Suspended Flux Research Articles

Sediment and Nutrient Retention in Ponds on an Agricultural Stream: Evaluating Effectiveness for Diffuse Pollution Mitigation

The creation of ponds and wetlands has the potential to alleviate stream water quality impairment in catchments affected by diffuse agricultural pollution. Understanding the hydrological and biogeochemical functioning of these features is important in determining their effectiveness at mitigating pollution. This study investigated sediment and nutrient retention in three connected (on-line) ponds on a lowland headwater stream by sampling inflowing and outflowing concentrations during base and storm flows. Sediment trapping devices were used to quantify sediment and phosphorus accumulations within ponds over approximately monthly periods. The organic matter content and particle size composition of accumulated sediment were also measured. The ponds retained dissolved nitrate, soluble reactive phosphorus and suspended solids during baseflows. During small to moderate storm events, some ponds were able to reduce peak concentrations and loads of suspended solids and phosphorus; however, during large magnitude events, resuspension of deposited sediment resulted in net loss. Ponds filtered out larger particles most effectively. Between August 2019 and March 2020, the ponds accumulated 0.306 t ha−1 sediment from the 30 ha contributing area. During this period, total sediment accumulations in ponds were estimated to equal 7.6% of the suspended flux leaving the 340 ha catchment downstream. This study demonstrates the complexity of pollutant retention dynamics in on-line ponds and highlights how their effectiveness can be influenced by the timing and magnitude of events.

Estimating metal loading into the sea from tidal rivers using total suspended solids and water quality models.

Metals are mainly transported with suspended sediments in tidal rivers, and it is difficult to describe the transformation process of metals. Freely dissolved metals and suspended metals (including acid-soluble, reducible, oxidizable, and residual metals) were separately analyzed according to a sequential extraction scheme. The regression of the observed suspended metals and total suspended solids (TSS) concentrations allowed us to couple the two pollutant types. TSS is a highly dynamic parameter, and a model can be developed to simulate TSS transport. Thus, a method including the following five steps was proposed to estimate the loadings of metals entering the sea using TSS concentrations and water quality models: (1) collecting and observing basic information on the hydrological conditions, pollution sources, and water quality of the studied river; (2) obtaining a regression model between the suspended metals and TSS and analyzing the potential of establishing a suspended metal flux model; (3) introducing a model describing the fluxes of water-soluble metals into the sea; (4) establishing a calculation model to determine the fluxes of suspended metals into the sea; and (5) characterizing the fluxes of metals into the sea. The method was programmed, and metal concentrations and fluxes could be characterized quickly when the basic river data were sufficient. In addition, if regional development scenarios could be set, metal loadings in all scenarios could be predicted through the procedure developed herein, and some effective suggestions on regional sustainable development might be proposed for decision makers. Integr Environ Assess Manag 2022;18:198-208. © 2021 SETAC.

Modeling spatio-temporal variability of suspended matter and its relation with hydrodynamic parameters in the northern Bay of Bengal

Variation of the non-algal suspended particulate matter (SM) was assessed, both on a spatial and temporal scale using satellite datasets. Located on one of the biggest deltas around the world, enormous rivers, and sediment discharge make this region’s suspended matters more prone to variations. Noticeable latitudinal transformations were found in SM as it ceased to exist after 21.5° N, with discrete seasonal changes that included summer SM concentration as high as 90–95 g/m3, while in winter it was 70–75 g/m3 on average near the river mouth. Such contrasting values are because of the variation in input from the nearby major rivers including Ganges–Brahmaputra, which in terms brings suspended load, particulate matters, nutrients, and other material fluxes along with it. However, other regions had a seasonally averaged concentration of 36 g/m3. Temporal analysis of SM revealed that it consisted of an increasing pattern between 2004 and 2010, but it gradually altered to decreasing trends from 2012 to 2018. Secchi depth, chlorophyll-a, nitrate, phosphate, silicate, sea level anomaly, current speed, temperature, and salinity are the hydrodynamic parameters those are considered in this article to find which one is well correlated with SM. Nitrate and silicate proved a significant positive correlation with SM, whereas chlorophyll-a, salinity, and Secchi depths were negatively correlated over the whole period. Eventually, further wavelet analysis gave rise to an interesting sign of the SM on chlorophyll-a for specific regimes of the time.

