Abdelrahman, M.A., and K.W. Bedford, Similarity analysis of the temporal variation of suspended sediment profiles, Journal Of Geophysical Research, 95 (C9), 16217-16227, 1990.
Ackers, P., and W.R. White, Sediment transport: new approach and analysis, Proc. Hydraulics Div., ASCE, 99 (HY11), 2041-2060, 1973.
Adams, A.E., O.R. Hinton, E.M. Valentine, and A.D. Tweedy, An acoustic imaging system for the. Concurrent measurement of suspended sediment concentration and particle velocity, Journal of the Acoustical Society of America, 104 (4), 2160-2166, 1998.
This paper presents work on a system providing concurrent concentration and two-dimensional (3-D) particle velocity measurements on suspended sediments in water. The paper shows how one-dimensional methods for independent measurement of sediment concentration and particle velocity can be combined and extended to provide the concurrent 2-D information. An experimental system is described in which suspensions of 0.5-mm diameter sand are illuminated by acoustic burst signals of 1- MHz frequency from two transducers. The relevant theory for determining sediment concentration and particle velocity is presented. The system geometry provides for the illumination of a 5-cm(3) volume at ranges of up to 1.1 m, although longer ranges an possible. Results are presented for concurrent concentration and particle velocity measurements for a falling curtain of sediment, and these are shown to be consistent with predicted values. The measurements have sufficient resolution, and can be made sufficiently rapidly, to investigate short time-scale phenomena in hydraulics, such as the effect of wave dynamics on sediment transport. The method presented could form the basis of an instrument giving sequenced acoustic images of the transport phenomena occurring within an observed volume. (C) 1998 Acoustical Society of America. [S0001-4966(98)06009- 3].
Admiraal, D.M., and M.H. Garcia, Laboratory measurement of suspended sediment concentration using an Acoustic Concentration Profiler (ACP), Experiments in Fluids, 28 (2), 116-127, 2000.
Vertical profiles of suspended sediment concentration have been gathered in a laboratory flume using a 2.25 MHz acoustic transducer. The acoustic concentration profiler (ACP) was calibrated in a vertical duct for homogeneous concentrations of two uniformly sized sediments. The transducer was then transferred to a 6 m horizontal flume where concentration profiles were measured in steady and unsteady flows. For the steady flow tests, concentration measurements made with the ACP and with suction samplers are compared. The results demonstrate that the ACP provides an accurate method of non-intrusively measuring sediment concentrations of more than 2.5% by volume.
Amos, C.L., and K.T. Tee, Suspended sediment transport processes in cumberland basin, bay of fundy, Journal Of Geophysical Research-Oceans, 94 (C10), 14407-14417, 1989.
Anilkumar, N., V.N. Sankaranarayanan, and V. Josanto, Studies on mixing of the waters of different salinity gradients using Richardsons number and the suspended sediment distribution in the Beypore estuary, south west coast of India, Indian Journal of Marine Sciences, 28 (1), 29-34, 1999.
The study was conducted up to 15 km upstream in the Beypore estuary of the Chaliyar river in Calicut. The study area was divided into four sections (5 ion interval) with two transverse stations on either side of each section. The logarithmic values of Richardsons number (log R-L) shows high variation at river mouth section of the estuary (section-I) and at about 10 km upstream (section-II) during the postmonsoon period. During the premonsoon period there was no noticeable variation in log R-L values at section-I and section-II and the estuary was found to be well mixed. During the monsoon period the stratification was higher and the variation in log R-L was high from flood to ebb tide. The lower part of the estuary is a turbidity maximum zone, especially during premonsoon season. During the postmonsoon period the concentration of suspended matter was not high compared to premonsoon and monsoon period. There was a high surface value during ebb tide in monsoon period.
Annandale, G.W., M. Demissie, E.J. Gilroy, T.A. Cohn, C.F. Nordin, E.A. Mcbean, W.P. Fitzpatrick, W.H. Kirby, G.D. Glysson, K. Wahl, and S. Alnassri, Uncertainty In Suspended Sediment Transport Curves - Discussion, Journal Of Hydraulic Engineering-Asce, 116 (1), 140-151, 1990.
Antsyferov, S.M., and R.D. Kosyan, Study of suspended sediment distribution in the coastal zone, Coast Eng, 14 (2), 147-172, 1990.
Antsyferov, S.M., and T.M. Akivis, Suspended sediment concentration under tidal flow, Okeanologiya, 38 (5), 766-772, 1998.
The objective of the paper is to give a procedure for prediction of the vertical profile of the cede-averaged sediment concentration for heterogeneous sediments under erodable rippled bed under the action of tidal flow. The theoretical and laboratory investigations on the steady fluid- sediment flow are used For this purpose. By analogy with the results concerning suspended sediments behavior under irregular waves we use the bed friction velocity for significant waves as a main value related to the hydrodynamics of the flow. To predict the vertical distribution of the ''easy" particles the Rouse's solution for the diffusion model is used. An additional term is introduced for "heavy" ones to take into account their inertial properties. The concentration field of heterogeneous sediments is considered as a sum of those of homogeneons groups (fractions) of particles. The bed friction velocities changes related to the formation of ripples are taken into account by means of the most reliable empirically-derived channel dynamics relations. The solution has been verified against the data obtained in Bahia Blanka Bay (Western Atlantic). The results seem to be quite satisfactory.
Arnott, R.W.C., and B.M. Hand, Bedforms, Primary Structures And Grain Fabric In The Presence Of Suspended Sediment Rain, Journal Of Sedimentary Petrology, 59 (6), 1062-1069, 1989.
Arnoux-Chiavassa, S., V. Rey, and P. Fraunie, Modelling of suspended sediment fluxes off the Rhone river mouth, Journal of Coastal Research, 15 (1), 61-73, 1999.
A three dimensional hydrodynamic model including the suspended sediment transport is presented and applied to the microtidal coastal region off the Rhone river mouth. The dependence of the solution on turbulent parametization is first numerically investigated. The model is then adjusted and applied to typical climate events encountered during a field campaign and an adequate agreement between numerical results and field measurements is obtained. Then, the suspended sediment transport is computed for climate conditions when relevant to the beach nourishment and shoreline evolution.
Asselman, N.E.M., Suspended sediment dynamics in a large drainage basin: the River Rhine, Hydrological Processes, 13 (10), 1437-1450, 1999.
The behaviour of suspended sediment in rivers is often a function of energy conditions, i.e. sediment is stored at low flow and transported under high discharge conditions. The timing of maximum sediment transport can, however, also be related to mixing and routing of water and sediment from different sources. In this study suspended sediment transport was studied in the River Rhine between Kaub and the German- Dutch border. As concentrations decrease over a runoff season and as the relationship between water discharge and suspended sediment concentrations during most floods is characterized by clockwise hysteresis, it is concluded that sediment depletion occurs during a hydrological year and during individual floods. However, analyses of the sediment contribution from the River Mosel indicate thar clockwise hysteresis may result from sediment depletion as well as from early sediment supply from a tributary. Thus, although the suspended sediment behaviour in the downstream part of the River Rhine is partly a transport phenomenon related to energy conditions, mixing and routing of water from different sources also plays an important role. Suspended sediment transport during floods was modelled using a 'supply-based' model. Addition of a sediment supply term to the sediment rating curve leads to a model that produces better estimates of instantaneous suspended sediment concentrations during high discharge events. A major constriction of the model is that it cannot be used to predict suspended sediment concentrations as long as the amount of sediment in storage and the timing of sediment supply are unknown. Copyright (C) 1999 John Wiley & Sons, Ltd.
Aziz, N.M., S.N. Prasad, and S.K. Bhattacharya, Suspended Sediment Concentration Profiles Using Conservation Laws, Journal Of Hydraulic Research, 30 (4), 539-554, 1992.
Bagnold, R.A., Auto-suspension of transported sediment; turbidity currents, Proc. Roy. Soc. London, A, 265, 315-319, 1962.
Bagnold, R.A., Mechanics of marine sedimentation, in The Sea, edited by M.N. Hill, pp. 507-528, Interscience, New York, 1963.
Bagnold, R.A., An approach to the sediment transport problem from general physics, U. S. Geological Survey Professional Paper, 422 (I), 1-37, 1966.
Bagnold, R.A., Deposition in the process of hydraulic transport, Sedimentology, 10, 45-56, 1968.
Bailard, J., An energetics total load sediment transport model for a plane sloping beach, Journal of Geophysical Research, 86 (C11), 10938-10954, 1981.
Bailard, J.A., Modelling on-offshore sediment transport in the surfzone, in 18th International Conference on Coastal Engineering, pp. 1419-1438, 1982.
Bailard, J.A., Surfzone wave velocity moments, in Conference on Coastal Hydrodynamics, pp. 328-342, ASCE, 1987.
Bakker, W.T., Sand concentration in an oscillatory flow, in 14th Coastal Engineering Conference, edited by ASCE, pp. 1129-1148, ASCE, Copenhagen, Denmark, 1974.
Bakker, W.T., and T.H. Doorn, Near bottom velocities in waves with a current, in 16th Coastal Engineering Conference, pp. 1394-1413, ASCE, Hamburg, Germany, 1978.
Beach, R.A., and R.W. Sternberg, Suspended sediment transport in the surf zone - response to infragravity motion, Marine Geology, 80, 61-79, 1988.
Beach, R.A., and R.W. Sternberg, Suspended sediment transport in the surf zone - response to incident wave and longshore current interaction, Marine Geology, 108 (3-4), 275-294, 1992.
Black, K.S., Suspended sediment dynamics and bed erosion in the high shore mudflat region of the Humber estuary, UK, Marine Pollution Bulletin, 37 (3-7), 122-133, 1998.
The transport of suspended sediment over intertidal mudflats is the principal agent by which sediment is exchanged between the high shore marsh region and the sub-tidal zone. A 16-day time- series of near-bed current velocity and water turbidity, collected during the LOIS LISP (Littoral Investigation of Sediment Properties) experiment on the upper shore of Spurn Eight, Humber estuary, is used to evaluate the mechanisms through which sediments are both deposited and recycled in this zone over a spring-neap tidal cycle, Data analysis indicates that a large proportion of the sediment is delivered to the high shore region during intermediate and spring tides in the form of a shallow, high velocity sheet of water. Neap tides are incapable of resuspending bottom sediments, and simply advect a washload of very small (<50 mu m diameter), low settling rate flocs back and forth across the mudflat. A central belt in the mid-shore region of the mudflat is the dominant source of eroded sediments to the high shore; however, comparison of the magnitude of the ambient tidally-induced bed stress to in situ measures of sediment cohesive strength reveals that some local erosion may occur in the high shore during maximum spring tides, Computation of the net suspended flux per tide reveals a temporally variable, predominantly onshore transport of sediments during the observation period. Modulation of this flux by surface gravity waves is discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.
Blewett, J., and D. Huntley, Measurement of suspended sediment transport processes in shallow water off the Holderness coast, UK, Marine Pollution Bulletin, 37 (3-7), 134-143, 1998.
A new benthic tripod system has been developed to study the processes responsible for suspended sediment movement in the shallow water (10-20 m depth) off the Holderness coast, N.E. England. About a month of data from a summer period and a winter period are described. The suspended sediment concentration (SSC) is found to vary due to the advection of spatial gradients of SSC by the tidal flows and to the resuspension of sediment from the seabed. Alongshore advection is identified through a strong negative correlation between SSC and salinity, associated with the movement of low salinity, high turbidity water associated with the Humber plume to the south. Resuspension occurs predominantly during storms, when the influence of waves increases the friction velocity at the seabed (estimated from the measured turbulence spectra) above a threshold value. In winter the threshold friction velocity is found to be approximately 0.028 ms(-1), consistent with a partially consolidated fine sediment seabed; in the summer period a somewhat lower threshold may be the result of a less consolidated layer of fine sediment depositing between the mild summer storms. The decay of the elevated SSC values after a storm is consistent with a sediment settling velocity in the range (1.8-2.8) x 10(-4) ms(-1), a value associated with fine silt or floculated clay particles. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
Bonta, J.V., Impact of coal surface mining and reclamation on suspended sediment in three Ohio watersheds, Journal of the American Water Resources Association, 36 (4), 869-887, 2000.
Prior to PL95-87 little research had been conducted to determine the impacts of mining and reclamation practices on sediment concentrations and yields on a watershed scale. Furthermore, it was unknown whether sediment yield and other variables would return to undisturbed levels after reclamation. Therefore, three small watersheds, with differing lithologies and soils, were monitored for runoff and suspended sediment concentrations during three phases of watershed disturbances: undisturbed watershed condition, mining and reclamation disturbances, and post-reclaimed condition. Profound increases in suspended-sediment concentrations, load rates, and yields due to mining and reclamation activities, and subsequent drastic decreases after reclamation were documented. Even with increases in runoff potential, reductions in suspended-sediment concentrations and load rates to below or near undisturbed- watershed levels is possible by using the mulch-crimping technique and by removing diversions. Maximum concentrations and load rates occurred during times of active disturbances that exposed loose soil and spoil to high-intensity rains. Sediment concentrations remained elevated compared with the undisturbed watershed when diversions were not well maintained and overtopped, and when they were not removed for final reclamation. Diversions are useful for vegetation establishment, but should be maintained until they are removed for final reclamation after good vegetative cover is established.
