A NEW DRAINAGE BASIN DELINEATION FOR THE SOUTHERN PATAGONIAN ICE FIELD BASED ON TERRASAR-X VELOCITIES AND TANDEM-X ELEVATIONS

Abstract. The drainage basins or catchments for the Patagonian Ice Field are part of glacier inventories like the Randolph Glacier Inventory (RGI) or the Global Land Ice Measurements from Space (GLIMS). These catchments are used in many glaciological studies for integrating remote sensing measurements over the area of a single glacier. An accurate basin boundary delineation is therefore important for applications like mass balance measurements for individual glaciers in Patagonia. Here we investigate existing catchment delineations of the Southern Patagonian Ice Field (SPI) with a modified watershed algorithm that is capable of including ice velocity measurements from SAR offset tracking during the delineation process. The classical watershed delineation is performed using only a DEM. We show that apart from the basins of Bernardo, Greve, Tempano and Occidental there is no dependence of the basin boundary on the measured ice velocity direction and that the glaciers of SPI flow in the direction of the steepest surface slope of modern high resolution DEMs like the TDM global DEM or SRTM. Additionally, a map of basin probabilities has been produced, which highlights several locations on the ice field where the delineation of the exact basin boundary is difficult.