Journal articles on the topic 'Sediment transport direction'
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1
Abrantes, João R. C. B., Nuno E. Simões, João L. M. P. de Lima, and Abelardo A. A. Montenegro. "Two-dimensional (2D) numerical modelling of rainfall induced overland flow, infiltration and soil erosion: comparison with laboratory rainfall-runoff simulations on a two-directional slope soil flume." Journal of Hydrology and Hydromechanics 69, no. 2 (May 21, 2021): 140–50. http://dx.doi.org/10.2478/johh-2021-0003.
Abstract:
Abstract This paper presents a two-dimensional (2D) numerical model of soil erosion and sediment transport resulting from rainfall induced overland flow. It is a spatial and temporal dynamic model combining physical and empirical laws and comprises: i) An overland flow module that solves the two-dimensional unsteady water flow equations on an infiltrating surface; ii) A soil infiltration module that uses a combined Horton-SCS scheme; and iii) A soil erosion and sediment transport module that solves the two-dimensional sediment transport equation, distinguishing between rill erosion, interrill erosion and sediment deposition. The performance of the model was evaluated by comparing its results with observed data from laboratory rainfall-runoff experiments on a two-directional 2.00 × 2.00 m2 soil flume set at 1% and 10% slopes in the x- and y-directions, respectively. The x-direction produced remarkably lower runoff and transported sediments than the y-direction. The numerical model significantly underestimated x-direction lower values of runoff and transported sediments. However, in the y-direction the model presented very good performance. Overall, in total terms (x- plus y-direction), the numerically simulated graphs of runoff and sediment transport were in very good agreement with corresponding experimental measurements, demonstrating the laboratory proof-of-concept of the model.
2
Al-Salem, K., and A. Al-Rashed. "Modeling of Sediment Transport Using Wave Height action in Fialaka Marina." IOP Conference Series: Earth and Environmental Science 958, no. 1 (December 1, 2021): 012023. http://dx.doi.org/10.1088/1755-1315/958/1/012023.
Abstract:
Abstract Failaka Island is the second-largest and one of the most important islands of Kuwait from the point of view of tourism located in the north Arabian Gulf. It has a marina constructed in 1979 and managed by the Ministry of Communication (MOC) and a tourism enterprise, and is widely used for its ferry landing facility. The coastal waters around Failaka are turbid and current velocities tend to be as high as ~0.5 m/s during spring tide. The marina basin, with axial plan view dimensions of about 285 m by 260 m experiences shoaling of naturally flocculated fine (cohesive) sediment and coarse sand in the entrance channel and more generally in the southern half of the basin. A particularly noteworthy zone of heavy and visible shoaling is along the inner side of the south breakwater close to the entrance. The marina at Failaka Island is suffering from siltation and sediment deposing issues. This study was carried out numerically to assess the annual sedimentation, sediment direction, and longshore current from locations around the existing marina to help in a suggestion of the solutions to reduce the siltation and sediment deposing based on sediments transport direction on marina entrance. A newly developed numerical solution for annual longshore sediments transport was used to estimate the total sediment transport and its direction. The study shows that the annual sediment transport directions which affect the Fialaka marina entrance are coming from the south to north due to wave action.
3
Cheng, Wufeng, Shenliang Chen, Jun Zhu, Xiaojing Zhong, Jin Hu, and Junli Guo. "Identification of the Sediment Movement Mechanism via Grain Size and Shape: A Case Study of a Beach in Eastern Hainan Island in South China." Water 15, no. 20 (October 17, 2023): 3637. http://dx.doi.org/10.3390/w15203637.
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This paper used dynamic image analysis (DIA) to analyze the grain size and shape data of beach surface sediments in Bao’ding Bay, eastern Hainan Island, China, and explored the effects of sediment transport modes and beach morphology on the grain size–shape trend curves. This paper adopted a method of combining grain size cumulative frequency curves and grain size–shape trend curves to identify three sediment transport modes: suspension, saltation, and traction, and analyzed the characteristics of the grain size–shape trend curves under different beach morphologies (reflective, intermediate, and dissipative). This paper found that the grain size–shape trend curves can effectively indicate the sediment transport modes and improve the accuracy of subpopulation division; the grain size–shape trend curves showed different distribution characteristics in the cross-shore and longshore directions, which are closely related to the beach’s morphology and sediment transport direction. This paper provides a new method and idea for studying beach sediment transport and sedimentary environment using sediment grain size and shape data.
4
ABO ZED, ABO BAKER I. "Effects of waves and currents on the siltation problem of Damietta harbour, Nile Delta coast, Egypt." Mediterranean Marine Science 8, no. 2 (December 3, 2007): 33. http://dx.doi.org/10.12681/mms.152.
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This study evaluates the effect of prevailing dynamic factors on the sedimentation process in Damietta Harbour along the Nile delta coast of Egypt. The monitoring program spanned the period between 1978 and 1999 and included measurements of waves, currents and bathymetric profiles. The evaluation was based on determination of erosion and accretion rates, current regime, sediment transport, wave characteristics and wave refraction. Results revealed that the predominant wave direction from N-NW sector (86 %) throughout the year is responsible for generation of a longshore eastward current. Less frequent waves from the N-NE sector generate an opposing longshore westward current. The refraction pattern for the prevailing wave direction indicates that the harbour and its navigation channel are located within a divergence of wave orthogonal and in an accretion sediment sink area. The annual net rate of littoral drift on the western side of the harbour is about 1.43 * 105 m3 (accretion), while the annual net rate of littoral drift on the eastern side is about 2.54 * 105 m3 (erosion). Currents fluctuate tremendously in speed and direction, especially during the winter months. Hence, sediment transport takes place in offshore, eastward, and onshore directions. Progressive vector diagrams show that the largest near bottom offshore, onshore and easterly net drift occurs during summer, spring and winter respectively. The onshore sediment transport generated during spring and summer plays an important role in the redistribution of eroded sediments during the winter. The overall study of dynamic factors indicated that the harbour site is characterized by eastern, western, offshore and onshore sediment movements. Therefore, the north-south orientation of the navigation channel, with its depth greater than the surrounding area, interrupts sediment drift from different directions and reduces the current speed. Consequently, the sediments sink within the navigation channel from different directions. The sources of sediments contributing to the siltation process of the harbour and its navigation channels are mainly derived from the Rosetta promontory, Burullus beaches, Damietta promontory and from offshore and the dumping area.
