First Nature Conservation Measures in the Rosenheim Area

1/17/2014Rosenheim

VERBUND Innkraftwerke GmbH implements surface water structure measures in the backwater area in Rosenheim.

The VERBUND Innkraftwerke GmbH has committed itself to implementing extensive ecological improvements in the backwater areas at the power plant locations on the Inn, within the framework of an agreement with the state of Bavaria and in particular with the Bavarian State Ministry for Environment and Health. In relation to this, selective structural measures downstream and upstream of the Rosenheim level will be implemented with the approval of the fishing association, the water board and the Lower Nature Conservation Authorities in the District Office of Rosenheim. The works are foreseen to be completed by the end of February 2014.

In intensive and close talks with the responsible authorities and local fishing authorities, so-called "restructuring measures" to the upper and downstream areas of the power plant levels in Rosenheim were submitted for approval in the previous year. All technical natural conservation approvals have in the meantime been granted, so that now all implementation works in the vicinity of the city of Rosenheim and in the municipality of Rohrdorf can commence. In the barrage area of Rosenheim the current floodplain is presently characterised by a narrow drift line and adjoining woods, which mostly comprise the non-native hybrid-poplar tree species. The available bank protection made up of armour stones is a technical construction method with cemented gaps. At Rohrdorf there is an older poplar planting area; characteristic woods of soft wood are merely interspersed and in immediate proximity of the bank. Through its stiffly regulated bank in its entire backwater area, the Inn is heavily compromised as a living space for fish. In total, on the banks and on the floodplain, there are hardly any dynamic processes taking place and the living space has fallen into disuse due to lack of dynamic changes in the river. The former gutters and oxbow lakes were silted up due to sediment deposits from the strong tidal sand in the river during floods. Open living spaces for the early stages of flood plain development are almost completely missing.

New habitats for fish and reptiles

Thanks to the construction measures which have now been introduced, such living spaces will be created once more through taking back the straightened bank shoreline as well as through the system of structures which resemble oxbow lakes. These have been rare on the river Inn near Rosenheim due to the lack of river dynamics and yet fulfil an important function for different animal and plant species. The low flow areas of the shallow water zones represent highly valuable habitats for young fish and can be used by the fish in the Inn as a flood and wintering area. Newly created dry sites near the dyke can be inhabited by species, whose natural living space is the gravel banks of former river channels. With the stone slabs of the fixed bank protection, new structures should be created, which along with protecting against erosion, will also fulfil ecological functions e.g. as a habitat for reptiles. River Inn sediments from the floodplains and the river banks are put back into the river Inn, where it can be deposited naturally. The duration of the works and the resulting pressure on nature will be kept to a minimum as much as possible in order to provide support for a speedy repopulation of the newly created living spaces during the breeding and spawning season. The implementation of the water body structuring measures is expected to take until the end of February 2014. The goal is to complete the main works before the birds' breeding season and the fish spawning season.

All in all the planned measures contribute considerably to maintaining and improving the diversity and the species-rich "Inn ecosystem ". Similar restructuring projects which have already been carried out since 2011 in the backwater areas of Wasserburg, Teufelsbruck and Gars successfully display the upgrading of the living space on the river Inn.

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