Debris flow ; Dendrochronology ; Geomorphological mapping ; Impact ; Mountain ; Poland ; Slope evolution ; Spruce ; Tree ; Tree line
Influence des arbres et desdébrisde bois grossiers sur les processus de transport et de dépôt dans la zone d'accumulation. Estimation de la durée pendant laquelle ces débris ont un impact sur les processus deversant.
The significance of channel recharge rates for estimating debris-flow magnitude and frequency
Bassin-versant ; British Columbia ; Canada ; Coulée dedébris ; Dynamique deversant ; Littoral ; Prévision ; Risque naturel
This paper deals with the determination of debris recharge rates in debris-flow channels based on knowledge of debris storage and the elapsed time since the last debris flow. Data are obtained from coastal British Columbia and a relation is obtained
Les debris flows : une dynamique deversant azonale ?
Concept ; Coulée dedébris ; Dynamique deversant ; Eau de fonte ; Montagne ; Mouvement de masse ; Pente deversant ; Précipitation ; Périglaciaire ; Versant ; Zonalité
Concept ; Debris flow ; Mass movement ; Meltwater ; Mountain ; Periglacial features ; Precipitation ; Slope ; Slope dynamics ; Slope gradient ; Zonality
La distribution desdebris flows à la surface du globe suggère une large azonalité de cette dynamique deversant, qui se cantonne cependant aux secteurs montagneux. Une pente forte et une quantité dedébris sans cohésion, aisément mobilisable lors
d'une saturation interstitielle du matériel liée à de fortes chutes de pluies ou à la fonte nivale brutale sont nécessaires, même si des forces internes peuvent également mettre en mouvement le matériel. Les périodes de retour des coulées dedébris
indiquées dans la littérature semblent dépendantes de la magnitude des épisodes, ainsi que des temps de reconstitution des stocks.
Alud de residuos ; Cuenca hidrográfica ; Deslizamiento deterreno ; Dinámica de vertiente ; Eslovenia ; Inclinación de la vertiente ; Modelo ; Precipitación
In this paper, debris-flow modeling is shown specifically on the basis of a potential debris flow from the Hrenovec torrential watershed above the village of Kropa in NW Slovenia. This site was chosen, because in this particular torrential watershed
a small surficial landslide turned into a debris flow during a storm on September 18, 2007. Using public available data on rainfall and topography, we developed two scenarios of debris-flow triggering with an estimated magnitude of 50.000 m3. - (L'A.).
To examine running distance of debris flows occurring on the talus slopes, rainfall experiments were carried out. The quantity Vt is defined as the reciprocal of the threshold value of Lc/Lt at which debris flows just reach the bottom of the talus
slope, where Lc is the horizontal length of the cliff and Lt is the horizontal length of the talus slope. The value of Vt is also a measure of the possibility of sedimentary outflow from the talus slope by debris flow. The value of Vt shows strong
correlation with the hydraulic conductivity of talus sediment (K) and the rainfall intensity (It). The outflow of debris from the talus slope can be predicted using the values of Lc, Lt, K, and It.
A great number of debris flows occurred during the flood catastrophes of the summer of 1987 in the Swiss Alps. Aerial photography, field investigations and eyewitness accounts documented and analysed the events. Apart from incision into weak bedrock
to estimate the most important flow parameters. These values are compared to debris flow data from Canada and Japan.
Debris flow ; Iceland ; Meteorology ; Oceanic climate ; Periglacial features ; Rainfall ; Slope ; Subarctic area
Origine de l'approvisionnement en eau, principal facteur moteur des coulées dedébris : pluie et/ou fonte des neiges augmentent l'écoulement superficiel et subsurfaçique amorcant l'écoulement dedébris. Distribution temporelle et spatiale dans une
Debris flows involved in the development of Pleistocene stratified slope deposits in Periglacial processes and landforms.
Coulée de blocs ; Dépôt de pente ; Expérimentation ; Géographie physique ; Géomorphodynamique ; Périglaciaire ; Sédimentologie ; Technique de recherche ; Versant
Two approaches to this problem : 1) the analysis of recent debris flows within an Alpine environment, and 2) laboratory experiments, simulating debris flows under different conditions. Sedimentological characteristics of debris flow material
are discussed, as well as relationships between physical and sedimentological properties. Resulting criteria for the recognition of debris flow material are given and the role of temperature is treated briefly.
The aim of this study was to combine dendrogeomorphological analyses with an assessment of germination dates of successor trees in order to understand the dynamics of past debris-flow events on a forested cone in the Valais Alps, Switzerland
. As a consequence of the deeply incised channel and the stabilization measures undertaken along the banks, signs of debris flows are missing in the tree-ring record for the past two decades.
The proposed method was applied to an actual landslide-induced debris flow that occurred on June 13, 1995 in a high-altitude mountainous region of southwestern China. The method depends on field measurements of channel dimensions and some empirical
equations for debris flow dynamics. Maximum discharge is one of the most important characteristics of debris flows, because it can be used for assessing the hazard potential of debris flows and for developing preventive measures to reduce the dynamic impacts
Alpine debris flows triggered by a 28 July 1999 thunderstorm in the central Front Range, Colorado
Colorado ; Coulée dedébris ; Etats-Unis ; Front Range ; Glissement de terrain ; Montagne ; Orage ; Pente deversant ; Propriétés du sol ; Précipitation ; Ravinement ; Topographie
Colorado ; Debris flow ; Front Range ; Gully erosion ; Landslide ; Mountain ; Precipitation ; Rainstorm ; Slope gradient ; Soil properties ; Topography ; United States of America
The AA. mapped the debris flows from color aerial photography and inspected many of them in the field. Three processes initiated debris flows : mobilization of shallow landslides in thick, often well vegetated, colluvium; transport of material
eroded from steep unvegetated hillslopes via a system of coalescing rills; the firehose effect which occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans. Based
on field observations and examination of soils mapping, the AA. identified a relation between the degree of soil development and the process type that generated debris flows.
