Numerical simulation of the wind influence on bottom shear stress and salinity fields in areas of Zostera noltei replanting in a Mediterranean coastal lagoon

The most interesting results concern the four nearshore replanting areas; two are situated on the eastern side of EB and two on the western side. The results of scen.#2 show that all these areas are subject to a downwind coastal jet. The destratification process is very beneficial; salinity always remains greater than 12 PSU for a N-NW wind of 80 km/h and a hydropower runoff of 250 m3/s. Concerning BSS, it presents a maximum near the shoreline and decreases along transects perpendicular to the shoreline. There exists a zone, parallel to the shoreline, where BSS presents a minimum (where BSS = 0). When comparing the BSS value at the four control points with the critical value, BSScr, at which the sediment mobility would occur, we see that for the smaller bottom roughness values (ranging from z0 = 3.5 × 10−4 mm, to 3.5 × 10−2 mm) BSS largely surpasses this critical value. For a N-NW wind speed of 40 km/h (which is blowing for around 100 days per year), BSS still largely surpasses BSScr - at least for the silt sediments (ranging from z0 = 3.5 × 10−4 mm, to 3.5 × 10−3 mm). This confirms the possibility that the coastal jet could be a stressor for SAV replanting.