Flood retention basin Straußfurt - Refurbishment and extension

Hochwasserrückhaltebecken Straußfurt
Hochwasserrückhaltebecken Straußfurt

The "Henschleben protective dam" and the "secondary dam", which separates flood retention areas 1 and 2 of the Straußfurt flood retention basin (HRB), are part of the construction measures. Tractebel Hydroprojekt was commissioned in 2021 by the operator of this dam, Thüringer Fernwasserversorgung, with the planning services for deficit elimination.

Under the boundary condition of limiting the necessary structural measures to the crown area, the choice for the protective dam was to raise the dam using wave deflectors. Shaft deflectors are proven construction elements used in valley dam construction to reduce the required freeboard height. The freeboard dimensioning, taking into account the wave deflectors, was carried out using the "Freibord" software of the TU Dresden or by calculating the so-called residual height of the wave run-up due to wind wave effects with wave deflectors.

By repairing the secondary dam, the original geometry of the dam will be restored and the dam crest will be made passable over a width of 3.20 meters. Making the secondary dam overflowable enables the flooding of flood protection area 2 to be automated without human intervention. The construction measures will create a dam embrasure with a coherent revetment. Geosynthetic concrete mats are used for this purpose. Geosynthetic concretemats consist of two high-strength, interconnected fabriclayers whose interspaces are filled with flowable mortar or fine-grained concrete. This is a simple, quick and economical construction method for erosion control and sealing.

The retention capacity of the HRB Straußfurt is to be expanded in the future. This is intended to improve flood protection for the areas along the lower Unstrut. The flood protection concepts for the middle and lower course of the Unstrut were drawn up by Tractebel Hydroprojekt. The plan is to raise the full water level target at the Straußfurt HRB by 1.0 m and thus expand the flood retention area by an estimated 10 million m³. The planning services for this were awarded to the HRB Straußfurt engineering consortium, in which Tractebel Hydroprojekt is collaborating with Inros Lackner SE as the lead partner.

Albrecht Köhler – Berlin