CAPTURE (Characterisation And Parameterisation of TURbidity in Estuaries under anthropogenic and climatic pressures, 2021-2023) is a project funded by the French Office for Biodiversity (OFB) in the framework of the Inter-Estuary Mission (MIE) programme. The overarching goal of the project is to move toward a global conceptualisation of sediment dynamics in tidal estuaries, at time scales of events to years. Based on in situ monitoring networks associated with numerical modelling approaches, we aim at characterising key sediment behaviours, as Estuarine Turbidity Maximum (ETM) and sediment (mud/sand) fluxes. This ambitious challenge will be tackled by comparing the largest and contrasted French estuaries (Gironde, Loire and Seine) with worldwide estuarine systems to generalize the characterization at a larger scale. More specifically, CAPTURE objectives are to address the following questions:
- What are the influences of estuarine key parameters (river supply, tide, waves, morphology, sediment type, dredging activities) on ETM characteristics (mass, location, formation/decay)? Do the systems have a maximum capacity to maintain sediment in suspension?
- What are the net sediment transfers (i.e. import and export) between the upstream continental catchment areas and downstream coastal seas (i.e. along the land-sea continuum), as well as between the main channel and the lateral intertidal flats?
CAPTURE outcomes will provide a better understanding why suspended sediment concentrations strongly differ in tidal estuaries. Indicators of potential turbidity levels will be derived for helping in evaluating the good environmental status of estuarine transitional waters in the context of the European Water Framework Directive (WFD). In addition, as fine particles are the main vectors of nutrients and pollutants along the land-sea continuum, addressing such questions will provide better estimates of bio-physical matter transfers at the estuary-sea interface.