TITLE:
Assessment of Climate Change Impact on Water Resources in the Upper Senegal Basin (West Africa)
AUTHORS:
Mamadou Lamine Mbaye, Stefan Hagemann, Andreas Haensler, Tobias Stacke, Amadou Thierno Gaye, Abel Afouda
KEYWORDS:
Climate Change Impact, Signal, Bias Correction, Upper Senegal Basin, Water Resources
JOURNAL NAME:
American Journal of Climate Change,
Vol.4 No.1,
March
23,
2015
ABSTRACT: This study assesses the potential impacts of climate
change on water resources and the effect of statistical bias correction on the projected
climate change signal in hydrological variables over the Upper Senegal Basin (West
Africa). Original and bias corrected climate data from the regional climate model
REMO were used as input for the Max Planck Institute for Meteorology-Hydrology Model
(MPI-HM) to simulate river discharge, runoff, soil moisture and evapotranspiration. The results during the
historical period (1971-2000) show that using the bias corrected input yields a
better representation of the mean river flow regimes and the 10th and
90th percentiles of river flow at the outlet of the Upper Senegal Basin
(USB). The Nash-Sutcliffe efficiency coefficient is 0.92 using the bias corrected
input, which demonstrates the ability of the model in simulating river flow. The percent bias of 3.88% indicates
a slight overestimation of the river flow by the model using the corrected input.
The evaluation demonstrates the ability of the bias correction and its necessity
for the simulation of historical river regimes. As for the potential changes of
hydrological variables by the end of 21st century (2071-2100), a general
decrease of river discharge, runoff, actual evapotranspiration, soil moisture is
found under two Representative Concentration Pathways (RCP4.5 and RCP8.5) in all
simulations. The decrease is higher under RCP8.5 with uncorrected data in the northern
basin. However, there are some localized increases in some parts of the basin (e.g.
Guinean Highlands). The projected climate change signal of these above variables
has the same spatial pattern and tendency for the uncorrected and bias corrected
data although the magnitude of the corrected signal is somewhat lower than that
uncorrected. Furthermore, the available water resources are projected to substantially
decrease by more than -50% in the majority of the basin (especially in driest and
hottest northern basin with RCP8.5 scenario) for all data, except the Guinean highlands
where no change is projected. The comparison of simulations driven with uncorrected
and bias corrected input reveals that the bias correction does not substantially
change the signal of future changes of hydrological variables for both scenarios
over the USB even though there are differences in magnitude and deviations in some
parts of the basin.