A parametric sensitivity analysis for prioritizing regolith knowledge needs for modeling water transfers in the West African critical zone

Hard rock aquifers (HRAs) in West Africa (WA) are located within a thick regolith layer. The representation of tropical integrated hydrological models lacks consensus on aquifer geometries and parameter ranges. Our main objective was to determine the knowledge requirements saturated hydraulic conductivity (Ks) model critical zone (CZ) HRAs WA. A parametric sensitivity analysis with focus Ks heterogeneity conducted (Parflow-CLM [Community Land Model]) Upper Ouémé catchment Benin (14,000 km2) at 1- × 1-km2 resolution. impact changes near subsurface (0.3-to-5-m depth) deeper (24- 48-m maximum assessed five modeling experiments. Streamflow largely dependent clay distribution less properties subsurface. Groundwater table depths amplitudes were controlled by vegetation topography as observed instrumented hillslopes for literature range. Experiments higher suggested threshold where dynamics become determined one-dimensional vertical more lateral processes. Such impacts from smaller scales need be accounted when upscaled larger domains (1- resolution or coarser). findings highlight new conceptual approach represent order develop catchment-scale CZ WA that capture