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1.
Crushed recycled glass was evaluated as an alternative to silica sand in dual‐media filters. Pilot scale inline filtration experiments were carried out using raw waters from three different water sources with turbidities between 6.0 and 14.0 NTU. Two physically identical filter columns were operated in parallel in the experiments. One filter consisted of 62.5 cm silica sand and 41.5 cm anthracite coal, whereas the other filter contained 62.5 cm crushed recycled glass plus 41.5 cm anthracite coal. The total bed depth was 104 cm for both filters. The properties of the media were as follows: Glass effective size = 0.77 mm, uniformity coefficient = 1.41. Sand effective size = 0.79 mm, uniformity coefficient = 1.33. Coal effective size = 1.45 mm, uniformity coefficient = 1.39. Experiments were repeated five times as follows: (i) Without the use of a coagulant, (ii–iii) with 5 and 10 mg/L of alum, and (iv–v) with 5 and 10 mg/L of ferric chloride. The filtration rate used was 11.5 m/h. Turbidity, particle counts, and head losses were measured and compared as functions of time. The following were observed: (i) Effluent turbidities and particle counts of the two filters were very close, i.e., essentially the same effluent quality was obtained when crushed glass was used instead of silica sand. (ii) In the majority of the tests, the filter with crushed glass generated both a smaller clean‐bed head loss and smaller clogging head losses than those of the filter containing sand. It is concluded that crushed glass may be a good alternative to silica sand in dual‐media filtration.  相似文献   

2.
The objective of this work was to evaluate crushed recycled glass as a medium for rapid filtration. In the first part of this work, physical and hydraulic characteristics of the glass medium were studied. In the second part, pilot scale inline filtration experiments were carried out using raw waters from three different water sources. Two physically identical filter columns were operated in parallel in all the experiments. One filter contained a silica sand medium that is widely used in Turkey, whereas the other filter contained crushed recycled glass. Experiments were repeated five times as follows: (i) Without the use of a coagulant, (ii–iii) with 5 mg/L and 10 mg/L of alum, and (iv–v) with 5 mg/L and 10 mg/L of ferric chloride. Turbidity, particle counts, and head losses were measured and compared as functions of time. The following were observed: (1) Provided that a coagulant was used, the filter containing crushed glass produced effluent turbidities and particle counts similar to those obtained with the sand filter. (2) The crushed glass medium generated both a smaller clean‐bed head loss and smaller clogging head losses than those of the sand filter. It is concluded that crushed glass shows significant promise as an alternative to silica sand in rapid filtration.  相似文献   

3.
Field experiments were conducted to evaluate the efficiency of iron-oxide-coated sand (ICS) and surfactant modified zeolite (SMZ) to remove viruses and bacteria from ground water. The reactive media were employed as filter packs of a pumping well that withdrew sewage effluent from a constructed wetland at a rate of 0.72 L/min. The contact time of the pumped water with the filter pack (10 cm thick) was about two minutes. Upgradient of the pumping well, the sewage effluent was spiked with MS-2 bacteriophage and E. coli. While the employed ICS filter pack failed to remove viruses and bacteria to a significant degree, the SMZ filter pack removed more than 99% of the viruses and 100% of E. coli from the ground water while fresh. In an additional field experiment using the same configuration but leaving the filter pack in place for more than five months, the SMZ filter pack was still removing 100% of E. coli , but failed to reduce virus numbers to a significant degree.  相似文献   

4.
Stream–subsurface exchange strongly influences the transport of contaminants, fine particles, and other ecologically relevant substances in streams. We used a recirculating laboratory flume (220 cm long and 20 cm wide) to study the effects of particle size, overlying velocity, and biofilm formation on stream–subsurface exchange of particles. Sodium chloride was used as a non‐reactive dissolved tracer and 1‐ and 5‐µm fluorescent microspheres were used as particulate tracers. Surface–subsurface exchange was observed with a clean sand bed and a bed colonized by an autotrophic–heterotrophic biofilm under two different overlying velocities, 0·9 and 5 cm s?1. Hydrodynamic interactions between the overlying flow and sand bed resulted in a reduction of solute and particle concentrations in the water column, and a corresponding accumulation of particles in both the sediments and in the biofilm. Increasing overlying velocity and particle size resulted in faster removal from the overlying water due to enhanced mass transfer to the bed. The presence of the biofilm did not affect solute exchange under any flow condition tested. The presence of the biofilm significantly increased the deposition of particles under an overlying velocity of 5 cm s?1, and produced a small but statistically insignificant increase at 0·9 cm?1. The particles preferentially deposited within the biofilm matrix relative to the underlying sand. These results demonstrate that hydrodynamic transport conditions, particle size, and biofilm formation play a key role in the transport of suspended particles, such as inorganic sediments, particulate organic matter, and pathogenic microorganisms in freshwater ecosystems, and should be taken into consideration when predicting the fate and transport of particles and contaminants in the environment. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

