(Dis)Connectivity in catchment sediment cascades : a fresh look at the sediment delivery problem
Australia ; Channel geometry ; Conceptual model ; Hunter River ; Hydrodynamics ; Model ; New South Wales ; Response time ; Sediment budget ; Sediment transport ; Spatial variation ; Watershed
This paper presents a conceptual framework for analysis of catchment (dis)connectivity that incorporates both spatial and temporal variability in the operation of the sediment cascade. This approach examines where blockages occur to disrupt
these longitudinal, lateral and vertical linkages in catchments. Depending on the position of blockages (termed buffers, barriers and blankets), and their sediment residence time, various parts of a catchment may be actively contributing sediment to the sediment
geomorphologists face in applying such a framework to understand the internal dynamics of the catchment sediment cascades, and forecast how environmental change might affect the operation of sediment fluxes into the future.
The spatio-temporal invariability of sediment concentration and the flow–sediment relationship for hilly areas of the Chinese Loess Plateau
China ; Concentrated flow ; Experimental catchment ; Flood ; Gansu ; Loess ; Model ; Plateau ; Sediment budget ; Sediment transport ; Soil erosion ; Water erosion ; Watershed
Ten experimental sites of entire slope and sub-watershed and 580 flood events at 3 locations in the hilly areas of the Chinese Loess Plateau are involved in this study. The analysis at the intra-event time scale shows that the instantaneous sediment
concentrations in runoff can generally approach the detach-limited maximum sediment concentration since the active massing wasting ensures an abundant sediment supply. Consequently, the event mean sediment concentration does not only remain fairly constant among
that a single proportional function is adequate to fit the flow–sediment relationship for any entire slope or sub-watershed, where eroded sediments are primarily sourced, over a considerable areal extent unless soil property has changed or check dams
River sediment supply, sedimentation and transport of the highly turbid sediment plume in Malindi Bay, Kenya
Bay ; Coastal current ; Coastal environment ; Kenya ; Land use ; Monsoon ; Sediment transport ; Turbidity ; Watershed
The current velocities, tidal elevation, salinity and suspended sediment concentrations (TSSC) were measured in stations located within Malindi Bay in the Northern region of the Kenya coast. It is established that Malindi Bay receives a high
terrigenous sediment load. The river freshwater supply into the bay is highly variable. Relatively low peak flows occurred in November during the North East Monsoon (NEM). The discharge of highly turbidity river water into the bay in April and May occurs
in a period of high intensity South East Monsoon (SEM) winds that generate strong north flowing current that transports the river sediment plume northward. The mechanism of advection of the sediment plume north or south of the estuary is mainly thought
to be due to the Ekman transport generated by the onshore monsoon winds. The high sediment discharge into Malindi Bay can be attributed to land use change in the Athi-Sabaki River Basin in addition to rapid population increase which has led to clearance
Uncertainty in the evaluation of sediment yield from badland areas : Suspended sediment transport estimated in the Araguás catchment (central Spanish Pyrenees)
Suspended sediment transport is probably the main process in sediment export from badland areas. In the Araguás catchment (central Pyrenees) there is a statistically significant positive linear relationship between maximum discharge and the maximum
suspended sediment concentration (SSC). In a study involving sampling during 2 moderate floods (August 2006 and February 2007) in the Araguás catchment it was observed that the mean suspended sediment particle size was significantly greater during
the highest SSC conditions. The results showed the great heterogeneity of particle sizes that can affect suspended sediment transport, which is usually estimated from concentration determined from turbidity values obtained using infrared devices and associated
with the corresponding discharge value. It is highlighted that the evaluation of sediment yield from badland areas using turbidity values involves significant uncertainty, and quantitative estimates of the errors involved are provided.
