Floods; designation of flood plains

The Bavarian Water Management Administration determines flood plains for a 100-year flood event, which are set by the district administrative authorities by legal ordinance.


The most effective way to avoid flood damage is to take precautionary measures to prevent potential damage from occurring in areas at risk of flooding. The Water Resources Act obliges the Länder to designate as floodplains within risk areas or assigned areas at least those areas in which a flood event is statistically to be expected once in 100 years and the areas used for flood relief and retention.

In Bavaria, there is a need to identify floodplains at all larger water bodies, the first and second order water bodies with a total length of 9,000 km, and especially in settlement areas at the smaller water bodies, the third order water bodies. These areas are determined by legal ordinance of the district administrative authority.

Technically, the evaluation of aerial photographs with subsequent water level calculation forms the basis for the determination of the flooded areas at the watercourses. After processing, these data represent the flood line for a flood event that statistically occurs every 100 years.

In the form of site plans, the water management offices pass these results on to the district administrative authorities for determination.

Various prohibitions apply in designated floodplains. For example, no new building areas may be designated in urban land-use plans or other statutes in accordance with the Building Code in designated floodplains. Exceptions are only possible under strict legal conditions.

Legal bases

Links to more information

  • Umweltatlas Bayern

    Der Umweltatlas Bayern ist eine Plattform, welche unter anderem Informationen über Hochwassergefahren und Hochwasserrisiken sowie zu vorläufig gesicherten, bzw. amtlich festgesetzten Überschwemmungsgebieten bereitstellt. Dieser Internet-Kartendienst bietet die Möglichkeit, sich einen Überblick darüber zu verschaffen, welche Gebiete in Bayern von Hochwasser betroffen sein können.

Status: 08.12.2021

Responsible for editing: Bayerisches Staatsministerium für Umwelt und Verbraucherschutz

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