Assessing future eco-hydrological behaviour of a typical Sahelian agro-ecosystem under climate change for the 21st century

Study Region The Sahel is dominated by a monsoon climate, where most of the population relies on subsistence agriculture. This study focuses on a typical agro-pastoral area in southwestern Niger. Study Focus Significant gaps remain in climate change impact projections in the Sahel. Indeed, capturing the impact of rapid hydrological processes necessitates high temporal resolution scenarios and adapted ecohydrological models, which has rarely been done in Sahel. This study addresses this gap by building climate scenarios at a 30-minute time step, by combining an observational dataset with CMIP6 projections for five models, two emission pathways (SSP245 and SSP585), and two horizons (2050 and 2100). These scenarios are used in a land surface model, SiSPAT, to assess future changes in water and energy cycles. Vegetation response to climate evolution is also considered. New Hydrological Insights for the Region All scenarios project a temperature increase for 2100 (+3.8°C for SSP245, +6.3°C for SSP585), with up to 10 days over 45°C during the growing season. Projected rainfall intensification is more uncertain (+27 to +56% by 2100). It leads to an increase in runoff (+168 mm/yr) and drainage (+132 mm/yr) for SSP585–2100, raising concern over flooding and soil erosion. Considering vegetation response to climate evolution strongly affects evapotranspiration seasonality (+/- 1 mm/day during some months). This study highlights the impact of climate scenarios on water and energy cycles with current agricultural practices.