Temporal variations of reservoir sediment sources in a small mountainous catchment in Korea
Analyse isotopique ; Bassin-versant ; Corée du Sud ; Développement durable ; Erosion des sols ; Erosion hydrique ; Espace-temps ; Lac artificiel ; Lutte contre l'érosion ; Modèle ; Montagne ; Orage ; Sédimentation
Erosion control ; Isotope analysis ; Model ; Mountain ; Rainstorm ; Reservoir ; Sedimentation ; Soil erosion ; South Korea ; Space time ; Sustainable development ; Water erosion ; Watershed
Field measurements, sampling, and fingerprinting of reservoir sediment were undertaken from July 2005 to November 2007 in a mountainous catchment in Korea. Source fingerprinting of reservoir sediment was conducted using cesium-137 (137Cs
). The relative contributions of gully bank and forest road, and forest floor material to reservoir sediment were calculated using a mixing model. Bank and forest road material, estimated to make up about 96% of the reservoir sediment, was the dominant source
. Enormous reservoir sedimentation occurred during a heavy rainstorm with an 80-year recurrence time. To maintain the sustainability of the reservoir in this study, therefore, temporal and spatial preparation strategies for heavy rainstorms and bank
and forest road erosion should be considered. However, spatial information on sediment sources from 137Cs fingerprinting is limited. To better identify the sediment sources spatially and temporally, further studies applying soil erosion models and more
Fault ; Geophysics ; Glaciation ; Glaciolacustrine ; Lacustrine sedimentation ; Lake ; Northern Sweden ; Seismicity ; Sweden ; Upper Pleistocene
The AA. present datasets from a hydroacoustic survey in July 2011 at Lake Torneträsk, northern Sweden. These hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment
accumulation since the beginning of deglaciation, and information on seismic activity along the Pärvie Fault. The AA. assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment
, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off-shore trace
of the Pärvie Fault could not be detected from the hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments.
Sediment production and yield from an alluvial gully in northern Queensland, Australia
Australia ; Gully erosion ; Precipitation ; Queensland ; Runoff ; Sediment budget ; Sediment transport ; Suspended load ; Water erosion ; Watershed
Sediment production, transport and yield were quantified over various timescales in response to rainfall and runoff within an alluvial gully, which erodes sodic soils of a small floodplain catchment along the Mitchell River, northern Australia
. Historical air photographs and recent global positioning system (GPS) surveys and LiDAR data documented linear increases in gully area and volume, indicating that sediment supply has been consistent over the historic period. Daily time lapse photography
of scarp retreat rates and internal erosion processes also demonstrated that erosion from rainfall and runoff consistently supplied fine washload sediment in addition to coarse lags of sand bed material. Total sediment yield estimated from empirical
washload and theoretical bed material load was dominated by fine washload. A lack of hysteresis in suspended sediment rating curves, scarp retreat and sediment yield correlated to rainfall input, and an equilibrium channel outlet slope supported
This article examines the sediment provenance in the Shudu Lake basin, northwest Yunnan Province, China, as revealed by composite fingerprinting. Based on this technique, variations in the geochemical signature as¬sociated with lacustrine sediment
deposits indicate that almost half of the total catchment sediment yield over an approximate 50-year period originated from channel banks. Conversely, the relative contributions of eroded sediment from both woodland and shrubland have generally remained
Fluvial deposit ; Hydrocarbon ; Lacustrine sediment ; Missouri ; Pollution ; Regression analysis ; Rill wash ; Spatial analysis ; Tracer ; United States of America ; Urban area ; Urban infrastructure ; Watershed
This study evaluates the spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in urban stream and pond sediments in Galloway Creek in Springfield, Missouri by focusing specifically on parking lots with and without coal-tar sealants
as contamination source areas. Multiple-linear regression analysis is used to evaluate the spatial connectivity of contaminated sediment to potential source areas and compare the relative influence of watershed source factors and reach sediment variability
on sediment PAH levels. Sediments from coal-tar sealed parking lots and the streams that drain them are enriched in PAHs at concentrations considered toxic to aquatic life. Metal and nutrient contaminants are poorly correlated with sealed lot area indicating
a wider range of urban source inputs. Finally, parking lots with coal-tar coatings contribute >80% of the total PAH concentration in urban stream and pond sediments in Galloway Creek.
