Rates of overbank sedimentation on the floodplains of British lowland rivers documented using fallout 137Cs
Bassin-versant ; England ; Fluviatile ; Géochimie ; Isotope ; Plaine d'inondation ; Royaume-Uni ; Sédimentation ; Taux de sédimentation ; Traceur ; Utilisation agricole du sol ; Utilisation du sol
Agricultural land use ; England ; Floodplain ; Fluvial processes ; Geochemistry ; Isotope ; Land use ; Sedimentation ; Sedimentation rate ; Tracer ; United Kingdom ; Watershed
Bomb-derived fallout 137Cs has been used as an environmental tracer. This study presents the 137Cs profiles for sediment cores collected from the floodplains of 12 lowland rivers in Britain and attempt to use the depths of the 1963 137Cs peak
in the sediment profiles to obtain estimates of contemporary overbank sediment accumulation rates at the sampling locations. The 137Cs concentrations associated with the individual sediment cores were also compared and interpreted in terms of the sediment sources
and the sediment transport and deposition processes involved.
Caucasus ; Europe ; Lacustrine sediment ; Lacustrine sedimentation ; Lake ; Mountain ; Sedimentology
Des observations de terrasses complétées par des analyses lithologiques et minéralogiques des sédiments lacustres et les datations au radiocarbone révèlent une certaine logique dans la distribution des sédiments du fond, leur épaisseur et le taux de
sédimentation, les changements de faciès et leur relation avec le relief.
Channel response to sediment wave propagation and movement, Redwood Creek, California, USA
California ; Carrying capacity ; Channel geometry ; Flood ; Fluvial processes ; Human impact ; River bed ; Sediment budget ; Sediment transport ; Stream ; United States of America
There were 3 purposes to this study. The first was to quantify the mechanisms and timing of channel response along a 100 km length of river following a major increase in sediment load. Channel response can be defined in several ways
, and in this paper the AA. use channel-bed elevation, channel width, pool-riffle morphology and sediment transport rates as measures of response. A second purpose was to define the magnitude and transit rates of an aggradational wave of sediment during a sequence
of moderate peak flows. The third objective was to compare and quantify changes in the mass of channel-stored sediment to sediment yields in the drainage basin.
Suspended sediment characteristics in the surf zone
Australia ; Beach ; Coastal environment ; Grain size distribution ; Hydrodynamics ; New South Wales ; Sea current ; Sediment transport ; Surf zone ; Suspended load
Suspended load is an important component of sediment transport in the surf zone. This study investigates the relationships between causative wave and current dynamics and resultant characteristics and distributions of suspended sediment in the surf
zone. Data of hydraulic and morphologic variations and sediment samples were directly collected for a range of conditions in the field and then analyzed quantitatively to detect significant patterns or interrelationships amongst variables.
La répartition des PCB et des pesticides organochlorés a été étudiée dans des sédiments de surface (0-2 cm) et dans les noyaux des sédiments (0-45 cm) de l'ouest de la mer Baltique et des eaux côtières du Mecklembourg-Poméranie occidentale en 1993
This paper discusses the effects of storm intensity on the magnitudes of slope failure and sediment yields in Japan. Data were analyzed for 813 river basins that experienced storm-induced failure as well as 30 basins with sediment yield data
. The basins were grouped into 3 categories according to storm intensity to examine the relation between rainfall and erosion magnitudes. Slope-failure magnitudes and sediment yields are also affected by hillslope inclination. The effect of hillslope
Most published interpretations of the stratigraphic data that form the basis for most of the world's Holocene sea-level curves do not consider palaeotsunamis as agents of coastal sedimentation. Biostratigraphic investigations of modern tsunami
sediments are crucial in this regard because they assist greatly in the identification of particular microfossil assemblages that can be used to distinguish coastal sediments deposited by palaeotsunamis from storm surges and also from those sediments
Dam ; Hydraulic works ; Model ; Poland ; Seasonal variation ; Sedimentation ; Silting ; Stream ; Suspended load ; Watershed ; Wisła
A general model of reservoir sedimentation is proposed and is tested by data on the long-term and seasonal courses of siltation in selected reservoirs in the Vistula drainage basin, Poland. The rate of sedimentation is analysed for both phases
Sediment transport processes in pool-riffle sequences
Carrying capacity ; Channel geometry ; England ; Flood ; Fluvial processes ; Grain size distribution ; Hydrodynamics ; Northumberland ; River bed ; Sediment transport ; Sedimentary structure ; Stream ; Threshold ; Tracer ; United Kingdom
This paper reviews the published data for sediment transport in pool-riffle sequences which suggests that a velocity or shear stress reversal hypothesis does not explain all of the published evidence of sediment transport. This conclusion
is explored in more detail using obsevations of sediment transport from the regulated River North Tyne.
This paper proposes, as a testable hypothesis, a basin-scale approach for interpreting the abundance of in situ produced cosmogenic isotopes, an approach which considers explicitly both the isotope and sediment flux through a drainage basin
. This model is designed for interpreting isotope abundance in sediment. The AA. suggest that measured isotope abundances may reflect spatially averaged rates of erosion if a basin is in isotopic steady state and if sampled sediments are well mixed.
