In the context of climate change, how do farmers change their practices or not, why, and with what consequences on water fluxes? Insights from the Rhine Valley (France, Germany, Switzerland)

Climate change is posing a threat on agricultural systems, mostly because it modifies the water ressources and dynamics: erosion, floods, drought… Adaptation is therefore becoming a vital issue (Darnhofer et al., 2010). These stakes are particularly high in the Rhine Valley, for agricultural systems are both importantly exposed and vulnerable, due to a significant change in the distribution and intensity of precipitations over the seasons (Riach et al., 2019), and their strong dependancy on a limited number of products (irrigated maize for the intensive crop production and drought sensitive grape varieties like Riesling for wine growing).In order to adapt to climate change, different practices are implemented: reduced soil tillage, soil cover, agroforestry, irrigation, new varieties etc., aiming at fighting against erosion, floods, fungi and/or retaining humidity, and thus modifying the water fluxes in the agroecosystems. In this quite homogeneous geographical area shared between France, Germany and Switzerland, facing the same climatical threats, the adaptation process nevertheless results in a very heterogeneous system, independent of borders. Actually, the choices to implement these practices depend on many factors: farmers’ observations and trials, perceptions of the impacts of climate change, awareness of environmental issues, economical and technical constraints, geolegal frames, and networks, including information exchanges between farmers, communication from agricultural organizations or associations and consumers’ demands. All farmers doesn't have the same goals and are neither equal in the face of the consequences of climate change, nor have the same opportunities to adapt. Moreover, these choices sometimes highlight contradictory objectives and debates, such as in the case of irrigation and glyphosate, and some adaptation measures can have paradoxical consequences on the hydrosystems. In fact, climatic change might lead to increase the gap between two agricultural models, two ways to face to environmental stakes.For this contribution, we based on semi-structured interviews with farmers (crops and wine growing), and we propose to analyze their choices. What adaptation practices do they adopt or not? Why? With which objectives and which consequences on hydrosystems? With wich difficulties and facilitating factors?