Omid Elmi (University of Stuttgart, Institute of Geodesy, Germany); Nico Sneeuw (University of Stuttgart, Institute of Geodesy, Germany)

The spatiotemporal coverage of in situ discharge databases is surprisingly poor, despite its extreme importance in hydrological modeling. It has been demonstrated that spaceborne sensors can sensibly contribute to deal with the growing lack of in situ discharge data. However, measuring river discharge as a three-dimensional parameter is not feasible with available spaceborne sensors as it is not possible to determine the actual water depth from the space. A number of successful methods have been introduced to estimate discharge through finding an empirical relationship between simultaneous in situ river discharge and satellite-based water level, or river width. We propose a method which uses both water level from altimetry and river width from imagery to form a 3D empirical model for estimating river discharge. The combination of both geometric variables results in a robust method, that is appropriate to a wide variety of river channel types. We validate our method against the extensive in situ data over the Niger, Congo, and Mississippi rivers which have very different geomorphological and climatic conditions.