Simulation of River Flow using Soil and Water Assessment Tool (SWAT) Model in Imo River Basin

Abstract

This study aims to simulate river flow using the Soil and Water Assessment Tool (SWAT) model for the Imo River Basin. Climate data, including daily rainfall, temperature, and others, were obtained from the Global Climate Forecast System Reanalysis weather database. The digital elevation model of the basin was obtained from the United States Geological Survey, the soil map from the Food and Agriculture Organisation Harmonized World Soil Database, and the monthly discharge data for the Imo River was obtained from the Imo River Basin Development Authority. These data were used to develop the SWAT model for the basin. The SWAT model for the Imo River Basin was calibrated and validated. The outcome of the model validation yielded a better response than calibration, given the performance indices producing NSE, PBIAS, and coefficient of determination values of 0.98, 4.35, and 0.87, respectively. The results showed that the calibration and validation for river flow performed very well for the Imo Basin. In most cases, the river discharge simulations followed the observed discharge data trend in the Imo basin. This suggests the SWAT model can reasonably simulate monthly river discharge for gauged and ungauged river basins through model parameter transfer. The outcome of this study will enhance the understanding of hydrological response parameters, especially in poorly instrumented regions with spatially similar physiographic attributes as the study area.

Keywords: SWAT, Simulation, Calibration, Validation, River flow, Imo River.