Availability of the current and future water resources in Central Africa, case of the large Sanaga catchment in Cameroon
Résumé
Study region: Mbakaou and Bamendjing basins (Sanaga River sub-basins).
Study focus: In this study, the availability of water resources was assessed over the period
2002–2019, based on the SWAT (Soil and Water Assessment Tool) hydrological model and certain
meteorological and spatial reference data available for the region (Merra2, Landsat, etc.). Forecasts
of its evolution were then made with the same tool (SWAT) over two futures periods (near
2024–2035 and medium: 2036–205) based on data from four (04) regional climate models
(RCMs) (CCCma, HIRHAM5, RCA4 and REMO) and future land use and land cover (LULC) data
simulated using the CA-Markov procedure. To separate the impact of climate variability (CV) and
land use and use and land cover changes (LULCCs) on future water resources, two evolution
scenarios (experiments) were established: (1) the impact of the CV, by associating future climate
data with LULC from the historical period; (2) the impact of LULCCs, by combining future LULC
maps with climate data from the historical period.
New hydrological insights for the region: The performances of the SWAT model are satisfactory in
calibration and validation on the two basins with R2, NSE and KGE greater than 0.68. Two models
(CCCma and REMO) predict a decline in water resources in these basins, and two others (HIRHAM5
and RCA4) the opposite. The REMO model seems the most reliable. It predicts a drop in
precipitation and runoff (SURQ) in the two basins that do not respectively exceed –19% and
–31%. CV is the only forcing whose impact will be visible in the dynamics of future water resources,
given the insignificant changes expected in the evolution of LULC patterns. The results of
this study could contribute to improving the management of water resources in the studied basins
and the region.
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