IMPACT OF LAND USE LAND COVER CHANGE ON RUNOFF AND SEDIMENT YIELD IN CASE OF AKAKI RIVER CATCHMENT.

Abstract

Land Use and Land Cover change has been considered as one of the factors that can alter both volumes and rates of runoff and sediment yield of Akaki River Catchment. Assessing the impact of land use land cover change on runoff and sediment yield at Akaki River Catchment using SWAT Model was the main objective of this study. Hydrological and Meteorological data together with spatial data were used to simulate the model. Land sat imageries of 2003, 2010 and 2017 time series which were collected from Ethiopian mapping agency have been used to develop Land use Land cover maps of three time series by ERDAS2014 software using supervised classification method. As a result of supervised classification of ERDAS software, Akaki River Catchment contains four land cover classes like water body, urban area, forest and agricultural land. Model performances have been evaluated during sensitivity analysis, calibration and validation as per performance indicators such as Nash-Sutcliffe efficiency and coefficient of determination. There was a significant and continuous land cover change from 2003 to 2017 years, especially urban was increased by 37.29% for 2017 land cover map than for 2003 land cover map whereas forest and agriculture were decreased by 5.6% and 31.57% for 2017 land cover map than for 2003 land cover map respectively. Model performance result showed that there were not significant variations over the catchment. However, as showed from the calibrated results the mean annual SURQ and SYLD have been increased by 24.26mm and 67.75t-ha for 2017 land cover map than for 2003 land cover map respectively. Therefore, this analysis of land use land cover changes together with quantifying the runoff and sediment responses to the changes will help the local governors and policy makers to prepare possible response strategies how to minimize the undesirable effects of future land use land cover change induced problems.