5
Shen, Jian, Dianci Chi, and Bingrou Xi. "Sediment distributions and transport patterns in the Pearl River Estuary and its adjacent coastal ocean." Advances in Engineering Technology Research 8, no. 1 (October 19, 2023): 398. http://dx.doi.org/10.56028/aetr.8.1.398.2023.
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Coastal sediment is important for the development of river deltas and for carrying both nutrients and pollutants into estuaries and coasts. Totally 265 surficial sediments collected from the Pearl River Estuary and its adjacent coastal ocean were analyzed by using Gao-Collins method to study the sediment transport path and deposition center. The Pearl River Estuary was an area of sandy mud sediment and showed some muddy patches. There were 5 distinguishable sediment convergence centers, which represent 3 types of sediment transport patterns and hydrodynamic environments. The net sediment transport pathways in the estuary and shelf sea were mainly in the offshore and landward direction, respectively. The analyzed results indicated that the main part of muddy sediment was confined to the mouth of the estuary due to the combined effects of the expansion and salinity intrusion.
6
Adel, Mnaf, and Ali N. Hilo. "The Effects of submerged vanes inclination angle on sediment transport into sub-channel." Wasit Journal of Engineering Sciences 11, no. 1 (April 1, 2023): 105–15. http://dx.doi.org/10.31185/ejuow.vol11.iss1.414.
Abstract:
The sub-channels that branch from the larger rivers may be manmade or natural. From the major channels, these sub-channels transfer sediments and water. The deposition of sediments at the entrance, sub-channel is a significant research challenge because it threatens the sub-facilities channel's and reduces the sub-carrying channel's capacity. Therefore, submerged vanes were used to reduce the amount of sediment entering the sub-channel. The goal of the vanes is to reduce the amount of sediment entering the sub-channel, hence redistributing sediment at the sub-entry channel's . They are vertically aligned with the flow direction and tilted at a certain angle. A physical model of the main channel, a sub-channel at a right angle, and a sediment feeder mechanism were developed. 51 tests were undertaken, 3 with submerged vanes and 48 without, with a varying number of submerged vanes (7, 5, 3 and 1). And angling it at various angles (10˚, 20˚, 30˚, and 40˚) in the discharge direction and with three sub-discharges of (19.1, 27 and 30.5 l/s), the sediment concentration flow was (6 kg/h). The weights of the sediments in sub-channel were calculated, and it was found that there is an effective use of these vanes and that the least amount of sediments is achieved when the angle is (20ᵓ). It was observed that the performance of the submerged vanes was significantly improved when there was a decrease in the discharge of the sub-channel.
7
Walstra, Dirk-Jan, J. De Vroeg, J. Van Thiel de Vries, C. Swinkels, A. Luijendijk, W. De Boer, R. Hoekstra, et al. "A COMPREHENSIVE SEDIMENT BUDGET FOR THE MISSISSIPPI BARRIER ISLANDS." Coastal Engineering Proceedings 1, no. 33 (October 25, 2012): 81. http://dx.doi.org/10.9753/icce.v33.sediment.81.
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In order to conceive any realistic plan for post-Katrina island restoration, it is necessary to understand the physical processes that move sand along the littoral drift zone off the coast of Mississippi. This littoral zone influences the character of the Mississippi barrier islands as they exist in an ever changing cycle. To help in this understanding, a sediment transport model was conducted to establish a current sediment budget for the islands. This study evaluated the existing regional sediment transport magnitudes and directions for the Mississippi and Alabama barrier islands fronting Mississippi Sound including daily conditions and hurricanes. A method was developed to incorporate all relevant hurricanes from 1917 to 2010 in the analysis. For the long term average net longshore transport along the southern shorelines of the barriers (i.e. exposed to the Gulf of Mexico), the contribution of year-averaged conditions and hurricanes are of similar order of magnitude, although the mean annual percentage occurrence of hurricanes is no more than about 3%. Along the northern shores (Mississippi Sound side) the transport is considerably smaller and the contributions of cold fronts and hurricanes to the sediment transports are more or less equal. For the year-averaged conditions (excluding hurricanes) a westward directed net transport is found. The net effect of the historic hurricanes is also westward in direction. However, for individual hurricanes (e.g. Camille and Katrina) the net transport along Ship Island can be directed eastward due to the dominance of ebb flows after the eye of the hurricane had passed.
8
Wang, Hongbing, Yuxi Wu, Xiaoming Wan, Lu Xia, and Si Wang. "Grain Size Characteristics of Surface Sediments and Their Migration Trends in the Nearshore Waters of East Guangdong." Sustainability 15, no. 14 (July 15, 2023): 11069. http://dx.doi.org/10.3390/su151411069.
Abstract:
By collecting surface sediment samples from 158 stations in the near-shore waters of eastern Guangdong, grain size analysis and grain size parameter calculations were performed to explore the characteristics and migration trends of surface sediments in the area. The analysis of the grain size results showed that the surface sediments in the nearshore waters of east Guangdong could be classified into nine sediment types, mainly including seven types of gravel sand ((g)S), gravel muddy sand ((g)mS), gravelly mud ((g)M), sand (S), silty sand (zS), sandy silt (sZ) and silt (Z). The relative percentages of gravel, sand, silt and mud were 0.7%, 40.56%, 46.7% and 12.04%, respectively. The average grain size varied from −2φ to 8φ, with an average of 4.94φ. The selection coefficient ranged from 0.44 to 3.78, with an average value of 1.8. The skewness distribution ranged from −0.34 to 0.67, with an average value of 0.07. By extracting and analyzing the spatial distribution information of grain size in the study area, using the Gao–Collins migration trend analysis method and incorporating dynamic factors such as tidal currents and waves, the transport direction and trend of surface sediments in the study area could be analyzed and inferred. The results show that the surface sediment migration trend was significant, migration on the north side of Nan’ao Island was in an east-to-west direction, and the sediment of Yifeng River was mainly deposited to the sand spout at the mouth of Lianyang River. After southward transport from the Houjiang waterway, the migration was mainly southeastward and the trend was quite significant until the 20 m isobath, where the trend gradually decreased. The sediments of the Rongjiang River were mainly deposited outside the mouth of Niutian Yang and Rongjiang River, and the surface sediments of Guang’ao Bay and Haimen Bay migrated in the northwest–southeast direction. After the 30 m isobath, the southeast corner of the study area migrated in the southeast–south direction. This sediment transport pattern revealed by the grain size migration trend is in good agreement with the physical and hydrodynamic conditions of the study area and provides an important reference for decisions regarding port dredging and waterway management in the area.
