Hydrological Response of Land Use Land Cover Change on Stream Flow of Anger Watershed, Blue Nile Basin, Ethiopia

Abstract

Stream flow of Anger watershed (7,982 km2), located in Western Oromia Regional State, Ethiopia was simulated by using soil and water assessment tool (SWAT) model. Assessment of layer staking, mosaicking, image classification and accuracy was carried by ArcGIS. The main target of this study was to determine the SWAT Model applicability and impact of past land-use land-cover change on stream flow of the Anger watershed. The time series data from 1990 to 1999 was used for model parameter calibration, and data from 2000 to 2004 were used to validate the model using the input parameter set. The performance of the SWAT model was evaluated by both R2 time series plots and ENS the statistical measures. The results of the model during calibration for monthly stream flow was R2= 0.90, ENS= 0.76 and during validation R2= 0.84, ENS= 0.63 respectively. Validation of image classification is achieved through Mosaicking image and Google Earth image. The performance of the Arc GIS model was evaluated by using the overall accuracy and kapa coefficient. The agreement between classified land use image and ground truth of the year 1986, 2000 and 2010 were showed a good agreement with result of overall accuracy=88%, 85% and 87% and kapa coefficient=81%, 79% and 82% respectively. Simulation of steam flow of the watershed under the impacts of past land-use land-cover changes can be determined by using SWAT model as a tool for water resources planning and management in this watershed.