Evaluation of the Agricultural Best Management Practices (ABMPs) and Their Effect on Discharge Reduction of Shiroro Dam Site using SWAT Model

• Ibrahim A. KUTI

  Author

• Sunday E. OGUNMOLA

  Author

• Peter A. ADEOYE

  Author

Best Management Practices (BMPs) have proven to be effective in reducing erosion, sediment yield, and nutrient loss. However, there is little information on their effects on annual inflow. This study used the SWAT model to delineate the Shiroro Dam, divide it into 18 subbasins and 35 hydrological response units, and further modifies the curve number and support practice factor to represent terrace, contour, and strip cropping on the agricultural land. The research calibrated and validated the inflow data from 2011 to 2021. Sequential Uncertainty Fitting (SUFI2) algorithm was used to perform calibration and validation. Whereas the objective function used was Nash-Sutcliffe efficiency (NSE). Other performance indices identified included the coefficient of determination (R²), P-factor, r-factor, and Percent Bias (PBIAS). The results show that the NSE values ranged from 0.58 to 0.65 in the validation stage. It implies that the models are satisfactory. In addition, the sensitivity analysis revealed that saturated hydraulic conductivity (SOL_K) was highly sensitive to inflow under terrace, contour, and strip cropping, with the highest t- statistic, implying that SOL_K influences the simulated inflow in the catchment. The percentage reductions in inflow under terrace, contour, and strip cropping were 23%, 8%, and 1.3%, respectively. It implies that terrace and contour implementations would reduce annual inflow to the Shiroro Dam and serve as appropriate conservation practices in the study area.

• FJET_21_38_38

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