Résumé
The Mediterranean coasts are subject to multiple environmental risks (erosion of the coastline, marine submersion, flooding, degradation of water quality) and overdeveloped anthropogenic pressures (urbanization, tourism, agriculture, industry, etc.). These natural and anthropogenic pressures already affect water resources and dependent coastal wetlands. For these coastlines, which are particularly rich in biodiversity, the consequences could get worse in the coming years as a result of climate change. In this context of increasing pressures, understanding the dynamics/trajectories of coastal hydrosystems appears to be the only robust approach allowing the establishment of integrated water resource management and territorial sustainability. To this end, this study proposes to demonstrate how the transdisciplinary approach between environmental sciences (hydrology, hydrogeology, hydroecology and geosciences) and human sciences (geography, cartography, history, anthropology) allows the production of a particularly rich common knowledge, which makes it possible to accurately analyze the dynamics and trajectories of coastal hydrosystems. Two coastal hydrosystems have been studied: the Biguglia lagoon (Corsica, France) and l'Etang de l'Or (Herault, France), through a detailed analysis of (i) the uses, practices, behavior and state of the coastal hydrosystems (surface and ground waters, lagoon and associated wetlands), (ii) planning and development policies and issues, and (iii) the governance of these spaces. Thanks to this information, it is thus possible to describe and to analyze the evolution of coastal hydrosystems over time. The correlation between the understanding of the hydrodynamic behavior of systems and socio-economic dynamics of land use planning allows the identification of causal links between anthropogenic development and the status of resources. Thanks to this collaborative work, the chronology and identification of resource degradation processes could be traced. By understanding the contemporary issues, the transdisciplinary approach provides new basis for thinking about the anticipation, the adaptation and the sustainable management of coastal hydrosystems. [Copyright Author(s) 2020. CC Attribution 4.0 License: https://creativecommons.org/licenses/by/4.0/legalcode]