Bowen, A.J., Simple models of nearshore sedimentation; beach profiles and longshore bars,, in The Coastline of Canada, Gelological Survey of Canada Paper 80-10, edited by S.B. McCann, pp. 1 - 11, 1980.
Bowen, A.J., On the kinematics of a sediment suspension, Eos, Trans, Agu, 71 (43), 1369, 1990.
Brasington, J., and K. Richards, Turbidity and suspended sediment dynamics in small catchments in the Nepal Middle Hills, Hydrological Processes, 14 (14), 2559-2574, 2000.
The Himalayan environment has, until recently, been perceived to be in a critical state of environmental decline, resulting From rapid population growth and associated land-use change. Recent research, however, has emphasized the difficulty of developing an objective appraisal of the state of the environment in a region where empirical data are scarce and unstructured and where an understanding of the spatial and temporal dynamics of natural environmental processes remains highly uncertain. This paper presents results from an intensive three-year project designed to help address the regional empirical deficit, establish detailed baseline environmental data and to gain an insight into storm period and seasonal suspended sediment dynamics. The instrumentation, calibration and analysis of high-frequency infrared turbidimetric records from a number of small subcatchments in the Nepal Middle Hills are reported. Storm period and seasonal Variation in turbidity and suspended sediment are examined and hysteresis patterns explored and explained. A variety of methods to estimate seasonal suspended sediment yield in a mixed land-use catchment are examined, and found to vary by up to a factor of five. Despite the inherent uncertainty, all estimates of catchment sediment yield are found to be high with respect to erosion plot studies from the local area, and this suggests the importance of riparian and channel erosion as major sediment sources. a finding consistent with other regional studies. Copyright (C) 2000 John Wiley & Sons, Ltd.
Braun, C., D.R. Hardy, R.S. Bradley, and M.J. Retelle, Streamflow and suspended sediment transfer to Lake Sophia, Cornwallis Island, Nunavut, Canada, Arctic Antarctic and Alpine Research, 32 (4), 456-465, 2000.
To ascertain the climatic controls on sediment transport to Lake Sophia, Cornwallis Island, Nunavut, Canada, we made detailed hydrological and meteorological measurements in the Sophia River watershed through the 1994 melt season. Streamflow and suspended sediment transport are limited, on an annual time scale, by the supply of snow and sediment in the watershed. Suspended sediment yield from the watershed was only 0.46 t km(-2), which is lower than any previously published yield for a stream in the High Arctic. Snowmelt runoff accounted for 88% of the annual suspended sediment load, whereas 6 and 9% were transported in response to a slushflow event and summer rainfall, respectively These measurements provide no direct evidence that modern-day sediment delivery to Lake Sophia is related to fluctuations in air temperature, which has implications for the paleoenvironmental signal preserved in Lake Sophia's laminated sediments. We suggest that on-site sediment transport studies are necessary to establish the relationships among geology, geography, climate, and hydrology unique to each watershed-lake system and need to be an integral part of any calibration attempt. Additional yeats of data are needed however to define the interannual variability of streamflow and sediment transport in response to climate.
Bronsdon, R.K., and P.S. Naden, Suspended sediment in the Rivers Tweed and Teviot, Science of the Total Environment, 251, 95-113, 2000.
Suspended solids concentrations were monitored over a 3-year period from April 1994 to March 1997 at two sites on the River Tweed and one on the Teviot, a tributary of the Tweed. Values of the median suspended solids concentration ranged between 6.6 and 8.0 mg 1(-1) for the three sites. The relationship between suspended solids concentration and flow varied both between years and by month, showing the influence of sediment supply and diatom growth. Estimates of the flux of suspended solids from the T-weed basin at the tidal limit ranged from 38 000 to 89 800 t year(-1), depending on the year. Converted into a yield, these values are at the lower end of the range of both published estimates and those for other LOIS rivers. (C) 2000 Elsevier Science B.V. All rights reserved.
Butt, T., and P. Russell, Suspended sediment transport mechanisms in high-energy swash, Marine Geology, 161 (2-4), 361-375, 1999.
Measurements of suspended sediment concentration at three heights above the bed, and cross-shore velocity at a single height were obtained usings miniature optical backscatter sensors and a miniature electromagnetic current meter, from the swash-zone of a high-energy macrotidal dissipative beach. Time- series from relatively low (H-s approximate to 0.8 m) and high (H-s approximate to 2.2 m) energy conditions were chosen for analysis. Possible onshore and offshore sediment transport mechanisms are identified as (a) sudden offshore to onshore velocity transition and turbulence in the swash-front leading to subsequent onshore advection by the uprush, and (b) low- frequency high-velocity backwashes exceeding a certain threshold for sediment suspension. These mechanisms are related to the velocity field through skewness and asymmetry. An increase in negative infragravity skewness in high-energy conditions suggests a potential shift towards offshore net transport. Time-averaged vertical profiles of cross-share suspended sediment flux were calculated from the velocity and concentration time-series. These show a tendency towards offshore transport in high-energy conditions, particularly at low levels in the water column. The actual sediment fluxes are believed to be more offshore than those calculated. One reason for this discrepancy is the inability of the instruments to detect swash activity at very low levels in the water column. (C) 1999 Elsevier Science B.V. All rights reserved.
Cacchione, D.A., P.L. Wiberg, J. Lynch, J. Irish, and P. Traykovski, Estimates of suspended-sediment flux and bedform activity on the inner portion of the Eel continental shelf, Marine Geology, 154 (1-4), 83-97, 1999.
Energetic waves, strong bottom currents, and relatively high rates of sediment discharge from the Eel River combined to produce large amounts of suspended-sediment transport on the inner continental shelf near the Eel River during the winter of 1995-1996. Bottom-boundary-layer (BBL) measurements at a depth of similar to 50 m using the GEOPROBE tripod showed that the strongest near-bottom flows (combined wave and current speeds of over 1 m/s) and highest sediment concentrations (exceeding 2 g/l at similar to 1.2 m above the bed) occurred during two storms, one in December 1995 and the other in February 1996. Discharge from the Eel River during these storms was estimated at between 2 and 4 x 10(3) m(3)/s. Suspended-sediment flux (SSF) was measured 1.2 m above the bed and calculated throughout the BBL, by applying the tripod data to a shelf sediment-transport model. These results showed initially northward along-shelf SSF during the storms, followed by abrupt and persistent southward reversals. Along-shelf flux was more pronounced during and after the December storm than in February. Across-shelf SSF over the entire measurement period was decidedly seaward. This seaward transport could be responsible for surficial deposits of recent sediment on the outer shelf and upper continental slope in this region. Sediment ripples and larger bedforms were observed in the very fine to fine sand at 50-m depth using a sector-scanning sonar mounted on the tripod. Ripple wavelengths estimated from the sonar images were about 9 cm, which compared favorably with photographs of the bottom taken with a camera mounted on the tripod. The ripple patterns were stable during periods of low combined wave-current bottom stresses, but changed significantly during high-stress events, such as the February storm. Two different sonic altimeters recorded changes in bed elevation of 10 to 20 cm during the periods of measurement. These changes an thought to have been caused principally by the migration of low-amplitude, long-wavelength sand waves into the measurement area. (C) 1999 Elsevier Science B.V. All rights reserved.
Cao, Z.X., Equilibrium near-bed concentration of suspended sediment, Journal of Hydraulic Engineering-Asce, 125 (12), 1270-1278, 1999.
A new approach is presented for calculating the equilibrium near-bed concentration of suspended sediment in an alluvial channel flour It is formulated from the balance between bed sediment entrainment and suspended sediment deposition across the near-bed boundary. The entrainment flux is determined making use of a turbulent bursting outer-scale-based function and the flux of deposition by the product of near-bed concentration and hindered settling velocity of sediment. A number of flume data records in the literature are analyzed to calibrate and verify the present approach. The observed near- bed concentrations for the data records are obtained by first isolating the suspended load transport rate from. the observed total load transport rate using Engelund and Fredsoe's bed-load formula and then equating the suspended load transport rate to the shape integration of Dyer and Soulsby. The present approach is shown to perform satisfactorily compared to the results of data analysis. It is found that the near-bed concentration is evidently dependent on sediment particle size in addition to the Shields parameter due to skin friction. This finding seems to challenge previous relationships that simply represent the near-bed concentration as empirical functions of the purely skin-friction-related Shields parameter.
Celik, I., and W. Rodi, Suspended Sediment-Transport Capacity For Open Channel Flow, Journal Of Hydraulic Engineering-Asce, 117 (2), 191-204, 1991.
Celik, I., and W. Rodi, Suspended Sediment-Transport Capacity For Open Channel Flow - Closure, Journal Of Hydraulic Engineering-Asce, 118 (5), 825-827, 1992.
Cellino, M., and W.H. Graf, Velocity profiles for particles and liquid in open-channel flow with suspended sediment - Discussion, Journal of Hydraulic Engineering-Asce, 125 (4), 432-433, 1999.
CERC, Shore protection manual, Washington, D.C., 1984.
Chapalain, G., L. Thais, and H. Smaoui, Modeling of a tidal bottom boundary layer with suspended sediment, Hydrobiologia, 414, 1-12, 1999.
A one-dimensional model of the vertical exchange of suspended sediment in a tidal boundary layer is proposed. The model includes two linearized momentum equations for the horizontal velocity components and a series of advection-diffusion equations for concentrations of suspended sediment of specific size. Turbulence generated at the sea-bed is computed with the aid of a two-equation closure describing the time-space evolution of the turbulent kinetic energy, K, and of the turbulence macroscale, Lambda (K-Lambda model). Special attention is paid to the bottom boundary condition for the sediment concentration, which is of mixed type to take into account downward fluxes at times of decelerating flow and slack waters. The model is applied to conditions encountered in a shallow site located in the eastern part of the English Channel. The model is forced with pressure gradients computed with a two-dimensional vertically-integrated tidal model covering the eastern English Channel and the southern part of the North Sea. The tidal currents and the total suspended sediment load predicted by the model are compared with field data collected over the full water depth.
Chapalain, G., and L. Thais, Tide, turbulence and suspended sediment modelling in the eastern English Channel, Coastal Engineering, 41 (1-3), 295-316, 2000.
The present paper is concerned with modelling fluid and suspended sediment dynamics in a tide-dominated environment. The procedure consists of a one-dimensional vertical model driven by an oscillatory horizontal pressure gradient derived from a two-dimensional vertically integrated tidal model. The vertical model includes two Linearised momentum equations for the horizontal velocity components and a series of advection- diffusion equation For concentrations of suspended sediment of specific size. Turbulence generated at the seabed is computed with the aid of a two-equation closure describing the time- space evolution of the turbulent kinetic energy k and of the dissipation late of the turbulent kinetic energy epsilon (standard k - epsilon model). A mixed type bottom boundary condition for the sediment concentration equations is adopted to take into account downward fluxes at times of decelerating flow and slack waters. The model is applied to the eastern part of the English Channel. The tidal currents, turbulent kinetic energy and the total suspended sediment load predicted by the model are compared with field data collected in two sites. The vertical structure of these flow properties is fairly well predicted by the present model. Better results are found at the measuring point located farther from the coastline where advective terms can be reasonably neglected. (C) 2000 Elsevier Science B.V. All rights reserved.
Chappell, N.A., P. McKenna, K. Bidin, I. Douglas, and R.P.D. Walsh, Parsimonious modelling of water and suspended sediment flux from nested catchments affected by selective tropical forestry, Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 354 (1391), 1831-1846, 1999.
The ability to model the suspended sediment flux (SSflux) and associated water flow from terrain affected by selective logging is important to the establishment of credible measures to improve the ecological sustainability of forestry practices. Recent appreciation of the impact of parameter uncertainty on the statistical credibility of complex models with little internal state validation supports the use of more parsimonious approaches such as data-based mechanistic (DBM) modelling. The DBM approach combines physically based understanding with model structure identification based on transfer functions and objective statistical inference. Within this study, these approaches have been newly applied to rainfall-SSflux response. The dynamics of the sediment system, together with the rainfall-river flow system, were monitored at five nested contributory areas within a 44 ha headwater region in Malaysian Borneo. The data series analysed covered a whole year at a 5 min resolution, and were collected during a period some five to six years after selective timber harvesting had ceased. Physically based and statistical interpretation of these data was possible given the wealth of contemporary and past hydrogeomorphic data collected within the same region. The results indicated that parsimonious, three-parameter models of rainfall-river flow and rainfall-SSflux for the whole catchment describe 80 and 90% of the variance, respectively, and that parameter changes between scales could be explained in physically meaningful terms. Indeed, the modelling indicated some new conceptual descriptions of the river flow and sediment-generation systems. An extreme rainstorm having a 10- 20 year return period was present within the data series and was shown to generate new mass movements along the forestry roads that had a differential impact on the monitored contributory areas. Critically, this spatially discrete behaviour was captured by the modelling and may indicate the potential use of DBM approaches for (i) predicting the differential effect of alternative forestry practices, (ii) estimating uncertainty in the behaviour of ungauged areas and (iii) forecasting river flow and SSflux in terrain with temporal changes in rainfall regime and forestry impacts.
Cheng, K.J., Bottom boundary condition for nonequilibrium transport of sediment, JGR, 89 (C5), 8209-8214, 1984.
Church, J.C., and E.B. Thornton, Effects if breaking wave induced turbulence within a longshore current model, Journal of Coastal Engineering, in press, 1993.