5.
Abstract

An in situ microbial filter technology is being tested and developed for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethylene (TCE). The current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the injection of a representative methanotrophic bacterium, Methylosinus trichosporium OB3b. This microbial filter strategy has been successfully demonstrated using emplaced, attached resting cells (no methane additions) in a 1.1 m flow-through test bed loaded with water-saturated sand. Two separate 24 h pulses of TCE (109 ppb and 85 ppb), one week apart, were pumped through the system at a flow velocity of 15 mm h?1; no TCE (< 0.5 ppb) was detected on the downstream side of the microbial filter. Subsequent excavation of the wet sand confirmed the existence of a TCE-bioactive zone 21 days after it had been created. An enhanced longevity of the cellular, soluble-form methane monooxygenase produced by this methanotroph is a result of the laboratory bioreactor culturing conditions. Additional experiments with cells in sealed vials and emplaced in the 1.1 m test bed yielded a high resting-cell finite TCE biotransformation capacity of about 0.25 mg per mg of bacteria; this is suitable for a planned sand-filled trench field demonstration at a Lawrence Livermore National Laboratory site.  相似文献   

6.
Suspended sediment particles contained in inflows of water systems of hydropower plants (HPPs) cause hydro-abrasive erosion of the hydraulic turbines and structures leading to significant maintenance costs, efficiency reductions, and downtime. Relevant parameters such as suspended sediment concentration (SSC), particle size distribution (PSD), shape, and mineralogical composition were measured with an online multi-frequency acoustic instrument and based on manually taken samples from the end of the sand trap of the Toss HPP in the Himalayan region, India. In the laboratory, the samples were analyzed using the gravimetric method, laser diffraction, turbidity, dynamic digital image processing, scanning electron microscope, petrography analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The online instrument and the samples provided measurement results at a single point. To investigate vertical gradients in concentration and particle sizes, additional samples were collected 9 times at 7 relative water depths. The SSC, most particle sizes, and particle shape were found to be evenly distributed over depth except d90, i.e. the diameter which is not exceeded by 90% of the particle mass. d90 measured at 76% of the water depth was in the range of fine sand and was multiplied by 1.05 to obtain an average value representative for the entire depth. Improved methodologies to quantify both particle shape and size in an analytical model for hydro-abrasive erosion are proposed. Also, the PSD measuring performance of laser diffraction and dynamic imaging was studied and similar values of the median particle sizes were obtained from both instruments. Further, multi-frequency acoustic, turbidity and laser diffraction techniques were found suitable for SSC measurement at the test case HPP.  相似文献   

7.
This paper builds on a recently published one-dimensional moving-boundary model of the coevolution of topset, foreset and bottomset in a reservoir that captures the dynamics of the internal muddy pond typical to reservoirs. This model was modified to account for different outlet locations at the reservoir＇s downstream end. This model considers a river carrying two sustained phases of sediments： coarse （sand） and fine （mud）. The coarse phase deposits in the topset and delta foreset, while the fine phase forms a dilute suspension of wash load in the river. As the river enters the reservoir, the muddy water plunges on the foreset to form a Froude-supercritical （purely depositional） turbidity current. This turbidity current emplaces the bottomset. The modified numerical model was tested against five laboratory experiments previously reported by the author. The model successfully locates the muddy-water/clear-water interface. In addition, modeled and measured bed deposits are in good agreement. Results clearly indicate that the location of the internal hydraulic jump plays a key role in the final bed deposit.  相似文献   

