A system has been established at the German Remote Sensing Data Center of DLR that allows the near-real time mapping and monitoring of flood situations. It consists of fully automatic processing chains for the derivation of the inundation extent based on Sentinel-1 and TerraSAR-X Synthetic Aperture Radar (SAR) satellite data.
All processing chains contain the following generic steps: automatic data ingestion, pre-processing of the Earth Observation data, computation and adaption of global auxiliary data (digital elevation models, topographic slope information and topographic indices, as well as reference water masks), unsupervised initialization of the classification, post-classification refinement and dissemination of the crisis information via a web-client.
While the systematically acquired Sentinel-1 data allow a continuous monitoring of inundated areas according to the predefined observation scenario of the European Space Agency (ESA), the TerraSAR-X flood processing chain is activated on-demand in case of emergency situations. For this purpose dedicated satellite acquisitions are tasked over flood-affected regions (e.g. in the frame of disaster response mechanisms such as the International Charter “Space and Major Disasters”).
The radar-based processing chains make use of an automatic hierarchical tile-based thresholding approach in combination with a fuzzy-logic-based post-processing step for the unsupervised extraction of the open flood extent.
The crisis information can provided via a web-client to authorized users.