Local and seasonal climate change and its influence on the hydrological cycle in a mountainous forested catchment

In the context of climate change, understanding how temperature and precipitation influence water resources is crucial to better predict their future dynamics, especially in sensitive environments such as mountainous forested regions. Climate model projections are widely used in hydrological models to predict the future of water availability and extreme events over large temporal and spatial scales. However, few studies have investigated changes in local climate and their influence on the hydrological behavior of mid-mountainous forested catchments. We used a long-term (1988-2018) daily dataset of hydro-climatic data for the Strengbach catchment (France; OHGE) to investigate changes in temperature, precipitation, and discharge at annual and seasonal scales. Our results showed that the local climate changed in line with global observations of increases in temperature (+0.04. C.yr(-1)) and total precipitation (+6.9 mm.yr(-1)). Climate change varied among seasons, with an increase in temperature in autumn (+0.07. C.yr(-1)), summer (+0.05.C.yr(-1)), and spring (+0.05.C.yr(-1)), but a decrease in winter (-0.03.C.yr(-1)). Total precipitation increased in summer (+4.2 mm.yr(-1)) and in winter (+2.1 mm.yr(-1)) due to more days with very heavy precipitation and heavy precipitation, respectively. The long-term hydrological behavior of the Strengbach catchment also changed, with a decrease in the discharge:precipitation ratio and fast flow volume, mainly during the winter. These results suggest that climate change, through its influence on vegetation, evaporation, and snow mantle dynamics can influence a catchment's hydrological behavior. This study expands the knowledge of climate change and its impact on the hydrological cycle in a mountainous forested area. However, it is limited by the lack of accurate measurements of actual evapotranspiration at the catchment scale, which is a major challenge for improving our understanding of the critical zone.