Influence of check dams on debris-flow run-out intensity

Abstract

Abstract. Debris flows are very dangerous phenomena claiming thousands of lives and millions of Euros each year over the world. Disaster mitigation includes nonstructural (hazard mapping, insurance policies), active structural (drainage systems) and passive structural (check dams, stilling basins) countermeasures. Since over twenty years, many efforts are devoted by the scientific and engineering communities to the design of proper devices able to capture the debris-flow volume and/or break down the energy. If considerable theoretical and numerical work has been performed on the size, the shape and structure of check dams, allowing the definition of general design criteria, it is worth noting that less research has focused on the optimal location of these dams along the debris-flow pathway.In this paper, a methodological framework is proposed to evaluate the influence of the number and the location of the check dams on the reduction of the debris-flow intensity (in term of flow thickness, flow velocity and volume). A debris-flow model is used to simulate the run-out of the debris flow. The model uses the Janbu force diagram to resolve the force equilibrium equations; a bingham fluid rheology is introduced and represents the resistance term. The model has been calibrated on two muddy debris-flow events that occurred in 1996 and 2003 at the Faucon watershed (South French Alps).Influence of the check dams on the debris-flow intensity is quantified taking into account several check dams configurations (number and location) as input geometrical parameters. Results indicate that debris-flow intensity is decreasing with the distance between the source area and the first check dams. The study demonstrates that a small number of check dams located near the source area may decrease substantially the debris-flow intensity on the alluvial fans.

Assessing the hydrological effect of the check dams in the Loess Plateau, China, by model simulations

“…Hassanli et al (2009) evaluated the effect of porous check dam location on the retention of fine sediments by field sampling and laboratory analysis in the Droodzan watershed, southern Iran. Remaître et al (2008) used a debris-flow model to evaluate the influence of the number and the location of the check dams on the debris-flow intensity in the Faucon watershed of south French Alps. The results indicated that check dams located near the source area may decrease debris-flow intensity more efficiently.…”

Improving risk assessment by defining consistent and reliable system scenarios

“…Yielding only individual predictions and not adequately including qualitative system changes (disruptions, Godet, 2000), deterministic models were found to be only partially useful when trying to predict future states of complex systems. If a sediment dosing system, typically composed of an approaching reach, a deposition basin, an open check dam and an outlet reach is considered, the evolution of the channel bed level in the retention basin during either the increasing or the decreasing part of the hydrograph can be accurately and precisely predicted by deterministic models (Armanini and Larcher, 2001;Miyazawa et al, 2003;Remaître et al, 2008). However, the simultaneous presence of woody debris transport phenomena obstructing the openings (e.g.…”

ASCHFLOW - A dynamic landslide run-out model for medium scale hazard analysis

“…A homogeneous erodible soil depth of 2.5 m was selected since there was a lack of information about this or a soil depth map (this depth was also assumed to quantify the release volume). Based on the geological, lithological and morphological description of the area and based on the account of historical data, a soil depth of 2-3.5 m was found to be the value that agrees best with the quantity of entrained material in past events (Remaître et al 2008;Quan Luna et al 2011, 2014. This was also done to assess the performance of the model Fig.…”