models (DEM) with 30m resolution. Parameters for soil erosion risk assessment is generated from using high-resolution satellite imagery and 30-meter resolution (DEMs). The parameters are integrated using weighted overlay analysis in Arc GIS generating final prioritazation. The delineated six watersheds have their own score values showing variabilities among themselves from 0.387(W3) highest to low value of 0.241(W5). Higher values showed high sensitivity of watersheds for degradation and the need for urgent attention to conservation. The findings of this study tells that where there is limited resources and vast degradation factors, prioritazation is an essential tool to address conservation efforts based on their urgency and conservation values at watershed scale. Therefore, this study recommends prioritazation for landscape restoration into a manageable planning unit; watershed scale is an essential decision making tool informing “where to invest first” to address restoration efforts based on its urgency.
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Watershed Prioritization, Soil Erosion Risk, Morphometric analysis, Ribb sub-basin.