Multidecadal changes in hydrological droughts across Sub-Saharan Africa

Abstract

Study Region: Sub-Saharan Africa, a region highly vulnerable to climate variability, faces significant challenges from hydrological droughts due to their widespread socio-economic and environmental impacts. Study Focus: This study investigates the spatiotemporal evolution of hydrological droughts and their links to meteorological droughts across Sub-Saharan Africa. Using the African Database of Hydrometric Indices (ADHI), we analyze streamflow data from 1466 gauging stations spanning 1951–2018 to detect trends in drought characteristics. New Hydrological Insight: A major shift in hydrological drought patterns occurred in the 1980s, with increased drought duration and severity during 1951–1980, followed by a general decrease from 1981 onward. Spatially, southern Africa experienced more frequent but shorter and less severe droughts, whereas central and eastern regions saw fewer but more intense and prolonged events. These spatial contrasts reflect differences in climate and basin characteristics. Although meteorological drought indices (SPI, SPEI) broadly align with hydrological drought trends, local factors introduce important variability. These findings enhance our understanding of drought dynamics in the region, with implications for water management, food security, and climate adaptation strategies.