Comparing Different Geophysical Methods in a Tidal Flat Area (Verdronken Land van Saeftinge, Westerschelde)

In order to validate existing models of sedimentation in active sedimentary environments, detailed stratigraphic information is indispensable. In the framework of the “Westerschelde” project different geophysical techniques, both land-based and sea-based, are developed and tested in the Verdronken land van Saeftinghe. This intertidal flat area is cut by numerous subtidal gullies, and high tidal amplitudes enable the application of different techniques at various water levels. Data acquisition focussed on the top 20 m of the active sediment bodies. Different techniques include very-high-resolution marine seismics (2D and pseudo-3D), geo-electrical methods (land and marine), electromagnetic techniques (land), high-resolution seismics (on land), ground penetrating radar (on land), and shallow manual drilling. In general the acoustic methods allowed the most detailed interpretation of the sedimentary structures. Electrical methods suffered from the effect of tidal action and proved to be very strenuous. The results indicate that not one single technique can provide all the answers, but only an integrated use of complementary methods will allow to get a better grip on the preservation potential in these sedimentary environments.