9
Anokhin, V. M., O. M. Vinogradova, I. M. Pyatov, and D. S. Dudakova. "Longshore Sediment Transport in Lake Ladoga Based on Analyses of the Heavy Mineral Fraction of Sand in Coastal Sediments." Известия Русского географического общества 155, no. 3-4 (December 1, 2023): 3–16. http://dx.doi.org/10.31857/s0869607123030023.
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Abstract—In order to identify the directions of transport of coastal sediments of Lake Ladoga, heavy mineral fraction was extracted from sand samples collected on all types of its shores. The mineral composition, size and roundness of particles − features characterising the degree of reworking of coastal sediments − were assessed under a microscopic analysis. We identified 4 clusters with similar degrees of reworking of the source material, which, based on the results of the factor analysis, were ranked by relative transport distance from insignificant to very significant. The maximum number of samples with small transport distances was found on the northern shores of the lake, which can be explained by the location of bedrock shores − the main sources of clastic material in the lake. Samples with maximum transport distances are relatively evenly distributed along all shores of the lake. The analysis of the results showed that on all shore reaches there is a transport of heavy fraction of bottom sediments in a certain direction: on the southern shore – to the west, on the western shore – to the north, on the northern shore – to the east and on the eastern shore – to the south-east. This allows us to conclude that there is a long-term trend of coastal sediment transport along the shores of Lake Ladoga in a clockwise direction.
10
Rachman, Cyril, and Yuyun Qomariyah. "INVESTIGATING THE LITTORAL TRANSPORT OF SEDIMENT ALONG THE NASESE COASTLINE, SUVA, FIJI ISLANDS." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 48. http://dx.doi.org/10.9753/icce.v36v.sediment.48.
Abstract:
The research investigated the current Nasese Coastline area from the impact of Littoral transport, a term used for the transport of non-cohesive sediments, i.e. mainly sand, along the foreshore and the shoreface of Nasese due to the action of the breaking waves and the longshore current. The littoral transport is also called the longshore transport or the littoral drift. The theoretical concept coastal sediment properties can be used to evaluate properties of sediment on site to avoid serve impacts towards the Suva Port in the future. The method used was on-site measurement by surveying to generate coastal profiles. Along with this, 1464 hours of wind data for the months of November and December 2019 were used to generate the frequency of the magnitude of Wind and the Direction using Wind Rose Plots for Meteorological Data. The movement of the sediments through the Beach Profiles agrees with the output generated Wind Directions. Therefore, Suva Port, may consider this situation in terms of the routine maintenance of dredging in order to sustain the acceptable depth of the Sea Port.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/vW05xoiNa_w
11
Budiman, Farid, Mochammad Meddy Danial, Jasisca Meirany, Arfena Deah Lestari, and Vivi Bachtiar. "STUDY OF WAVE DOMINANT DIRECTIONS ON SEDIMENT TRANSPORT IN THE ESTUARY OF KAPUAS RIVER, PONTIANAK, WEST KALIMANTAN." Jurnal Teknik Sipil 23, no. 1 (February 28, 2023): 112. http://dx.doi.org/10.26418/jtst.v23i1.57917.
Abstract:
The Kapuas River is a very important water transportation route in West Kalimantan, crossing 5 districts and 1 city. The problem that occurs in the shipping lane on the Kapuas River is the accumulation of severe sediment at the mouth of the estuary. This becomes an obstacle for ships with large loads to sail, for this reason, this research was carried out. The purpose of this study was to determine the dominant direction of waves and sediment transport. This study was calculated using the CERC (Coastal Engineering Research Centre) method and using secondary data. It was found that the dominant wave direction came from the North (N) direction with an incidence percentage of 22.496%. Percentage of occurrence from the Northwest (NW) direction is 12.145%, from the West (W) direction is 6.253%, and from the Southwest direction (SW) is 11.724%. While the amount of sediment transport from the Northwest is -393062.1306 m3/year with the characteristics of the sediment being clay, from the West it is -250.1672 m3/year with the sediment characteristics being silty clay and from the Southwest, it is 579090.2782 m3/year with sediment characteristics of silty clay. The results of the sediment calculation have negative results which indicate that there is no sediment transport from the Northwest and West, but the sediment is deposited. For this reason, it is necessary to carry out appropriate handling of these problems to reduce sediment build-up in the study area.
12
Karditsa, A., and S. E. Poulos. "The application of grain size trend analysis in the fine grained seabed sediment of Alexandroupolis Gulf." Bulletin of the Geological Society of Greece 47, no. 1 (December 21, 2016): 157. http://dx.doi.org/10.12681/bgsg.10917.
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Grain size trend analysis is a method that determines sediment transport direction, based on the relationship of grain size parameters (mean size, sorting, skewness). The application of the method in the seabed sediments of Alexandroupolis Gulf showed that there are three different sub areas of distinctive sediment movement of bottom sediments (water depths <40 m):(i) the eastern part, which is mainly influenced by the Evros river water/sediment influxes; (ii) the central part that is primarily controlled by the wave activity; and, (iii) the western part that is mainly influenced by the wind driven and/or thermo-saline coastal circulation.
13
Synková, Jana. "Possibility of utilization of direction construction in river revitalization." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 57, no. 5 (2009): 279–84. http://dx.doi.org/10.11118/actaun200957050279.