Analyse saisonnière et interannuelle de la dynamique des flux en suspension dans le bassin versant de l’oued Boukiou (nord-ouest de l’Algérie)

Pour comprendre l’impact des facteurs hydroclimatiques et géomorphologiques sur le transport solide dans les milieux méditerranéens semi-arides à l’échelle saisonnière et interannuelle, nous avons procédé à l’exploitation de données instantanées du régime hydro-sédimentaire du bassin-versant oued Boukiou (nord-ouest de l’Algérie) durant la période d’observation allant de 1972/1973 à 2004/2005. Cette approche a révélé l’ampleur du transport solide pendant les périodes d’érosion active de l’année. Par exemple, la contribution des crues s’est élevée à 74 % durant le printemps. La courbe cumulée des flux solides annuels transportés en suspension en période de crues a été marquée par des progressions très irrégulières relativement à celle des apports liquides. La décennie 1978/1979-1989/1990 marque bien le palier le plus productif en charge solide, soit un cumul de 54 % en apport solide sur les 33 années d’observation. En calculant la distribution statistique empirique des flux solides sur la période d’étude, nous avons défini le 50ème et le 95ème centile de leur distribution. Sur 50 % de la période de mesure, les flux ne dépassent pas 4 % du flux annuel moyen estimé à 50 740 tonnes. En revanche, pendant 5 % du temps, soit environ 18 jours par an, ils sont supérieurs à 70 %. Ces résultats témoignent de l’agressivité des rares averses sur des sols vulnérables aux variations climatiques irrégulière, ils aideront les décideurs pour la conception et l’utilisation des aménagements hydrauliques futurs dans cette région.

Quantifying bed‐related suspended load in gravel bed rivers through an analysis of the bedload‐suspended load relationship

AbstractSuspended load transport can strongly impact ecosystems, dam filling and water resources. However, contrary to bedload, the use of physically based predicting equations is very challenging because of the complexity of interactions between suspended load and the river system. Through the analysis of extensive data sets, we investigated extent to which one or several river bed or flow parameters could be used as a proxy for quantifying suspended fluxes in gravel bed rivers. For this purpose, we gathered in the literature nearly 2400 instantaneous field measurements collected in 56 gravel bed rivers. Among all standard dimensionless parameters tested, the strongest correlation was observed between the suspended sediment concentration and the dimensionless bedload rate. An empirical relation between these two parameters was calibrated. Used with a reach average bedload transport formula, the approach allowed to successfully reproduce suspended fluxes measured during major flood events in seven gravel bed alpine rivers, morphodynamically active and distant from hillslope sources. These results are discussed in light of the complexity of the processes potentially influencing suspended load in a mountainous context. The approach proposed in this paper will never replace direct field measurements, which can be considered the only confident method to assess sediment fluxes in alpine streams; however, it can increment existing panel tools that help river managers to estimate even rough but not unrealistic suspended fluxes when measurements are totally absent. © 2019 John Wiley & Sons, Ltd.

Response of lake-catchment processes to Holocene climate variability: Evidences from the NE Tibetan Plateau

Investigating the so-called Third Pole Environment (TPE) became a major concern during the last decades since it was recognized that the high-altitude region of the Tibetan Plateau (TP) is a key area for the understanding of cause-effect mechanisms driven by climate change and geodynamic processes. Studies on the hydro-climatic evolution during the Late Quaternary were mainly carried out by single lake records or alternatively by individual terrestrial sites. Integrated source-to sink studies considering lake–catchment interactions were extremely seldom utilized. We investigated such relationships in the Kuhai Basin on the north-eastern Tibetan Plateau and analysed sedimentary processes based on 30 onshore sections and three sediment cores from different locations and water depth in the lake basin. Grain size variations, ostracod assemblages, geochemical proxies and absolute dating (luminescence, radiocarbon, 210Pb/137Cs) were applied as key indicators that reveal interacting sediment fluxes under different hydro-climatic settings during the Younger Dryas interval and the Holocene. Our results indicate that wind-induced transportation processes and allocation of respective aeolian sands in the catchment are attributed to distinct phases of reduced effective moisture availability during summer time. Those phases corresponded to weak summer monsoon influence during the Younger Dryas interval, the Early Holocene (11.6–7.5 ka), dry-cold interlude (DCI: ca. 4.5–3.0 ka), Dark Ages Cold Period (DACP: ca. 1.8–1.1 ka) and the Little Ice Age (LIA: ca. 0.6–0.1 ka). Contemporaneous low lake levels during these periods corresponded with respective aeolian sand flux and variable composition of mixed sediments (fluvial and aeolian) in lake deposits. Different flux rates at the core sites could be assigned to local conditions in respect to inflow behaviour of individual drainage systems and nearshore morphology. Aeolian deposits in the catchment were not always preserved and underwent re-mobilisation during succeeding episodes and/or erosion during phases of high water availability. Wetter climatic conditions during the Mid-Holocene (ca. 7.5–5.1 ka), Roman Warm Period (RWP: ca. 2.8–1.5 ka) and Medieval Climate Anomaly (MCA: ca. 0.9–0.6 ka) revealed significant lake level rise due to enhanced river discharge, well documented by highest suspended flux rates, disappearance of ostracod communities at core sites and very low sand input. Climate shifts during the Holocene were linked to variations in effective moisture supply under the influence of the Asian summer monsoon (ASM) and the interplay with the mid-latitude westerlies (MLW). Cold-dry phases were likely a response to North Atlantic climatic anomalies transmitted by the MLW across the TP.

