Hydrological variability and flood risk in a forest watershed undergoing accelerated urbanization: the case of Mefou (South Cameroon)

Abstract

Climate change and variability and anthropogenic forcings such as land use change are the main forcings of river discharge variability and hydrological risks. However, these issues are very less addressed in central Africa. This article aims to investigate the impact of precipitation variability and land use change on the hydrological dynamics of the Mefou river over the recent period (1963–2018) and draw up a basin flooding risk areas map. To achieve these goals, hydrometeorological data of this basin were analyzed using the Pettitt and Mann Kendall tests. Likewise, flooding risk areas was produced from the Frequency Ratio (FR) model. Average and extreme flows of the Mefou river have increased since 1985-86, unlike the rainfall, which generally decreased for all seasons from the 1970s, apart from summer, where the reverse was observed. Changes in land use (an increase in impervious areas (+ 530%) and a decrease in forest (-52.9%) and water bodies(-80.4%)) seem to be the leading cause of the increase in flows observed. Floods are often recurrent in basins with such hydrological behaviour. To enable policymakers to reduce the vulnerability of populations to this disaster, the proposed flood map shows that 2.67%, 7.22%, 22.5%, 35.25% and 32.36% of the catchment area are respectively delineated into very low, low, medium, high and very high flood vulnerability classes. These results could be useful for the management of water resources and associated hydrological risks in the basin investigated.

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

“…Variations in river ow generally result from interactions between climate change and/or anthropogenic changes (Ebodé et Ebodé, 2022d). However, the study of the impact of these environmental forcings is done in different ways.…”

Hydropluviometric variability in a forest watershed undergoing accelerated urbanization: the case of Mefou (South Cameroon)

“…Beyond the climate change that is currently raging throughout Cameroun and Central Africa (Ebodé et al, 2020;Ebodé, 2022c), the studied basin (Mefou) has experienced accelerated and uncontrolled urbanization through an excessive spatial extension of the Yaounde city (Ebodé, 2022d;Ebodé, 2022e), whose population has multiplied by 10 in about thirty years, from 50 000 in 1957 to 1 500 000 in 2008.…”