Processos de recarga de águas subterrâneas na Bacia do Lago Chade com base em dados isotópicos e químicos

Abstract The Lake Chad Basin is Africa’s largest endorheic basin. Because water supply for the rural population and most of urban depends on groundwater, assessment groundwater recharge crucial. Recharge sources upper Quaternary aquifer are precipitation, rivers, swamps. Using chemistry, environmental ( 18 O, 2 H, 3 H) carbon 14 C) isotopes, processes can be assessed ages roughly estimated. For this purpose, more than 1,000 samples from surface precipitation were analysed hydrochemistry stable isotopes. Furthermore, H measurements C values dissolved inorganic northeastern part included in evaluation. isotope distribution shows recent north (Kanem Region), where very low indicate occurrence before 1960s bomb peak. Focused fresh river typical Salamat Region south Komadugu Yobe wetlands between Nigeria Niger. Slightly high δ-values occur Waza Logone area Cameroon. Groundwater along shore Bahr el Ghazal corridor show (δ O –0.78 to 7.45‰, δ –13.6 30.8‰). caused by that undergoes evaporative percolation. 600–4,150 years, estimated analyses combined with SO 4 concentrations, was residuals Mega it dried out completely.