Wash erosion on a debris covered slope in a semi-arid climate
Ablation spécifique ; Afrique du Sud ; Domaine aride ; Domaine semi-aride ; Eboulis ; Erosion des sols ; Erosion par ruissellement ; Expérimentation de terrain ; Géographie physique ; Orange Free State ; Versant ; Versantdedébris
Field experimentation on a steep debris slope. The rate of denudation in terms of rock density was found to be 17.8 mm per thousand years. This rather low figure results from several factors : e.g. good canopy and basal cover of vegetation, cover
by rock debris, very little disturbance by man or grazing animals and the lack of available material suitable for transport.
Site characteristics of debris flows and their relationship to alpine treeline
Avalanche ; Coulée boueuse ; Dynamique deversant ; Etats-Unis ; Limite supérieure de la forêt ; Montana ; Neige ; Photographie aérienne ; Système d'information géographique ; Terminologie ; Versant
Aerial photography ; Avalanche ; Debris flow ; Geographical information system ; Montana ; Slope ; Slope dynamics ; Snow ; Terminology ; Tree line ; United States of America
Over 150 debris flows in eastern Glacier National Park, Montana, were mapped from a combination of aerial photographs analysis and fieldwork, and categorized as to site characteristics that are suggestive of causal processes. The debris-flow sites
Detailed geomorphological mapping, supplemented by lichenometric datings and lacustrine sediment studies, shows that debris flow activity on the high-mountain Tatra slopes/South Poland/increased in both frequency and occurrence as well as magnitude
during the Little Ice Age. At present, debris flow activity is limited to apex sector of talus slopes. Only sporadically debris flows affect a whole slope. - (DG)
Debris flow during intense rainfall in Snowdonia, North Wales : a preliminary survey
Averse ; Dynamique deversant ; Géographie de l'Europe ; Géomorphodynamique ; Géotechnique ; Intensité ; Lave torrentielle ; Levée de berges ; Précipitation ; Rempart protalus ; Royaume-Uni ; Versant ; Wales
L'intensité des précipitations après l'été sec et chaud de 1983 a favorisé les laves torrentielles dans les montagnes du Pays de Galles. Etude géomorphodynamique et sédimentologique d'une coulée dedébris qui a incisé un versant et formé des levées
Recent rainfall-induced landslides and debris flow in northern Taiwan
Coulée dedébris ; Cyclone tropical ; Date 2000 ; Dynamique deversant ; Glissement de terrain ; Géotechnique ; Lithologie ; Mouvement de masse ; Pluie torrentielle ; Précipitation ; Roche volcanique ; Taïwan ; Versant
Debris flow ; Geotechnics ; Heavy rain ; Landslide ; Lithology ; Mass movement ; Precipitation ; Slope ; Slope dynamics ; Taiwan ; Tropical cyclone ; Volcanic rock
This paper discusses the factors initiating landslides and a large-scale debris flow in the Chonho area of Taipei County, which resulted from heavy rainfall during Typhoon Xangsane in November 2000. The morphology and triggering mechanism
of the landslides and the debris flow were investigated using aerial photographs taken over the past 20 years, field measurement of channel cross-sections, laboratory assessment of slope material properties, and slope stability analysis. The results indicate
that the landslides and the debris flow were strongly influenced by the physical properties of the underlying pyroclastic substrate and the pattern of bedrock discontinuities within the valleys.
Impact of small amounts of swelling clays on the physical properties of debris-flow-like granular materials. Implications for the study of alpine debris flow
Alpes ; Argile ; Contrainte de cisaillement ; Coulée dedébris ; Granulométrie ; Modèle ; Montagne ; Propriétés du sol ; Sol ; Suisse ; Versant
The aim of this study is to test whether a small content of swelling clay may have a significant impact on the rheology of a reconstituted debris-flow-like material. This has been carried out by using a well characterized mixture that simulates
the grain size distribution and composition of alpine debris flows up to 20 mm. The fraction of swelling clay was then varied and the rheological properties of the mixture tested using a large volume rheometer and a plate-plate geometry for the fine fraction.
Morphologic characteristics of debris flow fans in Xiaojiang Valley of southwestern China
Chine ; Coulée boueuse ; Cône de déjection ; Guangxi ; Géomorphométrie ; Modèle ; Mouvement de masse ; Pente deversant ; Statistique ; Sédimentologie ; Versant
Alluvial cone ; China ; Debris flow ; Geomorphometry ; Guangxi Zhuang ; Mass movement ; Model ; Sedimentology ; Slope ; Slope gradient ; Statistics
The features of morphometry and sedimentology of 54 debris flow fans in semiarid subtropics of southwestern China are summarized here based on field surveys, interpretations of aerial photographs and measurements of topographic maps. The influence
of depositional processes on the morphologic characteristics of debris flow fans is studied through depositional model experiments. These experiments were conducted near a debris flow gully just after debris flows took place.
Debris flows in a weathered granitic massif : Sierra de Gredos, Spain
Coulée boueuse ; Dynamique deversant ; Espagne ; Granite ; Montagne ; Météorisation ; Ravinement ; Réseau de drainage ; Sierra de Gredos
This study analyzes the impact of the mantle's structure and chemical composition on the formation and evolution of debris flows. Debris flows are influential in developing the drainage system in Sierra de Gredos, and the research suggests
that debris flows occurring in other weathered granitic mountain ranges have a similar impact.