Collins, A.L., D.E. Walling, and G.J.L. Leeks, Fingerprinting the origin of fluvial suspended sediment in larger river basins: Combining assessment of spatial provenance and source type, Geografiska Annaler Series a-Physical Geography, 79A (4), 239-254, 1997.
Investigation of the potential for using sediment fingerprinting to integrate both spatial provenance and source type information for larger drainage basins appears to be desirable. This contribution presents the results of adopting a composite fingerprinting procedure incorporating statistically verified multicomponent signatures and a multivariate mixing model to provide a preliminary integration of spatial provenance and source type information for the upper and middle reaches of the drainage basins of the Rivers Exe (601 km(2)) and Severn (4325 km(2)), UK. A nested approach is employed, whereby spatial provenance is addressed in terms of the distinct sub-basin zones constituting each study area as an entirety, and source type is then characterised within each of these distinct spatial zones in terms of surface (woodland, pasture, cultivated) and subsurface (channel bank) materials. The results demonstrate that the fingerprinting approach possesses considerable potential for integrating spatial provenance and source type information, and hence For improving the resolution of existing sediment source information for larger drainage basins.
Collins, D.N., Suspended sediment flux in meltwaters draining from Batura glacier as an indicator of the rate of glacial erosion in the Karakoram mountains, Journal of Quaternary Science, 13 (6), 1-10, 1998.
Suspended sediment content of samples of meltwater, collected at hourly intervals throughout an ablation season from the river draining from the terminus of Batura glacier in the Karakoram mountains, was determined gravimetrically with a view to assessing both temporal variations of sediment fur with discharge and annual total sediment yield from the highly- glacierised (56%) basin. The seasonal pattern of suspended sediment transport results from interaction between the hydrometeorologically-determined pattern of discharge with fine products of glacial abrasion stored at the glacier subsole. Large sediment pulses occurred in spring and early summer as discharge first exceeded levels last reached in the previous ablation season, after which sediment fur remained subdued. The pulses resulted from progressive expansion of the drainage network into partial areas of subsole which had remained isolated from flowing meltwater as the ablation area extended up-glacier. Total annual suspended sediment flux from Batura glacier basin was 6.086 +/- 10% kt km(-2) yr(1) or 10.144 +/- 10% kt km(-2) yr(1) for the glacierised area, since almost all the sediment is derived from the glacier subsole. Whilst not all suspended sediment is produced by glacial abrasion, and not all that so produced is acquired by meltwater in the same year, the rate of glacial abrasion beneath Batura glacier is estimated to lie between 3.45 and 4.21 mm yr(1), considerably higher than rates estimated for generally smaller glaciers in other mountain regions. Adding an unconstrained bedload estimate, the overall rate of lowering of the subsole of Batura glacier is about 7.7 mm yr(1), at the upper end of the global range of estimates. These rates of glacial erosion suggest that glaciers can accentuate or at least maintain relief against regional uplift rates in the tectonically-active Karakoram. The overall magnitude of debris removal points to glaciation having an impact, in the long-term, on the elevation of the Himalayan mountain belt through isostatic rebound.
Crawford, C.G., Estimation Of Suspended-Sediment Rating Curves And Mean Suspended-Sediment Loads, Journal Of Hydrology, 129 (1-4), 331-348, 1991.
Curto, L.A., On the motion of very small bodies in water waves, JGR, 90 (C1), 1127-1132, 1985.
Dally, W.R., and R.G. Dean, Suspended sediment transport and beach profile evolution, Journal of Waterway, Port, Coastal and Ocean Engineering, 110 (1), 15-33, 1984.
Dean, R.G., Heuristic models of sand transport in the surfzone, Conference on Engineering Dynamics in the Surf Zone, 1973.
Dean, R.G., Equilibrium beach profiles: U.S. Atlantic and Gulf Coasts, University of Delaware, Dept. of Civil Engineering, 1977.
Dean, R.G., Coastal sediment processes: toward engineering solutions, in Coastal Sediments '87, edited by N.C. Kraus, pp. 1-24, ASCE, New Orleans, Louisiana, 1987.
Dean, R.G., and R.A. Dalrymple, Water wave mechanics for engineers and scientists, 353 pp., World Scientific, Singapore, 1991.
Deigaard, R., J. Fredsoe, and I.B. Hedegaard, Suspended sediment in the surf zone, Journal of Waterway, Port, Coastal and Ocean Engineering, 112 (1), 115-128, 1986.
Deigaard, R., and J. Fredsoe, Shear stress distribution in dissipative water waves, Coastal Engineering, 13 (4), 357-378, 1989.
Devantier, B.A., and R. Narayanaswamy, A Suspended Sediment Flow Model For High Solids Concentration Using Higher Order Turbulence Closure, Advances In Water Resources, 12 (1), 46-52, 1989.
Ding, P.X., F.Y. Shi, and Y.Z. Kong, A three-dimensional diffusion equation of suspended sediment by waves and currents, Chinese Science Bulletin, 44 (19), 1814-1817, 1999.
Based on the law of mass conservation, a general three- dimensional diffusion equation of suspended sediment due to waves and currents, adaptable to estuarial and coastal areas, is derived by decomposing the instantaneous velocities and concentrations into three-different-time-scale components respectively. A three-dimensional suspended sediment diffusion equation adaptable to actual calculations is available as the result of the parameterizations of turbulent diffusion term and wave diffusion term. Different from the former diffusion equations, the influence of waves and currents on suspended sediment diffusion can be simultaneously reflected in the newly derived equation.
Doering, J.C., and A.J. Bowen, Wave induced flow and nearshore suspended sediment, in 21st Coastal Engineering Conference, edited by B.L. Edge, pp. 1452-1463, ASCE, Costa del Sol-Malaga, Spain, 1988.
Dunkerley, D., and K. Brown, Flow behaviour, suspended sediment transport and transmission losses in a small (sub-bank-full) flow event in an Australian desert stream, Hydrological Processes, 13 (11), 1577-1588, 1999.
The behaviour of a discrete sub-bank-full flow event in a small desert stream in western NSW, Australia, is analysed from direct observation and sediment sampling during the flow event and from later channel surveys. The flow event, the result of an isolated afternoon thunderstorm, had a peak discharge of 9 m(3)/s at an upstream station. Transmission loss totally consumed the flow over the following 7.6 km. Suspended sediment concentration was highest at the flow front (not the discharge peak) and declined linearly with the log of time since passage of the flow front, regardless of discharge variation. The transmission loss responsible for the waning and eventual cessation of Row occurred at a mean rate of 13.2% per km. This is quite rapid, and is more than twice the corresponding figure for bank-full flows estimated by Dunkerley (1992) on the same stream system. It is proposed that transmission losses in ephemeral streams of the kind studied may be minimized in flows near bank-full stage, and be higher in both sub-bank-full and overbank flows. Factors contributing to enhanced Row loss in the sub-bank-full flow studied included abstractions of Row to pools, scour holes and other low points along the channel, and overflow abstractions into channel filaments that did not rejoin the main flow. On the other hand, losses were curtailed by the shallow depth of banks wetted and by extensive mud drapes that were set down over sand bars and other porous channel materials during the how. Thus, in contrast with the relatively regular pattern of transmission loss inferred from large floods, losses from low flows exhibit marked spatial variability and depend to a considerable extent on streamwise variations in channel geometry, in addition to the depth and porosity of channel perimeter sediments. Copyright (C) 1999 John Wiley & Sons, Ltd.
Dyer, K.R., M.C. Christie, N. Feates, M.J. Fennessy, M. Pejrup, and W. van der Lee, An investigation into processes influencing the morphodynamics of an intertidal mudflat, the Dollard estuary, the Netherlands: I. Hydrodynamics and suspended sediment, Estuarine Coastal and Shelf Science, 50 (5), 607-625, 2000.
As part of an interdisciplinary experiment, a series of measurements have been obtained on the mudflats of the Dollard Estuary, the Netherlands. The aim was to investigate the sediment transport and accumulation processes occurring during the covering and uncovering of the mudflats, particularly as the area was known to be ebb current dominant. Current velocity measurements confirmed the ebb dominance, and suspended matter concentrations measured over several tidal cycles in calm weather revealed that the highest concentrations occurred at the beginning of the flood and the end of the ebb. The resulting sediment flux, however, was flood dominant. During windy weather the balance of flux changed to ebb dominance. Measurements of flee size and settling velocity show a major organic component produced by entrainment of a thin surface layer during the early flood tide. During a windy period settling velocities in the adjacent channel together with the concentration variations showed a phase lag with water depth and velocity. The highest settling velocities occurred at about slack water, and there were residual ebb fluxes of suspended sediment. It is concluded that the ebb dominance of the currents is not apparent in the sediment fluxes during calm weather, but in periods of high winds the flux is likely to be ebb directed, except when diatom productivity is high. The overall response is similar to that of flood dominated mudflats. (C) 2000 Academic Press.
Eidsvik, K.J., and T. Utnes, A model for sediment re-entrainment and transport in shallow basin flows, Coastal Engineer, 15, 247-256, 1991.
Engelund, F., and J. Fredsoe, A sediment transport model for straight alluvial channels, Nordic Hydrology, 7, 293-306, 1976.
Fairchild, I.J., J.A. Killawee, B. Hubbard, and W. Dreybrodt, Interactions of calcareous suspended sediment with glacial meltwater: a field test of dissolution behaviour, Chemical Geology, 155 (3-4), 243-263, 1999.
Dissolution of calcite and associated interactions of suspended sediment with aqueous solution were investigated in a tributary-free 600 m reach of the main meltstream draining the Tsanfleuron glacier, Switzerland, over a 24-h cycle during which solute concentrations varied inversely with discharge. Downflow, solute calcium, strontium, and alkalinity increased because of calcite dissolution. Using flow-through times from salt-dilution gauging, a consistent small sulphate excess at the downstream site was observed. Given the slowness of sulphate supply by pyrite oxidation, this excess sulphate can be attributed to mixing of around 1% of ion-rich water (seeping from till banks) with the main meltstream. Calcite dissolution is normally directly proportional to exposed surface area of the mineral, yet only a small increase in calcite dissolution was observed when suspended sediment increased by a factor of 25 to 1.3 g/l at peak flow. The suspended sediment displays little variation in size distribution with total suspended load, and contains 30-40% calcite with a minimum specific surface area (S) of 0.25 m(2)/g sediment. Application of the Plummer-Wigley-Parkhurst (PWP) model predicts dissolution rates broadly similar to those found at lower suspended sediment concentrations given this value of S. At higher suspended sediment loads predicted dissolution rates are too high. This discrepancy is reduced by use of the Buhmann-Dreybrodt (B-D) model which takes explicit account of the slowness of hydration of aqueous carbon dioxide, and the problem of mass transfer of H2CO3 given the surface area of calcite to volume of solutions considered. The remaining discrepancy implies less interaction than expected of suspended sediment particles with turbulent meltwater at high suspended sediment concentrations. The effects of proglacial modification of meltstream geochemistry in this case is a strong decrease in PCO2 accompanied by an increase in total ion load, but decreases in Mg/Ca and Sr/Ca, from the high values characteristic of low water-rock ratio interactions in subglacial environments and till. Nevertheless, the distinctive chemical imprint in meltstream chemistry of non-congruent mineral dissolution in low water-rock ratio glacial weathering environments remain. In contrast, in terrains where calcite is scarce, it will tend to dissolve congruently, contributing significantly to total solutes, and its dissolution will be less limited by CO2 reaction kinetics. (C) 1999 Elsevier Science B.V. All rights reserved.
Fang, H.W., and G.Q. Wang, Three-dimensional mathematical model of suspended-sediment transport, Journal of Hydraulic Engineering-Asce, 126 (8), 578-592, 2000.
This paper presents the basic equations for a mathematical model of sediment-laden flow in a nonorthogonal curvilinear coordinate system. The equations were derived using a tensor analysis of two-phase flow and incorporate a natural variable- density turbulence model with nonequilibrium sediment transport. Correspondingly, a free-surface and the bottom sediment concentration are employed to provide the boundary conditions at the river surface and the riverbed. The finite analytic method is used to solve the equations of mass and momentum conservation and also the transport equation for suspended sediment. To demonstrate the method, the sediment deposition for the Three Gorges Project is considered. The mathematical model specifies the boundary conditions for the inlet and outlet using data from physical model experiments. The results for the mathematical model were tested against laboratory measurements from the physical model experiment. Good agreement and accuracy were obtained.
Foster, I.D.L., and J.A. Lees, Changes in the physical and geochemical properties of suspended sediment delivered to the headwaters of LOIS river basins over the last 100 years: a preliminary analysis of lake and reservoir bottom sediments, Hydrological Processes, 13 (7), 1067-1086, 1999.
