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Résultats de la recherche (222 résultats)

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Fingerprinting upland sediment sources : particle size-specific magnetic linkages between soils, lake sediments and suspended sediments
  • Fingerprinting upland sediment sources : particle size-specific magnetic linkages between soils, lake sediments and suspended sediments
  • Analyse des groupes ; Bassin-versant ; Charge en suspension ; Cumbria ; England ; Erosion des sols ; Granulométrie ; Lac ; Royaume-Uni ; Susceptibilité magnétique ; Sédiment lacustre ; Sédimentologie ; Traceur ; Transport sédimentaire
  • Cluster analysis ; Cumbria ; England ; Grain size distribution ; Lacustrine sediment ; Lake ; Magnetic susceptibility ; Sediment transport ; Sedimentology ; Soil erosion ; Suspended load ; Tracer ; United Kingdom ; Watershed
  • Here, the AA. use magnetic fingerprinting to characterize soils, and examine their affinity with and contribution to suspended sediments transported within 2 subcatchments feeding Bassenthwaite Lake, northwest England. Combining the spatial
  • with the suspended sediments and lake sediments. Examination of the cluster affinity of the soils, suspended sediments and lake sediments indicates that topsoils of the upper Newlands Valley and subsoils around Keskadale Beck are a major source of the Newlands Beck
  • suspended load, and the recent (post-nineteenth century) sediments in the deep lake basin.
  • 2009
Sediment entrainment potential in modified alluvial streams : implications for re-mobilization of stored in-channel sediment
  • Sediment entrainment potential in modified alluvial streams : implications for re-mobilization of stored in-channel sediment
  • Carrying capacity ; Channel geometry ; Deforestation ; Fluvial erosion ; Grain size distribution ; Human impact ; Land use ; Sediment load ; Spatial variation ; Stream ; Tennessee ; United States of America
  • This study examines spatial patterns of sediment entrainment potential in 3 alluvial streams in the Lower Hatchie River Basin of western Tennessee with a history of channelization and significant land use change (historic deforestation). The purpose
  • is to determine if the streams have enough energy to transport the volumes of material they receive via bank failure processes. The results suggest that there is great potential for in-channel sediment storage features to be reworked and to serve as secondary
  • sources of sediment well into the future.
  • 2009
Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data
  • Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data
  • Sediment sources and sediment delivery under environmental change. Special issue
  • Amazonas River ; Brazil ; Discharge ; Fluvial hydrology ; Observation network ; Remote sensing ; Sediment budget ; Sediment transport ; Stream ; Suspended load
  • This study addresses the quantification of the Amazon River sediment budget which has been assessed by looking at data from a suspended sediment discharge monitoring network and remote sensing estimates derived from MODIS spaceborne sensor. Both
  • field and satellite-derived estimates of the sediment concentration of the Amazon River are combined to get an uninterrupted monthly average suspended sediment discharge from 1995 to 2007. Unlike the water discharge which exhibits a steady trend over
  • the same period at Óbidos (Brazil), the suspended sediment discharge increases since 1995.
