Hydrologic Modelling of Data Scarce Basin with SWAT Model: Capabilities and Limitations

Hydrologic modelling is pre-requisite to water resources management. Unfortunately, hydrologic modelling in data scare basin has always been difficult. The current study, explored the use of “data limited” model Soil Water Assessment Tool (SWAT) in modelling lower Aswa basin located in northern Uganda. The study adopted different techniques in generating and estimating various missing model parameters and input especially solar radiation, saturated soil hydraulic conductivity, available soil water content, Universal Soil Lost Equation erodibility factor and moist soil albedo. Soil Water Assessment Tool model was then manually calibrated using monthly historical streamflow records. The calibration was successful with coefficient of determination (R²) value of 0.618 and the Nash and Sutcliffe efficiency value of 0.47. Validation of the calibrated model using independent dataset shows even better model performance with Nash and Sutcliffe efficiency value of 0.64 and coefficient of determination (R²) value of 0.56. Successful calibration of hydrologic model Soil Water Assessment Tool under the data scarcity still proves the potential of the application of the model even in data limited basin, but more especially by water resources managers who needs understanding of existing condition and modelling possible future.