Bottom sediments from a single core retrieved from nine lakes and/or reservoir sites have been analysed for particle size, loss on ignition and the total concentration of Ca, Mg, Na, K, Fe, Al, Mn and P. Site differences reflect the relative significance of autochthonous and allochthonous contributions to the sedimentary record and are related to changes in sedimentation rate through time as determined from a Pb-210 and Cs-137 chronology determined for each core. Whilst changing sedimentation rates reflect both sediment influx from the contributing catchment and focusing within the lake basin, the patterns generally reveal changes associated with catchment disturbance over the last century. Calcium-rich sediments are found in two lakes draining catchments underlain by Oolitic limestones. Organic matter contents, as determined by low temperature loss on ignition, range from 13 to 25%. High organic matter levels are found in bottom sediments either where the contributing catchment has extensive blanket peat accumulations or in lakes with low sediment accumulation rates, where the organic matter content is more likely to be controlled by lake productivity. In general, organic matter content is inversely related to sedimentation rate and to sediment yield. Greatest down-core variations in sediment physical and geochemical signatures are found in lake sediment records where catchments have experienced significant increases in sediment influx from the catchment. The average sediment yield determined for each of the nine lake-catchments is inversely related to average organic matter and P content of the sediments, but an increase in sediment yield is associated with better sorting and a decrease in the proportion of coarse and medium silt sized particles. Six of the nine sites show evidence for significant increases in the total P load in their near-surface sediments, either resulting from higher than average sediment yields or as a result of significant increases in sediment-P concentrations. Copyright (C) 1999 John Wiley & Sons, Ltd.
Foster, I.D.L., and J.A. Lees, Changing headwater suspended sediment yields in the LOIS catchments over the last century: a paleolimnological approach, Hydrological Processes, 13 (7), 1137-1153, 1999.
This paper describes the methods used to reconstruct suspended sediment yields over the last century, based on Pb-210 and Cs- 137 dated bottom sediments in nine lake and/or reservoir catchments. Magnetic susceptibility and dry bulk density are used to correlate between multiple cores taken from each lake/reservoir basin in order to estimate sediment influx through time and reconstruct sediment yield histories. The catchments represent a range of morphological and land use systems, including upland moorland, upland forestry and upland and lowland agricultural systems. The reconstruction provides some background information on pre-20th century sediment yields and permits an evaluation of the effect of 20th century land management systems, especially upland afforestation and agriculture, on changing suspended sediment yields. Reconstructed sediment yields over the last century range from c. 7 to 86 t km(-2) yr(-1). Average post-1953 yields from pasture, arable, moor land and forested catchments are 13, 31, 29 and 13 t km(-2) yr(-1), respectively. The history of human disturbance in individual catchments is clearly recorded in the reconstructed sediment yields. Short-lived disturbance, such as afforestation, produces high yields (over 40 t km(-2) yr(-1)) for up to a decade after planting, but yields subsequently decline to pre-planting levels (c. 12 t km(-2) yr(-1)). Sustained increases in sediment yield are associated with arable, mixed agricultural and, to a lesser extent, grazing systems. While the strong controls exerted on sediment yield by human disturbance mask the potential effect of regional contrasts in runoff and topography between catchments, there is some evidence to suggest that a long-term climate change signal is recorded in the temporal trends in sediment yield from an analysis of Lamb weather types. Copyright (C) 1999 John Wiley & Sons, Ltd.
Fredsoe, J., Turbulent boundary layer in wave-current motion, Journal of Hydraulic Engineering, 110 (61), 1103-1120, 1984.
Fredsoe, J., O.H. Anderson, and S. Silberg, Distribution of suspended sediment in large waves, Journal of Waterway, Port, Coastal and Ocean Engineering, 111, 1041-1059, 1985.
Fredsoe, J., and R. Deigaard, Mechanics of Coastal Sediment Transport, 369 pp., World Scientific, Singapore, 1992.
Galappatti, G., and C.B. Vreugdenhil, A depth-integrated model for suspended sediment transport, Journal of Hydraulic Research, 23 (4), 359-377, 1985.
Garcia-Martinez, R., N. Saavedra, B.F. De Power, E. Valera, and C. Villoria, A two-dimensional computational model to simulate suspended sediment transport and bed changes, Journal of Hydraulic Research, 37 (3), 327-344, 1999.
This article presents a two-dimensional finite element mathematical model to simulate suspended sediment transport in coastal regions. Sediment transport is formulated in terms of a hydrodynamic model plus a convection-diffusion equation with source and sink terms representing the erosion and deposition processes. Test problems treating the evolution of a hypothetical dredged trench in a channel, perpendicular to the main flow direction, are used to evaluate the sensitivity of the model to empirical parameters. The model was calibrated, validated and later applied to predict the circulation patterns and bottom bed evolution in Puerto Miranda oil terminal, located in the Maracaibo Strait, Venezuela. Results show that the model is able to predict the bed evolution of the dredged access channels to the terminal. Notwithstanding the complexity of the sediment transport phenomena that occur in dredged trenches, the relatively simple model proposed herein is capable of giving useful results in practical problems.
Gerritsen, H., R.J. Vos, T. van der Kaaij, A. Lane, and J.G. Boon, Suspended sediment modelling in a shelf sea (North Sea), Coastal Engineering, 41 (1-3), 317-352, 2000.
This paper extends the modelling of suspended particulate matter (SPM) on the local coastal scale (described in preceding papers) to SPM modelling on the scale of the North Sea, focusing on representing SPM patterns and their seasonal distribution. The modelling includes a sensitivity study, in which model results are assessed using surface SPM concentration patterns extracted from NOAA reflectance imagery, as well as North Sea Project in situ data. Over the past decade or so, first-order estimates of the net suspended load and its associated sources and sinks have been available and are generally substantiated. However, developments in the simulation of large-scale SPM behaviour are still severely restricted by the available descriptions of available sediment sources and sediment erosion and deposition processes. This paper indicates how remotely sensed reflectance images can provide additional information on the spatial distribution of (sea surface) suspended sediments. A primary objective of this paper is to examine sensitivities of SPM simulations in 2D (vertically averaged) and 3D models. A boundary-fitted coordinate modelling approach with intra-tidal resolution and synoptic meteorology is applied, as well as more schematic approaches. A related objective is to examine how both limited in situ observational data and reflectance imagery can be used to assess and improve such simulations. An integrated modelling-monitoring approach, using inverse and 'Goodness-of- Fit' (GoF) approaches applied to remotely sensed reflectance imagery, is used to derive a structured sensitivity analysis providing a quantified assessment of the strengths and weaknesses of modelling and input data. It is shown that, especially in the coastal zone where salinity stratification may occur, 3D modelling is required while much of the sensitivity analysis can be based on a 2D modelling approach. This quantification of the effects of uncertainties of inputs and erosion/deposition parameters improves understanding of the sediment distribution and budgets on the North Sea scale. It is concluded that whilst process studies are likely to contribute to improving erosion/deposition algorithms, and model developments will provide enhanced dynamical descriptions, accurate overall simulation will remain dependent on some (inverse) processes to reduce the uncertainty in sediment sources. (C) 2000 Elsevier Science B.V. All rights reserved.
Gilmour, J., Experimental investigation into the effects of suspended sediment on fertilisation, larval survival and settlement in a scleractinian coral, Marine Biology, 135 (3), 451-462, 1999.
Laboratory and field experiments were used to determine whether high (similar or equal to 100 mg l(-1)), low (similar or equal to 50 mg l(-1)) and control (similar or equal to 0 mg l(-1)) levels of suspended sediment affected fertilisation, larval survival, and larval settlement in the scleractinian coral Acropora digitifera (Dana, 1846). Both high- and low-sediment treatments significantly decreased fertilisation, but post- fertilisation embryonic development was not inhibited by suspended sediments. Larval survival and larval settlement were significantly reduced in high- and low-sediment treatments. No difference was found between high- and low-sediment treatments in any of the three post-spawning processes investigated, suggesting that they are susceptible to sediment concentrations which are not exceptionally high even under natural conditions (>50 mg l(-1)). The introduction of an additional stress in the form of high levels of suspended sediments coupled with naturally high variability in recruitment may have a considerable effect on the successful supply and settlement of coral larvae to a reef. Given that many coral communities are open reproductive systems, the consequences of disturbance events are not likely to be restricted to the impact area. Recruitment to a population may be reduced significantly in the presence of high levels of suspended sediments because of effects on larval survival and settlement. Recruitment of larvae to adjacent populations may also be affected due to a decreased fertilisation success and potential increases in mortality of larvae passing through the affected site.
Glenn, S.M., and W.D. Grant, A suspended sediment stratification correction for combined wave and current flows, Journal of Geophysical Research, 92 (C8), 8244-8264, 1987.
Golz, E., Suspended Sediment And Bed Load Problems Of The Upper Rhine, Catena, 17 (2), 127-140, 1990.
Grant, W.D., and O.S. Madsen, Combined wave and current interaction with a rough bottom, Journal of Geophysical Research, 84, 1979-1808, 1979.
Green, M.O., and K.P. Black, Suspended-sediment reference concentration under waves: field observations and critical analysis of two predictive models, Coastal Engineering, 38 (3), 115-141, 1999.
Two commonly adopted but fundamentally different approaches for predicting time-averaged suspended-sediment reference concentration ((C) over bar(REF)) under waves are tested against field measurements and compared with each other. The first model relates (C) over bar(REF) to the cube of the non- dimensional skin friction, whereas the second model adopts a more complex function of excess skin friction incorporating the empirical constant gamma(0). The dataset is from the zone of wave shoaling seaward of an open-coast surfzone and includes measurements of waves, currents, suspended sediment and bedforms. Estimates of (C) over bar(REF) are derived from acoustic backscatter data, and the seabed and suspension process are described from video footage. When waves were energetic, the bed was deformed into large hummocks; during less energetic conditions, the bed was rippled. The time- averaged concentration profiles over the ripples were consistent with settling flux balanced by pure gradient diffusion and a sediment diffusivity that is constant with elevation above the bed. (C) over bar(REF) in that case is shown to apply at z = 0, where z is the elevation above the bed. Over the hummocks, there was a sheet flow at the base of the suspension and (C) over bar(REF) is shown to apply at z = 1 cm. The concentration profiles over the hummocks implied sediment diffusivity that varied linearly with elevation within similar to 10 cm of the bed and constant sediment diffusivity above that level. For both rippled and hummocky beds, gamma(0) derived from the field data was found to be sensitive to the value assumed for critical stress for initiation of sediment motion, which could explain the range of values reported in the literature for gamma(0). gamma(0) was also found to vary in a complex way with skin friction, which suggests that the reference-concentration model based on excess skin friction is not correctly formulated. Nevertheless, two functions for gamma(0) (one applying to rippled beds and the other to hummocky beds) were contrived to make the model fit the data. The model based on non-dimensional skin friction was found to be a good predictor of (C) over bar(REF) when a correction was made for flow contraction over ripples. The correction was not required for the hummocky bed, where sediment was being entrained in a thin sheet flow layer. The model based on non- dimensional skin friction correctly portrayed the relationship between flow and sediment response without contrivance and therefore should be the favoured approach in predicting reference concentration. (C) 1999 Elsevier Science B.V. All rights reserved.
Green, T.R., S.G. Beavis, C.R. Dietrich, and A.J. Jakeman, Relating stream-bank erosion to in-stream transport of suspended sediment, Hydrological Processes, 13 (5), 777-787, 1999.
We seek an improved and quantitative understanding of the sources and transport of sediment and attached phosphorus in upland catchments and downstream reaches of the Namoi River in New South Wales, Australia. Study of the sources of phosphorus and related sediment was motivated by severe problems with blooms of blue-green algae and toxic by-products in the Darling and Namoi Rivers. Using atmospheric fall-out of radionuclides as tracers, Olley et al. (1996) concluded that much of the sediment deposited in the lower reaches came from subsoil rather than topsoil. With this insight, we focus on quantifying sediment sources from stream bank erosion, especially in seasonally erosional reaches of Cox's Creek and the Mooki River. The approach presented here integrates interdecadal aerial photography, interseasonal field measurements of bank erosion processes, continuous monitoring of stream flow and turbidity and event sampling of suspended solids and phosphorus, with an analytical model of in-stream suspended sediment transport. We compare a lateral source term in the calibrated transport model with field-based and aerial measurements of stream bank erosion. Calibration of the in- stream model is illustrated for two reaches of the Mooki River, with the changes in parameter values being related to aspects of the hydraulic geometry and particle size. The processes of stream flow and bank erosion due to undercutting, desiccation, block failure and mass wasting of aggregated particles interact to produce instream fluxes of suspended sediment that are transported and redeposited downstream. The combined approach demonstrated here has potential for predictive spatial modelling of sediment concentrations and loads. Copyright (C) 1999 John Wiley & Sons, Ltd.
Greer, T., K. Bidin, and I. Douglas, A spreadsheet (Lotus 1-2-3) based technique for analysing storm suspended sediment data with particular reference to logging disturbance in tropical forests, Earth Surface Processes and Landforms, 23 (13), 1235-1246, 1998.
The procedure describes a simple and functional method using a commercial spreadsheet (Lotus 1-2-3) to calculate water and sediment yields from measured or given data sets. Suspended sediment concentrations are located on a storm hydrograph and concentrations for unsampled points on the hydrograph are estimated using the principle that the change in concentration between two sampled points will be proportional to the change in discharge between the same two points. The relationships are then solved by a cross-correlation equation using simple formulae in the form of triangle-square equations to calculate water and sediment yields between each sample time. The technique is applied to a 51 month data set from a long-term monitoring programme assessing the impacts of commercial logging operations in Sabah, East Malaysia. Yields for the monitoring period derived by the spreadsheet technique are compared with results from the application of more traditional discharge-sediment rating techniques. In the undisturbed catchment, yields derived from some rating equations compare favourably with the spreadsheet technique. However, in the disturbed catchment, rating techniques proved less applicable because of the continuously changing nature of the catchment in relation to vegetation recovery, exacerbating variation and scatter in the data set. The application of the spreadsheet technique provides detailed information at an individual storm level; however, working with the method on long-term discharge records requires a significant commitment of time as compared to the straightforward application of rating equations. (C) 1998 John Wiley Bi Sons, Ltd.