Abstract:
Directing and concentrating structures are used mainly on water coursers with unstable channel and major sediment transport or in areas with major bank erosion. The main purpose of these structures is to redirect water flow from the stressed and very often eroded bank to the centre of the channel or other parts of the channel, where the water flow may be used e.g. for dispersion of unsuitable deposit before its eventual stabilization by natural succession.Another important goal is to achieve a desired change of the stream channel by using the transporting power of the water flow and targeted depositing of sediment. In the area of the deflecting structure (deflector), so-called hydraulic shadow also appears where sediment deposits. The objective is to achieve depositing of sediments at desired places of the stream.It is possible to design a whole range of suitable or less suitable types of flow deflectors. In our article, we will particularly focus on problems of revitalization of a water course; that is design of structures from biological or biotechnical elements for channel stabilization.
14
Lai, Yong, and Kuowei Wu. "A Three-Dimensional Flow and Sediment Transport Model for Free-Surface Open Channel Flows on Unstructured Flexible Meshes." Fluids 4, no. 1 (January 24, 2019): 18. http://dx.doi.org/10.3390/fluids4010018.
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Three-dimensional (3D) hydrostatic-pressure-assumption numerical models are widely used for environmental flows with free surfaces and phase interfaces. In this study, a new flow and sediment transport model is developed, aiming to be general and more flexible than existing models. A general set of governing equations are used for the flow and suspended sediment transport, an improved solution algorithm is proposed, and a new mesh type is developed based on the unstructured polygonal mesh in the horizontal plane and a terrain-following sigma mesh in the vertical direction. The new flow model is verified first with the experimental cases, to ensure the validity of flow and free surface predictions. The model is then validated with cases having the suspended sediment transport. In particular, turbidity current flows are simulated to examine how the model predicts the interface between the fluid and sediments. The predicted results agree well with the available experimental data for all test cases. The model is generally applicable to all open-channel flows, such as rivers and reservoirs, with both flow and suspended sediment transport issues.
15
Alley, Richard B., Daniel E. Lawson, Edward B. Evenson, and Grahame J. Larson. "Sediment, glaciohydraulic supercooling, and fast glacier flow." Annals of Glaciology 36 (2003): 135–41. http://dx.doi.org/10.3189/172756403781816121.
Abstract:
AbstractGlaciers often advance over proglacial sediments, which then may enhance basal motion. For glaciers with abundant meltwater, thermodynamic considerations indicate that the sediment–ice contact in the direction of ice flow tends toward an angle opposed to and somewhat steeper than the surface slope (by slightly more than 50%). A simple model based on this hypothesis yields the extent of over-ridden sediments as a function of sediment thickness and strength, a result that may be useful in guiding additional fieldwork for hypothesis testing. Sediment-floored as well as rock-floored overdeepenings are common features along glacier flow paths and are expected based on theories of glacier erosion, entrainment, transport and deposition.
16
Fernandes, Elisa, Pablo da Silva, Glauber Gonçalves, and Osmar Möller. "Dispersion Plumes in Open Ocean Disposal Sites of Dredged Sediment." Water 13, no. 6 (March 15, 2021): 808. http://dx.doi.org/10.3390/w13060808.
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Management of estuarine systems under anthropogenic pressures related to port settlement and development requires thorough understanding about the long-term sediment dynamics in the area. In an era of growing shipping traffic and of ever larger ships; millions of tons of bottom sediments are dredged annually all over the world and the major question concerning dredging operations is not whether they should be done, because it is obvious that they are extremely important and necessary, but where the dredged sediments can be disposed of with the least possible ecological impact. The present study involves the evaluation of transport trends of dredged material from a turbid estuary disposed of in four different open ocean disposal sites using numerical model techniques, aiming to contribute to minimizing potential environmental impacts and maximizing efficiency of the dredging operation. The study is carried out in southern Brazil, investigating the fate of dredged material from the Port of Rio Grande, located inside the Patos Lagoon estuary. Simulations were carried with the TELEMAC-3D model coupled with the suspended sediment (SEDI-3D) module and incorporating results from the wave module (TOMAWAC) to evaluate the dispersion of the suspended sediment plume and its interaction with coastal currents. This modeling structure proved to be a valuable tool to study the hydrodynamics and sediment transport pathways in estuarine and coastal areas. Results indicate that the natural Patos Lagoon coastal plume was observed under the predominant ebb flows and NE winds, promoting fine sediment entrapment south of the mouth of the lagoon (in front of Cassino Beach). The dispersion plumes in the disposal sites responded to the wind intensity and direction and did not present any transport tendency towards Cassino Beach. Part of the dredged sediment disposed of in the proposed alternative sites located in deeper areas (Sites B and C) left the site and was transported parallel to the coast (SW–NE direction) according to the wind direction (NE–SW). The area where the disposal sites were located took around 4 days to recover from the dredging operation and reach the usual suspended sediment concentrations and the actual Port of Rio Grande Licensed Site for dredged material proved to be the best alternative among the investigated options.
17
Cerkowniak, Grzegorz R., and Marek Kowalewski. "Transport of Fine Sediments in MarineWaterbodies Near River Mouths: Preliminary Results." Archives of Hydro-Engineering and Environmental Mechanics 65, no. 4 (December 1, 2018): 255–75. http://dx.doi.org/10.1515/heem-2018-0016.
Abstract:
AbstractTransport of fine sediments depends mainly on the efficiency of flocculation. Flocculation, understood as the result of simultaneous processes of aggregation of particles and floc break-up, is a common phenomenon in marine environments. It is typical of fine sediments. This study presents a mathematical model of fine sediment transport. A model of flocculation is an important part of this model. Its main assumption is that flocculation is governed by turbulence. The model was qualitatively tested in a simplified theoretical waterbody. Such factors as the wind direction, wind speed, river discharge and concentration of suspension in the river were investigated. The results show that the proposed model describes reasonably well the lithodynamic processes characteristic of fine flocculating sediments. Thus it seems possible to apply it for description of fine sediment transport under real wave–current conditions that occur in many marine waterbodies near river mouths.
18
Yue, Zheng Wen, Rui Qiang Zhang, and Tian Ming Gao. "Research of Sand Drift Potential and Wind Conditions in Xilamuren Grassland." Advanced Materials Research 955-959 (June 2014): 3499–504. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.3499.
