Monitoring the topography of intertidal zones
Baie des Veys is located in a semi-diurnal macrotidal environment with a tidal range that reaches 8 m at high tides. At low tide, the surface of the uncovered intertidal zone is approximately 37 km2 with a lower part without any vegetation and covered with muddy and sandy sediments and an upper part colonized by halophyte species dominated by Spartina anglica. Monitoring the topography of intertidal zones, associated with the evolution of hydrodynamics, is particularly important because these environments provide many ecological and economic services and are buffer zones for the protection of the coast.
Previous research on the monitoring of these environments by several satellite missions (Sentinel1, 2 and Toolbox SWOT) clearly showed the interest of the SWOT mission, but it was still necessary to be able to calibrate and validate this data during the orbit at 1 day.
The Raz Blanchard site, northwest of the Cotentin, is an area characterized by very intense tidal currents, the strongest on the European coasts with current speeds that can locally reach 12 knots. As such, it is a privileged area of interest for the installation of tidal turbines, intended to recover energy from tidal currents, and the industry has expressed interest in this site. In terms of physical processes, it is a site where wave-current interactions manifest themselves in a very marked way, with effects of wave refraction and very regularly phenomena of wave blocking by opposing currents, causing breaking. Although probably difficult to carry out, the Cal/Val SWOT in this type of complex environment was a major challenge for the mission in order to properly target the potential contributions and limitations of SWOT measurements on a high current site.
During the SWOT fast sampling phase, the multi-scale processes observed in coastal areas were monitored using multi-sensor cross-approaches such as in-situ measurements, video camera, UAV, Lidar, satellites, and others. This has made it possible (1) to obtain a multi-scale temporal and spatial vision of the physical processes of tide, swell, storm surge and flow, and their interactions for a better understanding of coastal and estuarine hydrodynamics and its impact on morphological-sedimentary evolution of these environments and (2) to analyze the capacity and contribution of SWOT to measure water levels and these hydrodynamic processes, alone or in combination with other sensors.
Principal investigators: Laurent Froideval (CNRS), Julien Deloffre (Université de Rouen), Edward Salameh (CNRS)
Contact point for the study site : Laurent Froideval (laurent.froideval@unicaen.fr)