Greimann, B.P., M. Muste, and F.M. Holly, Two-phase formulation of suspended sediment transport, Journal of Hydraulic Research, 37 (4), 479-500, 1999.
Using a two-phase formulation, the vertical and horizontal momentum equations for sediment are used to obtain the concentration and velocity profiles of a dilute suspension of particles in a 2D uniform flow. Assuming the form of the vertical turbulent intensities and dilute concentrations of sediment, one can solve the equations analytically and compare them with experimental data. No empirical coefficients in the model are tuned to match individual experiments, for which the experimental data cover a large range of particle sizes and densities. The models are shown to accurately predict two experimentally observed but theoretically unexplained phenomena: the increased diffusive flux of large particles, and the measurable velocity lag of particles. The increased diffusion of large particles is shown to originate from the added diffusive nature of the sediment's Reynolds stresses. The horizontal velocity lag of particles is due to an induced velocity, termed the drift velocity, resulting from the correlation of particle concentration with areas of low horizontal velocity fluid.
Gross, T.F., and W.B. Dade, Suspended Sediment Storm Modeling, Marine Geology, 99 (3-4), 343-360, 1991.
Guillen, J., A. Palanques, P. Puig, X.D. De Madron, and F. Nyffeler, Field calibration of optical sensors for measuring suspended sediment concentration in the western Mediterranean, Scientia Marina, 64 (4), 427-435, 2000.
The water turbidity measured with optical methods (transmittance and backscattering) is usually expressed as beam attenuation coefficient (BAC) or formazin turbidity units (FTU). The transformation of these units to volumetric suspended sediment concentration (SSC) units is not straightforward, and accurate calibrations are required in order to obtain valuable information on suspended sediment distributions and fluxes. In this paper, data from field calibrations between BAG, FTU and SSC are presented and "best- fit" calibration curves are shown. These calibrations represent an "average" from different marine environments of the western Mediterranean (from estuary to continental slope). However, the general curves can only be applied fur descriptive or semi- quantitative purposes. Comparison of turbidity measurements using the same sensor with different calibration ranges shows the advantage of simultaneously combining two instruments calibrated in different ranges when significant changes in suspended sediment concentrations are expected.
Guza, R.T., and E.B. Thornton, Velocity moments in nearshore, Journal of Waterways, Port, Coastal and Ocean Engineering, 111 (2), 235-256, 1985.
Hagatun, K., and K.J. Eidsvik, Oscillating turbulent boundary layers with suspended sediment, Journal of Geophysical Research, 91 (C11), 13045-13055, 1986.
Hamblin, P.F., D.Z. Zhu, F. Chiocchio, C. He, and M.N. Charlton, Monitoring suspended sediment plumes by optical and acoustical methods with application to sand capping, Canadian Journal of Civil Engineering, 27 (1), 125-137, 2000.
There is a need to rapidly survey plumes of suspended sediment and to determine the quantity and transport of disturbed material that might arise from industrial and remedial activities in lakes and harbours. The example of sand capping of contaminated bottom sediments is used to illustrate the methodology. Capping of contaminated bottom sediments is one strategy for immobilizing contaminants. In a pilot-scale project, a 0.34 m thick cap of clean sand was deposited over a one hectare area in Hamilton Harbour. The objective of this study was to determine if in-place sediments could be disturbed by the capping operation. In the first of three approaches, the suspended sediment plumes created during the capping operation were monitored for evidence of suspension of bottom materials with underwater acoustic and optical profilers and other moored instruments. In-lake calibration of the instrumentation was based on the collection of over 300 grab samples. Three- dimensional rendering of a dense network of acoustic backscatter profiles revealed that there was no evidence that bottom sediment was resuspended. The density current flowing downslope close to the bottom caused by the capping material was examined and found too weak to erode bottom sediments. Finally, a quantitative estimation of the amount of sediment suspended in the plumes indicated little evidence for resuspension of in-place sediments. The methodology developed could also be applied to estimate the concentration and quantities of contaminants in sediments suspended by other remedial activities such as dredging.
Hardy, R.J., P.D. Bates, and M.G. Anderson, Modelling suspended sediment deposition on a fluvial floodplain using a two-dimensional dynamic finite element model, Journal of Hydrology, 229 (3-4), 202-218, 2000.
In this paper we outline a new numerical model for predicting floodplain sediment deposition resulting from out-of-bank flow in reach-scale natural compound channels. Simulation of this problem requires models capable of dealing with the hydraulic and sediment transport effects of a dynamically moving inundation front. as well as a complex set of flow processes including momentum exchange between main channel and floodplain, spillage of water across meander loops and the impact of complex topography. Whilst the treatment of dynamic moving boundary problems is difficult, but attainable in finite element hydraulic codes, the necessity to include dry areas within the model generates a number of problems that numerical solvers for fluvial sediment transport have, to date, failed to overcome. Accordingly, we develop a two-dimensional finite element approach that specifically accounts for sediment transport in domains undergoing wetting and drying. The hypothesis that at the reach-scale a two-dimensional depth averaged representation of flow and suspended sediment is able to reproduce observed deposition patterns is then tested against average annual rates determined using (137)caesium analysis of floodplain sediments. Using reasonable parameterisation and no calibration of the sediment transport component, the developed model is able to replicate an encouraging amount of the observed spatial variability in this data set. Whilst further testing of both the hydraulic and sediment transport components of the model is undoubtedly required, the results provide an initial assessment of reach scale process dominance for floodplain systems. (C) 2000 Elsevier Science B.V. All rights reserved.
Hasnain, S.I., and R.J. Thayyen, Discharge and suspended-sediment concentration of meltwaters, draining from the Dokriani glacier, Garhwal Himalaya, India, Journal of Hydrology, 218 (3-4), 191-198, 1999.
Discharge and suspended-sediment concentration in the proglacial river draining the debris-covered summer- accumulation type Dokriani glacier, Ganga river basin, India, was measured between May and October 1994. In the meltwater streams of the Ganga headwater, the pattern of sediment transport is strongly influenced by the monsoonal precipitation between July and mid-September. During this observation period a total discharge volume of 6238 x 10(4) m(3) and 15 x 10(4) tonnes of suspended-sediment was delivered from the catchment. The monsoonal months of July and August accounted for 64% of the discharge, 70% of suspended-sediment transport and 74% of the monsoonal rainfall. The focus of the present study is to estimate the contribution of glaciers in the monsoon-dominated central part of the Himalaya to sediment transport in the Himalayan rivers. (C) 1999 Elsevier Science B.V. All rights reserved.
Hattori, M., The mechanics of suspended sedimentdue to standing waves, Coastal Engineering in Japan, 12, 69-81, 1969.
Hattori, M., Delay distance in suspended sediment transport, Coastal Engineering Conference, 63, 1086-1095, 1974.
Hay, A.E., and A.J. Bowen, Spatially correlated depth changes in the nearshore zone during autumn storms, Journal of Geophysical Research, 98 (C7), 12,387-12,404, 1993.
He, Q., C.X. Yun, and W.R. Shi, Remote sensing analysis of surface suspended sediment concentration in the Changjiang Estuary, Progress in Natural Science, 9 (6), 440-446, 1999.
Key problem for studying river bed evolution of the Changjiang Estuary is the mechanism of sediment transport. This paper, based on an analysis of remotely sensed data, presents the principles of spatial distribution and variation of surface suspended sediment concentration in the Changjiang Estuary, as well as their relation to the vertical distribution of sediment concentration, which provides a scientific basis for the regulation of deepwater navigation channel in the Changjiang Estuary.
Hicks, D.M., B. Gomez, and N.A. Trustrum, Erosion thresholds and suspended sediment yields, Waipaoa River Basin, New Zealand, Water Resources Research, 36 (4), 1129-1142, 2000.
Characteristics of the suspended sediment load in the Waipaoa River, New Zealand, and in two of its tributaries (Mangatu and Te Arai Rivers) are examined for evidence of different dominant erosion processes in the basins upstream. Different shapes of the suspended sediment concentration-water discharge relations lead to differences in long-term average yield, event-yield magnitude-frequency relations, and relative importance of large flows and rare events. In the Mangatu River, frequent runoff events are relatively more important to the long-term yield (11,540 t km(-2) yr(-1)), half of the longterm average load is transported by events with return periods less than similar to 1 year, and there is little evidence of an erosion threshold limitation on sediment supply. This is consistent with the predominance in the Mangatu basin of hillslope erosion processes that involve scour by surface and channelized runoff, particularly gully erosion. This contrasts with the Te Arai River where sediment concentration tends to be much lower at low and moderate flows, frequent runoff events transport less of the long-term yield (4600 t km(-2) yr(-1)) than do rarer, large-magnitude flood events, event sediment yields are an order of magnitude lower during events with subannual return periods, and half of the long-term average load is transported during events with a return period of >2 years. Some of these characteristics appear to result in part from two populations of runoff events in the Te Arai basin; nonetheless, they are consistent with field evidence that most of the sediment supplied to the Te Arai stream network is generated by shallow landslides which are activated once a rainfall threshold is exceeded.
Hill, P.S., T.G. Milligan, and W.R. Geyer, Controls on effective settling velocity of suspended sediment in the Eel River flood plume, Continental Shelf Research, 20 (16), 2095-2111, 2000.
Bulk effective settling velocities required to explain sinking losses from the Eel River flood plume off the coast of northern California are of order 0.1 mm s(-1) for five different helicopter-based sampling surveys conducted in January and February 1998. These effective settling velocities exceed those expected for single-grain sinking and implicate flocculation as an important mechanism for speeding the removal of sediment from the Eel River plume. The relative constancy of effective settling velocities despite widely varying winds, waves, and currents is consistent with photographs in the plume that show little variability in flee size with total suspended sediment mass concentration, turbulent-kinetic-energy dissipation rate, elapsed time since sediment within flocs left the river mouth, or depth. These observations of floc size contrast with those made in winter 1997 during the exceptionally large New Year's flood. During that event, increases of flee size with depth are evident. In 1997, higher sediment concentrations associated with the significantly larger discharge likely allowed flocs to grow substantially as they sank through the plume, whereas in 1998 low concentrations precluded significant increases in flee size with depth. These observations do not support the hypothesis that concentration controls maximal flee size; rather they indicate that the growth rate of flocs is a function of concentration. Using a published relationship between flee size and settling velocity for the Eel shelf suggests that approximately three fourths of the sediment in the plume was packaged as flocs during the 1998 floods. (C) 2000 Elsevier Science Ltd. All rights reserved.
Hillier, S., Particulate composition and origin of suspended sediment in the R. Don, Aberdeenshire, UK, Science of the Total Environment, 265 (1-3), 281-293, 2001.
Characterising the nature and origin of suspended particulate and colloidal matter in surface waters is a necessary first step in determining the role of these materials in the transport of pollutants. With this aim in mind, samples of suspended sediment were collected from the R. Don, Scotland, and analysed by a combination of X-ray diffraction (XRD) and vertically attenuated infrared spectroscopy (VATIR). Additionally, the carbon and nitrogen contents of the sediment were measured. Samples were collected at eight sites along the river from the headwaters to the mouth, twice during periods of base flow, and once during a storm. During the base flows, the amount of suspended solids was typically no more than 1-10 mg l(-1), whereas the high flow samples contained up to 150 mg l(- 1). XRD showed that the crystalline component of the high flow samples consisted of the clay minerals illite, chlorite, kaolin, hydroxy-interlayered vermiculite, and a 10/14 Angstrom regularly interstratified mica/vermiculite. Non-clay components included quartz, feldspars, amphibole and goethite. Kaolin progressively increased in relative abundance downstream. The clay mineralogy of base flow samples was more or less identical to high flow samples but the non-clay components were reduced and, additionally, talc and calcite were present. The identification of many of the crystalline components was confirmed by VATIR, and amorphous silica was identified, particularly in base flow samples. Organic components were identified as wax, protein, and humate/fulvate. Proportionally more protein and wax components relative to silicates occurred in base flow samples, whereas the humate/fulvate component was most clearly identified in samples from the storm. Organic matter contents ranged from approximately 24% during base flow to 13% during the storm, whilst the C/N ratio showed a progressive decrease downstream, irrespective of flow conditions. Both the characteristics of the mineralogy and the organic matter suggested that topsoils were the primary source of the suspended sediment in the R. Don. However, the presence of talc and calcite were believed to fingerprint ground water sources, which together with the in-stream production of diatoms, may have accounted for a significant mass fraction of the suspended particulate matter during base flows. (C) 2001 Elsevier Science B.V. All rights reserved.
Hinch, E.J., An averaged equation approach to particle interactions in a fluid suspension, JFM, 83 (4), 695-720, ?
Hodgkins, R., Controls on suspended-sediment transfer at a high-Arctic glacier, determined from statistical modelling, Earth Surface Processes and Landforms, 24 (1), 1-21, 1999.
