Did you know that the Hochwasserrückhaltebecken Auhof is more than just a flood control system? It is a vital part of Vienna’s flood management. It is also a significant ecological area.
The Rückhaltebecken Auhof is also known as Hochwasserrückhalteanlage in Auhof. It can also be called Hochwassersammelbecken in Weidlingau or Rückhalteanlagen in Hadersdorf-Weidlingau. It is located on the border of the 13th and 14th districts. These districts are Hietzing and Penzing. The Hochwasserrückhaltebecken Auhof was built as part of the Wienfluss regulation. Its main task is to capture the rapidly rising and falling flood waves. These waves are typical of the Wien River.
Let’s delve into the history of the Wienfluss regulation. In the 1880s, the Vienna City Building Authority started working on regulation plans for the Wien River. The final project combined the Wien River and the Vienna City Railway. This combination offered technical and economic advantages.
The project spanned about 17 kilometers. It was divided into three main parts. The first part involved constructing the future river course. The riverbed and banks were built to support future vaulting if needed. For example, the vaulting at Naschmarkt was added between 1913 and 1915. The second part focused on building collection channels on both sides of the Wien River. The third part involved building floodwater retention basins in Weidlingau. This was at the beginning of the regulated section.
Construction on the first section of the Hochwasserrückhaltebecken began on April 1, 1895. Work on the second section started two years later. The construction work was completed on November 19, 1899. The rack systems were installed by the end of the following year.
Since June 15, 2001, both the Rückhaltebecken and the office building of the municipal Wien River Authority have been under historical protection.
The floodwater retention basins, also called “Haltungen,” are located near Weidlingau. They are at the western end of the regulated Wien River section. They sit where the Mauerbach flows into the Wien River. This area is between the Lainzer Tiergarten and the Westbahn railway line. The area covers about 37 hectares.
The Vienna City Building Authority oversaw the planning and construction. Franz Berger served as the director and Franz Kindermann as the construction manager. The construction work was carried out by “Doderer, Göhl & Sager.” The rack systems were made by R. Ph. Waagner.
Normally, the Wien River carries about 200 liters of water per second. In extreme cases, this can quickly rise to over 450,000 liters per second. The location at the mouth of the Mauerbach was chosen carefully. Long-term observations showed that dangerous flood waves occurred when both rivers flooded simultaneously.
The basins were designed to handle a maximum of 480 cubic meters of water per second from the Wien River. They also handle 130 cubic meters of water per second from the Mauerbach. This totals 610 cubic meters of water per second. Of this, 400 cubic meters per second can flow directly towards the Donau Canal through the redesigned channel. The remaining 210 cubic meters of water per second are held back in the retention basins. This continues until the flood wave subsides and the Wien River can handle more water.
These six Rückhaltebecken on the Wien River can hold 1,160,000 cubic meters. The one on the Mauerbach holds 150,000 cubic meters. The Auhof retention basins not only serve to protect against flooding. They also form the largest wetland biotope in western Vienna. The fauna and flora are largely left to themselves. The recurring floods create conditions similar to those in alluvial areas.
The Hochwasserrückhaltebecken Auhof exemplifies how engineering can work in harmony with nature. It protects Vienna. It also provides a habitat for diverse wildlife.