Solr Search · GéoProdig, portail d'information géographique

On the ages and magnitude of debris flows in the Polish Tatra mountains

On the ages and magnitude of debris flows in the Polish Tatra mountains
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)

Matrix granulometry of catastrophic debris flows (December 1999) in central coastal Venezuela

Matrix granulometry of catastrophic debris flows (December 1999) in central coastal Venezuela
The purposes of this note are to : briefly describe and illustrate some relevant geomorphic effects of the 1999 debris flows, determine the particle-size distribution of the interstitial matrix from one of the larger valleys (Naiguatá river
) affected by debris flows, and discuss the grain-size distribution with regard to the buoyancy and competence of the debris flows for boulder transport.

Lichenometrical studies and dating of debris flow deposits in the High Tatra Mountains, Poland

Lichenometrical studies and dating of debris flow deposits in the High Tatra Mountains, Poland
Dating ; Debris flows ; Holocene ; Lichenometry ; Little ice age ; Paleogeography ; Poland ; Quaternary ; Tatra Mountains
of the investigated debris flows were triggered during the later part of the Little Ice Age, due to alluviation. During the last hundred years, only a few debris flows have occurred.

Dendrochronological analysis of debris flow disturbance on Rishiri Island

Dendrochronological analysis of debris flow disturbance on Rishiri Island
Alluvial cone ; Debris flow ; Dendrochronology ; Gully erosion ; Hokkaido ; Impact ; Island ; Japan ; Methodology ; Slope ; Volcano
The main objective of this study are to clarify the geomorphic history of debris flows by cross-dating the ring series of buried dead trees and by investigating the age structure and distribution of even-aged stands, and also to examine the effects
of debris flow disturbances on tree ring-width variations.

Debris flows in a weathered granitic massif : Sierra de Gredos, Spain

Debris flows in a weathered granitic massif : Sierra de Gredos, Spain
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.

Morphometric and geotechnical controls of debris flow activity, southern Coast Mountains, British Columbia, Canada

Morphometric and geotechnical controls of debris flow activity, southern Coast Mountains, British Columbia, Canada
British Columbia ; Canada ; Debris flow ; Geomorphometry ; Geotechnics ; Pic discharge ; Regression analysis ; Statistics ; Watershed
This paper presents preliminary results from a study, based on 34 debris flow basins in the southern Coast Mountains of British Columbia, in which the AA. use both morphometric and geotechnical variables to characterize the intensity of the supply
processes feeding the debris flow system. They then explore correlations between these parameters and debris flow activity and discuss the possibilities of predicting debris flow volumes from peak discharge data. The method is applicable to small basins

Morphologic characteristics of debris flow fans in Xiaojiang Valley of southwestern China

Morphologic characteristics of debris flow fans in Xiaojiang Valley of southwestern China
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.

GIS-assisted modelling for debris flow hazard assessment based on the events of May 1998 in the area of Sarno, Southern Italy : Part I. Maximum run-out

GIS-assisted modelling for debris flow hazard assessment based on the events of May 1998 in the area of Sarno, Southern Italy : Part I. Maximum run-out
Debris flow ; Geographical information system ; Italy ; Methodology ; Model ; Mountain ; Natural hazards ; Slope dynamics ; Southern Italy
Coulée de débris ; Dynamique de versant ; Italie ; Italie du Sud ; Modèle ; Montagne ; Méthodologie ; Risque naturel ; Système d'information géographique
Based on the debris flow events that occurred in May 1998 in the area of Sarno, this paper presents an approach to simulate debris flow maximum run-out. It first characterizes the morphology and presents the volume and mobility. It follows
of debris flows. Ultimately, this procedure will contribute towards real-time hazard mitigation and the development of new successful mitigation strategies.
with the calibration of a relationship between the volume and the mobility of these flows. The resulting equation is then embedded into ArcGIS with code written in Visual Basic for Applications (VBA) to allow the automatic production of maps of the maximum extent

Spatial and temporal diversity for debris-flow meteorological control in subarctic oceanic periglacial environments in Iceland

Spatial and temporal diversity for debris-flow meteorological control in subarctic oceanic periglacial environments in Iceland
Debris flow ; Iceland ; Meteorology ; Oceanic climate ; Periglacial features ; Rainfall ; Slope ; Subarctic area
Climat océanique ; Coulée de débris ; Domaine subarctique ; Fonte des neiges ; Islande ; Météorologie ; Pluie ; Périglaciaire ; Versant
Origine de l'approvisionnement en eau, principal facteur moteur des coulées de débris : pluie et/ou fonte des neiges augmentent l'écoulement superficiel et subsurfaçique amorcant l'écoulement de débris. Distribution temporelle et spatiale dans une

Failure and flow on a 35o slope : causes and three-dimensional observations

Failure and flow on a 35o slope : causes and three-dimensional observations
Three-dimensional characteristics of the active debris flow are reconstructed from mudlines on 58 trees still standing in the flow path. Mudline formation only on the up-flow side of trees indicates relatively high viscosity of the debris flow
. Mudline height is a function of the maximum thickness and velocity of the flow at any tree.

