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Topic 9 - Debris-flow Countermeasures

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Topic 9 - Debris-flow Countermeasures
Recent experimental results obtained at the University of Trento show that a liquid-granular wave can impact against a vertical obstacle producing two different mechanisms of reflection, depending on the Froude number: if the front is sufficiently fast, the flow is completely deviated in the vertical direction, producing a vertical jet-like bulge, while if it is relatively slow it can be totally reflected in direction normal to the obstacle. The standard theoretical approaches for the analysis of the dynam
Topic 9 - Debris-flow Countermeasures
In Japan, the recent check dam (sabo dam) construction has been the open-type of the continuity of sediment routing from upstream to downstream a reach in a river basin. Not only in Japan but also in other countries, a lot of experimental and numerical research has been conducted on sediment control using open-type sabo dams. Plans for size and location have been drawn up for grid-type sabo dams with heights of around 20 meters, which is the highest grid-type sabo dam in Japan, in the Amahata river in Yamah
Topic 9 - Debris-flow Countermeasures
The south eastern part of the Pyrenees is currently affected by debris flow phenomena. The combination of Mediterranean and Continental climate, the orography (up to altitudes of 3300 m), the glacial materials on the slope’s surface, the lack of arboreal coverage compared with the rest of the Pyrenees, the high seismicity and the increasing human occupation in the valleys, put altogether is a very dangerous combination and makes the debris flow management extremely difficult. The first monitoring system f
Topic 9 - Debris-flow Countermeasures
This paper describes the effect of two successive check dams on the debris flow event which occurred on 21 July, 2009 in Hofu City, Yamaguchi Prefecture, Japan. The debris flow event caused sediment deposition in the check dams in the Tsurugi and Hachimandani River. In the former river with two successive closedcheck dams, driftwood did not accumulate in the check dams but in the central region of the river bend. In the latter river with two successive open-check dams, driftwood accumulated in the opening o
Topic 9 - Debris-flow Countermeasures
Debris flow barriers and breakers protect human settlements, infrastructure and supply lines from torrential disasters by dissipating the energy of debris flow (floods), dosing (filtering) coarse solid components and deflecting the flows from the areas at risk. The function and design of these structures has to follow the principles of the EUROCODE standards. In order to establish a comprehensive “state-of-the-art” for torrent control engineering an interdisciplinary working group (ON-K 256) was establi
Topic 9 - Debris-flow Countermeasures
A new type of flexible net barrier system designed to protect against debris flows with volumes of up to 1000 m3 has been developed. A detailed study and testing programme, conducted for the first time, has demonstrated their highly cost effective and efficient design in comparison to massive concrete barriers. A multi-step impact model was developed describing the filling process and the acting forces to the barrier simultaneously. During debris flow events, the total pressure distribution on the net can b
Topic 9 - Debris-flow Countermeasures
Due to climate warming which came after the ending of the Small glacial age, surface and subsurface reservoirs started to form on the mo - raine-glacial complexes of the northern slope of the Zailiysky Alatau Mountain Range. Breakout of these reservoirs led to disastrous debris flows in the middle of the 20th century. Up to 60s of the 20th century rainfall-caused debris flows with rare frequency were considered to be of main danger and construction of large check dams forming debris-flow reservoirs was assu
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