Gis - Based Evaluation Of Temporal Soil Erosion Risk Analysis Using Rusle Model: A Case Of Koka Lake Watershed , Oromia, Ethiopia

Abstract

Soil Erosion Poses A Severe Threat To Land Productivity, Water Resources, And Ecological Stability, Particularly In Erosion-Prone Areas Like The Koka Lake Watershed In Oromia, Ethiopia. This Study Aimed To Assess The Spatial And Temporal Dynamics Of Soil Erosion Over A 24-Year Period Using An Integrated Gis-Based Revised Universal Soil Loss Equation (Rusle) Model. Multi-Source Data Including Satellite Imagery (Landsat), Digital Elevation Models (Dem), Soil Surveys, Land Cover Data, And Rainfall Records Were Employed To Compute Rusle Factors (R, K, Ls, C, And P) For The Years 2000, 2006, 2012, And 2024. Advanced Geospatial Tools Such As Google Earth Engine (Gee), Arcgis 10.8, And Envi Facilitated Image Classification, Factor Modeling, And Erosion Mapping. The Major Findings Revealed A Sharp Increase In Soil Erosion Over The First Decade Of The Study Period With Maximum Annual Soil Loss Rising From 129.69 T/Ha/Year In 2000 To 163.21 T/Ha/Year By 2012, Primarily Driven By Deforestation, Agricultural Expansion, And Lack Of Conservation Practices. Spatial Analysis Identified Erosion Hotspots In Steep Upland Agricultural Zones With Sparse Vegetation And Inadequate Soil Management, Particularly In The Northeastern And Central Parts Of The Watershed. However, By 2024, Erosion Rates Declined To 126.76 T/Ha/Year, Reflecting The Positive Impact Of Soil And Water Conservation Interventions Such As Terracing, Afforestation, And Gully Rehabilitation Under Programs Like The Sustainable Land Management (Slm) Initiative. Vegetation Cover And Topographic Features (Slope Length And Steepness) Were The Most Influential Parameters Affecting Erosion Severity, While Poorly Implemented Support Practices Contributed To Erosion Persistence In Some Areas. This Study Highlights The Ongoing Challenge Of Soil Erosion In The Koka Lake Watershed And Demonstrates That Integrated Soil And Water Conservation Measures?�?Such As Terracing, Afforestation, And Gully Rehabilitation?�?Have Significantly Reduced Erosion Rates By 2024. The Use Of Geospatial Technologies And The Gis-Based Rusle Model Proved Essential In Assessing Erosion Severity And Identifying High-Risk Areas, Offering A Powerful Decision-Support Tool For Land Management. It Is Recommended That These Practices Be Strengthened And Scaled Up, Particularly In Erosion Hotspots, Alongside The Establishment Of Long Term Monitoring Systems And Active Community Participation, To Ensure The Sustainable Management Of The Lake Koka Watershed.