Sands Escaping Haeundae Beach

Lee, H.J.; Do, J.-D.; Kim, S.S., and Lim, H.S., 2018. Sands Escaping Haeundae Beach. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1006–1010. Coconut Creek (Florida), ISSN 0749-0208.Haeundae Beach has been hypothesized to lose sands from the nearshore of the western extremity of its pocket-beach system with a tidal range of 0.5 – 1.2 m. To test the hypothesis, a measurement station was located in this area to observe a suspended transport of sands near the seabed. The hydrodynamic measurements included water level, wave, currents and suspended sediment concentration with a benthic tripod for longer than one month of the 2013–2014 winter. In addition, a Telemac-2D tide model was run to simulate tidal currents for the same period of time as the measurements. A total of 6 events of two tidal cycles each were selected and analyzed to represent a variety of combinations of tidal phase, wave energy and wave direction. The results show that the suspended sand transport occurred continuously and was controlled predominantly by ebb-dominant tidal currents. Thus it was always directed offshore. Waves higher than 1 m sporadically took place during the measurements. However, high waves could just reorient the offshore suspended sand transport from obliquely to normal to the shoreline. This is because they created residual currents flowing roughly parallel to the shoreline. Neither offshore wave direction nor tidal phase evidently influenced the characteristics of residual currents. Therefore, the escape of the Haeundae sand from the area of interest has been proven to occur year round intrinsically by tidal currents. Waves intermittently contribute much to enhancing the suspended sand flux offshore by vigorous resuspension processes.

Partitioning sediment flux by provenance and tracing erosion patterns in Taiwan

AbstractWe critically evaluate the potential and limitations of an alternative way to calculate erosion rates based on petrographic and mineralogical fingerprints of fluvial sediments coupled with gauged sediment fluxes. Our approach allows us to apportion sediment loads to different lithological units, and consequently to discriminate erosion rates in different tectonic domains within each catchment. Our provenance data on modern Taiwanese sands indicate focused erosion in the Backbone Range and Tananao Complex of the retrowedge. Lower rates are inferred for the northern part of the island characterized by tectonic extension and for the western foothills in the prowedge. The principal factor of uncertainty affecting our estimates is the inevitably inaccurate evaluation of total sediment load, because only the suspended flux was measured. Another is the assumption that suspended load and bed load are derived from the same sources in fixed proportions. Additional errors are caused by the insufficiently precise definition of lithologically similar compositional end‐members and by the temporal variability of sediment composition at the outlet of each catchment related to the spatial variability of erosional processes and triggering agents such as earthquakes, typhoons, and landslides. To evaluate the robustness of our findings, we applied a morphometric technique based on the stream‐power model. The results obtained are broadly consistent, with local discrepancies ascribed to poorly constrained assumptions and choices of scaling parameters. Our local erosion estimates are consistent with GPS uplift rates measured on a decadal timescale and generally higher than basin‐wide results inferred from cosmogenic‐nuclide and thermochronology data.

