Evaluating Impact of Land-Use/Land-Cover Change on Surface Runoff using Arc SWAT Model in Sore and Geba Watershed, Ethiopia

Abstract

The aim of this study is to assess the impact of LULC change on surface runoff in the watershed of Sore and Geba, the upper Baro-river basin covering an area of approximately 6551 km² in Ethiopia. Landsat images were used to analyze the LULC change trends for the periods of three decades (1987-2017). LULC map of the area produced using the maximum likelihood algorithms based supervised image classification. Trends in LULC change showed that farm land has augmented by 16.55% within the periods of between 1987 and 2017with annual expansion by 36.15 km² at the expense of other land use types such as open forest, dense forest and wood land. The Soil and Water Assessment Tool (SWAT) model has been used to evaluate the impacts of LULC change on surface runoff. Nine sensitive flow control parameters were identified and used for calibration of the model.  In both calibration and validation periods, good performance was obtained.  Results show between 1987 and 2017, a 16.5% cultivated land expansion was observed which may explain an increase of about 6.65 m³/s (32 mm) in annual surface runoff. In general, during the study period significant influence of LULC change were reflected in changes to the hydrologic system of the region with an important management implication for this region as well as other similar regions in Ethiopia.

Keywords: Land use change, Sore and Geba watershed, Surface runoff, SWAT

DOI: 10.7176/JEES/9-10-02

Publication date:October 31^st 2019