Influence of experimental removal of large woody debris on spatial patterns of three-dimensional flow in a meander bend

Influence of experimental removal of large woody debris on spatial patterns of three-dimensional flow in a meander bend
Cours d'eau ; Débris ligneux ; Ecoulement fluvial ; Etats-Unis ; Expérimentation ; Géométrie hydraulique ; Midwest ; Modèle ; Méandre
Channel geometry ; Experimentation ; Meander ; Midwest ; Model ; Stream ; Stream flow ; United States of America
This study reports the results of a large woody debris (LWD) removal experiment in a meander bend along a low-energy stream in the Midwestern United States. The results indicate that the LWD obstruction influenced 3D flow structure in this bend
at all flow stages. After the removal of LWD from the bend, both downstream and secondary velocities increased and, though still weak, secondary flow intensified.

Flow disturbance caused by cross-stream coarse woody debris

Flow disturbance caused by cross-stream coarse woody debris
Canada ; Channel geometry ; Hydraulic works ; Ontario ; River bed ; Roughness ; Spatial analysis ; Stream ; Stream flow ; Turbulence ; Wood
The aim of this study is to identify the spatial extent of flow disturbance caused by coarse woody debris positioned normal to the flow between 75° and 105°to the downstream flow direction. A reprsentative reach of the Pine River, Ontario, was used
for intensive study, and results were compared to similar obstructions elsewhere on the same river (n = 48) as well as on another system (Wilmot Creek, n = 1066) with a high volume of woody debris.

Geomorphological characteristics of small debris flows on Junior's Kop, Marion Island, maritime sub-Antarctic

Geomorphological characteristics of small debris flows on Junior's Kop, Marion Island, maritime sub-Antarctic
The geomorphological characteristics of small debris flows in a maritime sub-Antarctic environment are described. The morphological and sedimentological characteristics of the debris flows are comparable to debris flows documented for other parts
of the world; their initiation appears closely linked to the unusual environment in which they are found. The debris flows are triggered by sediment mobilization upon saturation of the frost-heaved surface gravel and overland flow over the low-permeability
and frost-susceptible slope materials. Morphological effects of the flows are short-lived due to obliteration by subsequent frost heave activity.

Surficial patterns of debris flow deposition on alluvial fans in Death Valley, CA using airborne laser swath mapping data

Surficial patterns of debris flow deposition on alluvial fans in Death Valley, CA using airborne laser swath mapping data
Alluvial cone ; California ; Cartography ; Debris flow ; Geomorphometry ; Mountain ; Remote sensing ; Slope dynamics ; United States of America
California ; Cartographie ; Coulée de débris ; Cône de déjection ; Dynamique de versant ; Etats-Unis ; Géomorphométrie ; Montagne ; Télédétection
The AA. utilize fine-scale morphometric measurements to map debris flow deposition and determine if the 2 zones of deposition are consistent between multiple alluvial fans in Death Valley, California. They postulate that the current assertion of 2

High-resolution analysis of debris flow-induced channel changes in a headwater stream, Ashio Mountains, Japan

High-resolution analysis of debris flow-induced channel changes in a headwater stream, Ashio Mountains, Japan
Channel geometry ; Debris flow ; Fluvial dynamics ; Geomorphometry ; Geophysics ; Honshu ; Japan ; Mountain ; Sampling ; Stream
Coulée de débris ; Cours d'eau ; Dynamique fluviale ; Echantillonnage ; Géomorphométrie ; Géométrie hydraulique ; Géophysique ; Honshū ; Japon ; Montagne
Changes in channel size and shape caused by a debris flow event along the length of a headwater stream (HWS) in the Ashio Mountains were captured with the aid of repeat high-definition surveys using terrestrial laser scanning (TLS) techniques
. The HWS was classified into 3 distinct reaches below the debris flow initiation zone. Morphometric analyses from the TLS point cloud revealed that debris flow erosion produced a distinct nonlinear change in channel dimensions in the downstream direction

Debris flows initiated by runoff, erosion, and sediment entrainment in western North America. Special issue

