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Topic 8 - Prediction and Assessment of Debris Flow Hazards

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Topic 8 - Prediction and Assessment of Debris Flow Hazards
Effective management of debris-flow hazard relies on accurate assessments of debris-flow susceptibility. Mathematical models of rainfall infiltration and slope stability can be applied to predict the temporal and spatial variation of debris-flow susceptibility. These models require high-resolution (<10 m) topographic data, as well as (ideally also high-resolution) data on initial groundwater conditions, physical properties of near-surface earth materials, depth to bedrock, and rainfall. A case study from th
Topic 8 - Prediction and Assessment of Debris Flow Hazards
With the objective of providing guidance for an early detection of phenomena potentially giving raise to Debris Flow, one of the main topics is the preliminary identification of areas at risk. In case of early warning a coarser identification of areas at risk should be sufficient. In this perspective, the hazard of phenomena, as component of risk, can be estimated in a simplified way. In the framework of the IMPRINTS European Research Project (FP7), a toolbox for fast assessment of debris flow hazard has be
Topic 8 - Prediction and Assessment of Debris Flow Hazards
The area of Fiames is located on a narrow and flat valley, 2 km north to Cortina d’Ampezzo, and is bounded on the right side by the Pomagagnon and Pezorìes peaks. At the transition between rock vertical cliffs and talus, about twenty debris channels originate and affect the talus till the bottom of the valley. The Strobel and South Pezorìes channels were recently routed by debris flows in 2004 and 2006. Field surveys, topographical and geo-morphological measurements were carried out to recognize the sed
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Burned watersheds in Southern California steeplands can be particularly susceptible to debris flow. Rapid assessments of potential debris-flow hazards following a fire are necessary to provide timely information to the public, land managers, and emergencyresponse agencies about locations most prone to debrisflow impact. Here we present a method to implement a set of existing debris-flow susceptibility models along a drainage network using input variables that are quantified for the contributing drainage bas
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Debris flows triggered by earthquakes are recognized globally for their huge destructive power. Studies on the development features of debris flow are essential for disaster prevention and mitigation and the results can be used as a scientific basis for assuring public security, preventing debris-flow disasters and reconstructing the afflicted areas by earthquake. Taking the, Niujuan Gully, as the case study area, this paper discusses field observations of the initiation and path of debris flows in the epic
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Every year, debris flows cause huge damage in mountainous areas. Due to population pressure in hazardous zones, the socio-economic impact is much higher than in the past. Therefore, the development of indicative susceptibility hazard maps is of primary importance, particularly in developing countries. However, the complexity of the phenomenon and the variability of local controlling factors limit the use of processbased models for a first assessment. A debris flow model has been developed for regional susce
Topic 8 - Prediction and Assessment of Debris Flow Hazards
In August 2009, Typhoon Morakot hit Taiwan and induced tremendous disasters, including large-scale landslides and debris flows. One of these debris flows was suffered by the Daniao tribe in Taitung, eastern Taiwan. The volume was in excesses of 500,000 m3, much larger than the original design mitigation capacity. The DEBRIS-2D program developed by (Liu et alii, 2009) was applied in a hazard assessment at this particular site two years before the disaster. The model predicted a hazard zone that was close to
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Hazard assessment and the design of mitigation measures against mountain hazards are usually based on statistically derived magnitude-frequency relationships of process parameters such as discharge, flow velocity, or the volume of debris deposits. However, with respect to debris flows there is a particular lack of such data, as these processes are rare phenomena, the systematic measurements of relevant parameters have only been carried out in selected watersheds within the last decades. In some areas, geomo
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Debris flow and landslide forecast is an important means of disaster reduction. This paper took Liangshan Yi Autonomous Prefecture, Sichuan Province as the study area. Analyzing distribution rules of debris flow and landslide under different underlying surface’s conditions, it used the extension theory to erect to debris flow forecasting model and the information content analysis method to erect the landslide forecasting model. These models obtained 3 hours’ forecasting precipitation by processing some
Topic 8 - Prediction and Assessment of Debris Flow Hazards
The paper presents a method of a short-term forecast for meteorologically initiated debris flows of different genesis. A diversity of an environment of Greater Caucasus predetermines a wide spectrum of geologic-geomorphologic processes and non-reliable meteopredictors which cause debris flows formations. The water impulse which causes the debris flows formation is connected with showers (pluvial genesis) and also with glaciers thawing and snow (glacial genesis and snow genesis). However debris flows of poly
Topic 8 - Prediction and Assessment of Debris Flow Hazards
A method of debris-flow hazard analysis, using the Cemagref LAVE2D model, within a scenariobased approach, is applied to a torrent of the French Pyrenees. A preliminary analysis of the catchment shows that some risk of debris-flow occurrence is present and that scenarios should be constructed accordingly. Numerical simulations are carried out on the basis of these scenarios. They produce maps of maximum extension of debris flows in relation to qualitative levels of probability of occurrence. Simulations als
Topic 8 - Prediction and Assessment of Debris Flow Hazards