  • 2009
Elevated sedimentation in lake records linked to agricultural activities in the Ishikari River floodplain, northern Japan
  • Elevated sedimentation in lake records linked to agricultural activities in the Ishikari River floodplain, northern Japan
  • Aménagement hydraulique ; Analyse isotopique ; Bassin-versant ; Géochimie ; Hokkaidô ; Japon ; Plaine d'inondation ; Réseau de drainage ; Sédiment lacustre ; Taux de sédimentation ; Téphrochronologie ; Utilisation agricole du sol
  • Agricultural land use ; Drainage network ; Floodplain ; Geochemistry ; Hokkaido ; Hydraulic works ; Isotope analysis ; Japan ; Lacustrine sediment ; Sedimentation rate ; Tephrochronology ; Watershed
  • The purpose of this study was to examine the historical change in sedimentation rates in lakes that have been impacted by river regulation and agricultural activities in the Ishikari River floodplain. The AA. dated sediment cores using 137Cs dating
  • and tephrochronology, and they estimated sediment sources from 137Cs concentrations in the topsoil of representative land covers (river banks, adjacent floodplains, cultivated lands, and reed swamps). They then focused on the changes in the lake sedimentation rate
  • before and after the establishment of agricultural drainage network. Third, they compared the sedimentation rates from drainage networks across 8 different lakes, each of which is associated with different surrounding land-use conditions. Their approach
  • 2009
Changing dynamics due to natural reforestation in the Dragonja catchment, SW Slovenia
  • Land use ; Model ; Reforestation ; Sediment budget ; Slope gradient ; Slovenia ; Soil erosion ; Spatial distribution ; Suspended load ; Watershed
  • With the spatially distributed erosion and sediment delivery model WATEM/SEDEM, the hillslope sediment delivery to the river channel was calculated on the basis of parameters (soil and precipitation parameters, a DEM and land use) measured
  • in the field and laboratory in 2002 and land use maps based on aerial photographs from 1954 to 1975, 1985 and 1994. For 2 independent calibrations WATEM/SEDEM modelled a sharp decline of 69% in total hillslope sediment delivery from 1954 to 2002. As the sub
  • -catchments Rokawa and Upper Dragonja did not reforest in the same way, the sediment yield response is different as well. The sources of fine sediment were determined by analysing the hysteresis of the discharge waves, and the suspended sediment texture
  • . The sediment that leaves the catchment originates from 3 sources : hillslopes, erosional bedrock banks and sedimentary riverbanks. The analysis of the suspended sediment texture suggests that during a discharge wave the suspended sediment originates
  • predominantly from the hillslopes. The sedimentary riverbanks are not an important source of suspended sediment.
  • 2009
Meso-scale catchment sediment budgets : combining field surveys and modeling in the Dragonja catchment, southwest Slovenia
  • Meso-scale catchment sediment budgets : combining field surveys and modeling in the Dragonja catchment, southwest Slovenia
  • Bank erosion ; Mediterranean area ; Model ; Sediment budget ; Sediment load ; Slovenia ; Suspended load ; Watershed
  • In this paper, the AA. present a methodology to construct a sediment budget for meso-scale catchments. They combine extensive field surveys and expert knowledge of the catchment with a sediment delivery model. The meso-scale Mediterranean drainage
  • basin of the Dragonja (91 km2), southwest Slovenia, was chosen as case study area. The sediment budget presented is based on spatially distributed, detailed on-site measurements of bed erosion and bank erosion, modelled hillslope sediment flux
  • , and measurements of transport of fine and coarse sediment, as well as of floodplain and terrace deposition. The results imply a build-up of sediment in the valleys catchment. However, extreme flood events may flush large amounts of sediment stored in the lower
  • 2009
The role of floodplains in attenuating contaminated sediment fluxes in formerly mined drainage basins
  • The role of floodplains in attenuating contaminated sediment fluxes in formerly mined drainage basins
  • England ; Floodplain ; Geographical information system ; Metals ; Mining activity ; Pollution ; Sediment budget ; United Kingdom ; Watershed ; Yorkshire
  • This paper describes a two stage sediment budgeting technique to estimate the total volume of metal contaminated sediment stored within the River Swale, UK. This operates by dividing the catchment, and likely sediment stores, into two physically
  • and geomorphologically distinct areas (tributaries and the trunk channel). The AA. use a combination of techniques to establish the volumes of metal contaminated sediment remaining within the River Swale. Firstly, using detailed field sampling and a geographical
  • information system (GIS), they estimate the volumes of sediment remaining within one formerly mined tributary (Gunnerside Beck) which is then extrapolated to represent the contaminant volumes on other tributaries of the River Swale. Secondly, combining fresh
  • field data with a range of existing data, volumes of contaminated sediment on the main stream of the River Swale are established. This two tier approach shows that significant volumes of contaminated sediment remain within the River Swale and it may take
  • over 5000 years for all of the metal rich sediment to be removed from the catchment.