Debris flows initiated by runoff, erosion, and sediment entrainment in western North America. Special issue
California ; Colorado ; Debris flow ; Forecast ; Gully erosion ; Mass movement ; Montana ; Mountain ; Natural hazards ; Rill wash ; Simulation ; Slope ; Soil properties ; United States of America ; Water erosion
California ; Colorado ; Coulée de débris ; Erosion hydrique ; Etats-Unis ; Etats-Unis du Nord-Ouest ; Montagne ; Montana ; Mouvement de masse ; Propriétés du sol ; Prévision ; Ravinement ; Risque naturel ; Ruissellement ; Simulation ; Versant
The papers in this special issue represent recent advances in understanding debris flows that initiate by surface runoff and increase in volume through entrainment of sediment : 5 papers focus on debris flows in areas burned by wildfire, and 3
papers focus on debris flows in unburned areas. They are organized into 4 groups and are presented in the following order : 1) initiation studies, 2) entrainment and volumetric studies, 3) predictive methods, and 4) mitigation issues.

Recent rainfall-induced landslides and debris flow in northern Taiwan

Recent rainfall-induced landslides and debris flow in northern Taiwan
Debris flow ; Geotechnics ; Heavy rain ; Landslide ; Lithology ; Mass movement ; Precipitation ; Slope ; Slope dynamics ; Taiwan ; Tropical cyclone ; Volcanic rock
Coulée de débris ; Cyclone tropical ; Date 2000 ; Dynamique de versant ; Glissement de terrain ; Géotechnique ; Lithologie ; Mouvement de masse ; Pluie torrentielle ; Précipitation ; Roche volcanique ; Taïwan ; Versant
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.

Debris flow triggered by rapid snowmelt : a case study in the Gleidarhjalli area, northwestern Iceland

Debris flow triggered by rapid snowmelt : a case study in the Gleidarhjalli area, northwestern Iceland
Cold area ; Debris flow ; Iceland ; Lichenometry ; Natural hazards ; Slope dynamics ; Vulnerability
Coulée de débris ; Dynamique de versant ; Fonte de neige ; Islande ; Lichénométrie ; Risque naturel ; Vulnérabilité ; Zone froide
This paper describes and emphasises the role of rapid snowmelt as a mechanism for the release of debris flows in a sub-polar basaltic fjord setting. Post-event mapping of erosional and depositional landforms showed strong geomorphic impacts
of debris flows and their role in mass transfer in a mountainous environment. The denudation rate for the single event is estimated. The use of a new lichen growth curve provides relative dating of previous unreported events. Finally, the paper estimates
the mean return period for debris-flow events in the Gleidarhjalli area as 4-5 years, thus constituting a serious threat to the community.

Real-time measurement and preliminary analysis of debris-flow impact force at Jiangjia Ravine, China

Real-time measurement and preliminary analysis of debris-flow impact force at Jiangjia Ravine, China
Carrying capacity ; China ; Debris flow ; Grain size distribution ; Hydrodynamics ; Impact ; Natural hazards ; Risk management ; Watershed ; Yunnan
Bassin-versant ; Capacité de charge ; Chine ; Coulée de débris ; Date 2004 ; Gestion du risque ; Granulométrie ; Hydrodynamique ; Impact ; Risque naturel ; Yunnan
Impact forces associated with major debris flows (Jiangjia Ravine, China, August 25, 2004) were recorded in real time by a system consisting of 3 strain sensors installed at different flow depths. An approach including low-pass filtering and moving
average methods were used to preprocess the recorded signals. It was found that the peak grain impacts at different depths were non-synchronous within the debris flows. The impact loadings were far greater than, and not proportional to the fluid pressures
. Analysis of the impact force of 38 debris flow surges gives an empirical value for the ratio of the hydrodynamic pressure to the momentum flow density, i.e. the product of debris-flow density and mean velocity square, which provides a very valuable basis
for understanding debris flow dynamics and designing debris flow management systems.

Volumetric analysis and hydrologic characterization of a modern debris flow near Yucca Mountain, Nevada

Volumetric analysis and hydrologic characterization of a modern debris flow near Yucca Mountain, Nevada
Debris flow ; Mountain ; Natural hazards ; Nevada ; Numerical model ; Photogrammetry ; Precipitation ; Sediment budget ; Slope dynamics ; Soil erosion ; United States of America
This report documents modern hillslope erosion and debris flows that occurred on July 21 or 22, 1984, following intense rainfall on the south-facing hillslope of Jake Ridge. Analytical photogrammetric techniques were used to map and measure
the volumes of sediment eroded and deposited by these flows. The volumetric results, combined with a hydrologic analysis of the precipitation event that caused the debris flows, help characterize the potential hazards from debris flows and quantify modern

Résultats de la recherche (4459 résultats)

Affinez votre recherche