In this paper, we perform a societal and economic risk assessment for debris flows at the regional scale, for lower Valtellina, Northern Italy. We apply a simple empirical debris-flow model, FLOW-R, which couples a probabilistic flow routing algorithm with an energy line approach, providing the relative probability of transit, and the maximum kinetic energy, for each cell. By assessing a vulnerability to people and to other exposed elements (buildings, public facilities, crops, woods, communication lines),
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Debris flow moves in manner of successive surges and deposits by piling of surges. The surge occurs randomly and varies in properties and magnitude. This study explores the probability distribution of velocity and derives the distribution of flow depth based on observations in Jiangjia Gully in the southwest of China. The Weibull distribution is found to be well applicable to both the velocity and depth, with parameters varying in a rather small range. Therefore, the distribution is expected to hold in gene
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Taiwan is an island located in the subtropical zone where typhoons often bring heavy rainfall. In addition, streams and geology results in a high susceptibility to debris flow. Especially after the Chi-Chi earthquake on September 21, 1999, the geological condition of the mountain area located in the central part of Taiwan has been more susceptible to natural disasters of debris flow. Fractured geological units and landslides caused by frequent earthquakes provide abundant source material for debris flow. Fo
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Glacier-lake outburst is common in Tibet. Global warming is expected to increase the frequency of outburst. This paper attempts to find out the relationship between the outburst and annual temperature variation based on analysis of 16 outburst events in Tibet. Multiyear climate data from meteorological stations in the study area are used. We find that the outbursts are sensitive to acute change in annual temperature. Specifically, the outburst probability increases when average annual temperature rises by m
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Assessment of a mudflow hazard in the current period of unstable climate and possible extreme situations is especially important for the Caucasian Black Sea coast. Here mudflows constantly threaten to economic and tourist’s objects and happen due to the mass construction of different structures, including their probable appearance during preparation of XXII Olympic Winter Games of 2014 in Sochi. The hazard assessment of mudflows is made through analyzing their activity and the degree to which they affect
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Glacial lake outburst floods (GLOFs) are potentially highly dangerous events and have contributed to numerous disasters in history. Today, computer models are standard tools to estimate the magnitude of hazardous events in the future and to support risk mitigation. The present paper explores the potentials and limitations of modelling for predicting the motion of potential future GLOF events, based on examples from the Pamir (Tajikistan). Since the flow behaviour of GLOFs is in between debris flows and floo
Topic 8 - Prediction and Assessment of Debris Flow Hazards
In this work, a multidisciplinary study is presented in which potential debris flow events are studied from their beginning to their end. The case study is located on the Amalfi Coast where historical events of debris flow are well documented in 1910, 1924 and 1954. An integrated approach was used for the geomorphology and geo-pedology of volcanic deposits. The matches found between morphotypes, depositional and pedological processes and soil characteristics made it possible to develop a detailed map of the
Topic 8 - Prediction and Assessment of Debris Flow Hazards
In Switzerland a well-established method for debris flow hazard assessment is in use. However the method requires delineation of endangered areas by the expected intensity for a given return period. For this reason there is a strong need for process-based models to improve the quality of hazard mapping and for planning and evaluation of mitigation measures. In this paper, we present the application of a Swiss modeling system for rapid mass movements. The RAMMS debris flow model is a two-dimensional model fo
Topic 8 - Prediction and Assessment of Debris Flow Hazards
We present a methodology for generalised regional- scale forecast of debris flow activity for territories with uniform conditions of debris flows formation. In the high mountain region of the Central Caucasus the trend of activation of debris flows processes is connected with the degradation of glaciers. For the development of debris flows forecast combined physical– statistical models based on long-term observation series are shown to be optimal. The authors develop an original and simple method of debri
Topic 8 - Prediction and Assessment of Debris Flow Hazards
We hypothesize that the number of shallow landslides a storm triggers in a landscape increases with rainfall intensity, duration and the number of unstable model cells for a given shallow landslide susceptibility model of that landscape. For selected areas in California, USA, we use digital maps of historic shallow landslides with adjacent rainfall records to construct a relation between rainfall intensity and the fraction of unstable model cells that actually failed in historic storms. We find that this fr
Topic 8 - Prediction and Assessment of Debris Flow Hazards
Althoug Unzen volcano has been declared to be in a state of relative dormancy, basing on the latcst researchthe latest formed 11# lava lobe now represents a potential slope failure mass. This paper concentrates on the stability of the 11# lava lobe and its possible critical sliding mass. Based on the proposed Geographic Information Systems (GIS) three-dimensional (3D) slope stability analysis models, a 3D locating approach has been used to identify the 3D critical sliding mass and to analyse the 3D stabilit
Topic 8 - Prediction and Assessment of Debris Flow Hazards
The area of International Karakorum Highway (KKH), a mountain highway connecting northern Pakistan with northwestward China, is an area with dense and frequent glacial debris flow disasters due to the special glacial geology and landform. In this area the three basic conditions inducing glacial debris flow have developed,namely the widely distributed glacial till and ice-snow colluvium, which arise from collapse and landslide, provide the main solid sources of glacial debris flow; the very high and steep sl
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