Reply to 20. preparation of a flood report

20. preparation of a flood report

A flood risk assessment is requested for the Alterlangen urban area, in particular Erlenfeld. There is also the question of what measures should be taken to prevent renewed flooding.

Response from the Office for Environmental Protection and Energy:
The risks of flooding in the Wiesengrund are already well known and have been assessed. The Wiesengrund is largely in the Regnitz floodplain. The Regnitz is a 1st order watercourse, which means that the calculation of the floodplain is the responsibility of the Free State of Bavaria (Nuremberg Water Management Office). Every citizen can find out about the expected flooding risks and heights via the following portal: https: //geoportal.bayern.de/bayernatlas/?lang=de&topic=ba&bgLayer=atkis&catalogNodes=11.
The so-called HQ100 (= flood that occurs with this intensity every 100 years) is decisive for official protective measures or building regulations. The portal can also be used to view all expected flood risks in the event of more frequent or more extreme floods. Every person with property in a floodplain (HQ100) or a flood hazard area is also obliged to take adequate precautions against the risk of flooding. As the Wiesengrund is very wide and undeveloped, the water can spread over a wide area in the event of flooding and extremely rapid or deep flooding is not to be expected. The residential areas in question would only be marginally affected by an HQ100 (see figure below).
As part of the application for the StUB, the approval authority would be the government of Middle Franconia. The impact on the floodplain and possible flooding events caused by the StUB must be addressed in the application and will be examined by independent state legal and technical authorities (government and water management authority). Should there be any effects on flooding or runoff behavior, approval can only be granted if appropriate protective measures or precautions are taken.
The dangers posed by heavy rain are to be recorded and analyzed city-wide in the near future by means of a heavy rain hazard map. However, these are independent of the already known flood hazards emanating from the Regnitz and other bodies of water and can occur throughout the city. Furthermore, it is the duty of every property owner to protect themselves adequately against heavy rainfall. The heavy rain hazard map is also intended to help identify potential hazards so that they can be counteracted in a targeted manner.