Effects of climate and anthropogenic changes on future variability in flows in the So’o River Basin (South of Cameroon)

Abstract

Due to climate and environmental changes, sub-Saharan Africa (SSA) has experienced several drought and flood events in recent decades with serious consequences on the economy of the sub-region. In this context, the region needs to enhance its capacity in water resources management, based on reliable forecasts. The objective of this article was to study ​​the evolution future (near (2022-2060) and distant (2061-2100)) flows in the So’o River Basin (SRB) in Cameroon. The Cellular Automata (CA)-Markov was used to predict the future land cover evolution of the basin, and the outputs of two regional climate models-RCMs (RCA4 and CCCma) were used to predict the future climate in the basin. Distribution mapping was used for correcting precipitation and temperature biases in the outputs of the climate models used. The soil and water assessment tool (SWAT) model was used to simulate the future flows in the SRB. The results obtained show that a change in precipitation in line with the predictions of the CCCma model will lead to a decrease in river discharge in the basin, except under the RCP8.5 scenario during the second period (2061-2100), where will note an increase compared to the historical period of approximately +4%. It is projected that the decrease in precipitation and river discharge will occur mostly in the autumn months during 2020s, 2040s and 2070s. Results from the RCA4 model project an increase in precipitation which will lead to an increase in river discharge by more than +50%, regardless of the period and the scenario considered. In general, this increase will be greater during the dry seasons (winter and summer), while the decades at the end of the century (2080 to 2100) will be the wettest. An increase in discharges was noted in some cases despite a drop in rainfall, particularly in the case of discharges simulated for the second period (2061-2100) from the outputs of the CCCma model. This seems to be a consequence of the increase in impervious spaces, all the more the runoff increases during this period according to the model. Results from this study could be used to enhance water resources management in the basin investigated and the region.