Flood-prone areas of the Elbe from 01.10.2018, amended 21.01.2019 (WMS service)

Flood-prone areas of the Elbe (ügG) of 01.10.2018, amended 21.01.2019
In addition to the specified flood area, the ügG were also determined for the Elbe and publicly interpreted in map form. The public interpretation was pointed out by public notice of 20 September 2018 (Dresden Official Journal, No 38/2018). The legal basis for the map presentation and public announcement is Section 75(1)(1) and (2) and Section 75(4) SächsWG in conjunction with Section 72(3) SächsWG. These are areas that are only flooded if an HQ100 is exceeded or if flood protection systems fail to protect against an HQ100. Flood-prone areas are generally outside the floodplains established for HQ100 and adjacent to their external border.

The purple or pink shaded sugs are located outside the areas protected by public flood protection systems and can be flooded in a flood event of the Elbe, as is statistically expected once in 200 years (HQ200). The technical determination of the ügG for an HQ200 was carried out with the 2D-HN model Elbe of the Free State of Saxony, updated after 2013, specifically on the basis of the calculation results from 2017 on behalf of the LH Dresden.

The orange-striped surface marks congruently the areas flooded by the Elbe in the event of failure of public flood protection systems in the case of an HQ100 and an HQ200.
Technical reasons: No numerical model results are available for areas flooded in the event of HQ100 and simultaneous failure of a public flood control system. However, a simplified GIS-technical determination of a possible flood area in a dike fracture scenario showed only minor deviations (+/-) compared to the 2d-HN-modeled flood area of the HQ200 (Q=4930 m3/s). This is due to a different distribution of the water level (WSP) situation, which was assumed for the dike fracture scenario. It can be inferred from this review that the ügG pursuant to Paragraph 75(1)(1) and (2) of the SächsWG are almost identical in area coverage and in the WSP location, i.e. that the HQ100 (in the event of failure of the HWSA) and HQ200 are practically identical here.
A common flood-prone area with an identical external border is therefore shown in the maps. Due to the higher load capacity of the 2d-HN model results for the surface propagation and distribution of the WSP location behind the dike, the HQ200 scenario is used for this purpose. This means that the water level layers modelled for HQ200 (2017 modelling) can be used for projects on the areas concerned.

The water regulations to be observed for construction projects and development plans in these areas are Section 75(5) and (6) SächsWG and, in addition, Section 78b WHG.

With the public interpretation of the new cards in the period from 1 October 2018 to 15 October 2018 pursuant to § 72(3) SächsWG, the ügG become valid. At the same time, the previously publicly available maps of the ügG in the protected area behind the public flood protection systems of the inner city/Friedrichstadt and Pieschen /Mickten /Kaditz areas lose their validity.