Observed changes in monthly baseflow across Africa
Jessica R. Ayers, Gabriele Villarini, Yves Tramblay, Hanbeen Kim
Abstract
Baseflow is an important water resource because it supplies streamflow between precipitation events and during dry seasons. We report the first continental assessment of baseflow in Africa by analyzing the baseflow index, baseflow seasonality, and monthly baseflow trends for three periods (1950–2018, 1950–1980, and 1981–2018). To explain changes in baseflow, we analyze precipitation trends. Results highlight that the baseflow season in west-central Africa occurs during August–November. In southern and northern Africa, the baseflow season is similar (January–May and January–April, respectively). Trend analysis detected monthly baseflow decreases in west-central Africa over the entire record and from 1950 to 1980, with increases after 1980. A clear pattern was absent in southern Africa for the whole record, but increases were detected earlier and decreases from 1981 to 2018. In northern Africa, decreasing baseflow trends were pronounced over the whole record, with no clear shift present. Precipitation trends were only consistent with baseflow changes in west-central Africa.