Spatial Assessment of Land Degradation Risk in the Choke Mountain Watershed

Abstract

Assessing land degradation is essential for identifying susceptible regions and planning sustainable landscape management approaches. This research employed a combination of geographic information system (GIS) and multicriteria analysis (MCA) to delineate and evaluate land degradation within the Choke Mountain watershed of the upper Blue Nile. The Analytical Hierarchy Process (AHP) was employed to standardize all indicators and assign weights through comparison. A comprehensive analysis of physical, chemical, and biological indicators of land degradation was carried out. The results showed that about 50.64% of the watershed is at a high to very high risk of soil erosion, with an average loss of 44 t of soil per hectare each year. More than half of the watershed also exhibits moderate-to-high biological degradation levels, as evidenced by sparse vegetation cover and low levels of soil organic matter. About 70.7% of the area experiences only a mild physical degradation type. Biological degradation was rated as low in 37.4% of the watershed and moderate in 55.5%. The chemical degradation assessment revealed that most of the area (55.6%) has neutral soil pH values between 6.7 and 7.3. The integrated MCA results showed that 1.2% of the watershed is very low, 25.5% is low, 37.15% is moderate, and 36.15% is highly degraded in the Choke Mountain watershed. Overall, the main causes of land degradation in the Choke Mountain watershed are severe soil erosion, deforestation, and biomass deterioration. The most evident signs of land degradation are extensive biodiversity decline and soil erosion. Therefore, implementing comprehensive land management strategies is essential to prevent land degradation, enhance soil organic matter, and increase vegetation cover.