8.
Measurement of particle rotation in a saltation layer   总被引：1，自引：0，他引：1       下载免费PDF全文
Two computational methods to measure particle rotations from shadow images of sand particles saltating in a wind tunnel are presented. One method calculates the maximum of the cross‐correlations through multiple angular rotations of an imaged particle. The second method polar transforms both images and then calculates the correlation coefficient for multiple pixel displacements in the θ axis, corresponding to particle rotations. The results from both methods were analysed as a function of height above sand bed (3.7–33.4 mm) and particle size (0.32–0.93 mm equivalent mean diameter). Our results indicate little evidence that particle rotation speeds depend on either their size or height above the sand bed. Though similar results were obtained from both methods, there existed different advantages and disadvantages between the methods. Erroneous results likely arose from particles that were inadequately described by a 2‐D rotation axis, or from poorly imaged particles. At a wind tunnel speed of about 12 m/s, most particles rotated at around 300–400 rev/s. Negative rotations were also found, and their proportion was approximately 15% within the total range of ?450 to 850 rev/s. The ratio of displacement kinetic energy to rotation energy was compared across the various groups and had values between 15 and 40. The quotient showed little dependence on height, though decreased with increasing particle size. Wider applicability of the measurement methodology to study snow particle rotation is also discussed. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

9.
The ionic tracers lithium, sodium, chloride and bromide were used to measure flow loss in a small stream (≈? 10 ls?1). An injectate containing all four tracers was added continuously at five sites along a 507 m study reach of St Kevin Gulch, Lake County, Colorado to determine which sections of the stream were losing water to the stream bed and to ascertain how well the four tracers performed. The acidity of the stream (pH 3.6) made it possible for lithium and sodium, which are normally adsorbed by ion exchange with stream bed sediment, to be used as conservative tracers. Net flow losses as low as 0.8 ls?1, or 8% of flow, were calculated between measuring sites. By comparing the results of simultaneous injection it was determined whether subsections of the study reach were influent or effluent. Evaluation of tracer concentrations along 116 m of stream indicated that all four tracers behaved conservatively. Discharges measured by Parshall flumes were 4–18% greater than discharges measured by tracer dilution.  相似文献   

10.
Ten large volume water samples were taken from the Rhône River (Switzerland-France) in November, 1989 for recovery of total suspended sediment by continuous flow centrifugation. the samples were freeze-dried and analysed for particle size, organic carbon, total nitrogen, and carbonate. for comparative purposes, four bed sediments collected in July, 1989 are also described. the Rhône can be subdivided into three sections on the basis of the origins of the water. the first section is the Upper Rhône River draining into Lake Geneva. Waters are derived from glaciers, with low temperature and conductivity and high turbidity. Suspended sediment is coarse, has a bimodal distribution, and is low in both organic matter and carbonate. the second reach is from Lake Geneva to the confluence with the Saône at Lyon and has warmer water with higher conductivity and very low turbidity. Suspended sediment is higher in organic matter, with high carbonate originating from the lake. the final section is from Lyon to Arles, with warmer water and higher conductivity and turbidity due to modification by the Saône. Sediment is rich in organic matter, which May, account for an observed decline in oxygen in the river waters downstream from Lyon. Carbonate in these sediments also decreases due to increased turbidity from the Saône. Suspended sediments other than from the Upper Rhône show a remarkable consistency in grain size, predominantly in the fine silts (mode 9-11 μm). This consistency indicates a high degree of suitability for geochemical analysis. Bed sediments were bimodal throughout, with a dominant coarse population in two out of the four samples. Grain size statistical parameters could be easily explained by application of the theory of mixing of two major populations in the sand size (bed traction load) and the fine silt/clay size (suspended sediment load).  相似文献   

11.
The use of metallic iron filters (Fe0 filters) has been discussed as a promising low‐cost option for safe drinking water production at household level. Filter clogging due to the volumetric expansive nature of iron corrosion has been identified as the major problem of Fe0 filters. Mixing Fe0 and sand (yielding Fe0/sand filters) has been proposed as a tool to extent filter service life. However, no systematic discussion rationalizing Fe0/sand mixtures is yet available. This communication theoretically discussed suitable Fe0/sand proportions for efficient filters. Results suggested that Fe0/sand filters should not contain more that 50 vol% Fe0 (25 wt% when Fe0 is mixed with quartz). The actual Fe0 percentage in a filter will depend on its intrinsic reactivity.  相似文献   

