Rehabilitation of the river Lutz in Ludesch und Thueringen (Austria, province Vorarlberg)

The project "Renaturation of the Lutz" aimed at improving the ecological condition of the Lutz River while maintaining flood safety. To optimize the planning, a hydraulic model test was carried out.

A section of the hydraulic engineering model of the Lutz during a flood event.
© BAW-IWB

The aim of the "Renaturation of the Lutz" project was to improve the ecological condition of the Lutz while maintaining flood security. A hydraulic engineering test was carried out to optimize the planning.

The Lutz in the area of the villages Ludesch und Thueringen (Vorarlberg) was hard trained, straightened and provided with a number of drop structures, not passable for fish. This type of river training is outdated, in the present case, it is already damaged and in some cases even threatened with destruction, and it massively impeded the migration of organisms in the water. For this reason, renaturation planning was carried out for a 1.6 kilometers section of the Lutz with the aim of improving both the flood protection for the neighbouring towns and the aquatic ecology. As part of these measures, the old and partly already eroded drop structures and the continuous walls at the banks should be completely removed and replaced by new methods of bed and bank protection such as

- structured ramps and open rip raps for bed protection
- Short groynes for bank protection
- restored continuity, continuous low water course and stimulation stones to improve water ecology and structural wealth.

The Lutz before restoration - high cascades prevent the fish from to migrate upstream, the high walls of the hard-regulated river are in poor condition and hinder access to the water.

At the Institute for Hydraulic Engineering and Calibration of Hydrometrical Current-Meters, the planned measures were checked and optimized using a 1 to 30 scale physical model test. The main aspects of stability of the riverbed and bank as well as adequate protection of the settlements against flooding during flooding and the sustainability of the renaturation must be guaranteed.

You can see the Lutz model in a test flume in our large hall. The model mainly consists of sand and stones.
© BAW-IWB

Model of the selected river section - model length 30 m, model width 2 m

The planning was optimized by the model test. Among other things, the following was achieved:

  • Reduction of construction costs by reducing the size and amount of required stones
  • Sustainable flood protection and stability of the river bed and bank up to a 500-year flood by improvements in the areas of bank protection and river bank protection
  • Ensuring the sustainable improvement of the ecological status of the water (low flow course, bank, low maintenance effort)

The measures were implemented in the winter periods 2015/16 and 2016/17.

Images: Photos of the construction work from 29th, April 2016 (photo 1 + 3 + 5) and planned project in the physical model 2015 (photo 2 + 4 + 6)

CUSTOMER: Lutz Water Collective Ludesch-Thueringen-Bludesch