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.
Highlights
Many uncertainties are associated with climate predictions in West Africa [1]
This study aims to assess future runoff projections in the upper Niger basin by using multiple climate and hydrological models
The results indicate that multi climate and multi hydrological model simulations help to reduce hydro-climatic modelling uncertainties
Summary
Many uncertainties are associated with climate predictions in West Africa [1]. This is attributed to the complexity of the regional climate and the influence of regional geographic features, such as deserts, land cover variations, mountain chains, large lakes, land-sea contrasts, and the sea surface temperatures (SSTs) of the adjacent ocean [2]. Climate patterns in the historical periods are not properly documented [3] and satellite-based observations have been identified with inherent biases [2]. This has led to contradictory results from climate trend studies at local and sub-regional scales [4]. A vivid example is the “Sahelian paradox”, which is an observed runoff increase in some Sahelian catchments of the Niger basin, such as in Nakanbe (Burkina Faso), Sirba (Niger), and Mekrou (Benin), despite a decrease in rainfall [6,7]
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