Limitation of the ÜG Elbe of 01.10.2018, amended 21.01.2019

Limitation of the ÜG Elbe of 01.10.2018, amended 21.01.2019 Floodplain of the Elbe in Dresden for a 100-year event (HQ100, 4370 m3/s): The previous set ÜG of the Elbe for a flood event, as it is statistically expected once in a hundred years (HQ100), applied since October 2004. Since then, it has been amended twice, first in January 2012 and later in June 2016 following the completion of the public flood protection systems in the districts of Innenstadt/Friedrichstadt and Pieschen/Mickten/Kaditz, each limited to the protected areas. The exclusion of the established ÜG of the Elbe has now been reviewed on the basis of updated model principles throughout the city and adapted to new findings. The state capital Dresden is obliged to do so in accordance with § 76(2) sentence 3 of the Water Resources Act (WHG). A two-dimensional hydrodynamic-numeric simulation model developed at the TU Dresden, Institute of Hydraulic Engineering and Technical Hydromechanics was used for the technical determination of the ÜG, which was comprehensively updated after the Elbe flood of June 2013 on the initiative of the Free State of Saxony at the Technical University of Nuremberg (2D-HN model Elbe). After a further model update, which was carried out in 2017 on behalf of the state capital Dresden again at the Technical University of Nuremberg, the modeled flood areas were determined for an HQ100, among other things. The new maps of the ÜG Elbe are again based on a flood event, as can be statistically expected once in a hundred years, flow rate 4370 m3/s at the Dresden-Augustusbrücke level. For this purpose, the flood areas calculated for HQ100 were homogenized and plausible. Calculated island locations < 500 m2 were integrated into the ÜG Elbe and calculated island locations larger than 500 m2 remained as island locations outside the specified ÜG. In the definition of the ÜG, as in the previous ÜG, the interactions of the Elbe with other flowing waters, groundwater and sewerage, which may also lead to flooding, as well as temporary constructions, e.g. sandbag walls or other protective measures taken to prevent flooding, were not taken into account. Excluded from the ÜG are the areas protected by public flood protection systems designed and constructed for an HQ100. This concerns protected areas in Dresden's city centre and Friedrichstadt, in the districts of Pieschen, Trachau, Trachenberge, Mickten and Kaditz as well as in the areas of Stetzsch, Gohlis and Cossebaude. The newly defined floodplain of the Elbe for an HQ100 was shown in maps in accordance with § 72(2)(2) SächsWG. With the public interpretation of the new cards in the period from 1 October 2018 to 15 October 2018 pursuant to Paragraph 72(3) of the SächsWG, the new ÜG became valid as a fixed ÜG Elbe. At the same time, the previous ÜG Elbe of October 2004 expired with its amendments. The amendment of 21 January 2019 concerns only one area in the area of the Enderstraße. A review of the defined floodplain showed that it is technically and legally justified not to designate an area west of the Ender Strait as floodplain calculated as flooded. Therefore, this area was removed from the ÜG and added to the flood-prone area. The ÜG ends there coming from the east at the Enderstraße.