  • 2009
Holocene sediment budgets for upland catchments : the problem of soilscape model and data availability
  • Holocene sediment budgets for upland catchments : the problem of soilscape model and data availability
  • Sediment dynamics. Special issue
  • Action anthropique ; Allemagne ; Bassin-versant ; Bilan sédimentaire ; Erosion des sols ; Holocène ; Modèle ; Périglaciaire ; Rheinland-Pfalz ; Taux de sédimentation ; Utilisation du sol
  • Germany ; Holocene ; Human impact ; Land use ; Model ; Periglacial features ; Rhineland-Palatinate ; Sediment budget ; Sedimentation rate ; Soil erosion ; Watershed
  • This study presents a Holocene sediment budget for the upland catchment of the Speyerbach in the Palatinate Forest, southwestern Germany. The influences of both, data availability and the choice of an appropriate soilscape model on the sediment
  • budget calculations are investigated. For budget calculations the spatial distribution of soils was derived from the soil map 1:50,000. In order to model the sediment budget a reference soil thickness (a so-called soilscape model), which represents
  • thickness of the MSS is a crucial point. Therefore a statistical model using the local profile descriptions of the soil database for the Speyerbach catchment was set up. The error estimation for sediment budget based on the Speyerbach data is complicated
  • . Future work will address the estimation of human impact by the analysis of historical data and datings of colluvial layers as well as a field validation of the computed sediment budgets.
  • 2009
Flocculation : a key process in the sediment flux of a large, glacier-fed lake
  • Flocculation : a key process in the sediment flux of a large, glacier-fed lake
  • British Columbia ; Canada ; Charge en suspension ; Floculation ; Lac ; Lac glaciaire ; Sédiment lacustre ; Sédimentologie
  • British Columbia ; Canada ; Flocculation ; Glacial lake ; Lacustrine sediment ; Lake ; Sedimentology ; Suspended load
  • This study investigates the consequences of flocculation for sediment flux in glacier-fed Lillooet Lake, British Columbia, based on density, fractal dimension, in situ profiles of sediment concentration and size distribution, and settling velocity
  • measurements of sediment settling velocity in glacier-fed lakes are required to better constrain flux rates, and permit comparison between flocculation in lacustrine environments with existing studies of estuarine, marine and fluvial flocculation.
  • 2009
A kinematic wave based watershed model for soil erosion and sediment yield
  • A kinematic wave based watershed model for soil erosion and sediment yield
  • Geographical information system ; India ; Maharashtra ; Model ; Remote sensing ; Sediment budget ; Soil erosion ; Watershed
  • In this study, a finite element method based soil erosion and sediment yield model has been developed for overland and streamflow. The one dimensional conservation of mass of sediment flow equation has been solved based on kinematic wave flow
  • distributed model has been used for the estimation of soil erosion and sediment outflow by discretizing the watershed into small grids. The soil erosion and sediment outflow model has been developed and applied to Khadakohol watershed located in Nashik
  • 2009
Sediment budget for subalpine watersheds, Lake Tahoe, California, USA
  • Sediment budget for subalpine watersheds, Lake Tahoe, California, USA
  • Badland ; California ; Erosion ; Lithology ; Meltwater ; Mountain ; Sediment budget ; United States of America ; Watershed
  • The aim of this study was to quantify suspended sediment loading from different landscape components of Ward and Blackwood Creeks on granitic and meta-sedimentary terrain as a means of identifying and ranking dominant erosional processes. This paper
  • presents the results of three-year study of spring snowmelt runoff in watersheds of Lake Tahoe, using a network of 9 nephelometric turbidometers. Highly eroded badland areas originating from volcanic mudflow parent material had high sediment yields
  • . Analysis of sediment loading patterns during high and low flow events indicates that main channel-low gradient reaches act as temporary storage for fine sediment; storing during lower flows and releasing during higher flows.
