Extracting River Discharge from Satellite Altimetry

The global database of available and freely accessible discharge data is unsatisfactory and does not meet the needs and require-ments of the global hydrological community. Over the past sev-eral years alternatives, such as satellite altimetry, have been in-vestigated for monitoring inland water level. In this contribution we propose an algorithm to extract river discharge by comput-ing a reliable level-discharge relationship. The prerequisite for computing a high-quality level-discharge is a reliable level from satellite altimetry. Therefore, our algorithm contains an unsuper-vised classification procedure that sifts all the waveforms into dif-ferent classes. A suitable retracking algorithm for each class is applied to the classified waveforms. With the height information from satellite information improved, we obtain a reliable level-discharge relationship, allowing the determination of discharge from satellite altimetry for time periods without in situ measure-ments. The algorithm is validated by comparing altimetric dis-charge predictions to in situ discharge measurements. 1. Data In this study, in order to receive a maximum data coverage in space and time, runoff data are collected from different sources: • GRDC (Global Runoff Data Center