Estimating groundwater recharge across Africa during 2003–2023 using GRACE-derived groundwater storage changes

Abstract

Study Region:Africa, with its diverse climatic zones from the humid Congo Basin to the arid Sahara Desert, where groundwater is influenced by climate variability, land use, and human activities. Study Focus:The main objective is to estimate groundwater recharge across Africa from 2003 to 2023 using a novel approach that uses GRACE-derived groundwater storage changes. New Hydrological Insights for the Region:This study provides new insights into the spatial patterns and temporal variability of groundwater recharge across Africa, highlighting the influence of climate variability on the continent’s groundwater resources. Key findings include distinct regional differences in recharge, with higher values in humid regions like the Congo Basin and lower values in arid regions like the Sahara Desert. Substantial interannual variability in recharge is largely driven by year-to-year variations in precipitation and modulated by major modes of climate variability, especially the Pacific Decadal Oscillation. The sensitivity of groundwater recharge to hydroclimatic extremes, with droughts causing significant declines and wet periods leading to above-average replenishment. Regions with low recharge rates or high variability, such as Northern Africa, are particularly vulnerable to climate change impacts and unsustainable groundwater abstraction. The findings emphasize the need for sustainable groundwater management strategies that consider the spatial and temporal variability of recharge, as well as the potential impacts of climate change on groundwater resources.