Exploring future water resources and uses considering water demand scenarios and climate change for the French Sèvre Nantaise basin

Abstract. Incorporating human influences within water resources modelling, in the context of global change, has proven to be a fruitful approach for improving the assessment of the impact of climate and water demand changes on hydrology and water demand satisfaction. In this study, we use an integrated water resources management model that details water withdrawal for irrigation, drinking water supply, cattle watering and industry, as well as releases from wastewater treatment plants, drinking water network leakages, and industrial activities, within a catchment subject to human influence. Using this modelling approach and collaborating with relevant stakeholders through workshops, we developed a series of future water demand scenarios to examine the sustainability of water use in the future. Our findings indicate that climate change will be the primary driver of changes in water resources and water demand satisfaction. Moreover, we found that low flows and water demand satisfaction will greatly decline in the future. A single climate projection indicates a less drastic deterioration of the system in certain areas of the catchment. We found that adapting water uses could help mitigate the negative impacts, though it is not fully satisfactory. The irrigation sector is set to be the most impacted in terms of water demand satisfaction. The study presents a methodological framework that helps to provide water sector managers with tailor-made results to support the design of effective adaptation measures.