The Rheindamm could also look different soon.
©Stiplovsek
A pre-stretching dam on the Rhine near the mouth of the river in Lake Constance has to be rebuilt.
The International Rhine Regulation (IRR) informed on Wednesday that there will be an overflow stretch of about 800 meters on the right-hand side. The construction work, which cost around six million euros, has already begun and will continue until spring. A second stage will follow in winter 2023/24, it said.
Up to three million cubic meters of solids
The regulation of the Rhine in 1900 to increase flood safety resulted in silting up in the new estuary of the Rhine in Lake Constance near Hard – after all, the Rhine transports between two and three million cubic meters of solids into Lake Constance every year. In order to prevent the Fussacher and Harder Buchs from silting up, the mouth of the Rhine has been pushed miles out into Lake Constance by channeling the river within dams since the 1970s. This stretch is about 4.5 kilometers long.
According to the IRR, the dam on the right-hand side is now lower in sections than planned in the project from 1972 to 1979. If the dam were raised in this area, it would have negative effects in the event of a flood. At that point, the Rhine could no longer flow directly into the lake, which would cause the water level to rise in the protrusion and rise upstream of the Rhine. As a further consequence, an uncontrolled overflow of the pre-stretching dams could not be ruled out. This could also lead to dam failures.
After detailed investigations, the IRR has now decided to keep the dam partially deep in the relevant area and to make it overflowable. In this way, the water level upstream of the Rhine remains stable even during high water. In concrete terms, the right-hand pre-stretching dam in the Hard-Schleienlöcher area will be raised by a maximum of one meter over a length of around 800 metres. For the subsequent 800 meters, the dam will be kept low and built to be safe from overflows. Over the next 400 meters, the dam will be raised by a maximum of 0.2 meters and structurally updated. Ecological design measures are also taken. During the construction work, the hiking trails in the vicinity of the construction site will remain closed. The landing stage for the motor ship “Oesterreich” and the steamer “Hohentwiel” will be adapted to the new conditions.
