Bed stabilisation measures in the Landquart River

After the floods in 1910, the River Landquart between gorge “Klus” and the mouth in the Rhein-River was regulated. The 4.5 km long section was canalised and the bed was fixed with grade control structures (Fig. 1). River training works were applied in order to stop the enduring erosion process. In 1969 physical model tests were held to prove the sills which have been established to stabilise the river bed.

As less sills were realised than projected and due to a decrease of the bed-load transport, the process of erosion continuous. Following then the rip-rap foundations of the banks and the sills are at risk.

The intent concept for that river section of the Landquart-River plans to construct the block ramps by filling the scour hole immediately downstream the sills. Due to the high specific discharges (20 to 40 m²/s) the design of these structures is associated with major insecurities.

The purpose of present investigation is the assessment of feasibility for block ramps and the development of the required basics to design block ramps with allow the substitution of the sills.