Shallow-Water Hydrography in Portugal Using ERS-SAR Data

Introduction The aim of hydrography is basically to chart the underwater topography. A precise knowledge of the sea-bottom features has great relevance mainly in shallow waters, where navigational safety must be assured at any cost. Ideally, one should have available a complete series of maps of the sea-bottom topography. approximately 100 km x 100 km. Although the basic information provided by ERS-SAR is only qualitative, in terms of bright and dark departures from the surrounding mean radar intensity, numerical models have been developed to quantify a SAR image in terms of depths. These models have been incorporated into the Bathymetry Assessment System (BAS), developed in the Netherlands by ARGOSS. BAS calculates the seabed topography based on ERS-SAR images and on a limited set of soundings (Fig. 1).