Data for: Groundwater vulnerability to pollution in Africa’s Sahel region

Protection of groundwater resources is essential to ensure quality andsustainable use. However, predicting vulnerability to anthropogenicpollution can be difficult where data are limited. This is particularly truein the Sahel region of Africa, which has a rapidly growing population andincreasing water demands. Here we use groundwater measurements oftritium (3H) with machine learning to create an aquifer vulnerability map(of the western Sahel), which forms an important basis for sustainablegroundwater management. Modelling shows that arid areas with greaterprecipitation seasonality, higher permeability and deeper wells or watertable generally have older groundwater and less vulnerability to pollution. The most important spatially continuous predictor was elevation. Groundwater vulnerability is based on recent recharge, implying a sensitivity also to a changing climate, for example, altered precipitation or evapotranspiration. This study showcases the efficacy of using tritium to assess aquifer vulnerability and the value of tritium analyses in groundwater, particularly towards improving their spatial and temporal resolution.