Developing a new stream metric for comparing stream function using a bank–floodplain sediment budget : a case study of three Piedmont streams
Carrying capacity ; Comparative study ; Floodplain ; Piedmont ; Sediment budget ; Sediment load ; Stream ; Suspended load ; United States of America ; Virginia
A bank and floodplain sediment budget was created for 3 Piedmont streams tributary to the Chesapeake Bay. The watersheds of each stream varied in land use from urban (Difficult Run) to urbanizing (Little Conestoga Creek) to agricultural (Linganore
Creek). The aim of the study was to determine the relation between geomorphic parameters and sediment dynamics and to develop a floodplain trapping metric for comparing streams with variable characteristics. Net site sediment budgets were best explained
by gradient at Difficult Run, floodplain width at Little Conestoga Creek, and the relation of channel cross-sectional area to floodplain width at Linganore Creek. A correlation for all streams indicated that net site sediment budget was best explained
by relative floodplain width (ratio of channel width to floodplain width). A new geomorphic metric, the floodplain trapping factor, was used to compare sediment budgets between streams with differing suspended sediment yields. This trapping factor promises
This article examines the characterisation of the Rota Wewa tank cascade system in the vicinity of Anuradhapura, Sri Lanka. Sedimentological analyses show that a precise age determination and the reconstruction of sediment and water fluxes
as triggered by human-environment interactions are difficult. This is caused by the shallow character of the wewas leading to the steady redeposition of the tank sediments by wave motions during the wet season and agricultural use of the desiccated wewas during
the dry season. Beyond, the sediments analysed allow to distinguish between the weathered parent bedrock and the overlying sediments.
The performance of grass filter strips in controlling high-concentration suspended sediment from overland flow under rainfall/non-rainfall conditions
Flume experiments on simulated grass strips were conducted using combinations of 3 slope gradients, 5 slope positions (from upslope to downslope), 2 flow rates and different sediment concentrations under simulated rainfall and non-rainfall
conditions. The results showed that sediment deposition efficiency increased with vegetative filter strips (VFS) width as a power function. Rainfall significantly reduced sediment deposited within VFS. Higher sediment concentration corresponded to a larger
sediment deposition load but reduced deposition efficiency. Flow rate had a negative effect on deposition efficiency but no effect on deposition load. Sediments were more easily deposited at the upper slope position than downslope, and the upper slope
position had a higher percentage of coarse sediments. Flow velocity was the most sensitive factor impacting sediment deposition. The results from this study should be useful to control sediment flowing into rivers in areas with serious soil erosion.
2013
[b1] Key Lab. of Water Sediment Sciences, College of Water Sciences, Normal Univ., Beijing, Chine
Nineteenth-century sediment yields from the Southern Blue Ridge Mountains
Comparative study ; Cultivated land ; Deforestation ; Land use ; Mountain ; Nineteenth Century ; North Carolina ; Sediment budget ; Soil erosion ; Twentieth Century ; United States of America ; Watershed
This paper describes late 19th-century sediment yield reconstructed for 2 small, low-order catchments in the Southern Blue Ridge Mountains of North Carolina at a time when each catchment had been partially cleared for agricultural activities
and/or timber harvest. Historical sediment yield values are compared and contrasted to modern values obtained for the adjoining and better-known Piedmont province, and to modern values recorded in both provinces. Although early slope stabilization resulted
in lower sediment yield, there was a time lag between slope stabilization and a return to pre-disturbance sediment yield in small catchments in both physiographic provinces. The remobilization of anthropogenic sediment stored in small catchments has been
as influential in the Blue Ridge as in the Piedmont in terms of 20th-century fluvial sediment dynamics.
Transport and deposition of fine sediment in open channels with different aspect ratios
Cross section ; Fluvial dynamics ; Model ; Numerical model ; Sediment transport ; Simulation ; Stream ; Stream flow ; Suspended load
This paper investigates by means of several large eddy simulations how the channel aspect ratio affects the transport and settling of suspended sediments. The numerical method is successfully validated using data of a physical experiment of fine
sediment net deposition in an open channel flow. The channel aspect ratio, A, is known to be the determining factor for the development, strength and distribution of the turbulence-driven secondary flow, and it is demonstrated that A influences the primary
flow, turbulence quantities and the transport and fate of fine sediments. The secondary flow locally supports or hinders the falling of fine sediment particles in a turbulent flow, which results in a non-uniform deposition of fine sediments over
the cross-section. While the channel aspect ratio has a large influence on the distribution of suspended sediments within the cross-section, its effect on the cross-sectional averaged deposition is negligibly small.
