Modelling the recent variations of water balance components and water availability within the Senegal River basin: using WEAP21 model.

Abstract

The availability of water in the Senegal River basin is a basic issue for moving towards efficient resource management. Given the extent of the river and the large number of stations, hydrological modelling is a reliable means of assessing the evolution of the water balance and availability over the last 30 years. This paper aims to evaluate water balance components and to model the water balance over the Senegal River basin from 1989 to 2020. The streamflow data have been calibrated and validated with the PEST program incorporated in WEAP with a NSE equal to 0.98, a PBIAS of 7% and a R2 of 0.98. The water balance has been computed using the Soil Moisture Method which use mainly climate data and runoff data to output different results driving to an analysis of the water balance components. The results have shown that the precipitation is the main alimentation of the river with a mean rainfall of 267,255.84 Mm3; the losses by evapotranspiration are 246,892.45 Mm3. According to the conventional formula, the water balance would be equal to 20,363.38Mm3 in the Senegal River basin. The modelling of the water balance in this basin will allow a further study concerning the effect of climate change on the hydrological and ecological system of the Senegal River basin. A variation in the resource and hydrological parameters was noted. Although the 30 years see a decrease in rainfall, runoff increases. However, it remains to integrate the water use parameters for better conclusions.