Basin-scale performance of a semidistributed rainfall-runoff model for hydrological predictions and water resources assessment of large rivers: The Congo River

Gaps in hydrological information of the Congo Basin increase uncertainties in understanding hydroclimatic processes in the basin, and consequently the risks associated with decision making for major water resources development plans. There is also uncertainty about the predictions of future climate and land use change. These challenges make it essential to explore possible approaches to close the information gaps. Some of the gaps can be filled using hydrological simulation models, which if they prove practical, can be established with available data, but generate sufficiently reliable information for management purposes. This paper discusses the results of applying a semidistributed rainfall-runoff model which was established for the whole Congo Basin, using the available historical data, with an ultimate goal of understanding processes of runoff generation as well as assessing the impacts of future climate and land use changes on water resources availability, including options for water resources development in the basin. Issues of water resources assessment in the basin, approaches used to address them and some directions for future research are discussed. It is noted that the hydrological model applied in this study for the Congo Basin is able to capture the timing and magnitude of high and low flows satisfactorily, irrespective of the subbasins are located in headwater areas, downstream areas or at the outlets of regions strongly affected by wetlands and lakes. There remain a number of opportunities to improve the methods used for water resources assessment within the basin.