Mechanisms and Rates of Groundwater Recharge at Timbuktu, Republic of Mali

Groundwater recharge at Timbuktu, Mali, occurs at a minimal rate of 4 mm annually, constituting just 1–2% of the region's average precipitation. This limited recharge is primarily driven by runoff and channeling in depressions between dunes, known as 'mares,' which retain water for extended periods post-rainy season. The study, using chloride budgets from well clusters and soil profiles, also revealed that occasional high nitrate concentrations in soil and groundwater are likely due to nitrogen-fixation by cyano-bacteria thriving on the moist soil surfaces of these mares. This finding underscores the region's highly variable precipitation patterns and highlights a sustainable water demand by local settlements relative to the assessed recharge rates.

Jacks, G., & Traoré, M. S. (2014). Mechanisms and Rates of Groundwater Recharge at Timbuktu, Republic of Mali. Journal of Hydrologic Engineering, 19(2), 422–427. https://doi.org/10.1061/(asce)he.1943-5584.0000801