Simple linear regression models have been widely employed in the analysis of suspended-sediment concentration (SSC) time series from glacierized catchments, although they have many limitations. This paper builds regression models which address these shortcomings and permit inferences concerning the controls on suspended-sediment transfer from a glacier at 78 degrees N in the Svalvard archipelago. A bivariate regression model, deterministically predicting SSC from discharge alone, explained less than 15 per cent of the variance in SSC. A multivariate model, incorporating additional potentially explanatory variables, offered little improvement. Diurnal hysteresis in the data gives rise to quasi-autocorrelation in the residual series from regression models. This was effectively removed by incorporating dummy diurnal variables into the multivariate model. The presence of a first-order autoregressive, stochastic process gives rise to true autocorrelation in the residual series from regression models. This was accommodated by incorporating an ARIMA (1,0,0) term into a multivariate autoregression model. The model-building process yielded a systematic progression in the explanation of variance in SSC, stripping away pattern in the autocorrelation function of the residual series; mean model error was reduced from 54 per cent to 6 per cent. The dependence of SSC on the magnitude of discharge is weak and highly variable, whereas the dependence of current SSC on recent values of SSC, revealed through the stochastic term, is an order of magnitude greater and relatively constant during the melt season. The dominant control on SSC throughout the melt season is therefore short- term sediment availability. The simple and largely unchanging stochastic process generally responsible for generating the observed SSC series implies a simple and unchanging glacier drainage system. Copyright (C) 1999 John Wiley & Sons, Ltd.
Hodson, A.J., and R.I. Ferguson, Fluvial suspended sediment transport from cold and warm-based glaciers in Svalbard, Earth Surface Processes and Landforms, 24 (11), 957-974, 1999.
An analysis of temporal variability in proglacial suspended sediment concentration is undertaken using time series data collected from three Svalbard basins which include one largely cold-based glacier (Austre Broggerbreen), one largely warm- based glacier (Finsterwalderbreen) and one intermediate polythermal glacier (Erdmannbreen). The temporal variability in proglacial suspended sediment concentration is analysed using multiple regression techniques in which discharge is supplemented by other predictors acting as surrogates for variability in sediment supply at diurnal, medium-term and- seasonal timescales. These multiple regression models improve upon the statistical explanation of suspended sediment concentration produced by simple sediment rating curves but need to account for additional stochastic elements within the time series before they may be considered successful. An interpretation of the physical processes which are responsible for the regression model characteristics-is offered as a basis for comparing the different arctic glaciofluvial suspended sediment transport systems with that of their better known temperate glaciofluvial counterparts. It is inferred that the largely warm-based glacier is dominated by sediment supply from subglacial reservoirs which evolve in a similar manner to temperate glaciers and which cause a pronounced seasonal exhaustion of suspended sediment supply. The largely cold-based glacier, however, is dominated by sediment supply from marginal sources which generate a responsive system at short time scales but no significant seasonal pattern. The intermediate polythermal glacier basin, which was anticipated to be similar to the warm-based glacier, instead shows a highly significant seasonal increase in suspended sediment supply from an unusual subglacial reservoir emerging under pressure in the glacier foreland; The temperate model of glaciofluvial suspended sediment transport is therefore found to be of limited use in an arctic context. Copyright (C) 1999 John Wiley & Sons, Ltd.
Holdaway, G.P., P.D. Thorne, D. Flatt, S.E. Jones, and D. Prandle, Comparison between ADCP and transmissometer measurements of suspended sediment concentration, Continental Shelf Research, 19 (3), 421-441, 1999.
For more than a decade, acoustic Doppler current profilers, ADCPs, have been in common use measuring current profiles. It has been recognised over this period that the backscattered ADCP signal could be used to not only evaluate the Doppler shift, but also offered the possibility to extract information on the scatterers. The present work reports on an analysis of opportunistic backscatter measurements collected using a 1 MHz ADCP system, to assess the potential of ADCPs to measure suspended sediment concentration quantitatively, The data were gathered during a water monitoring campaign which deployed ADCPs, near-bed and profiling transmissometers, and in situ bottle samplers. Although the original study was not specifically designed to test the capability of ADCPs to evaluate suspended sediment concentration, sufficient data were collected to examine the use of ADCPs for such measurements. The backscattered amplitude from one ADCP beam was recorded for quality control to assess the accuracy of velocity measurements. However, in this study these data have :also been used to examine the potential of ADCPs for suspended sediment measurements. To investigate ADCPs in this role, the backscattered signals from one range cell has been calibrated against in situ bottle samples of the suspended material. Using this calibration, the backscattered signals have been inverted to give time series profiles of suspended particulate matter. To assess these profiles, comparisons have been made with in- situ calibrated profiling and moored transmissometers. The outcome from the present study shows ADCP results which are comparable with the transmissometer observations, and clearly demonstrate the potential of ADCPs for directly measuring suspended sediment profiles. (C) 1999 Elsevier Science Ltd. All rights reserved.
Hom-ma, M., K. Horikawa, and R. Kajima, A study of suspended sediment due to wave action, Coastal Engineering in Japan, 8, 1965.
Horikawa, K., and A. Watanabe, Turbulence and sediment concentration due to waves, Coastal Engineering in Japan, 13, 1970.
Horikawa, K., S. Hotta, and N.C. Kraus, Literature review of sand transport by wind on a dry sand surface, Coastal Engineer, 9, 503-526, 1986.
Huang, X., and M.H. Garcia, Pollution of gravel spawning grounds by deposition of suspended sediment, Journal of Environmental Engineering-Asce, 126 (10), 963-967, 2000.
Observations have shown that accumulation of fine sediment in the pores of spawning open-work gravel have a detrimental effect on stream biota. The rate of deposition is intimately linked to the concentration of suspended fines near the gravel bed. If interstitial voids in coarse sediment deposits are filled or covered with sand or inorganic fine materials, their habitat value is greatly reduced. In this paper, a simple method is proposed to predict analytically the concentration profile and transport of fine suspended sediment when a steady, uniform suspension flows from a sediment-covered bed to an open-work gravel bed. Comparisons of the analytical model predictions with previous laboratory observations show reasonable agreement. The proposed solution can be used to estimate "clarification distances" for streams carrying fine sediments over open-work gravel beds.
Humiston, R.T., Cross-shore sediment transport on a naturally barred beach, M.S. thesis, Naval Postgraduate School, 1993.
Hunt, J.N., The turbulent transport of suspended sediment in open channels, Royal Society of London, 224, 322-335, 1954.
Hwang, P.A., Comment on ' On the motion of suspended sand particles', JGR, 90 (C2), 3253-3254, 1985.
Ingram, J.J., S.R. Abt, and E.V. Richardson, Sediment Discharge Computation Using Point-Sampled Suspended-Sediment Data, Journal Of Hydraulic Engineering-Asce, 117 (6), 758-773, 1991.
Johns, B., T.J. Chesher, and R.L. Soulsby, The Modelling Of Sandwave Evolution Resulting From Suspended And Bed Load Transport Of Sediment, Journal Of Hydraulic Research, 28 (3), 355-374, 1990.
Johnson, J.E., and R.T. Hines, Effect of suspended sediment on vulnerability of young razorback suckers to predation, Transactions of the American Fisheries Society, 128 (4), 648-655, 1999.
The decline of native fishes in North America is principally a result of altered habitats. and the impact of mainstream dams has accounted for many of the habitat changes. Diminished turbidity, and introduced nonnative predators were investigated as possible reasons for the decline of endangered razorback suckers Xyrauchen texanus in the Colorado River. In laboratory tests, young razorback suckers selected clear water over two water samples with higher concentrations of suspended sediment. In clear water, however, young razorback suckers were extremely susceptible to predation: native Colorado squawfish Ptychocheilus lucius consumed 90% of test razorback suckers, and nonnative green sunfish Lepomis cyanellus consumed 99.6%. As turbidity increased, razorback sucker predator avoidance improved and differences in predator success disappeared. Winter-spring spawning by razorback suckers in Lake Mohave, along with the extreme susceptibility of larvae to predation in clear water, may account for total recruitment failure in that lake. However, in upper basin rivers, suspended sediments remain high enough to limit predation by fishes tested, suggesting that other impacts, including contaminants and lack of floodplain habitat, may be thwarting recruitment in those rivers.
Jouanneau, J.M., C. Garcia, A. Oliveira, A. Rodrigues, J.A. Dias, and O. Weber, Dispersal and deposition of suspended sediment on the shelf off the Tagus and Sado estuaries, SW Portugal, Progress in Oceanography, 42 (1-4), 233-257, 1998.
The Portuguese margin in front of the Tagus and Sado rivers is characterized by a narrow shelf incised by numerous canyons and by a large mud deposit. The two estuaries that feed this continental margin have distinct impact. The suspended particulate matter concentration values in the mouth of the Tagus are four times higher than in the Sado. During the summer the surface nepheloid layer is always larger than during the winter when it is restricted near the mouth of the estuary. This nepheloid layer may reach 30 km in length extending westward. The bottom nepheloid layer usually shows higher nephelometer values, and has a typical distribution: it is usually diverted southward in the direction of the Lisbon Submarine Canyon. We estimate the amount of suspended matter being discharged annually from the Tagus estuary to be between 0.4 and 1 x 10(6) t. The area covered by fine deposits is about 560 km(2). Hence the thickness of sediments deposited annually should be between 0.07 and 0.18 cm. The sedimentation rates calculated from the Pb-210 excess vary between 0.16 and 2.13 cm y(-1) which correspond to the maximum rate. For a layer of 1 cm thick, 81,000 t of particulate organic carbon (POC) should be trapped. That would represent, with a minimum sedimentation rate between 0.07 and 0.18 cm y(-1), an entrapment of 6000- 15,000 t POC y(-1). The trace metals content of box core samples clearly shows the anthropogenic impact in the uppermost level (5 cm thick) in the Tagus estuary and in all the sedimentary deposits (15 cm thick) on the shelf muddy area. Despite the narrowness of the shelf, a significant part of continental fluxes fails to reach the deep ocean. (C) 1998 Elsevier Science Ltd. All rights reserved.
Katopodi, I., and J.S. Ribberink, Quasi-3D Modelling Of Suspended Sediment Transport By Currents And Waves, Coastal Engineering, 18 (1-2), 83-110, 1992.
Kennedy, J.F., and F.A. Locher, Sediment suspension by water waves, in Waves on Beaches, edited by R.E. Meyer, pp. 249-298, Academic Press, New York, 1972.
Kineke, G.C., and R.W. Sternberg, The Effect Of Particle Settling Velocity On Computed Suspended Sediment Concentration Profiles, Marine Geology, 90 (3), 159-174, 1989.
Knapp, R.T., Energy-balance in stream flows carrying suspended laod, Transactions, American Geophysical Union, 19, 501-505, 1938.
Komar, P.D., The longshore transport of sand on beaches, Ph.D. dissertation thesis, University of California, San Diego, 1969.
Kosyan, R.D., Vertical distribution of suspended sediment concentration seaward of the breaking zone, Coastal Engineer, 9, 171-187, ?
Kriebel, D.L., Beach and dune response to hurricanes, M.S. thesis thesis, University of Delaware, 1982.
Kriebel, D.L., and R.G. Dean, Numerical simulation of time-dependent beach and dune erosion, Coastal Engineering, 9 (3), 221-245, 1985.
Kriebel, D.L., Verification study of a dune erosion model, Shore and Beach, 54 (3), 13-21, 1986.
Lake, R.G., and S.G. Hinch, Acute effects of suspended sediment angularity on juvenile coho salmon (Oncorhynchus kisutch), Canadian Journal of Fisheries and Aquatic Sciences, 56 (5), 862-867, 1999.
To determine the roles of suspended sediment angularity and concentration as contributors to stress and mortality in salmonids, we exposed juvenile coho salmon (Oncorhynchus kisutch) to anthropogenically derived "extremely angular" and "round" silicate sediments over a range of concentrations in 96-h experiments. Stress responses (e.g., decreased leukocrit) were elicited by exposure to both sediment shapes when concentrations were >40 g.L-1, corresponding to the minimum concentration at which physical gill damage was observed. Extremely angular sediments also caused stress responses (e.g., elevated hematocrit, decreased leukocrit) at concentrations <41 g.L-1. However, we found no difference between sediment shapes in causing mortality at any sediment concentration. Further, mortalities were not observed until concentrations were about 100 g.L-1, a value that is about an order of magnitude greater than high natural concentrations in salmonid rivers. Natural fluvial suspended sediments cause fish stress and mortality at much lower concentrations than we found with our anthropogenically derived suspended sediments.
Larson, M., and N.C. Kraus, SBEACH: numerical model for simulating storm-induced beach change, U. S. Army Corps of Engineers, 1989.
Leigh, K.A., and R.V. Hyne, Inhibition of particle aggregation in fluvial suspended sediment by formaldehyde, Water Research, 33 (4), 1101-1107, 1999.
Freshwater fluvial suspended sediment particle size characteristics alter temporally when allowed to stand, undergoing continuous aggregation to form larger composite particles (aggregates or flocs) that can settle from the water column and are stable to hand shaking. Treatments to inhibit the spontaneous aggregation of laboratory prepared and fluvial suspended sediments were investigated. A novel method using formaldehyde to fix suspended sediment was developed, which inhibited aggregation of the suspended particles. The formaldehyde-treated particle suspensions formed fragile aggregates on settling, but they were redispersed by hand shaking. When assessed by particle size distribution, photography and turbidity measurements following resuspension, treatments with 2% (v/v) formaldehyde showed little alteration of the initial existing particles or aggregate composition and turbidity. The fixation of fluvial water samples with formaldehyde immediately after collection allowed the transportation and storage of the samples containing suspended sediment for laboratory analysis, weeks after collection. (C) 1999 Elsevier Science Ltd. All rights reserved.