Abstract:
Using the wind data in Xilamuren desert grassland by wind erosion monitoring system to record the years of 2011-2013 as the research foundations, through the statistics of wind and sand transport potential research, from aspect of the characteristics of blown sand environment Xilamuren desert grassland which can be shown the research area are mainly affected by the westerly, Northwest westerly wind or northwest wind three group interaction. The study area of annual sediment potential had mainly effected by westerly and Northwest westerly wind direction ,with wind direction variability index in 0.51°~ 0.61°, belonging to the intermediate ratio range of direction. Annual sediment potential was between 135.95VU ~214.1VU,belongs to the small and medium-sized wind environment. The spring sand transport potential and the resultant sand transporting potential than the other three seasons of sediment transport potential and the resultant sand transporting potential, the main direction of resultant sand transporting potential to Northwest westerly direction, wind direction variability index is relatively large. For spring grassland vegetation coverage rate is lowly, wind speed is large, characteristics of sand is belong to rich material, which should we to retain sand material through the appropriate protective measures to reduce wind erosion. So analyzing the wind regime and the theory of sediment transport potential calculation, provide scientific theoretical basis for the prevention and treatment of sand and harm to the Xilamuren grassland sand flow process.
19
Guerrero, Rocío, Juan L. Valenzuela, Alejandro I. Monterroso, and Carlos Asensio. "Impact of Wind Direction on Erodibility of a Hortic Anthrosol in Southeastern Spain." Agriculture 11, no. 7 (June 24, 2021): 589. http://dx.doi.org/10.3390/agriculture11070589.
Abstract:
We tested an efficient, easily and economically manufactured wind-transported particle collector of our own design, called a multidirectional trap (MDt), on fine-tilled Anthrosols. Results from the logs of nine vaned masts, each with four MDt collectors at different heights, showed a clear predominance of northeast and south winds. After analyzing sediment transport rates and their balance, we found that sediments from the south were being deposited rather than lost. A large amount of phyllosilicates, which are highly adhesive sediments, and therefore, increase aggregation, decreasing erodibility, were captured in the upper traps. Moreover, they are rich in calcium carbonate, mainly calcite, which is a powerful aggregate, and therefore, also decreases their wind erodibility. Sediments from the northeast, however, with almost double the total mass transport, contained the largest amount of captured quartz, promoting abrasion and increasing soil erodibility. Nevertheless, large amounts of organic matter found in sediments from the NE led to some aggregation, which balances material lost.
20
Zhang, Cun Yong. "Suspended Sediment Transport in Lianyungang Nearshore Area." Applied Mechanics and Materials 170-173 (May 2012): 2204–8. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2204.
Abstract:
Hydrological observations at 13-19 stations were conducted synchronically in Lianyungang nearshore area during the spring and half tide in winter and summer respectively. Data of suspended sediment concentrations (SSC), currents and water levels at observation stations were used to study the suspended sediment transport by the method of mechanism decomposition. The advection transport plays an important role during the whole observations, with the direction generally same to the flood current. The tidal pumping transport plays a significant role in the nearshore area, which is the main factor for the periodical variation of SSC. The direction of the tidal pumping transport is mainly toward the land, which indicates that the periodic component of SSC is transport to the land with the form of peaks in the bottom layer. The results may help to improve understanding of the coastal engineering and environmental applications related to sediment transport.
21
Pourteimouri, Paran, Geert Campmans, Kathelijne Wijnberg, and Suzanne Hulscher. "BEACH BUILDINGS ON POLES AND THEIR IMPLICATIONS FOR DUNEWARD SEDIMENT TRANSPORT: A NUMERICAL STUDY." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 23. http://dx.doi.org/10.9753/icce.v37.sediment.23.
Abstract:
Sandy beaches are attractive worldwide. An increasing number of beach users induces a higher demand for buildings at the beach-dune interface. These buildings alter the local flow speed and direction which, in turn, changes the aeolian sand transport around buildings, and the sediment supply to the dunes. This study aims to understand how and to what extent beach buildings on poles affect duneward sediment transport.
22
Nielsen, Peter. "TOWARDS MODELLING COASTAL SEDIMENT TRANSPORT." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 144. http://dx.doi.org/10.9753/icce.v21.144.
Abstract:
Sediment transport data from the field and laboratory tests are used to gain insight into two fundamental questions. Firstly: What is the relative importance of coexisting waves and currents for the resulting sediment transport? Secondly: Is the influence of grain size as strong as traditional models predict, or is it as weak as the empirical CERC-formula indicates? Wave tank data reveal that the oscillatory velocity will in most cases determine the direction as well as the magnitude of the shore normal sediment transport, and wave flume data on shore normal transport as well as field data on littoral drift show weaker grain size dependance than traditional sediment transport models predict. It is suggested that wave dominance as well as weak grain size dependence are manifestations of the fact that the dominant transport mechanisms are often more organised than the diffusion process on which many traditional models are based.
23
Zanke, Ulrich, Aron Roland, and Andreas Wurpts. "The Reason for the Rise in Critical Shear Stress on Sloping Beds." Water 15, no. 16 (August 18, 2023): 2976. http://dx.doi.org/10.3390/w15162976.
Abstract:
In sediment mechanics, the conditions for the onset of sediment movement are of particular importance. However, despite decades of research, questions remain unanswered. Thus, physical logic suggests that sediments move more easily on beds inclined in the direction of flow than on horizontal beds and that transport rates are correspondingly increased. However, numerous studies have shown that sediments require increased rather than decreased shear stress to move on sloping beds and that transport rates are lower instead of increased. Since an early publication on this issue by Ashida and Michiue in 1973, many possible effects have been suggested for this apparent contradiction. The literature almost consistently concludes that high relative roughness (d/h), i.e., low water cover (h/d), is mainly responsible for this contradictory effect. This is true for current-induced sediment transport and for the initiation of debris flow. In this paper, an analytical solution for the effect of small water coverage on the transport process is developed. Effects of low coverage also occur on beaches during wave runup and runoff and thus control the formation of steep or less steep beaches. The present paper shows that the effect of turbulence damping occurring under low water coverage plays a decisive role here.
24
Mir-Gual, Miquel, Guillem X. Pons, and Irene Delgado-Fernández. "Field-Measurement of Surface Wind and Sediment Transport Patterns in a Coastal Dune Environment, Case Study of Cala Tirant (Menorca, Spain)." Journal of Marine Science and Engineering 11, no. 12 (December 14, 2023): 2361. http://dx.doi.org/10.3390/jmse11122361.