Use of ADCPs for suspended sediment transport monitoring: An empirical approach

AbstractA horizontally mounted 300 kHz acoustic Doppler current profiler was deployed in Fraser River at Mission, British Columbia, to test its capability to detect size‐classified concentration of suspended sediment. Bottle samples in‐beam provide a direct calibration of the hADCP signals. We also deployed a 600 kHz vertically mounted ADCP from a boat in combination with bottle samples. Fraser River at Mission is 525 m wide with moderate suspended sediment concentration (up to 350 mg L−1 in our measurements, mostly silt), and a modest sand load only at high flows. We use an entirely empirical approach to calculate the sediment load using ADCPs to test the reliability of acoustic methods when assumptions embedded in the sonar equation about the relation between suspended sediment size and concentration, and acoustic signals are violated. vADCP calibration using matched individual bottle samples and acoustic backscatter departed from the expected theoretical relation. Calibration using depth‐averaged sediment concentration and acoustic backscatter more closely matched theoretical expectations, but varied through the season. hADCP calibrations conformed with theoretical expectations and did not exhibit seasonal variation. Silt and sand were successfully discriminated; however, silt dominates the correlations. We found no coherent relation between acoustic attenuation and silt concentration. In‐beam results are extended by correlation to estimate mean sediment concentration and total suspended flux in the entire channel: this auxiliary correlation cancels any calibration bias and permits monitoring of size‐classified suspended sediment in absence of detailed information of sediment grain‐size distribution.

Sediment transport dynamics in the swash zone under large-scale laboratory conditions

A laboratory experiment was carried out to study sediment transport dynamics occurring in the swash zone of a coarse-sandy beach built in a large-scale wave flume. Hydro- and morpho-dynamic as well as sediment transport data were collected using sensors mounted on a scaffold rig deployed in the lower swash zone close to the moving bed. The high resolution of near-bed data permitted quantitative evaluation of suspended and sheet flow contributions to the total sediment transport. Although sheet flow sediment fluxes were higher than suspended fluxes, the vertically integrated suspended sediment load overcame the sheet flow load during uprush and it was on the same order of magnitude during backwash. The observed cumulative sediment transport was generally larger than the morphological changes occurring shoreward of the rig location implying either an underestimation of the offshore sediment transport or an overestimation of the onshore fluxes obtained from concentration and velocity profile data. Low correlations were found between net swash profile changes and runup parameters suggesting that local hydrodynamic parameters provide little or no predictability of accretion and erosion of an upper beach which is near equilibrium. The balance between erosion and deposition induced by individual swash events brought a dynamic equilibrium with small differences between the profiles measured at the start and at the end of the run.

Estimation of the annual discharge of suspended matter by the rivers of North Siberia and the Far East

New estimates of the suspended sediment fluxes from the medium and large rivers of Siberia and the Russian Far East are presented on the basis of the calculations over the period of the instrumental surveys. The method of calculations accounting for the intra-annual discharge variability is considered and its hydrogeological substantiation is given. The obtained estimates are compared with the results of previous studies. The role of the geological evolution and glaciation history concerning the contemporary suspended sediment fluxes is shown. The prevalence of the valley (coastal and slope) generation of the suspended flux over the watershed generation on the territory of the Russian drainage basin is assumed.

Modeling the migration and accumulation of technogenic elements in the sedimentary strata of inland water bodies

Problems of pollution of water bodies are studied based on a theoretical description of migration and accumulation of suspended solids. The main stages of the study include the analysis of available field data, the development of mathematical models of interaction between suspended solid fluxes in the bottom zone, and numerical experiments. The scientific and methodological issues of studying pollutant spreading are discussed. Physical parameters are evaluated. The processes of pollution accumulation in silts are considered. Specific studies of technogenic pollutant migration in Valdai Lake are considered as examples.

Ambient suspended particulate matter and ionic speciation in Asian countries during 1998—2007

Atmospheric acid precursor emissions in Asia are increasing at a significant rate. This is expected to continue for the next several years. This main purpose for this study is to observe the concentration variations of PM(2.5), PM(2.5-10), PM(10), total suspended particulates (TSP), atmospheric particulates, and dry deposition fluxes of ionic species in Asian countries during the years 1998-2007. The results show that the average ionic species concentration order for chloride ions (Cl(-)) in PM(10) was China > Taiwan > Korea. The average ionic species concentration order for nitrate ions (NO(3)(-)) species in PM(10) was China > Taiwan > Korea for Asian countries. In addition, the average ionic species sulfate ion (SO(4)(2-)) concentrations in PM(10) were 13.248 and 18.497 (μg/m(3)) in Taiwan and China, respectively, during the years 1998-2006. However, the average ionic species concentrations order for ammonium ions (NH(4)(+)) in PM(10) was Taiwan > China > Korea the years 2000-2006. Moreover, the average ionic species concentration order for chloride ions (Cl(-)) in PM(2.5) was Japan > Taiwan > Korea > China in the years 1998-2006. And the average ionic species concentration order for nitrate ions (NO(3)(-)) in PM(2.5) was Korea > China > Japan > Taiwan for Asian countries during 1998-2006. Moreover, the average ionic species concentration order for sulfate ions (SO(4)(2-)) in PM(2.5) was China > Korea > Taiwan > Japan in the years 1998-2006. As for the average ionic species concentration order for ammonium ion (NH(4)(+)) in PM(2.5), China > Taiwan > Japan > Korea in the years 1999-2006. Finally, the mean ionic species of nitrate ions (NO(3)(-)), sulfate ions (SO(4)(2-)) and ammonium ions (NH4(+)) were found highest in China compared with the rest of the other Asian countries during the years 1998-2006.

