Convection-permitting regional climate simulations reveal stronger drying and snow loss in semi-arid mountainous basins of Morocco Lahnik, O. /Tramblay, Yves /Lguensat, Redouane Bastin, S. Robin, Y. Andersson, J. C. M. Hanich, L. bias correction (CDF-T) climate change impacts convection-permitting climate model mountain hydrology RegIPSL snow processes Mountainous basins in semi-arid regions are among the most climate-sensitive environments, yet their hydro-climatic processes remain poorly represented by regional climate models. This study provides the first hydrological evaluation of a convection-permitting regional climate model (WRF3) with a spatial resolution of 3 km in mountainous basins of Morocco in North Africa, using a multi-model hydrological framework (HYPE and GR4J-CemaNeige). Results show that hydrological simulations forced by the convection-permitting WRF3 model provide a better agreement with observed streamflow and a set of different hydrological signatures than those forced by the coarser, convection-parameterized WRF20 model (20 km). Under the SSP5-8.5 scenario, the projections indicate precipitation decreases of 31%-62%, increases in potential evapotranspiration of 16%-27%, and streamflow reductions ranging from 64%-87%, depending on the climate forcing (WRF3 versus WRF20). There is a systematically stronger reduction in water resources in WRF3 projections than in WRF20 that is consistent across different basins. Snow contributions decline more strongly in simulations forced by the convection-permitting regional climate model (WFR3), leading to a shift from a snow-dominated to a predominantly rain-dominated hydrological regime. These results highlight the added value of high-resolution climate modelling in capturing fine-scale mountain processes, strengthening the confidence in climate-impact assessments, and also reveal the severe vulnerability of semi-arid mountainous water resources to future warming. The more pessimistic scenarios obtained with the convection-permitting regional climate model call for a reassessment of currently available scenarios for future water resources in semi-arid mountainous regions obtained with coarse resolution climate models. 2026 text https://www.documentation.ird.fr/hor/fdi:010097367 fdi:010097367 Lahnik O., Tramblay Yves, Lguensat Redouane, Bastin S., Robin Y., Andersson J. C. M., Hanich L.. Convection-permitting regional climate simulations reveal stronger drying and snow loss in semi-arid mountainous basins of Morocco. 2026, 40 (6), e70590 [18 p.] EN MAROC ZONE SEMIARIDE