Abstract:
Blowouts are integral features of coastal dune fields. Their presence enhances both geomorphological and ecological diversity and enables the movement of sand by wind. Their role as a ‘transport corridor’ may be, however, considered negative from a coastal management perspective in heavily touristic areas, where the existence of blowouts close to the foredune can enhance the loss of sediment from the beach. This paper investigated the relationship between airflow dynamics and patterns of sediment transport from the beach to established dunes through a trough blowout located on the foredune. Seven three-cup anemometers were used to measure wind speed and direction over a 24 h sampling period at a frequency of 1 min under onshore (parallel to the blowout axis) medium and high wind speeds (max of 17.9 ms−1). To measure sediment transport, a total of 12 vertical sand traps were located at three positions along the length of the deflation basin. The results indicated that small amounts of sediments went into the blowout from the beach and that the highest rates of sediment remobilization took place within the deflation basin. These results highlight two processes: (a) flow channelization induced by the blowout topography caused an increase in wind speed and sediment transport toward the depositional lobe, and (b) the presence of embryo dunes and herbaceous vegetation at the beach–blowout boundary effectively reduced the amount of sediment transport from the beach to the landform. The results confirmed the significant role that vegetation plays in controlling sediment movement and conserving the beach–dune system.
25
Tribhaskoro, Whisnu, Sugeng Widada, and Warsito Atmodjo. "Sedimentasi di Sekitar Bangunan Groin di Pantai Komodo Kota Tegal." Indonesian Journal of Oceanography 4, no. 3 (August 27, 2022): 01–12. http://dx.doi.org/10.14710/ijoce.v4i3.13261.
Abstract:
Bangunan pelindung pantai berupa groin yang terdapat pada Pantai Komodo yaitu memiliki fungsi sebagai penahan aktivitas transport sedimen yang terjadi pada sepanjang pantai sehingga dapat meminimalisir terjadinya abrasi yang telah terjadi. Tujuan dari penelitian ini adalah menghitung dan menganalisis pengaruh gelombang laut terhadap angkutan sedimen serta mengidentifikasi besaran laju sedimentasi yang disebabkan olah gelombang laut yang disebabkan oleh angin di Pantai Komodo Kota Tegal. Data utama yang digunakan yaitu data laju sedimentasi yang diambil menggunakan sedimen trap dan data gelombang lapangan yang diambil menggunakan ADCP sedangkan untuk data pendukung yaitu data angin selama 11 tahun yang diperoleh dari Ogimet dan Peta RBI Kota Tegal. Penentuan lokasi pengamatan dilakukan dengan metode Purposive Sampling yang mewakili kondisi secara keseluruhan daerah dan memperhatikan kemudahan pencapaian. Hasil yang diperoleh Gelombang pada Musim Barat datang dari arah Barat Laut dengan membentuk sudut gelombang pecah sebesar 35,520o dan kecepatan arus sepanjang pantai sebesar 1,109 m/dt, pada Musim Peralihan 1 yaitu dari arah Barat Laut dengan membentuk sudut gelombang pecah sebesar 9,081o dan kecepatan arus sepanjang pantai sebesar 0,322 m/dt, pada Musim Timur arah gelombang datang dominan dari Timur Laut dengan membentuk sudut gelombang pecah sebesar 15,355o dan kecepatan arus sepanjang pantai sebesar 0,645 m/dt, sedangkan untuk Musim Peralihan 2 dari arah Timur Laut dengan membentuk sudut gelombang pecah sebesar 9,041o dan kecepatan arus sepanjang pantai sebesar 0,320 m/dt. Transpor sedimen terbesar terjadi pada Musim Barat sebesar 1307,421 m3/hari, sedangkan terkecil terjadi pada Musim Peralihan 2 sebesar 230,310 m3/hari dan laju sedimentasi terjadi pada groin yang berkisar dari 9,049 gr/m2/hari – 21,527 gr/m2/hari dengan jenis sedimen yaitu pasir.Kata kunci : arus sejajar pantai, laju sedimentasi, transport sedimen, groin dan Pantai Komodo. Coastal protection buildings in the form of groin found on Komodo Beach have a function as a barrier to sediment transport activities that occur along the coast so as to minimize the occurrence of abrasion that has occurred. The purpose of this study is to calculate and analyze the effect of waves on sediment transport and to identify the magnitude of the sedimentation rate caused by sea waves caused by wind at Komodo Beach, Tegal City. The main data used are sedimentation rate data taken using sediment traps and field wave data taken using the Acoustic Doppler Current Profiler (ADCP) while for supporting data, namely wind data for 11 years obtained from Ogimet and the RBI Map of Tegal City. Determination of the location of observations is done based on conditions that can represent the overall condition of the area and pay attention to the ease of achievement. The results obtained from the waves in the West Season come from the North West by forming a breaking wave angle of 35,520° and the current speed along the coast is 1,109 m/s, in Transition Season 1 that is from the North West direction by forming a breaking wave angle of 9,081° and the current velocity along the coast is 0,322 m/s, in the East Season the direction of the incoming waves is dominant from the North East by forming a breaking wave angle of 15,355° and the current velocity along the coast is 0,645 m/s, while for Transitional Season 2 from North East direction by forming a breaking wave angle of 9,041° and the current velocity along the coast of 0,320 m/s. The largest sediment transport occurred in the West Season of 1307,421 m3/day, while the smallest occurred in Transitional 2 Season of 230,310 m3/day and the sedimentation rate occurred on the the groin which ranged from 9,049 gr/m2/day - 21,527 gr/m2/day with the type of sediment, which is sand.Keywords : longshore current, sedimentation rate, sediment transport, groin and Komodo Beach
26
Ostrowski, Rafał. "Influence of Wave Shape on Sediment Transport in Coastal Regions." Archives of Hydro-Engineering and Environmental Mechanics 65, no. 2 (December 1, 2018): 73–90. http://dx.doi.org/10.1515/heem-2018-0006.