Enhancing filterability of flat-sheet membrane by addition of cationic polymer for sludge thickening system

The efficiency of coagulation-coupled membrane filtration as an alternative process for sludge thickening was evaluated using various parameters that could influence the thickened sludge, such as mixed liquor suspended solids (MLSS) concentration, viscosity, critical flux and soluble microbial products. Dead-end filtration experiment and determination of critical flux were conducted to investigate the change in permeation across the membrane after addition of coagulant. PVDF flat-sheet membrane with 0.08 mm pore size was used in the experiment. Two separate submerged systems were run in parallel, one with coagulant and the other served as the control. A significant difference between the transmembrane pressures (TMPs) of the two systems was observed. It was found that an increase in soluble microbial products (SMPs) concentration decreases filtration flux, which in turn increases TMP. PSD analysis confirmed that larger flocs were formed after addition of coagulant. Confocal laser scanning microscopy (CLSM...

Cross-shore sediment transport and morphological response on a macrotidal beach with intertidal bar morphology, Truc Vert, France

A 3-week field investigation was conducted on a macrotidal beach with intertidal bar morphology with the aim of quantifying cross-shore sediment transport rates and beach response. Cross-shore transport rates were estimated in four different ways: (1) net transport from bed-level changes; (2) measured suspended sediment fluxes; (3) sediment fluxes associated with migrating wave ripples; and (4) total load transport predicted using the Bailard [Bailard, J.A. 1981. An energetics total load sediment transport model for a plane sloping beach. Journal of Geophysical Research, 86, 10938–10954.] model. Excellent qualitative agreement was found between the different measures under all recorded wave conditions, with onshore (offshore) sediment transport and beach accretion (erosion) observed under low-to- moderate (high) wave conditions. The agreement is due to the strong correspondence between the direction of mean cross-shore flows across the intertidal bar surface and that of the sediment transport. Significant onshore mean flows ( u = 0.1–0.2 m s − 1 ) were persistently observed under low wave conditions, and these were strongest in shallow water depths ( h < 1 m). These flows are attributed to the (weak) three-dimensional water circulation in the surf zone associated with the intertidal bar-rip morphology and caused onshore bar migration. Under high wave conditions, on the other hand, strong mean cross-shore flows ( u = 0.2–0.4 m s − 1 ), due to the bed return flow, were consistently directed offshore and resulted in bar destruction. Under low wave conditions, vertically-integrated suspended fluxes, ripple transport rates and predicted total transport fluxes were remarkably similar, but when the fluxes are integrated over a complete tidal cycle, they are considerably smaller than that derived from bed-level changes based on low tide surveys.

The effect of bedform dynamics on computing suspended sediment fluxes using optical backscatter sensors and current meters

The sensitivity of the suspended sediment flux is tested with respect to rapid changes in bed-level across the surf zone of a sandy beach. The suspended flux was computed using a fixed instrument array, but bed-level changes due to ripple migration caused the instrument elevations to be significantly changed during the course of the experiment. The nominal elevations of the instruments were adjusted during data processing (using the MOBS array) to maintain a fixed elevation with respect to bed-level changes. The resultant suspended sediment concentrations and fluxes were significantly different from the unadjusted data, and for the present data set O(35%) less when averaged over the tide. The maximum difference between adjusted and unadjusted fluxes may be O(260%). The results indicate that changes in bed-level, particularly those due to bedform migration, must be accounted for when processing OBS data if reliable estimates of suspended sediment transport are to be obtained in the field.

