How sustainable land management practices may impact water resources in the Sahel: Insights from an integrated critical zone modelling approach

Study region The study was conducted in the south-western Sahel of Niger, within a small experimental catchment of the AMMA-CATCH observatory characterized by degraded soils, short high-intensity rainfall events, and increasing implementation of sustainable land management (SLM) practices such as micro-dams. Study Focus This study investigates the hydrological impacts of SLM practices on runoff generation, soil water storage, and groundwater recharge using the integrated hydrological model ParFlow-CLM combined with field observations. The model was first calibrated under pre-intervention conditions using event-based runoff observations. Micro-dams were then introduced using equivalent Manning roughness coefficients calibrated against observations to represent their hydraulic effects on a Sahelian hillslope. New hydrological insights for the region Results show that the model reproduces the observed reduction in event-based runoff induced by SLM practices. Under the 8% managed-area scenario, corresponding to the 8% field implementation stage (0.64 ha over the modeled 8 ha hillslope), runoff coefficients decreased from 0.24 to 0.13 in observations and from 0.25 to 0.17 in simulations. Simulations also indicate enhanced infiltration and increased event-based soil water storage in the upper soil profile, reducing soil moisture stress during dry periods. Simulations suggest that hillslope-scale, diffuse groundwater recharge increased from about 15–17% of annual rainfall, while hillslope-scale runoff declined from 15% to 9%. These findings highlight the potential of SLM interventions to improve water availability and hydrological resilience in Sahelian environments.