Abstract:
AbstractThe paper deals with the influence of the wave shape, represented by water surface elevations and wave-induced nearbed velocities, on sediment transport under joint wave-current impact. The focus is on the theoretical description of vertically asymmetric wave motion and the effects of wave asymmetry on net sediment transport rates during interaction of coastal steady currents, namely wave-driven currents, with wave-induced unsteady free stream velocities. The cross-shore sediment transport is shown to depend on wave asymmetry not only quantitatively (in terms of rate), but also qualitatively (in terms of direction). Within longshore lithodynamics, wave asymmetry appears to have a significant effect on the net sediment transport rate.
27
Hardisty, J. "Measurement of shallow water wave direction for longshore sediment transport." Geo-Marine Letters 8, no. 1 (March 1988): 35–39. http://dx.doi.org/10.1007/bf02238004.
28
Oh, Jung-Eun, Yeon S. Chang, Weon Mu Jeong, Ki Hyun Kim, and Kyong Ho Ryu. "Estimation of Longshore Sediment Transport Using Video Monitoring Shoreline Data." Journal of Marine Science and Engineering 8, no. 8 (July 30, 2020): 572. http://dx.doi.org/10.3390/jmse8080572.
Abstract:
Video monitoring systems (VMS) have been used for beach status observation but are not effective for examining detailed beach processes as they only measure changes to the shoreline and backshore. Here, we extracted longshore sediment transport (LST) from VMS in order to investigate long- and short-term littoral processes on a pocket beach. LST estimated by applying one-line theory, wave power, and the oblique angle of incident waves were used to understand shoreline changes caused by severe winter storms. The estimated LST showed good agreement with the shoreline changes because the sediments were trapped at one end of the pocket beach and the alongshore direction of transported sediments was corresponded to the direction of LST. The results also showed that the beach that was severely eroded during storms was also rapidly recovered following the evolution of LST, which indicates that the LST may play a role in the recovery process while the erosion was mainly caused by the cross-shore transport due to storm waves. After the beach was nourished, beach changes became more active, even under lower wave energy conditions, owing to the equilibrium process. The analysis presented in this study could be applied to study inhomogeneous beach processes at other sites.
29
Liu, Haoran, Kehui Xu, Yanda Ou, Robert Bales, Zhengchen Zang, and Z. George Xue. "Sediment Transport near Ship Shoal for Coastal Restoration in the Louisiana Shelf: A Model Estimate of the Year 2017–2018." Water 12, no. 8 (August 6, 2020): 2212. http://dx.doi.org/10.3390/w12082212.
Abstract:
Ship Shoal has been a high-priority target sand resource for dredging activities to restore the eroding barrier islands in LA, USA. The Caminada and Raccoon Island pits were dredged on and near Ship Shoal, which resulted in a mixed texture environment with the redistribution of cohesive mud and noncohesive sand. However, there is very limited knowledge about the source and transport process of suspended muddy sediments near Ship Shoal. The objective of this study is to apply the Regional Ocean Modeling System (ROMS) model to quantify the sediment sources and relative contribution of fluvial sediments with the estuary and shelf sediments delivered to Ship Shoal. The model results showed that suspended mud from the Atchafalaya River can transport and bypass Ship Shoal. Only a minimal amount of suspended mud from the Atchafalaya River can be delivered to Ship Shoal in a one-year time scale. Additionally, suspended mud from the inner shelf could be transported cross Ship Shoal and generate a thin mud layer, which is also considered as the primary sediment source infilling the dredge pits near Ship Shoal. Two hurricanes and one tropical storm during the year 2017–2018 changed the direction of the sediment transport flux near Ship Shoal and contributed to the pit infilling (less than 10% for this specific period). Our model also captured that the bottom sediment concentration in the Raccoon Island pit was relatively higher than the one in Caminada in the same period. Suspended mud sediment from the river, inner shelf, and bay can bypass or transport and deposit in the Caminada pit and Raccoon Island pit, which showed that the Caminada pit and Raccoon Island pits would not be considered as a renewable borrow area for future sand dredging activities for coastal restoration.
30
Zorndt, Anna Christina, Andreas Wurpts, Torsten Schlurmann, Nino Ohle, and Thomas Strotmann. "DUNE MIGRATION AND SAND TRANSPORT RATES IN TIDAL ESTUARIES: THE EXAMPLE OF THE RIVER ELBE." Coastal Engineering Proceedings 1, no. 32 (January 19, 2011): 38. http://dx.doi.org/10.9753/icce.v32.sediment.38.
Abstract:
Large parts of the tidal estuary of river Elbe (Germany) are characterized by regular patterns of sand dunes. They are presumed to evolve due to complex sand transport mechanisms and show multi-faceted migration patterns. Direction and magnitude of their migration are influenced by hydrodynamic boundary conditions such as river runoff and tides. Dune Migration can lead to residual sand transport rates, depending on its direction and magnitude and the dune’s characteristics. The understanding of dune migration patterns and associated sand transport is the basis of an effective sediment management as well as an important requirement for planning offshore structures. This study focuses on methods for computing migration and sand transport rates in automated ways. In a comparison and validation of different approaches, a cross-correlation technique was found to produce best results. From a unique data set of up to six annual bathymetrical multi-beam soundings between 1995 and 2010, dune characteristics and migration rates were processed and analysed autonomously. The findings show that in a long perspective, average dune migration and sand transport rates in the present study reach are directed upstream.
31
Ondara, Koko, and Semeidi Husrin. "CHARACTERISTICS OF BREAKING WAVES AND ANALYSIS OF SEDIMENT TRANSPORT IN TELUK KENDARI." Jurnal Ilmu dan Teknologi Kelautan Tropis 9, no. 2 (January 2, 2018): 585–96. http://dx.doi.org/10.29244/jitkt.v9i2.19293.
