Evaluating Climate Change Scenarios For Regional Hydrological Management In Mountainous Semi-Arid Environments

Snow processes play a relevant role in semi-arid mountainous basins where snowmelt dynamics conditions the availability of water resources. In such environments, many rivers flow during the dry season due to the water storage in the snow cover while heavy rainfall events sporadically trigger severe flood events. These particularities confer to these areas special interest due to their high sensitivity in the hydrological response against changes in the meteorological conditions. This issue could be critical in many regions of the world linked to semi-arid mountain areas (e.g., the Atlas Mountains, Andean Cordillera,…) and presents a real challenge for future modifications of water management policies. This study highlights the utility of generating regionalized climate change scenarios in semi-arid environments to assess the most sensitive hydrological processes allowing us to predict future changes in water resources availability and hydrological responses. To do that, climate change scenarios from the ICCP were performed at the Guadalfeo River basin (southern Spain) where the fluvial dynamics is bound to the intermittent persistence of snow throughout the year. For this, statistically downscaled data from the Canadian Centre for Climate Modeling Model (CGCM2) given by a previous study were used and the local topographic effect of precipitation and temperature were added. Besides, a physically-based model, calibrated and validated at the study site, was used to reproduce the seasonal changes in the forcing agents-discharge relationship and the availability of water resources. The results show a significant change in the rainfall-runoff relationship in autumn conditioned by the decrease of snowfall associated to the climate sceneries. This effect also involves an enhanced severity of the floods during this season. Furthermore, a loss of 40% of water resource availability is observed related to a decrease of 2/3 of the snow inputs within winter and spring