12.
Continuous flow centrifugation (CFC) is a well‐established technique used in natural surface water studies to collect large amounts of suspended solids, thus allowing a broad spectrum of measurements. However, a potential contamination or changes in the particle size distribution during the centrifugation may restrain the use of CFC effluents for element analysis in the colloidal and dissolved fractions. In this paper we evaluate the possibility of using the effluent of a Westfalia centrifuge (type KA2‐06‐075, 9700 rpm) for such analysis. This evaluation is based on two laboratory experiments with deionized and tap water and two field experiments in rivers. Elemental concentration changes across the CFC were assessed from the CFC influent and effluent after a filtration at 0·45 µm. Significant increases were found, mainly in the field experiments at a high suspended solids level and a slightly acid pH. A hypothesis was made on the origin of these increases as a superposition of a centrifuge intrinsic contamination and a particle fragmentation effect. A numerical model based on elemental concentration measurements (inductively coupled plasma mass spectrometry) gave a particle fragmentation level of 0·55% (mass percentage of particles broken up into smaller fragments during centrifugation). In another experiment, a direct particle counting (single particle counter) shows an excess of particles smaller than 500 nm in the CFC effluent, corresponding to a fragmentation level of 0·11%. In consequence, the use of CFC effluent for element analysis is possible in low‐turbidity river or lake waters, but should be carefully considered in waters with high suspended matter contents. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

13.
Eddy correlation techniques are standard tools in micrometeorology and oceanography to measure momentum and contaminant transport across turbulent boundary layers. They can, in theory, be used to estimate the net vertical suspended sediment flux directly over different areas of an alluvial channel boundary, and thus disclose ongoing erosion/deposition patterns. The basic principles and main problems in applying the technique to alluvial suspension are first introduced. Results from a trial application of the method in a large sand bed river are then presented; the focus of the analysis is on the substantial (and surprising) contributions of multi-minute flow fluctuations to suspension work in the study environment. The data were collected in a 10 m deep channel of the Fraser River near Mission, British Columbia, Canada. Turbulent fluctuations of flow components streamwise and normal to the bed, along with the output of an optical suspended sediment sensor, were monitored over 7 h, 1 m above the bed. Flow velocities averaged 0·9 ms?1 and mean suspended sediment concentrations 500 mgl?1, at sensor level above 1–5 dm high dunes. Spectral analysis of the records reveals that approximately 30 per cent of the vertical suspended sand mixing across the sensor level (and roughly as much of the momentum exchange) was linked to gradual flow oscillations with periods between 1 and 13·6 min (underlying briefer, turbulent fluctuations). Extended periods of sediment-rich, slightly upward directed but slower mean flow alternated with periods of sediment-poor, slightly downward and faster mean flow; these slow fluctuations involved 10–20 cms?1 changes in 5 min average flow speed, 2–4· changes in vertical flow angle and 100 mgl?1 changes in mean sand concentration. To obtain accurate eddy-correlation estimates of the vertical suspension flux in the study conditions, hour-scale flow and turbidity records that include many of these multi-minute cycles appear to be necessary. The spectra of the Fraser River near-bed signals do not conspicuously differ in overall shape (in terms of low-frequency content and location of peak) from turbulent spectra encountered in some atmospheric boundary layers. Nonetheless, the long period fluctuations observed on the Fraser River may not be turbulent; rather they may reflect slowly evolving perturbations in the near-bed streamlines, caused by bedform translation or gradual fluctuation within the large-scale streamwise cells of the secondary flow.  相似文献   

14.
Measurements are presented of the properties of suspended particulate matter (SPM) in the estuarine turbidity maximum (ETM) of the upper Humber and Ouse estuaries during transient, relatively low freshwater inflow conditions of September 1995. Very high concentrations of near-bed SPM (more than 100 g l−1) were observed in the low-salinity (less than 1), upper reaches. SPM within the ETM consisted largely of fine sediment (silt and clay) that existed as microfloc and macrofloc aggregates and individual particles. Primary sediment particles were very fine grained, and typically, about 20–30% was clay-sized at high water. The clay mineralogy was dominated by chlorite and illite. There was a pronounced increase in particle size in the tidal river, up-estuary of the ETM. The mean specific surface area (SSA) of near-bed SPM within the ETM was 22 m2 g−1 on a spring tide and 24 m2 g−1 on a neap tide. A tidal cycle of measurements within a near-bed, high concentration SPM layer during a very small neap tide gave a mean SSA of 26 m2 g−1. The percentage of silt and clay in surficial bed sediments along the main channel of the estuary varied strongly. The relatively low silt and clay percentage of surficial bed sediments (about 10–35%) within the ETM’s region of highest near-bed SPM concentrations and their low SSA values were in marked contrast to the overlying SPM. The loss on ignition (LOI) of near-bed SPM in the turbid reaches of the estuary was about 10%, compared with about 12% for surface SPM and more than 40% in the very low turbidity waters up-estuary of the ETM. Settling velocities of Humber–Ouse SPM, sampled in situ and measured using a settling column, maximized at 1.5 mm s−1 and exhibited hindered settling at higher SPM concentrations.  相似文献   

