Alte Aare: a flagship project for nature conservation and flood protection
The Alte Aare (old Aare) region between Lyss and Meienried is the largest wetland area in Switzerland and a site that is of national importance. However, the river has the potential to cause great damage to the neighbouring residential areas when water levels rise – which happened most recently during the floods of 2006 and 2007. With its ambitious project, the Wasserbauverband Alte Aare (Alte Aare hydraulic engineering association), of which 10 of the local municipalities are members, has demonstrated that nature conservation and flood protection can go hand in hand. Basler & Hofmann was responsible for the implementation of flood-prevention measures at the heart of the conservation area. This included the most extensive use of deadwood (over a stretch of six kilometres) in a single project in Switzerland – a measure taken to improve the ecology of the area.
Wasserbauverband Alte Aare
More space and more effective dams
The flood protection and environmental conservation measures for the Alte Aare focused on creating more space for the floodplain (and therefore a greater draining capacity) and revitalising the area with a number of different measures. Several dams were also constructed to provide flood protection for the local municipalities. The result was a project that won praise from flooding experts and conservationists alike.
A wetland area can only be an area of real natural diversity when the water is allowed to shape the landscape and create a number of different habitats. The Alte Aare’s ability to do just this was reduced by the re-routing of the river in the past. The revitalisation measures have created a number of areas that mimic the natural landscape, such as pioneer areas, softwood groves, backwaters, marshes and amphibian ponds. The use of deadwood, an idea put forward by Basler & Hofmann, was a key element of the project, with various structures such as tree groynes, felled trees and tree-trunk sills being used to create a lively and varied current and new habitats.
Construction project optimisation, invitation to tender, construction documents, construction site supervision, environmentally friendly site support including invasive plant strategy, pedological site support, environmental remediation.