The role of land use/cover type in influencing hydrological component of a watershed in Chancho and Sorga Sub-watersheds, East Wollega Zone, Oromia, Ethiopia

Abstract

Watershed hydrology can be influenced by land use/cover types of the study areas. The activities of humans exert more pressure in influencing the natural dynamism of the watersheds and hydrology through continuous and steep slope cultivation of land. The objective of this study was to assess the influences of land use/cover types and slope gradient on hydrological component of a watershed. The hydrological component of a watershed was simulated by SWAT model with arc-GIS where land use/cover map, slope map and hydrological response unit were used as an input. Farmland land has produced more surface runoff and water yield as compared to the other land use types followed by urban land, while Forest and grassland produced less surface runoff and water yield but higher in evapotranspiration, percolation, ground and lateral flow of water than cultivated and urban land. Area of farmland land is more responsive to the change of surface runoff and water yield than others land use/cover types. As farmland land size increases both surface runoff and water yield tends to decrease and had a negative correlation, whereas, other hydrological variables were less responsive to the change in land size. Slope gradient of land use/covers type contributes to the water imbalance of the watersheds. As slope increases surface runoff and water yield also decreases in farmland, grass, and forest land, whereas, increases in urban land as slope increased. The influences of land use/cover types and slope gradient on the watershed hydrology were more observed where human action is high in terms of continuous and steep slope cultivation and urban built-up expansion and appropriate land use and watershed management is paramount important for water balance in the watershed.