Contemporary Subaqueous Dune Field Development Over an Abandoned River Mouth (Ebro Delta)

Abstract

High-resolution multibeam bathymetry, bottom sediment samples and time series of current intensities and directions were collected over a dune field in the Ebro Delta coastal area. Aerial photographs were used to analyse the morphological changes of the river mouth since 1946. The bathymetry show a ~6.4 km2 dune field located at a water depth of 6–15 m, with dunes of 1.3 m median height and 250 m median wavelength. The location of the dune field coincides partially with a former river mouth, an area that emerged in 1946. Onset of dune field development is believed to have started in the 1940s, when the Cape Tortosa river mouth was abandoned and the shoreline underwent a severe retreat. Currently, the recorded high-energy current events induced by northwesterly winds result in a dynamic seabed over the dunes, including ripple development, suggesting that the dune field is active mostly during these high-energy periods