  • 2009
The impact of environmental changes on the sediment loads of Norwegian rivers
  • The impact of environmental changes on the sediment loads of Norwegian rivers
  • Sediment sources and sediment delivery under environmental change. Special issue
  • Agricultural land use ; Climatic change ; Erosion rate ; Flood ; Human impact ; Norway ; Sediment transport ; Soil erosion ; Stream ; Water erosion
  • The aim of this paper is to discuss some examples where detailed measurements of the sediment load have been made during extreme events. A selection of rivers representing the range of sediment yields and processes in various parts of Norway has
  • been studied in sediment monitoring programmes carried out by the Norwegian Water Resources and Energy Directorate. The combined effects of climate change and human impact on sediment transport in rivers appear to enhance downstream sediment delivery.
  • 2009
Sedimentation effects of the Dongting Lake Area
  • Sedimentation effects of the Dongting Lake Area
  • Action anthropique ; Biodiversité ; Chine ; Déséquilibre écologique ; Hunan ; Impact ; Lac ; Marécage ; Pollution de l'eau ; Ressource halieutique ; Sable ; Sédimentation lacustre
  • Biodiversity ; China ; Ecological imbalance ; Fishing resources ; Human impact ; Hunan ; Impact ; Lacustrine sedimentation ; Lake ; Sand ; Swamp ; Water pollution
  • According to a long series of measured sediment data, the sedimentation effects of the Dongting Lake Area (DLA) were studied in light of the relationship between sedimentation characteristics and resources and environment. The result shows
  • that the long-term deposition and the impact of human activities have led to a cycle of the evolution of sedimentation pattern, resulting in sediment disaster effects and resources effects in the DLA. The main features are presented. They will help to develop
  • rationally resources, protect eco-environment and adjust scientifically sedimentation betwen lakes and rivers in the Dongting Lake Area. Rational development and utilization of marshland resources have produced tremendous economic benefits.
  • 2009
Establishing a Holocene sediment budget for the river Dijle
  • Establishing a Holocene sediment budget for the river Dijle
  • Sediment dynamics. Special issue
  • Agricultural land use ; Belgium ; Flemish Brabant ; Forest ; Holocene ; Human impact ; Sediment budget ; Sedimentology ; Soil erosion ; Suspended load ; Watershed
  • A Holocene sediment budget was constructed for the Dijle catchment in the Belgian loess belt, in order to understand long-term sediment dynamics. Hillslope sediment redistribution was calculated using soil profile information from 809 soil augerings
  • of sediment units show an important increase in alluvial deposition from medieval times onwards, indicating the important influence of agricultural activities that developed from that period. Sediment budgets for the various tributary catchments provide
  • an insight in the sources and sinks of sediment at different scales within the catchment.
  • 2009
The influence of raindrop induced saltation on particle size distributions in sediment discharged by rain-impacted flow on planar surfaces
  • The influence of raindrop induced saltation on particle size distributions in sediment discharged by rain-impacted flow on planar surfaces
  • Experiment plot ; Grain size distribution ; Model ; Precipitation ; Raindrop erosion ; Saltation ; Sediment transport ; Slope gradient ; Soil erosion ; Soil properties ; Water erosion ; Watershed
  • In this paper, the results produced by simulations using a mechanistic model of sediment transport by rain-impacted flow are used to illustrate how sediment transport by suspended load, raindrop induced saltation and flow driven saltation may
  • influence sediment composition as slope length and storm intensity vary without factors such as aggregate breakdown and the development of surface crusts influencing the results.
  • 2009
Preliminary modelling of sediment production and delivery in the Xihanshui River basin, Gansu, China
  • Preliminary modelling of sediment production and delivery in the Xihanshui River basin, Gansu, China
  • Sediment sources and sediment delivery under environmental change. Special issue
  • Bank erosion ; China ; Gansu ; Gully erosion ; Land use ; Mass movement ; Model ; Sediment budget ; Sediment transport ; Soil conservation ; Soil erosion ; Watershed
  • This paper describes the preliminary application of a spatially-distributed method to quantify patterns and rates of sediment production in the Xihanshui basin, a tributary of the upper Yangtze; and to predict its routing to a downstream point
  • is therefore to assess the relative importance of sediment production processes under different climate and land cover conditions, and the controls of the spatial structure of delivery ratios within this large catchment, rather than to make explicit forecasts
  • of sediment production and yield for practical purposes.
