Historic flood delineation and analyses for Elbe/Vltava catchment (2018-10-02)

<br/> Activation date: 2018-10-02 <br/> Event type: Flood <br/> <br/> Activation reason: <br/> In June 2013, &nbsp;wide flooding and consequent damage and losses occurred in Central Europe, affecting especially Southern and Eastern Germany and some areas in Czech Republic, Austria and Switzerland. It was one of the largest floods in the past two centuries.The outcome of EMSN-056 activation aims to provide further results to help in the analysis of this flood event dynamics. The current study delimits the flood extent of every available source, not analysed before, during more than one month from 02/06 to 05/07/2013 (Product 1), and chronologically compare results to provide information on the evolution of the event (Product 2).The time frame of interest (Summer of 2013) is previous to the European Sentinel satellites launch, hence the search of archived acquisitions included a wide number of sensors. SAR sensors, not affected by clouds, were prioritized but images were scarce; hence, the analysis also included optical imagery, being the cloud coverage too high in the available acquisitions. All the efforts were put in processing all types of images maximising the spatial and temporal coverage of results.Product 1: Observed Flood ExtentsIndividual extent of floods for each SAR image were obtained by exploiting the differences in backscatter between water and land surfaces applying a threshold of decibel values. The optical images have been analysed looking at the differences on spectral absorption characteristics of water bodies and ground objects in the visible and infrared bands. Results obtained from radar and optical approaches were refined and homogenised with the aim of making them comparable while ensuring the consistency of the product.Product 2: Evolution of Observed FloodsThe Evolution of the Observed Flood Extent for the period of interest has been analysed using the observed flood extents by date from Product 1. Only results sharing spatial coverage could be compared to study the evolution of the flood extents.Two reference figures were available to compare with: (1) The extent of the water in normal conditions (RNW) and (2) The extent of the flood for a return period of 200 years (200Y).&nbsp; Examples shown below correspond to AOI 01, where 8 dates were coincident in the 99% of the AOI. The complete results for the four AOIs are available in the activation report.&nbsp;&nbsp;Elbe River near Boizenburg, Germany (AOI 01) <br/> <br/>