Lemke, K.A., Transfer Function Models Of Suspended Sediment Concentration, Water Resources Research, 27 (3), 293-305, 1991.
Lenzi, M.A., and L. Marchi, Suspended sediment load during floods in a small stream of the Dolomites (northeastern Italy), Catena, 39 (4), 267-282, 2000.
Suspended sediment load was analyzed in a small, high-gradient stream of the Eastern Italian Alps which was instrumented to measure discharge and sediment transport. The ratio of suspended to total sediment yield and the relations between sediment concentration and water discharge were analyzed for seven floods which occurred from 1991 to 1996 in summer and autumn (from June to October). Different patterns of hysteresis in the relation between suspended sediment and discharge were related to types and locations of active sediment sources. The within-storm variation of particle size of suspended sediment during a major flood indicates a coarsening of transported material for increasing discharge. An analysis of grain size has shown that erosion areas on hillslopes were the main sources of suspended load. (C) 2000 Elsevier Science B.V. All rights reserved.
Lewis, A.J., and T.C. Rasmussen, Determination of suspended sediment concentrations and particle size distributions using pressure measurements, Journal of Environmental Quality, 28 (5), 1490-1496, 1999.
We present an automated, in-situ technique for measuring suspended-sediment concentrations and particle-size distributions. The technique uses pressure transducers to continuously monitor the fluid density, which is shown to be directly related to the mass of sediments suspended in the water column. We estimate the depth-integrated mass of 5 g of suspended sediments with an accuracy of 3%, corresponding to a suspended sediment concentration of 542 +/- 14 mg L-1. Particle-size distributions of the sediments were estimated from the rate of change of the suspended-sediment concentrations coupled with Stokes' Law. We evaluated the accuracy using three size classes of precision glass microspheres. Good agreement between observed and calculated fall times was only found for the smallest size fraction (106 to 150 mu m). Larger particles (180 to 250 mu m and 300 to 425 mu m) fell slower than predicted by Stokes' Law, presumably due to the onset of turbulent non around the particles. Also, equal masses of two different sizes of microspheres did not fall independently of each other. The larger microspheres were slowed by thr presence of the smaller particles while the smaller microspheres were accelerated, presumably due to entrainment of smaller particles in the wake of the larger particles. Application to laboratory characterization of soil sedimentation processes, as well as field applications for automated suspended sediment monitoring, prov ides the ability for real-time determination of depth-integrated sediment characteristics.
Li, Y.G., and T.M. Parchure, Mudbanks of the southwest coast of India. VI: Suspended sediment profiles, Journal of Coastal Research, 14 (4), 1363-1372, 1998.
Physical factors influencing suspended fine sediment loads in the region of mudbanks off Alleppey on the southwest coast of India are examined. Sediment dynamics of mudbanks is known to be predominantly governed by waves, and suspended sediment concentration in this area is closely correlated to local entrainment and settling fluxes due to waves, which at times are modulated by effects of weak currents. A simple, semi- empirical model that accounts for the vertical fluxes of fine, cohesive sediment in water and across the water-fluid mud interface due to waves and a weak current has been formulated to simulate suspension concentration profiles. The model is initially tested against laboratory flume data on wave-induced entrainment of muds, which shows the importance of mud rheology in governing resuspension. The model is then used to simulate suspended sediment concentration profiles measured near the Alleppey Pier under monsoonal waves that create mudbanks close to shoreline. Profiles are generated to represent five documented stages of mudbank evolution from formation to dissipation. Because the field data are very sparse in terms of spatial and temporal coverage, only a limited comparison of model and field is achieved. In spite of this limitation, the exercise shows that it should be possible to obtain reasonably reliable site-specific results on predicted profiles of suspended sediment over mudbanks, provided adequate field data are available for selecting representative values of the empirical parameters for calibration of the model.
Li, B.G., D. Eisma, Q.C. Xie, J. Kalf, Y. Li, and X. Xia, Concentration, clay mineral composition and Coulter counter size distribution of suspended sediment in the turbidity maximum of the Jiaojiang river estuary, Zhejiang, China, Journal of Sea Research, 42 (2), 105-116, 1999.
Measurements of current velocities, concentrations of suspended matter and Coulter counter size distributions of the suspended matter during the tidal cycle at the surface, at mid-depth and near to the bottom were carried out during spring and neap tide in the Jiaojiang river estuary, Zhejiang, China. The results indicate that a lutocline was present during most of the tidal cycle. except during the highest tides when the suspended- matter concentrations were approximately uniform over the entire water depth. Suspended-matter concentrations showed a relation with maximum flow velocities in the surface water and with increasing flow velocities in the bottom water, with regular deposition and resuspension during the tidal cycle. The clay mineral composition of the suspended matter indicated that most of the suspended matter was supplied by the Chang Jiang river. There was probably also some local supply and local sorting. The suspended-matter particle size, measured with a Coulter counter, became larger (with a larger standard deviation) when the suspended-matter concentration increased, and smaller when the suspended-matter concentration decreased. Size sorting during the tidal cycle indicated deflocculation and reflocculation processes; break-up of about 10 to 20% of the flocs in suspension is sufficient to produce the shift in the Coulter counter size distributions observed. This led to the conclusion that the trend in the smectite concentration in the estuary was the result of local sorting of smectite- containing particles after flee break-up. (C) 1999 Elsevier Science B.V. All rights reserved.
Li, D.X., X.K. Wang, and D.C. Wang, Velocity profiles for particles and liquid in open-channel flow with suspended sediment - Discussion, Journal of Hydraulic Engineering-Asce, 125 (4), 433-434, 1999.
Li, Y., and J. Li, A suspended sediment satellite sensing algorithm based on gradient transiting from water-leaving to satellite-detected reflectance spectrum, Chinese Science Bulletin, 45 (10), 925-931, 2000.
In order to remove the fluctuating atmospheric effects from the Case 2 water, an algorithm for retrieval of suspended sediment concentration from NOAA weather satellite imagery was developed under a new approach. This model is based on the linear response from water-leaving to satellite-detected reflectance spectra, simply reflected by the gradient for correlation curve between reflectance of the advanced very high resolution radiometer (AVHRR) channels 1 (R-1, 580-680 nm) and 2 (R-2, 720-1 100 nm). Proportional factor for this gradient transiting, mathematically represented as (t(d2)/t(d1)) (t(oz2)/f(oz1)), depends on a ratio of atmospheric transmittance for such two channels, including ozone and diffuse transmittance. As a simple but efficient algorithm of gradient, the algorithm of alpha R-1-R-2 is selected to retrieve gradient a and then sea surface suspendend sediment concentration.
Liden, R., A new approach for estimating suspended sediment yield, Hydrology and Earth System Sciences, 3 (2), 285-294, 1999.
A semi-distributed conceptual model, HBV-SED, for estimation of total suspended sediment concentration and yield at the outlet of a catchment was developed and tested through a case study. The base of the suspended sediment model is a dynamic hydrological model, which produces daily series of areal runoff and rainfall for each sub-basin as input to the sediment routine. A lumped measure of available sediment is accumulated continuously based on a linear relationship between log- transformed values of rainfall and erosion, while discharge of suspended sediment at the sub-basin outlet is dependent on runoff and amount of stored available sediment. Four model parameters are empirically determined through calibration against observed records of suspended sediment concentration. The model was applied to a 200 km(2) catchment with high altitude differences in the tropical parts of Bolivia, where recorded suspended sediment concentrations were available during a two-year period. 10,000 parameter sets were generated through a Monte Carlo procedure to evaluate the parameter sensitivity and interdependence. The predictability of the model was assessed through dividing the data record into a calibration and an independent period for which the model was validated and compared to the sediment rating curve technique. The results showed that the slope coefficients of the log- transformed model equations for accumulation and release were much stronger than the intercept coefficients. Despite an existing interdependence between the model parameters, the HBV- SED model gave clearly better results than the sediment rating curve technique for the validation period, indicating that the supply-based approach has a promising future as a tool for basic engineering applications.
Lin, P., J. Huan, and X. Li, Unsteady transport of suspende dload at small concentrations, J. Hydr. Division, ASCE, 109 (1), 86-98, 1983.
Loizeau, J.L., and J. Dominik, Evolution of the Upper Rhone River discharge and suspended sediment load during the last 80 years and some implications for Lake Geneva, Aquatic Sciences, 62 (1), 54-67, 2000.
During this century, the characteristics of the Upper Rhone River discharge, flowing into Lake Geneva, have been altered in response to the changes which have occurred in its watershed. Principally, numerous hydroelectric dams have been constructed on the course of the Rhone River tributaries. At present the major reservoirs can hold about 1220 10(6) m(3) of water, which represents 1/5 of the total annual Rhone River flow. Flow regime characteristics of the river have been modified by the dam operations. Water is released from reservoirs during winter and stored in summer. Large floods have also been reduced in amplitude and frequency. From the available literature data, sediment rating curves have been calculated and used to estimate the evolution of the sediment load from the Rhone River to Lake Geneva. They show that sediment input has decreased by at least a factor 2. This reduction has impacted the occurrence of underflows along the lake bottom, due to the reduction of sediment-laden floods, which in turn may have considerable negative effects on the reoxygenation of Lake Geneva deep waters.
Lopes, V.L., P.F. Ffolliott, and M.B. Baker, Impacts of vegetative practices on suspended sediment from watersheds of Arizona, Journal of Water Resources Planning and Management-Asce, 127 (1), 41-47, 2001.
Effects of vegetative practices on suspended sediment discharge from ponderosa pine forests and pinon-juniper woodlands in north-central Arizona are examined. Sediment-rating curves were developed to analyze the impacts. Disturbance from vegetative practices generally increased suspended sediment transport above those of control (reference) watersheds. Completely cleared and strip-cut ponderosa pine watersheds produced higher sediment concentrations than did a control watershed. Likewise, cabled and herbicide-treated pinon-juniper watersheds yielded higher sediment-laden streamflows than did a control. Sediment transport regimes are also related to streamflow-generation mechanisms and hydrograph stages. Although about 85% of the data analyzed represented snowmelt-runoff events in both vegetative types, derivation of sediment-rating curves based on streamflow-generation mechanisms improved the sensitivity of the analysis. Sediment data collected during rising and falling hydrograph stages varied between the two vegetative types. Sediment concentrations were generally higher in the rising stage than in the falling stage for ponderosa pine watersheds. There was no clear evidence of higher sediment concentrations in the rising stage of the hydrograph as compared to the falling stage in the pinon-juniper watersheds.
Lygouras, J.N., K.N. Tarchanidis, and P.G. Tsalides, Suspended sediment and dye concentration measurements using a digital technique, International Journal of Electronics, 87 (1), 107-118, 2000.
This paper presents a new digital technique for measuring the concentration of the suspended sediment and dye materials in fluids. The method is based on the measurement of the attenuation of a sinusoidally modulated light beam penetrating a small sample Volume of the fluid. The method of direct digital synthesis is used to produce a sine wave in the input stage, giving a high stability in the amplitude and frequency of the light-beam modulating waveform. This sinusoidal waveform drives six infrared or colour light emitting diodes, depending on the material to be detected. The system facilitates optical fibres to transfer the optical signal to and from the sampling point. The collected light is converted through photodiodes to an attenuated sinusoidal electrical signal. In contrast to the conventional optical sediment detection devices, here synchronous amplitude demodulation is used instead of conventional analogue low-pass filters. Therefore, the information concerning the amplitude is pure and a very high signal to noise ratio can be achieved. The use of a sinusoidal waveform instead of rectangular pulses having high harmonic content results in less influence on the receiver from higher frequencies. The above improvements resulted in a high resolution instrument.
Lyne, V.D., B. Butman, and W.D. Grant, Sediment Movement Along The United-States East Coast Continental Shelf .2. Modelling Suspended Sediment Concentration And Transport Rate During Storms, Continental Shelf Research, 10 (5), 429-460, 1990.
Madsen, O.S., and W.D. Grant, Quantitative description of sediment transport by waves, in 15th Coastal Engineering Conference, pp. 1093-1112, ASCE, Honolulu, Hawaii, 1976.
McLean, S.R., Modelling sediment suspension under waves, EOS, Trans., AGU, 71 (43), 1369, 1990.
McLean, S.R., Depth-integrated suspended-load calculations, Journal of Hydraulic Engineering, 117 (11), 1440-1458, 1991.
McLean, S.R., On the calculation of suspended load for noncohesive sediments, Journal of Geophysical Research, 97 (C4), 5759-5770, 1992.
McTigue, D.F., Mixture theory for turbulent diffusion of heavy particles, in Theory of dispersed multiphase flow, pp. 227-250, Academic Press, 1983.
Meade, R.H., N.N. Bobrovitskaya, and V.I. Babkin, Suspended-sediment and fresh-water discharges in the Ob and Yenisey rivers, 1960-1988, International Journal of Earth Sciences, 89 (3), 461-469, 2000.