15.
One of the critical technological parameter in operation of aerated submerged fixed‐bed biofilm reactor (ASFBBR) is the control over process of biofilm detachment. Both, an excessive growth of biomass with its accumulation in the bioreactor and an exceeded biofilm detachment rate, cause serious operational and technological problems. The studies presented in this paper demonstrate that in an ASFBBR reactor with a PVC bed carrier media, an effective way to maintain a proper shear stress acting on the biofilm and causing its detachment could be an internal recirculation of wastewater instead of backwashing with wastewater or air flushing. In case of polishing of oil‐refinery wastewater with average COD loading rate equal to 9 g COD/(m2 day), the minimum value of the hydraulic loading rate in such reactor is 1.9 m3/(m2 h), at which there was no excessive growth of biofilms. Despite a significant decrease of the biofilms thickness and amount of biomass in the reactor, there was no significant decline in the efficiency of pollutant removal from oil‐refinery wastewater, which made it possible to obtain the quality of effluent at the outlet of the bioreactor significantly below the water permits and standards.  相似文献   

16.
This paper presents a study on suspended particle transport in porous medium with the aid of a sand layer transportation–deposition testing system to determine the kinetic characteristics of particles in porous medium under variable temperatures. Quartz sand and quartz powder were chosen as the porous medium and particle in the tests, respectively. Four size compositions and two operational modes, that is, temperature reduction mode (changing from 18°C to 5°C) and temperature increment mode (changing from 18°C to 35°C), were adopted. The turbidity and concentration of quartz powder were measured under various conditions. We observed a high temperature‐independent correlation between them. Breakthrough curves under different conditions were analysed using this testing system. The results showed that changes in temperature affected the particle transport process to some extent, and the degree of influence was closely related to the time moment of the temperature change onset. Moreover, we found a hysteresis phenomenon in the breakthrough curve under both temperature reduction and increment conditions. The results also indicated that the temperature effect was particularly significant for smaller particles. The typical curves to represent particle transport process under variable temperatures were put forward according to the results. To explain the test results, four factors, that is, water viscosity, adsorption effect, double layer force, and particle kinetic energy, were considered and categorized as promotion or constraining factors.  相似文献   

17.
Aeolian sand transport is a complicated process that is affected by many factors (e.g. wind velocity, sand particle size, surface microtopography). Under different experimental conditions, erosion processes will therefore produce different results. In this study, we conducted a series of wind tunnel experiments across a range of wind velocities capable of entraining sand particles (8.0, 10.0, 12.0, and 14.0 m s-1) to study the dynamic changes of the shear velocity, aerodynamic roughness length, and sand transport. We found that the shear velocity and aerodynamic roughness length are not constant; rather, they change dynamically over time, and the rules that describe their changes depend on the free-stream air velocity. For wind tunnel experiments without feeding sand into the airflow, the sand bed elevation decreases with increasing erosion time, and this change significantly affected the values of shear velocity and aerodynamic roughness length. A Gaussian distribution function described the relationships between the sand transport rate (qT) and the duration of wind erosion (T). It is therefore necessary for modelers to consider both deflation of the bed and the time scale used when calculating sand transport or erosion rates. © 2018 John Wiley & Sons, Ltd.  相似文献   

