Groundwater recharge from heavy rainfall in the southwestern Lake Chad Basin: evidence from isotopic observations

We examine groundwater recharge processes and their relationship to rainfall intensity in the semi-arid, southwestern Lake Chad Basin of Nigeria using a newly compiled database stable isotope data (?2H, ?18O) from rainfall. ?18O signatures proximate surface waters are enriched 18O relative regional trace focused evaporated via ephemeral river discharge Chad; remote channels is comparatively depleted associated with diffuse recharge, often sand dunes. Stable ratios O H samples regress value along local meteoric waterline that weighted mean composition rainfall, consistent exceeding 60th percentile monthly precipitation intensity. The observed bias heavy suggests intensification tropical under global warming favours this basin.