8.03.01 - Torrent, erosion and landslide control

About Unit

All over the world society faces different forms of erosion, among which water erosion and landslides are particularly significant and destructive. Especially torrential processes like overflows and flooding (debris-flows, debris-floods, intensive bedload transport), depth and lateral erosion and geomorphic processes on the hillslopes, like landslides, represent a serious hazard for settlements and infrastructure located in torrential valleys and on torrential fans. Devastating events are mostly triggered by local rainfall events of high intensity and short duration. Sediment production and transport represent a hazard for human settlements but in the same time are an important factor for bedload equilibrium in larger rivers (Hübl, 2011). The solution for all these problems is integrated forest and water management which begins in torrent catchments. Integrated torrent, erosion and landslide control is one of the basic conditions for sustained progress of society and the states respectively. The staff of unit 8.03.01 is aware of international ambitions to move away from "natural hazard defence" towards "risk management of natural perils", with a focus on managing the consequences of these hazards and risks.

The working scope of the Unit 8.03.01 is focused on:

  1. Better understanding of torrential, erosion and landslides processes and phenomena, and their interaction with forest ecosystems.
    We often lack sufficient data about small, as well as, large torrent areas, therefore, the analysis of past events and the prediction of possible phenomena by use of methodology of identification and interpretation of "silent witnesses" (German "Stumme Zeugen") at the ecologically stable conditions could be of great help. Silent witnesses are geomorphic and biologic evidence of past flood and erosion events found in the field and evidence in the nature, which give experts important information about recent development of torrents, erosion and landslides processes

  2. Preventive measures and regimes
    Preventive measures are essential for reducing the possibility of occurrence of an adverse effect of water or disaster and for the reduction of damage potential.
    • systems of continuously overview on the situation in torrential catchments and appropriate quick and efficiently response on increasing hazard potential
    • engineering hazard assessment of torrential, erosion and landslides processes, preparation of related hazard and risk maps
    • planning, design and executing of protection works and mitigation measures (technical, soil-engineering ...)
    • maintenance of protection systems and structures.

Bedload transport control is successfully carried out by correctly positioned and designed consolidation and retention structures. These structures are generally integrated in a system and therefore their functions are interactively supplementing.

Only well maintained torrent control structures and systems can perform the required function. Damaged structures and structures that are not maintained regularly do not protect but offer a deceptive impression of security. In case of their destruction the consequences may be even worse then if there would be no protective structures at all. It is therefore essential that they are well and regularly maintained.

An important improvement in Europe in the field of the reduction of flood risks is European Directive 2007760/EC on the assessment and management of flood risks which, instead of the principle ensuring a certain degree of flood safety, introduces a principle of risk management.

Keywords: natural hazard assessment, torrent, erosion, landslide, integrated forest and water management, integrated torrent, erosion and landslide control, integrated risk management


State of Knowledge

The "hot topics":

  • event documentation (with special focus on silent witnesses of torrential, erosion and landslides processes)
  • possibilities of forest management regarding reduction of problematic of woody debris (drift woods) during the torrential floods:

    - from the point of view of forest planning and silviculture activities
    - from the point of view of exploitations works
    - from the point of monitoring in torrents