Hydrological Modelling of Ungauged Mamu River Basin Using SWAT Model

Abstract

Hydrological modeling of ungauged basins is necessary for decision and policymaking in water 
resources management. The Mamu River Basin is characterized by a wide range of environmental 
pressures such as erosion-caused devastation. The impact of climate change is likely to have 
considerable implications for water resource planning in the Basin. Despite these challenges, there 
is no gauged data available to evaluate the water resources of the Mamu River Basin. The objective 
of this study is to simulate river discharge in the ungauged Mamu River Basin using Soil and Water 
Assessment Tools (SWAT). A regionalization approach was employed to simulate the river flow at 
the Ebenebe axis of the Mamu River. Calibrated and validated model parameters from gauged Imo 
River were transferred to the Mamu River Basin. Shuttle Radar Topographic Misson-Digital 
Elevation Model (SRTM-DEM), land use, soil data, and rainfall data for the Mamu River Basin 
were used to improve the model. The SWAT model simulated streamflow for the basin and this was 
validated using discharge measurements along the Mamu River from 01/01/2021to 31/12/2022. 
During the validation process, the model performance indicators, NSE, R2, and PBIAS values were 
0.77, 0.95, and 15 respectively. This study showed that the SWAT model can simulate river 
discharge in an ungauged river basin and will enhance our understanding of the hydrological 
response of the ungauged Mamu River Basin to environmental changes.