Geometry and dynamics of wave ripples in the nearshore zone of a coarse sandy beach

Extensive measurements of ripple characteristics and dynamics along with associated suspended sediment fluxes and hydrodynamic conditions were made in the shoaling and surf zones of a macrotidal coarse grained beach at Sennen Cove, Cornwall, England (median grain diameter 0.69 mm). Suborbital vortex ripples were observed during the majority of the study period with height ∼5 cm and length ∼35 cm. The scale and shape of the ripples did not vary significantly as the bed shear stress increased during wave shoaling and breaking. However, ripple migration rates (onshore directed) were strongly dependent on their location relative to the breakpoint, increasing from ∼0.1 cm min−1 under shoaling waves to 2 cm min−1 in the outer surf zone during low‐energy conditions. Farther inside the surf zone, ripples persisted but migration rates slowed, probably owing to the presence of the offshore‐directed mean flow which impedes landward migration of the ripples. Under low‐wave conditions (during which measured sediment fluxes peaked around the outer surf zone and decreased through the saturated surf zone), bed form transport rates under shoaling waves were of the same magnitude as net suspended sediment fluxes but at least an order of magnitude smaller in the outer surf zone. Under high‐energy conditions (during which suspended sediment fluxes in the surf zone were offshore directed owing to the presence of the seaward directed mean flow), bed form transport rates were several orders of magnitude smaller than suspended fluxes.

Influence of the macrotidal environment on the source to sink pathways of suspended flux in the Gulf of Kachchh, India: evidence from the Ocean Colour Monitor (IRS‐P4)

A series of tide‐synchronous satellite images, obtained from the Ocean Colour Monitor (OCM) onboard the Indian Remote Sensing Satellite (IRS‐P4), in situ measurements and hydrodynamic model simulations were used to describe dispersal pathways and sources of total suspended matter (TSM) in the Gulf of Kachchh, a macrotidal system with insignificant freshwater inputs. Strong alongshore currents are prevalent at the mouth that move in (out) clockwise during flood (ebb) and undergo cyclic, dynamic changes with the tidal phases. The Gulf, unlike other regions of the Indian coastline, has dynamic turbidity that is zonal (very high in the outer Gulf and in the creeks of the Gulf), particularly during flooding, and reduced in the central region throughout the entire tidal cycle. From this dynamic turbidity with regard to the prevalent currents, it is deduced that inland amplifying flood currents draw in TSM‐rich offshore waters into the Gulf, and are the major source of turbidity in the outer regions of the Gulf. In the inner Gulf, because of these high‐magnitude currents, scouring of the creek bed leads to resuspension to create higher turbidity. Most of the scoured flux sinks off the mouths of these creeks because of the fanning out of ebbing flows from the narrow creeks into the wider Gulf. The areas under specific influence of different sources of turbidity are delineated schematically.

ESTIMATING OF TRANSPORT OF SEDIMENT AND NUTRIENTS IN THE LOWER MEKONG BASIN

The transportation of sediment and nutrients in the lower Mekong basin was studied. The influence of a dam in the mainstream on the downstream area was analyzed by comparing data from before and after construction. No change of discharge was seen in the downstream area. However, the suspended sediment flux decreased significantly, and its ratio of decrease was higher near the dam. The daily data of suspended flux and nutrient flux was estimated from the relationship among the discharge and the suspended and nutrient fluxes. The balance of sediment and nutrients was calculated, and maps of their transportation were created. The tendency of deposition and erosion could be understood. Most suspended sediment of the mainstream was supplied from the upstream area of Chiang Saen. In contrast, all phosphorus was supplied from the tributaries and the river channel.

Evaluation of Longshore Transport Equations with OBS Sensors, Streamer Traps, and Fluorescent Tracer

Abstract Measurements of longshore sediment transport rate were conducted on a reflective to intermediate sandy beach during energetic sea breeze activity. The suspended load transport was obtained with optical backscatter sensors, current meters, and streamer traps, whereas the total load rate was measured with fluorescent sand tracer. The streamer trap measurements revealed an exponential vertical distribution of the suspended sediment flux, with the degree of vertical mixing decreasing in the onshore direction. A continuous time series of longshore suspended sediment flux across the surf zone was obtained by combining streamer trap measurements with data collected with surf zone instruments. Comparison of the suspended longshore flux with the total longshore flux derived from the dispersal of fluorescent tracer indicated that the relative contribution of suspended load to total load was ca. 35%. The movement of sand tracer further demonstrated that nearshore sediments were transported obliquely across ...