In flowing waters, the bottom breakthrough is the breakthrough of the river bed through erosion . The result is a sudden, severe deepening of the water with effects on the water table, the bank structure and endangering structures such as bridges. The bottom penetration occurs with movable, i.e. H. in loose rock or sediment lying river bed, if this is in the "state of latent erosion"; this means when a coarse top layer protects finer, underlying sole material from erosion. If the surface layer cracks open during major flood events, bottom penetration occurs.
A bottom breakthrough can occur naturally, but mostly occurs as a result of human interference in the body of water or the river bed. The reason is increased erosion power, e.g. B. by straightening the bed (with higher flow velocity), changing the catchment area (flood hydrographs changed by sealing or changing land use), narrowing the water profile, e.g. B. by bridge piers, or similar reasons. Strong erosion processes such as bottom penetration always occur during floods. The actual bottom breakthrough occurs above all when the river bed consists of erosion-resistant hard substrate such as gravel or blockwork that is deposited on softer sediments or rocks such as clay or marlstone. If the gravel and gravel layers on the river bed are removed by initially slow and continuous erosion processes, the layers underneath that are now exposed erode and the river quickly digs into the terrain. This process is particularly problematic for structures in bodies of water such as bridge piers or power plants. A bottom breakthrough represents an irreversible change in the water body without tough technical expansion measures. This is mainly due to the fact that the erosion-resistant gravel bodies were mostly formed under different climatic conditions in the Ice Ages and can no longer be reproduced today.
- Stabilization of the Lower Salzach riverbed shortly before the start
- Austro-Hungarian dissonances about the expansion of the Danube
- Archived copy ( memento of the original from September 24, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- Heinz Patt, Peter Gonsowski, Daniel Vischer, Andreas Huber: Hydraulic Engineering: Fundamentals, Design of hydraulic engineering structures and plants. Springer-Verlag, 2011. ISBN 978-3-642-11963-7 p. 74
- Major project is intended to slow down further deepening of the river bed
- Collapse of the Kufstein motorway bridge