18.
Different studies investigating the stability of mixed sediment have found that the fine fraction can either stabilize or mobilize the bed. This study aims to find where the transition between these two modes occurs for sandy sediment and to identify the underlying (grain-scale) processes. Flume experiments with bimodal sediment were used to investigate near-bed processes of a non-cohesive sediment bed, and in particular how the grain shape and the ratio of different grain sizes influence bed mobility. Medium sand (D50,c ≈ 400 μm) was mixed with 40 % fine material of different diameters (D50,f = 53; 111; 193 μm) and subjected to increasing flow velocities (U = 1.3–22.2 cm s-1). The bed mobility (i.e. the change of the bed level over time), turbidity and near-bed hydrodynamics were analysed. Selected results were compared with similar previous experiments with spherical glass beads. The findings indicate that, due to the complex grain shapes of natural sediment, a sand bed is more stable than a bed composed of glass beads. The grain-size ratio RD = Dc /Df between the coarse and fine grain diameters controls whether the mixed bed is stabilized or mobilized by the presence of fines, with the transition between the modes occurring at RD = 4–5.5. Mixed beds with a very low RD < 2 behave like a unimodal bed. The results suggest that RD and grain shape influence bed roughness, near-bed flow, bed microstructure and the flow into and through the upper bed layers, which subsequently governs bed mobility. The interplay between all these processes can explain the transition between the stabilizing effect (high RD, small pore space) and the mobilizing effect (low RD, large pore space) of a fine fraction in a grain-size mixture. © 2018 John Wiley & Sons, Ltd.  相似文献   

19.
The velocity of a wind‐blown sand cloud is important for studying its kinetic energy, related erosion, and control measures. PDA (particle dynamics analyser) measurement technology is used in a wind tunnel to study the probability distribution of particle velocity, variations with height of the mean velocity and particle turbulence in a sand cloud blowing over a sandy surface. The results suggest that the probability distribution of the particle velocity in a blowing sand cloud is stochastic. The probability distribution of the downwind velocity complies with a Gaussian function, while that of the vertical velocity is greatly complicated by grain impact with the bed and particle–particle collisions in the air. The probability distribution of the vertical velocity of ?ne particles (0·1–0·3 mm sands) can be expressed as a Lorentzian function while that of coarse particles (0·3–0·6 mm sands) cannot be expressed by a simple distribution function. The mean downwind velocity is generally one or two orders greater than the mean vertical velocity, but the particle turbulence in the vertical direction is at least two orders greater than that in the downwind direction. In general, the mean downwind velocity increases with height and free‐stream wind velocity, but decreases with grain size. The variation with height of the mean downwind velocity can be expressed by a power function. The particle turbulence of a blowing sand cloud in the downwind direction decreases with height. The variations with height of the mean velocity and particle turbulence in the vertical direction are very complex. It can be concluded that the velocity of a sand cloud blowing over a sandy surface is mainly in?uenced by wind velocity, grain impact with the bed and particle–particle collisions in the air. Wind velocity is the primary factor in?uencing the downwind velocity of a blowing sand cloud, while the grain impact with the bed and particle–particle collisions in the air are the primary factors responsible for the vertical velocity. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

20.
For the southern branch of the Rhine–Meuse estuary, The Netherlands, a two-dimensional horizontal suspended sediment transport model was constructed in order to evaluate the complicated water quality management of the area. The data needed to calibrate the model were collected during a special field survey at high river runoff utilizing a number of techniques: (1) turbidity probes were used to obtain suspended sediment concentration profiles; (2) air-borne remote sensing video recordings were applied in order to obtain information concerning the spatial distribution of the suspended sediment concentration; (3) an acoustic probe (ISAC) was used to measure cohesive bed density profiles and (4) an in situ underwater video camera (VIS) was deployed to collect video recordings of the suspended sediment. These VIS data were finally processed to fall velocity and diameter distributions and were mainly used to improve insight into the relevant transport processes, indicating significant erosion of sand from the upstream Rhine branch. For quantitative calibration of the model, the data from the turbidity profiles were used. Sedimentation and erosion were modelled according to Krone and Partheniades. The model results showed a good overall fit to the measurements, with a mean absolute error of 18 per cent (standard fault = 1 per cent), corresponding to concentrations of about 0·020 (upstream) to 0·005 kg m−3 (downstream). The overall correlation between observed and simulated suspended sediment concentrations was 0·85. The remote sensing video recordings were used for a qualitative calibration of the model. The distribution pattern of the suspended sediment on these photos was reproduced quite well by the model. However, a more accurate calibration technique is needed to enable the use of aerial remote sensing as a quantitative calibration method. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

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