Abstract:
Currently, soil erosion and sedimentation are the major watershed problems in Ethiopian
highland. This study was aimed to assess rate of soil loss and sediment yields for past three
decades (1990-2021) from Tullu Gana Watershed in Horo Guduru Wollega Zone, Ethiopia.
Rainfall, soil, Digital Elevation Model, Land use and Land cover (LU/LC) data were used as
input data sets to generate RUSLE factor values. In this study, integration of RUSLE with GIS
environment was used. Spatial data layers of the five factors of RUSLE values were computed
using ArcGIS 10.4 software. The Sediment Delivery ratio was determined from drainage area.
to estimate sediment yield . The study result showed that, total annual soil loss within the last
three decades was 135,882.255 ton yr−1
, whereas total annual sediment yield estimated to be
26089.392 ton yr-1 from 15451.21 hectares. Furthermore, six land use land cover class were
recognized and their extents were varies from earliest to recent of study periods. Also, the study
area were identified into six critical sub watershed and prioritized based on mean soil loss rate
for future conservation planning .From six critical sub watershed, Sw2, Sw4 categorized in
very high severity class, Sw3, Sw5, Sw6 categorized in high severity class whereas Sw1
categorized in low severity class. Overall, understanding amount of soil loss and sediment yield
and mapping its distribution is an important and effective for identifying erosion prone areas
as well as for sustainable land management.Therefore,Tullu Gana Watershed needs immediate
intervention for better conservation planning by considering identified priority classes and
hotspot areas.
