Influence of Parameter Sensitivity and Uncertainty on Projected Runoff in the Upper Niger Basin under a Changing Climate

Abstract

Hydro-climatic projections in West Africa are attributed with high uncertainties that are difficult to quantify. This study assesses the influence of the parameter sensitivities and uncertainties of three rainfall runoff models on simulated discharge in current and future times using meteorological data from eight Global Climate Models (GCM). The IHACRES Catchment Moisture Deficit (IHACRES-CMD) model, the GR4J, and the Sacramento model were chosen for this study. During the model evaluation, 10,000 parameter sets were generated for each model and used in a sensitivity and uncertainty analysis using the Generalized Likelihood Uncertainty Estimation (GLUE) method. Out of the three models, IHACRES-CMD recorded the highest Nash-Sutcliffe Efficiency (NSE) of 0.92 and 0.86 for the calibration (1997–2003) and the validation (2004–2010) period, respectively. The Sacramento model was able to adequately predict low flow patterns on the catchment, while the GR4J and IHACRES-CMD over and under estimated low flow, respectively. The use of multiple hydrological models to reduce uncertainties caused by model approaches is recommended, along with other methods for sustainable river basin management.