Effectiveness of GIS Based Hydrological Modeling Tool for Sustainable Sediment and Water Management in Asa River Catchment, Nigeria

Abstract

In this study, Soil and Water Assessment Tool (SWAT) was interfaced with Mapwindow-GIS to simulate the hydrology, predict sediment yield, water yield and water balance into sub-basins of Asa river catchment in Kwara State, Nigeria. SWAT was calibrated and validated using measured flow data from January, 2008 to December, 2014. The model was evaluated using Coefficient of Determination, R2 and Nasch-Sutcliffe Efficiency, NSE which give acceptable results of 0.76 and 0.85 for Calibration and 0.70 and 0.74 for validation stage. Highest Annual Sediment yield of 20.71t/ha was recorded in sub-basin 13 while the lowest value of 8.9t/ha was recorded in sub-base 16. Annual sediment production rate was estimated as 437.6t/ha/yr while the total sediment yield of 4,376.t/ha was produced in the watershed during the simulation period. Predicted values of sediment concentration is highest in sub-basin 23 (153,045.9mg/l) and has a lowest value of 26,781.9 mg/l in sub-basin 1. Categorization of erosion prone areas showed that 12 sub-basins are in low erosion prone zone, two (2) sub-basins moderate zone, 14 in severe while 3 sub-basins are in extreme category. The outcome of this study confirmed that SWAT can be adopted as a decision support tool for sustainable sediment and water management in the basin and other watershed in Sub Saharan Africa Countries.