  • 2009
Modelling the effects of land-use change on runoff and sediment yield for a meso-scale catchment in the Southern Pyrenees
  • Modelling the effects of land-use change on runoff and sediment yield for a meso-scale catchment in the Southern Pyrenees
  • Sediment sources and sediment delivery under environmental change. Special issue
  • Catalonia ; Forest ; Land use ; Model ; Sediment budget ; Spain ; Water erosion ; Watershed
  • The land-use change over the last 50 years with subsequent effects on water and sediment export was modelled with the process-based, spatially semi-distributed WASA-SED model for the meso-scale Canalda catchment in Catalonia, Spain. It was forwarded
  • that the model yielded plausible results for runoff and sediment yield dynamics without the need of calibration. As there are only a very limited amount of measured data available on sediment budgets with altered land-use and climate change settings, the WASA-SED
  • model was used to obtain qualitative estimates on the effects of past and future change scenarios to derive a baseline for hypothesis building and future discussion on the evolution of sediment budgets in such a dryland setting. The reliability
  • 2009
The potential impact of projected change in farming by 2015 on the importance of the agricultural sector as a sediment source in England and Wales
  • The potential impact of projected change in farming by 2015 on the importance of the agricultural sector as a sediment source in England and Wales
  • Sediment sources and sediment delivery under environmental change. Special issue
  • Agricultural land use ; Agricultural practice ; England and Wales ; Model ; Sediment budget ; Soil erosion ; Suspended load ; United Kingdom ; Water quality ; Watershed
  • The work reported in this contribution used a novel modelling framework to assess the impact of projected change in farming by 2015 on the relative input of the agricultural sector to the total suspended sediment load delivered to all rivers across
  • England and Wales. It required national scale sediment source apportionment to assess the current contributions of diffuse agricultural and urban sector losses, channel bank erosion and point source discharges to the total suspended sediment loads
  • delivered to all rivers. Results suggested that the agricultural sector dominates present day (year 2000) sediment inputs to rivers. Key limitations of the integrated modelling approach are discussed.
  • 2009
Seasonal patterns of suspended sediment transport in an abandoned farmland catchment in the Central Spanish Pyrenees
  • Seasonal patterns of suspended sediment transport in an abandoned farmland catchment in the Central Spanish Pyrenees
  • Central Pyrenees ; Land use ; Mediterranean area ; Mountain ; Plant cover ; Seasonality ; Sediment transport ; Spain ; Suspended load ; Water erosion ; Watershed
  • This study investigated the suspended sediment response of the Arnás research catchment (in the headwaters of the Aragón River), affected in the past by agricultural practices and more recently by plant recolonization, in relation to its
  • hydrological functioning. The magnitude of suspended sediment transport and its temporal distribution were firstly analysed, then relationships between suspended sediment transport, and rainfall and discharge variables at the event scale were explored
  • , and the roles played by different hydrological processes in the sediment response were assessed. Finally, analysis was undertaken of the hysteretic effect of suspended sediment concentrations (SSCs) and discharge during floods, in order to clarify the runoff
  • generation and suspended sediment transport processes operating within the catchment.
  • 2009
Changes in bedload transport rate associated with episodic sediment supply in a Japanese headwater channel
  • Changes in bedload transport rate associated with episodic sediment supply in a Japanese headwater channel
  • Carrying capacity ; Dam ; Discharge ; Experimental catchment ; Grain size distribution ; Honshu ; Hydraulic works ; Japan ; Sediment load ; Sediment transport ; Watershed
  • The aim of this study was to clarify the behavior of the supplied sediment in headwater channels based on experimental sediment release in the Hirudani experimental watershed located in central Japan. The specific objectives included observing
  • changes in the bedload rate for various grain-size fractions during a sediment-supply event, and elucidating the influence of the grain-size distribution of the bed-surface material and the bed forms on the bedload rate. The results provide information
  • on the sediment accumulation and sorting processes after episodic sediment release in gravel-bed rivers.
  • 2009