Hydrological extremes such as floods have enormous environmental, social and economic consequences, and the effects of climate change effects combined with a growing population in ill-planned flood-prone coastal and river areas, are expected to increase their impacts in the future. With more lives and assets at risk, governments are increasingly investing in flood reduction measures to improve or at least maintain the current safety level.

As of today, constellations of a multitude of spaceborne sensors are used to monitor the World’s floodplains and to keep track of ongoing floods. By assimilating quality information derived from satellite Earth observation into numerical models, uncertainties in flood predictions are reduced, enabling an improved evidence-based emergency response. Moreover, reanalysis of satellite data collections produces comprehensive records of past floods and thus improves understanding of historical flooding trends. A variety of retrieval algorithms and data assimilation filters are available to produce quality information that greatly enhances the ability of flood managers to take action and to address the underlying risks.