Salzach - Block ramps to stabilize the river bed

Following flood damage to the tracks of the Austrian Federal Railways (ÖBB) in the Eschenau (Salzburg) area, model tests were carried out in 1999 to develop a solution that would prevent this from happening in the future.

The photo shows one of the ramps developed in the model test, which stabilize the river bed of the Salzach and thus protect the parallel running railway line from erosion. You can see the railway line. The water flows faster over the ramp and is coloured white by the air mixed in.
© Office of the Salzburg State Government

Downstream of Taxenbach (close to Eschenau) the Salzach river is sloped by 2.5 % over a length of 800 m. In addition, the river is characterised by a winding river course in a narrow valley and rather unfavourable geological conditions.

As a result, floods often caused major damage which led, amongst others, to the destruction of the railway tracks located close to the riverbank. For the restoration and stabilisation of the river stretch, the institute prepared a design proposal with the help of a physical model test. This proposal includes the construction of 4 block ramps with a height of 3.5 m (2 ramps) and 4 m (2 ramps), respectively, complemented by an existing bottom sill.

The implementation of the proposed measures was part of a multi-annual construction programme, which was carried out under the technical supervision of the institute. The observations of the river stretch so far show that the chosen solution works suitable for stabilising the river bed.

Damaged Austrian Federal Railways line along the river Salzach (after flood in 1985), the right margin of the picture shows a part of the flooded Salzach. The river valley is very narrow at this point. The flood caused bank erosion, large parts of the grassy bank have slid into the river, the rail track of the railway line is washed out and hangs in the air.
© Office of the Salzburg State Government

Damaged Austrian Federal Railways (OEBB) line along the Salzach river (after the flood 1985)

Physical model experiment on a scale of 1 to 30, you can see a winding watercourse in the laboratory hall in a bricked channel. The right bank of the model river is covered with branches similar to vegetation in nature, the left bank is covered with stones. A panel shows the details of the flow and experiment.
© BAW-IWB

Physical model of the Salzach river scaled 1 to 30

Salzach Eschenau in the physical model with the initial sole layer, you can see the physical model in an overview with the initial sole layer before an experiment. The curved watercourse in the brick-built model river leads through the entire laboratory hall. The river has a riverbed of sand and a river bank which is covered with stones for protection.
© BAW-IWB

Salzach Eschenau - initial state of the river bed of the physical model

Aerial view of the project section on the Salzach after the rehabilitation, you can see an aerial view of the Salzach from the section in question. The river runs in a curvy course in the middle of the picture with the direction of flow from bottom to top. On the left side of the river runs the federal road and the railway line. On the right is a partly wooded, partly grass and bush covered river bank. The 4 newly built ramps for the stabilization of the riverbed are recognizable because of the white foaming water.
© Office of the Salzburg State Government

Arial view of the project reach of the Salzach after the restoration and stabilisation of the reach