Vienna is preparing for extreme weather: retention basins are being upgraded!

Vienna is preparing for extreme weather: retention basins are being upgraded!

A violent flood event in September 2024 deeply shocked the Viennese population. Brown masses of water quickly transformed the Vienna River into a raging torrent and flooded the banks. The retention basins in Auhof, which had not been used so heavily for 125 years, were completely filled for the first time. In just two hours, an incredible 440,000 liters per second flowed through the Vienna River, while the normal value is around 200 to 500 liters. This event shook the city awake and once again underlined the need for flood protection measures, as reported by [heute.at](https://www.heute.at/s/neue-schutz Becken-wien-ruestet-sich-gegen-hochwasser-120142982), among others.

In order to ensure the safety of the people of Vienna, extensive renovation work is currently underway on the retention basins in Auhof. Environmental councilor Ulli Sima (SPÖ) emphasizes that the defensive walls will be raised by up to one meter to protect the city from a potential flood that could occur every 5,000 years. Thanks to renovation measures, the entire retention technology is being upgraded; The capacity of the pools is almost 1.2 million cubic meters. These retention basins not only play a central role in flood protection, but are also a valuable natural biotope that provides habitat for beavers, otters and over 120 species of birds. The renovation is scheduled to be completed by the end of 2026, as the [press portal of the City of Vienna](https://presse.wien.gv.at/presse/2025/11/10/sima-schuechner-pipal-leixner-wehrmauern-am-wienfluss- Werden-fuer-5-000-jaehrliches-hochwasser-geruestet) highlights.

Measures to improve flood protection

Flood protection is of central importance for Vienna. In addition to the retention basins, the city's defensive walls are also being strengthened, including on the Danube Canal and through the construction of a new wall in Ludwiggasse, which is scheduled to be completed by 2025. Work is also underway on the Liesingbach: natural protective structures are planned here that will help increase flood safety and ecological diversity. These comprehensive measures are necessary because climate change increases the frequency and intensity of such extreme weather events, according to TU Wien.

The flood experienced in September 2024 was classified as extreme, but Vienna survived comparatively well. This puts the city in a favorable position to better meet future challenges. However, climate change has the potential to trigger flood disasters sooner than expected, making a proactive approach to flood protection essential. In this context, it is also important to emphasize the connection between individual and public flood protection measures. A study by the Vienna University of Technology shows that both private measures, such as insurance, and public projects, such as dam construction, are necessary to minimize flood damage.

In summary, it can be said that Vienna is working intensively on improving flood protection. With constant investments in projects that take both nature and human habitat into account, the city shows how important it is to protect residents from the consequences of climate change.