Of the world's great rivers, the Ob and Yenisey rank among the largest suppliers of fresh water and among the smallest suppliers of suspended sediment to the coastal ocean. Sediment in the middle reaches of the rivers is mobilized from bordering terraces and exchanged between channels and flood plains. Sediment in the lower reaches of these great rivers is deposited and stored (permanently, on a millennial time scale) in flood plains. Sediment discharges, already small under natural conditions, are diminished further by large manmade reservoirs that trap significant proportions of the moving solids. The long winter freeze and sudden spring breakup impose a peakedness in seasonal water runoff and sediment discharge that contrasts markedly with that in rivers of the tropics and more temperate climates. Very little sediment from the Ob and Yenisey rivers is being transported to the open waters of the Arctic Ocean under present conditions.
Middleton, G.V., and J.B. Southard, Mechanics of sediment movement, 401 pp., SEPM, Tulsa, Oklahoma, 1984.
Moore, B.D., Beach profile evolution in response to changes in water level and wave height, M.S. thesis thesis, University of Delaware, 1982.
Muste, M., and V.C. Patel, Velocity profiles for particles and liquid in open-channel flow with suspended sediment - Closure, Journal of Hydraulic Engineering-Asce, 125 (4), 434-435, 1999.
Nadaoka, K., H. Yagi, and H. Kamata, A simple quasi-3-d model of suspended sediment transport in a nonequilibrium state, Coastal Engineering, 15 (5-6), 459-474, 1991.
Neal, C., H.P. Jarvie, and T. Oguchi, Acid-available particulate trace metals associated with suspended sediment in the Humber rivers: a regional assessment, Hydrological Processes, 13 (7), 1117-1136, 1999.
Information on the distribution of acid-soluble Al, Ba, Co, Cr, Ni, Fe, Mn and Pb associated with suspended sediment is presented for the major Humber rivers draining into the North Sea. The data analysed are based on two major data sets: the Land-Ocean Interaction Study (LOIS) and Environment Agency (EA) regional monitoring programmes. Trace metal particulate concentrations show a large variation over space and time. Three types of pattern are observed. First, Ba and Pb are highly and linearly correlated and they have an order of magnitude higher concentrations to the north of the region owing to localized bedrock mineralization, historic mining activity and the associated contamination of floodplain areas during the 18th and 19th centuries (type 1). Secondly, there are strong interelement relationships between Al, Co, Ni and Fe (and to a lesser extent Mn) and between these elements and suspended sediment concentrations (type 2) and the points for all the rivers lie on the same straight line. For type 2 elements, concentrations are enriched by a factor of three within the industrially affected rivers in the central and southern parts of the area: the rural Swale in the north of the area also has enhanced concentrations of type 2 elements in relation to higher suspended sediment concentrations. Thirdly, chromium shows about a thirty-fold enrichment in the industrial rivers (type 3). The relationships between all the trace metals are represented by a simple three-component mixing scheme involving natural background materials, industrially generated particulates and resuspended floodplain sediments contaminated by historic mining activity. The need for (a) focused studies to identify and describe key type localities for specific industrial and urban pollution sources and (b) further exploration of the wealth of information contained within the EA database, is highlighted. Copyright (C) 1999 John Wiley & Sons, Ltd.
Nielsen, P., I.A. Svendsen, and C. Staub, Onshore-offshore sediment movement on a beach, in Coastal Engineering Conference, pp. 1475, 1978.
Nielsen, P., Suspended sediment in vortex flow, JFM, 1982.
Nielsen, P., On the motion of suspended sand particles, JGR, 89 (C1), 616-626, 1984.
Nielsen, P., Suspended sediment concentrations under waves, Coastal Engineer, 10, 23-31, 1986.
Nielsen, P., Coastal bottom boundary layers and sediment transport, World Scientific, Singapore, 1992.
O' Conner, B.A., and J. Nicholson, A three dimensional model of suspended particulate sediment transport, Coastal Engineer, 12, 157-174, 1988.
Osborne, P.D., and B. Greenwood, Frequency Dependent Cross-Shore Suspended Sediment Transport .1. A Non-Barred Shoreface, Marine Geology, 106 (1-2), 1-24, 1992.
Osborne, P.D., and B. Greenwood, Frequency Dependent Cross-Shore Suspended Sediment Transport .2. A Barred Shoreface, Marine Geology, 106 (1-2), 25-51, 1992.
Ostendorf, D.W., and O.S. Madsen, An analysis of longshore currents and associated sediment trasnport in the surf zone, pp. 84-96, R. M. Parsons Laboratory, Massachusetts Institute of Technology, 1979.
Ostendorf, D.W., Longshore dispersion over a flat beach, J. Geophys. Res., 87 (C6), 4241-4248, 1982.
Pantin, H.M., Interaction between velocity and effective density in turbidity flow: phase-plane analysis, with criteria for autosuspension, Marine Geology, 31, 59-99, 1979.
Pantin, H.M., Comments on: experimental test of autosuspension, Earth Surface Processes and Landforms, 7, 503-505, 1982.
Paola, C., and J.B. Southard, Autosuspension and the energetics of two-phase flows: Reply to comments on "Experimental test of autosuspension" by J.B Southard and M. E. Mackintosh, Earth Surface Processes and Landforms, 8, 273-279, 1983.
Parker, G., Discussion of: Experimental test of autosuspension (Southard and Mackintosh, 1981), Earth Surface Processes and Landforms, 7, 507-510, 1982.
Pazos, O., M.A. Nombela, and F. Vilas, Continental contribution of suspended sediment to an estuary: Ria de Vigo, Scientia Marina, 64 (3), 295-302, 2000.
Five rivers that flow into the Ria de Vigo were sampled during a period of 2 years from January 1995 to February 1997. Their catchment area approximates 45.3% of the total drainage into the Ria de Vigo. Flow rates and suspended matter (sm) data were recorded to calculate the volume of runoff. The mineralogy was studied using XRD. Three of the five rivers had been previously sampled during a period of one and a half years, from 1987 to 1989, permitting the comparison of data then and now. The results show low contributions of suspended matter from the rivers but that anthropogenic (land use and forest fires) factors have a direct influence on the increase of suspended matter. The mineralogy is very similar in all five rivers without any appreciable seasonal change, although an increase in the amount of gibbsite was found during periods of unusual erosion.
Pentz, S.B., and R.A. Kostaschuk, Effect of placer mining on suspended sediment in reaches of sensitive fish habitat, Environmental Geology, 37 (1-2), 78-89, 1999.
The McQuesten River system in central Yukon Territory, Canada, contains placer mines and reaches of sensitive fish habitat. Suspended sediment is supplied to the system by erosion of previously mined disturbed areas, bank erosion, resuspension of placer sediment deposited on bars, and active placer-mine discharges. Direct discharge from active placer mines did not have a large impact on suspended sediment in reaches of sensitive fish habitat in 1994-1995, although only two mines were active and concentrations did periodically exceed water quality objectives. Erosion of previously mined disturbed areas had a pronounced effect on suspended sediment during spring snowmelt and summer rainstorms in 1994-1995. Deposits in previously mined areas should be stabilized to reduce erosion and its downstream impact on fish habitat.
Perez, B.C., J.W. Day, L.J. Rouse, R.F. Shaw, and R. Wang, Influence of Atchafalaya River discharge and Winter frontal passage on suspended sediment concentration and flux in Fourleague Bay, Louisiana, Estuarine Coastal and Shelf Science, 50 (2), 271-290, 2000.
Suspended sediment concentrations and fluxes between Fourleague Bay, Louisiana and the northern Gulf of Mexico were sampled every 3 h for 3 months to examine the importance of atmospheric cold fronts and riverine forcing on the functioning of this estuarine system. A cold front index was developed and used to identify major winter frontal passages likely to have the largest effects on material concentrations and transport. Suspended sediment concentrations ranged from 11 to 1527 mg l(- 1); the highest values occurred during winter frontal passages and the lowest during calm periods. High concentrations are generated by a continuous source of sediment from the Atchafalaya River and resuspension of benthic sediment via high intensity winds associated with cold fronts along with sufficient duration to keep the sediment in suspension. Spring peak discharge of the Atchafalaya River increased water levels and sediment concentrations in the bay leading to strong seasonal net exports of water (1.02 x 10(9) m(3)) and sediment (1.72 x 10(8) kg) into the Gulf of Mexico through Oyster Bayou over the 89-day study. Net fluxes associated with tidal forcing were nearly balanced with a small net export due to freshwater input. The combination of high volumes of water originating from the northern bay and the restricted outlet to the Gulf often cause increased water levels and inundation of the surrounding marshes and potential advection of sediments onto the marsh surface. The results suggest that marsh drainage often increases the particulate organic carbon export as a result of marsh flushing. (C) 2000 Academic Press.
Phillips, J.M., B.W. Webb, D.E. Walling, and G.J.L. Leeks, Estimating the suspended sediment loads of rivers in the LOIS study area using infrequent samples, Hydrological Processes, 13 (7), 1035-1050, 1999.
A central objective of the LOIS Community Research Programme is to provide estimates of the land-ocean flux of suspended sediment from the LOIS study area. While high frequency (15- minute interval) suspended sediment concentration data are recorded within the programme at six tidal limit sites, infrequent (weekly-monthly) sampling undertaken by the Harmonized Monitoring (HM) Programme provides additional concentration data for 23 tidal limit sites in the LOIS study area. In order that these infrequent data can be used to generate sediment flux estimates, the accuracy and precision of 22 load estimation procedures are assessed in the context of sampling frequency (weekly, fortnightly and monthly) and basin scales representative of the LOIS study area. Sampling frequency is demonstrated to exert a significant influence on the precision of the individual procedures, with precision being inversely related to sampling frequency. Accuracy is less clearly influenced by sampling frequency, although different procedures were identified as being the most accurate at the three sampling frequencies. Basin scale is shown to exert a significant influence upon accuracy and precision, with the performance of the load estimation procedures being inversely related to basin scale. For one interpolation procedure, an error correction procedure is developed, based on the strong relationship identified in this study between the error associated with individual flux estimates and the ratio of mean sampled discharge to the mean discharge obtained from the high frequency record. This relatively high resolution error correction method is applied to HM data from eight tidal limit sites in the LOIS area, and corrects the initial annual load estimates to provide values that are considered to be more representative of rivers from the LOIS study area. Copyright (C) 1999 John Wiley & Sons, Ltd.
Phillips, J.M., M.A. Russell, and D.E. Walling, Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments, Hydrological Processes, 14 (14), 2589-2602, 2000.
Fine-grained (< 62.5 <mu>m) suspended sediment transport is a key component of the geochemical flux in most fluvial systems. The highly episodic nature of suspended sediment transport imposes a significant constraint on the design of sampling strategies aimed at characterizing the biogeochemical properties of such sediment. A simple sediment sampler, utilizing ambient flow to induce sedimentation by settling, is described. The sampler can be deployed unattended in small streams to collect time-integrated suspended sediment samples. In laboratory tests involving chemically dispersed sediment, the sampler collected a maximum of 71% of the input sample mass. However, under natural conditions, the existence of composite particles or flocs can be expected to increase significantly the trapping efficiency. Field trials confirmed that the particle size composition and total carbon content of the sediment collected by the sampler were representative statistically of the ambient suspended sediment. Copyright (C) 2000 John Wiley & Sons, Ltd.
Pirmez, C., L.F. Pratson, and M.S. Steckler, Clinoform development by advection-diffusion of suspended sediment: Modeling and comparison to natural systems, Journal of Geophysical Research-Solid Earth, 103 (B10), 24141-24157, 1998.
Clinoforms are the building blocks of prograding stratigraphic sequences. These sigmoid-shaped surfaces can be found forming today on modern deltas. Sedimentation rate profiles over the clinoform surface of these deltas show low rates of sediment accumulation on both topset and bottomset regions, with a maximum accumulation rate on the upper foreset region. We present a model for the formation of clinoforms that relies on the interpretation of modem clinoform sedimentation as a result of the distribution of shear stresses at the mouth of a river. Model clinoform surfaces are generated using an equation for the conservation of suspended sediment concentration, together with a conservation of fluid equation for simple time-averaged flow velocity fields. In the model, suspended sediment is advected horizontally into a basin, and gravitational settling of sediment particles is counteracted by vertical turbulent diffusion. In shallow water, shear stresses are too large to allow deposition, and sediment bypasses the topset region. With increasing water depth, near-bed shear stresses decrease, and sediment is allowed to deposit at the foreset region, with gradually decreasing rates toward deeper water. This sedimentation pattern leads to progradation of the clinoform surfaces through time. The clinoform surfaces produced by the model capture the fundamental morphological characteristics of natural clinoforms. These include the gradual slope rollover at the topset and bottomset, steeper foreset slopes with increased grain size, and an increase in foreset slope through time as clinoforms prograde into deeper water. Because the parameters controlling the model clinoforms have a direct relation to physical quantities that can be measured in natural systems, the model is an important step toward unraveling the physical processes associated with these deposits.
Prandle, D., J.C. Hargreaves, J.P. McManus, A.R. Campbell, K. Duwe, A. Lane, P. Mahnke, S. Shimwell, and J. Wolf, Tide, wave and suspended sediment modelling on an open coast - Holderness, Coastal Engineering, 41 (1-3), 237-267, 2000.
An intensive series of observations off the Holderness coast was followed by a related set of modelling applications. Observations included: aircraft and satellite remote sensing, H.F. and X-band radar, ship surveys and in situ instruments on the sea bed and at the sea surface. These observations aimed to monitor, over three successive winter periods, the dynamics and sediment distributions in the vicinity of this rapidly eroding coastline