CryoSat-2 for hydrological purposes : data processing, visualization and analysis

Abstract

CryoSat-2, a remote sensing satellite of ESA, which is originally designed for the monitoring of sea and land ice surfaces, provides global radar altimetry data, that can also be used for other areas of application. This thesis will analyze its capability for hydrological studies of rivers, more precisely of their water level, extent and slope. For this purpose a GUI based on MATLAB, called CryoTrack, has been developed, which allows the operator to comprehend the tracks of the CryoSat-2 satellite on a global grid and to access their measurements for selected area and date. This data was used to determine water extent and slope of rivers, by combining the information of several radar altimetry quantities. Analyzing several intersections between the satellite tracks and the Niger River, algorithms for the designation of river width and slope were derived and tested for their capabilities and limitations. The transitions between water and land surfaces can be detected for wide rivers and their distance allows an estimation the river width. The moderate accuracy of this water extent calculation stands in contrast to the very good results of the slope computation between two or more intersections in the second part of the analysis.