Soil Erosion Risk Assessment in Nashe Dam Reservoir Using Remote Sensing, GIS and RUSLE Model Techniques in Horro Guduru Wollega Zone, Oromia Region, Ethiopia

Ayana Abera Beyene

doi:10.11648/j.jccee.20190401.11

Abstract

Soil degradation is wide spread and serious throughout the Ethiopian Highlands. It is also a major watershed problem in many developing countries causing significant loss of soil fertility, loss of productivity and environmental degradation. This research has, therefore, been carried out to evaluate the soil erosion risk and quantify the major land use land cover changes over the past 20 years (1996-2016) in the Nashe watershed. The research integrates the Revised Universal Soil Loss Equation (RUSLE) with a Geographic Information System (GIS) and Remote Sensing (RS) to quantify the potential soil erosion risk and land use land cover changes. Rainfall data, soil data, DEM data and satellite image were used as input data sets to generate RUSLE factor values. Raster calculator was used to interactively calculate potential soil loss and prepare soil erosion risk map. For the land use land cover change calculation two satellite images of two year interval ( Landsat TM 1996 and Landsat 2016) has been utilized. As a result the potential soil erosion risk and land use land cover map of 1996 and 2016 of the study area was generated. The result showed that the potential annual soil loss of the watershed ranges from 0.00 to 243..065ton/ha/yr. and the mean annual soil loss rate is 45.7ton/ha/yr. Concerning the land use land cover change Grass land decline from (8.85%) to (6.85.4%), open forest changes from (47.10%) to (22.75 %) and settlement land changes from (4.42%) to (7.59%). On the contrary farm land changes from (27.18%) to (45.55%), bare lands increase from (5.40%) to (5.55%) and water body changes from (7.06%) to (12.10 %). By the LULC analysis it has been found that the grass land and forest land declined from 1996-2016. On other hand, the rest of the land cover types have increased.

Highlights

IntroductionSoil degradation by accelerated water and wind-induced erosion is a serious problem and will remain so during the 21st century, especially in developing countries of tropics and subtropics
Soil degradation by accelerated water and wind-induced erosion is a serious problem and will remain so during the 21st century, especially in developing countries of tropics and subtropics.Worldwide degradation of agricultural land by erosion, salinization, and water logging is causing the irretrievable loss of an estimated 6 million hectares each year
Rainfall erosivity (R) factor of the Revised Universal Soil Loss Equation (RUSLE) was estimated from the rainfall data according to the equation given by Hurni [10], derived from a spatial regression analysis (Hellden, 1987), for Ethiopian condition: R= -8.12 +0.562 * P

Summary

Introduction

Soil degradation by accelerated water and wind-induced erosion is a serious problem and will remain so during the 21st century, especially in developing countries of tropics and subtropics. Worldwide degradation of agricultural land by erosion, salinization, and water logging is causing the irretrievable loss of an estimated 6 million hectares each year. As cited in Abey (2007), in Ethiopia land degradation in the form of soil erosion and declining fertility is serious challenge to agricultural productivity and economic growth [4]. Soil conservation is a significant socio-environmental issue that reflects the wellbeing of the people in every country in the world and information on the factor leading to soil erosion can be used as a perspective for the development of appropriate land use plan. There are wide varieties of models available for assessing soil erosion risk.

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