Hydrological modelling in data-scarce catchments: Black Volta basin in West Africa

A lumped version of the conceptual HBV-IWS version (Hydrologiska Byrans Vattenbalansavdelning) hydrological model was applied on the Black Volta Catchment in the West African sub-region (a data-scarce catchment) to investigate the performance of the model in the study area. In assessing the robustness of the model and how well it performs in the study area, different optimization methods were used. The Robust Parameter Estimation (ROPE) algorithm was used to generate and calibrate 10,000 best parameter sets in a computer framework with initially set model parameter ranges. The model performed well with an average NS of 0.75 and 0.6 for calibration and validation respectively for subcatchments Lawra and Chache. The performance also improved when a higher weight was given to the low-flows during the optimization. Results also show that the model reacts well to precipitation signals. For a proper management of the water resources and hydropower in the West Africa sub-region and for good policy decisions and investments in water related projects, a robust hydrological model would be essential and crucial for the Black Volta Catchment. The results of this study will be an essential input to a further study in assessing the effects of climate change on the hydrology of the West African sub-region.