Small-scale effects of annual and woody vegetation on sediment displacement under field conditions
The AA. examined the effects of mound-forming shrubs and annual plants on sediment dispersal at small spatial scales in the semi-arid shrubland of the northern Negev Desert of Israel. They conducted a field experiment to test the displacement
of dyed sediment by wind, runoff and rain splash in 5 × 5 cm areas on shrub-mounds, placed under the canopy and on mound margins, and on the biological soil crust-covered intershrub space. As experimental treatments, they used artificial rain covers
and removal of annuals and their litter. It is showed that : most sediment displacement was caused by rainsplash; overhead cover by shrub canopy had the largest reducing effect on sediment loss; Removal of low annual herbs and litter increased sediment loss
in all locations; A combination of shrub, annual plants and litter reduces erosion most efficiently; Sediment loss by wind in the dry season was very small, in spite of strong winds.
Comparison of two stream gauging systems for measuring runoff and sediment yield for a semi-arid watershed
Arizona ; Comparative study ; Experimental catchment ; Instrumentation ; Research technique ; Sediment budget ; Semi-arid area ; United States of America ; Water erosion ; Watershed
An arid watershed at the Walnut Gulch Experimental Watershed (WGEW) near Tombstone, AZ, was instrumented with both systems and hydrologic and sediment data were collected and compared during a 2 year period. Total sediment yield for the entire
) sediment fractions exported, but consistently underestimated the coarse (> 0.5 mm) sediment fractions. This study outlines the benefits and limitations of the pump sampler based system for monitoring sediment concentration and yield in high-energy headwater
Factors influencing storm-generated suspended-sediment concentrations and loads in four basins of contrasting land use, humid-tropical Puerto Rico
Land use ; Precipitation ; Puerto Rico ; Rainstorm ; Runoff ; Sediment transport ; Statistical analysis ; Suspended load ; Tropical zone ; Watershed
The significant characteristics controlling the variability in storm-generated suspended-sediment loads and concentrations were analyzed for 4 basins of differing land use (forest, pasture, cropland, and urbanizing) in humid-tropical Puerto Rico
. A model of sediment availability and hysteresis was developed. Statistical analysis involved stepwise regression on factor scores. The explanatory variables were attributes of flow, hydrograph peaks, and rainfall, categorized into 5 flow periods. Sediment
availability in the study basins is related to land use and underlying geology. The supply of sediment and its location in the watershed have a strong influence on how current and previous storm events, and flow and rainfall between storm events, affect
This study explores the main factors controlling sediment and water discharge in the Santiago and Pánuco Rivers, the two largest rivers of central Mexico. Santiago River flows over a tectonically active margin draining to the Pacific Ocean
, and Pánuco River flows into the passive margin of the Gulf of Mexico. Mean annual and monthly values of suspended sediment load and water discharge spanning around 50 years were used to evaluate sediment load and water discharge in these two rivers
. The results indicated that Santiago River delivers to the ocean around 45% more sediment than Pánuco River. However, the AA. found that Santiago River has about half the water discharge of Pánuco River. The difference in sediment and water discharge for both
Ajustement fluvial ; Aménagement hydraulique ; Années 1962-2000 ; Charge en suspension ; Chine ; Cours d'eau ; Domaine aride ; Erosion des berges ; Huanghe ; Sable ; Sédimentation ; Transport sédimentaire
Arid area ; Bank erosion ; China ; Fluvial adjustment ; Huang He ; Hydraulic works ; Sand ; Sediment transport ; Sedimentation ; Stream ; Suspended load
% and led to the development of a unique bank-to-channel sediment transfer (BCST). This BCST process, in combination with the decreased flow which caused suspended sediment effluxes to decrease by 30%, enhanced sediment deposition in the channel and provided
a mechanism of channel adjustment to decreased flow in sand-banked rivers. As the lateral channel erosion is a substantial sediment source of river sediments, about 64%, and leads to lateral channel shifts for sand-banked rivers, channel bank stabilization
The AA. report on an experiment in a field-scale flume in which sediment supply is increased to a gravel bed with alternate bars. Sediment was recirculated in the experiments, but augmented in 2 steps, after which the bed was allowed to reach a new
steady state. The transport rate at the end of the experiment was 3 times larger than at the start. High-resolution sediment flux and topographic measurements, grain size derived from photographs, and hydrodynamic modeling allow to document
the topographic and textural response of the bed to increased sediment supply. The spatial patterns of bed topography and texture were forced by the flume setup and the initial and final steady states included long stationary alternate bars with associated grain
size sorting. Bed topography and textural patterns adjusted to increased sediment supply over different timescales. Adjustments in local topography and sorting, primarily in the form of smaller, migrating bars, continued for a period approximately equal