Integrated Water Resources Management in Burkina-Faso through numerical modeling: Case study of the Mouhoun Basin

Abstract

This study is being conducted in the Mouhoun watershed, which covers an area of 91,036 km2. It is located in West Africa, in Burkina Faso. This is an area where the pressure on water resources is enormous due to high population growth. In addition, the high climate variability leads to a high variability in the hydrological regime, which hinders the availability of water resources and strongly influences the management of water resources in the locality. Due to the problem of lack of data, the Nwokuy sub-basin was used as a modeling area. Two models were used, namely the GR2M model and the WEAP model. The GR2M (the hydrological model) was applied to fill the gaps in the historical flow data set obtained at the Nwokuy station and provided a time series of uninterrupted flows. The model was calibrated and validated for the sub-basin with a model performance (NSE equal to 56.27 and 67.5 respectively for the calibration and validation periods) and a coefficient of determination equal to 0.37 and 0.67 respectively in calibration and validation over the period 1989-2013. The flow thus generated has a certain degree of uncertainty that should not be overlooked, but it is reasonable to use it in view of the acceptable performance of the hydrological model. With the WEAP model, four scenarios were created, the minimum flow, the average flow, the maximum flow and the Samendeni scenario (which takes into account the existence of the Samendeni dam). The Samendeni flow scenario considers that in a deficit year, the existence of the dam could reduce the river flow by 50%. It is therefore important to know the effect that the existence of the dam may have on the demand for water in the future. Projections have been made up to the year 2100. The application of scenarios using the WEAP model shows that in deficit years as well as in wet years, water demands for irrigation and domestic use are covered at 100% for minimum, medium, and maximum flow scenarios. However, a major anthropogenic action such as the construction of the Samendeni dam could, in the more or less distant future, lead to cases of unmet demand. The Samendeni flow scenario shows that the water deficit for irrigation could start in 2080 and the water deficit for domestic needs in 2090. In view of these results, it is therefore important to come to the formulation of some measures for a good integrated water resource management in this basin.