Estimating sediment transport and reservoir sedimentation in an EIA framework (a case study applied to the Pequenos Libombos dam in Southern Mozambique)
Weathering - erosion - sedimentation. New studies in morphodynamics and processes
Carrying capacity ; Dam ; Grain size distribution ; Hydraulic works ; Interannual variability ; Model ; Mozambique ; Sediment transport ; Suspended load
This paper summarises an attempt to assess current rates of reservoir siltation and the level of effectiveness of the methods used to estimate sediment transport and reservoir sedimentation in an EIA (environmental assessment impact) framework
Accumulation rate ; Arctic Region ; Biostratigraphy ; C 14 dating ; Core sampling ; Marine sedimentation ; Ocean ; Palaeomagnetism ; Stratigraphy
Deep-sea sediments recovered from 6 sites visited during the International Artic Ocean Expedition of 1991 were examined to determine sedimentation rates in the eastern Artic Ocean basin. The AA. determine low-field magnetic susceptibility
in addition to anhysteretic and natural remanent magnetization and use these measurements in conjunction with carbonate stratigraphy (from one selected core), as well as radiocarbon dating of surface sediments (from two cores), to deduce sedimentation rates.
Sediment fluxes and particle grain-size characteristics of wind-eroded sediments in Southeastern Australia
Aeolian features ; Arid area ; Australia ; Cultivated land ; Dust storm ; Grain size distribution ; New South Wales ; Organic materials ; Sandy soil ; Sediment transport ; Semi-arid area ; Soil ; Suspended load ; Wind erosion
Grain-size characteristics and the flux of sediment transported by wind from a cultivated paddock in a Quaternary relict dune field, at Mendook, are described: distribution of soil mass with height; particle-size characteristics of suspended
sediments; relationship of sediment flux to wind erosivity and duration.
Annual variation ; Bulgaria ; Data base ; Drainage network ; Human impact ; Hydraulic works ; Sediment budget ; Statistics ; Stream ; Suspended load
This paper reports the results of continuing studies of sediment loads in Bulgarian rivers, with the purpose of elucidating the natural and regional distribution of natural and anthropogenic changes in sediment load through time.
Changes in the hydrology and sediment transport produced by large dams on the lower Ebro river and its estuary
Ebro ; Estuary ; Fluvial hydrology ; Hydraulic works ; Seasonal variation ; Sediment transport ; Spain ; Stream ; Tarragona ; Water use
The aim of this paper is to analyse the changes in the hydrology and sediment transport in the lower Ebro river and its estuary as a consequence of dam construction and increased water uses in the basin. Changes at different time-scales
are specifically considered : long-term changes (years to decades), seasonal changes and daily changes. A critical analysis of the existing data on sediment transport in the present century is also presented.
Identifying sediment sources in a partially logged catchment using natural and anthropogenic radioactivity
Australia ; Carrying capacity ; Drainage network ; Grain size distribution ; Isotope analysis ; New South Wales ; Sediment budget ; Soil erosion ; Tracer ; Watershed
This paper demonstrates the use of radium-isotope ratios to trace sediment in a catchment with a uniform granite lithology. Radionuclide concentrations in transported sediment are measured spatially and temporally, and the likely effects of particle
size and density separation during transport are examined. Using this technique, the AA. are able to identify the source of coarse-grained (bed-load) sediment deposited in the drainage network of a catchment subjected to logging. The AA. consider
that the methods discussed in this paper are complementary to the traditional sediment budget approach.
Processus dynamiques dans la distribution des sédiments de la plate-forme continentale du Rio Grande do Sul (Brésil)
Atlantique Sud ; Bathymétrie ; Brésil ; Distribution spatiale ; Glacio-eustatisme ; Granulométrie ; Hydrodynamique ; Plate-forme continentale ; Quaternaire ; Rio Grande do Sul ; Sédiment marin ; Sédimentologie
Bathymetry ; Brazil ; Continental shelf ; Glacio eustatic change ; Grain size distribution ; Hydrodynamics ; Marine sediment ; Quaternary ; Rio Grande do Sul ; Sedimentology ; South Atlantic Ocean ; Spatial distribution
Présentation des processus ayant contribué à la distribution des sédiments superficiels de la plate-forme continentale du Rio Grande do Sul. Mise en évidence d'un régime sédimentaire terrigène prédominant sur la plate-forme et le talus continental
de la région étudiée, avec la présence considérable de sédiments reliques et palimpsestes. Les sédiments modernes sont restreints et liés à l'influence du fleuve de la Plata et de la lagune des Patos.
Bank erosion ; California ; Carrying capacity ; Channel geometry ; Environmental management ; Fluvial dynamics ; Gully erosion ; Mass movement ; Mudflow ; Rill wash ; Sediment budget ; Sierra Nevada ; Slope dynamics ; Soil erosion ; Tanzania
Many land-management decisions would be aided by an understanding of the current sediment production and transport regime in a watershed and of the likely effects of planned land use on that regime. Sediment budgeting can provide this information
. Methods used in fieldwork and analysis must be selected according to the types of hillslope and channel processes active, the goals of the analysis, and the level of precision required. Methods for evaluating erosion and sediment transport rates
Impact of land-use practices on the sediment yield of a partially disturbed Mediterranean catchment
Agricultural land use ; Barcelona ; Land use ; Mediterranean area ; Nitrate ; Road ; Sediment budget ; Sediment load ; Solution load ; Spain ; Watershed
Etude semi-quantitative de l'influence des différentes techniques d'occupation du sol sur le transport des sédiments dans un bassin-versant méditerranéen: le bassin d'Arbúcies sur la côte catalane. Les routes non revêtues, la construction d'une
autoroute et les surfaces agricoles sont des facteurs importants pour la perte des sédiments et l'augmentation de la charge (soluble et solide).
Bimodal fluvial bed sediments: origin, spatial extent and processes
Carrying capacity ; Fluvial processes ; Grain size distribution ; Gravel ; River bed ; Sand ; Sediment load ; Sediment transport ; Statistics
Historically fluvial channels have been broadly classified as either gravel or sand bedded. However, a third type, bimodal, also exists. In this case significant quantities of both gravel and sand are present. Studies into bimodal sediments have
within bimodal sediments on entrainment and transport processes are also explored.