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

L Krieger,D Floricioiu,E Johnson

doi:10.5194/isprs-annals-iv-3-w2-2020-133-2020

Abstract

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.

Highlights

Glaciers are important contributors to the global sea level rise
Due to the steeper slopes on the Patagonian Ice Field compared to the Greenland study area in Greenland (Krieger et al, 2020) we increased the uncertainty of the DEM elevations in the Monte Carlo experiment to σDEM = 25 m
In order to define seed pixels that mark the start of the basin delineation process, we selected all glaciers with an area larger than 35 km2 as defined in the Randolph Glacier Inventory (RGI) and marked all pixels touching the iceland interface on the glacier termini (RGI Consortium, 2017)

Summary

Introduction

Glaciers are important contributors to the global sea level rise. In order to better understand the variations in ice flow dynamics and their response to climate change, the estimation of the total glacier mass balance and its individual components are necessary. For the surface mass balance and if volumetric changes are measured, accurate delineations of the glacier drainage basins are needed. This could potentially direct the actual ice flow away from the DEM aspect angle and alter the basin boundaries.

Results

Conclusion