Spatial modeling of erosion hotspots using GIS-RUSLE interface in Omo-Gibe river basin, Southern Ethiopia: implication for soil and water conservation planning

Rediet Girma,Eshetu Gebre

doi:10.1186/s40068-020-00180-7

Abstract

Soil degradation due to soil erosion is one of the major environmental threats in developing countries. In resource limited conditions, computing the spatial distribution of soil erosion risk has become an essential and practical mechanism to implement soil conservation measures. This study aimed to assess the spatial distribution of soil loss in Omo-Gibe river basin using the integration of computer-based RUSLE and ArcGIS 10.7.1 to identify areas that require erosion prevention priority. Once raster layer of the input parameters was created, overlay analysis was carried to assess the spatial distribution of soil loss. The estimated annual soil loss varies from 0–279 t ha−1 yr−1 with a mean annual soil loss of 69 t ha−1 yr−1. The empirical analysis also confirmed that the basin losses a total of about 89.6 Mt of soil annually. Out of the total area; 7% was in very sever class, 4.8% was found in the sever and 8.7% was categorized in very high range. The remaining area were ranging from low to high erosion risk class. The influence of the combined LS factor for soil loss is significant. It was observed that small area of the Omo-Gibe basin contributed for the significant amount of soil loss. The finding of this study is in a good agreement with previous studies. Compared to the country permissible soil loss rate, 26% of the entire basin significantly exceeds the country threshold value (TSL = 18 t ha−1 yr−1). As a result, precedence and immediate attention should be given to those erosion prone areas. The study output could deliver watershed management experts and policy makers for better management implementation and resource allocation based on the local context.

Highlights

The world-wide adverse influence of soil erosion has been considered as the most critical issues resulting in both on-site and offsite effects (Zhou et al 2014; Aiello et al 2015; Zhou and Wu, 2008)
This assesses the spatial distribution of soil loss and identify areas that require prior soil conservation measures using Revised Universal Soil Loss Equation (RUSLE) integrated with geographic information system (GIS) at Omo-Gibe river basin
This study was intended to assess the spatial distribution of soil erosion using GIS-RUSLE interface model (Fig. 2)

Summary

Introduction

The world-wide adverse influence of soil erosion has been considered as the most critical issues resulting in both on-site and offsite effects (Zhou et al 2014; Aiello et al 2015; Zhou and Wu, 2008). Quantitative estimation of soil loss to identify erosion prone areas provides useful information to implement suitable intervention measures (Wischmeier and Smith 1978; Shi et al 2004; Haregeweyn et al 2013). In this regard, the integration of Revised Universal Soil Loss Equation (RUSLE) with geographic information system (GIS) provides a rather simple and yet comprehensive erosion quantification framework (Gelagay and Minale, 2016). The model has been tested in different part of Ethiopia by modifying some of the factors and found valid (Meshesha et al 2012; Belayneh et al 2019) In this background, this assesses the spatial distribution of soil loss and identify areas that require prior soil conservation measures using RUSLE integrated with GIS at Omo-Gibe river basin

Objectives

Methods

Results

Conclusion