Abstract:
One of the problems that often occured in the bay area is a sedimentation process that occurred continuously, causing silting. The movement of sediment material in the process of sedimentation is influenced by the movement of the water flow like the tides, winds, currents and waves. The aim of this study was to determine the characteristics of the hydrodynamic conditions, particularly the distribution pattern and the capacity of the sediments in the Kendari Bay with oceanographic modeling approach. Bathymetry data measured at the site of the research conducted in August 2015. The analysis of distribution patterns of sedimentation, sedimentation capacity, wave hindcasting, wind data and tidal data using software, hindcasting results indicate the dominant wind direction coming from the east. Type tides in Kendari Bay is a mixed mainly semiurdunal tides. The concentration of suspended sediment at low tide is greater than at high tide. Keywords: sediment transport, wave characteristics, Kendari Bay, hydro - dynamics, mike21
32
Kleinhans, M. G., A. W. E. Wilbers, and W. B. M. ten Brinke. "Opposite hysteresis of sand and gravel transport upstream and downstream of a bifurcation during a flood in the River Rhine, the Netherlands." Netherlands Journal of Geosciences 86, no. 3 (September 2007): 273–85. http://dx.doi.org/10.1017/s0016774600077854.
Abstract:
AbstractAt river bifurcations water and sediment is divided among the downstream branches. Prediction of the sediment transport rate and division thereof at bifurcations is of utmost importance for understanding the evolution of the bifurcates for short-term management purposes and for long-term fluvial plain development. However, measured sediment transports in rivers rarely show a uniquely determined relation with hydrodynamic parameters. Commonly a hysteresis is observed of transport rate as a function of discharge or shear stress which cannot be explained with the standard sediment transport predictor approach. The aim of this paper is to investigate the causes of hysteresis at a bifurcation of the lower Rhine river, a meandering river with stable banks, large dunes during flood, and poorly sorted bed sediment. The hydrodynamics and bed sediment transport were measured in detail during a discharge wave with a recurrence interval larger than 10 years. Surprisingly, the hysteresis in bedload against discharge was in the opposite direction upstream and downstream of the bifurcation. The upstream clockwise hysteresis is caused by the lagging development of dunes during the flood. The counter-clockwise hysteresis downstream of the bifurcation is caused by a combination of processes in addition to dune lagging, namely 1) formation of a scour zone upstream of the bifurcation, causing a migrating fine sediment wave, and 2) vertical bed sorting of the bed sediment by dunes with avalanching lee-sides, together leading to surface-sediment fining and increased transport during and after the flood. These findings lead to challenges for future morphological models, particularly for bifurcations, which will have to deal with varying discharge, sediment sorting in the channel bed, lagging dunes and related hydraulic roughness.
33
A, Rabiu, and Maigari A S. "Flow velocity and implication on particle size of bottom sediment in the commodore channel lagos, southwestern nigeria." Global Journal of Pure and Applied Sciences 29, no. 1 (May 16, 2023): 19–27. http://dx.doi.org/10.4314/gjpas.v29i1.3.
Abstract:
Flow velocity generally influences the erosion, transport and deposition of sediments. Flow velocity and in relation to particle size distribution in the Commodore channel was investigated with the Acoustic doppler current profiler (ADCP), echosounder and veen van grab. Those equipment were deployed through a low draft survey boat to acquire acoustic and sediment data covering the study area. The ADCP measured the current velocity along fourteen established transect lines while twenty surface sediments samples were collected along the banks and center of the channel respectively. Sediment samples were analyzed for grain size distributions and mineralogicaly composition while the acoustics data were analyzed with Matlab software to produce velocity profiles for the channel area. The study aimed to determine the magnitude and direction of flow of water along the channel with a view to ascertain the sediment transport process. Results indicated no significant difference in flow velocities along the different channel points. The flow velocity was however slightly higher around the channel mouth than in mid and upper reaches of the channel. The flow velocities showed negative correlation of (– 0.54 and – 0.28) with the sediment characteristics indicating that the sediment particle size distributions is unrelated to the flow velocity. This anomaly in the equilibrium flow velocity suggest the impact of dredging and the continuous ebbing and flooding of tidal water which resulted to reworking of the sediment particle sizes prior to deposition. The sediment distributions were fine sand, moderately sorted, fine skewed with leptokurtic peaked. Significant fractions of the sediments were deposited in fluvial and shallow marine environments while a few were deposited in the beach and turbidity environment. Sediments and acoustic data interpreted from the study suggest that sediment supply to the area was by fluvial processes through the barrier lagoon drainage basin.
34
Jarocki, Walenty. "WAVE EFFECT ON THE COAST FORMATION AND EROSION." Coastal Engineering Proceedings 1, no. 7 (January 29, 2011): 12. http://dx.doi.org/10.9753/icce.v7.12.
Abstract:
Various authors explain differently the mechanism of action of waves on the_ sediment movement. Some authors consider that the waves are raising the soil fractions from the bottom and water currents transfer them along the seaboard. The other authors suppose that each wave shears some soil in the bottom in littoral zone of the waves and wind is oblique to the shoreline. Beach currents catch and transport the sediment particles along the seaboard. These authors suppose when the wind is in the direction of seaboard /from sea/ then the bottom currents move in the opposite direction. These currents transport the ground particles in the direction of sea and thus the seaboard erosion arises. When the wind direction is opposite, the botto currents arise in the direction of seaboard and they cause the transportation of ground and the accumulation of seaboards. These reasons show that the action of waves would cause only the separation of ground particles and their asoeading. Our last investigations and observations of the sediment movement have led the conclusion that the waves may cause the raise of the sediment partciles and also their transport. The character of this transport depends on the wave kind and on the height and length of waves. General quantity of the lifted particles by means of waves increases as the power of waves or height and length of waves increases. If the power of waves decreases these particles fall. The waves are able to transport the bed load and detritus load without cooperation of the water current in spite of horizontal or inclined bottom. Under the action of waves the sediment moves the oscillatory movement. The waves move the bed load in the shallow exterior zones with the horizontal bottom only, towards the wave propagation. This material may be moved perpendicular the slope, according to the wave direction or in the opposite on< If the approaching wave creates the acute angle to the shoreline then the bed load moves near the seaboard. The transport of the bed load and of detritus loai change if the water current and waves appear simultaneously. The water current acts generally on the detritus load because the water moves this material easier than the bed load which rolls on the bottom.
35
Wei, Hong, Wen Dai, Bo Wang, Hui Zhu, Fei Zhao, Haoyang Jiao, and Penghui Li. "An Improved Flow Direction Algorithm That Considers Mass Conservation for Sediment Transport Simulations." Water 15, no. 23 (November 27, 2023): 4111. http://dx.doi.org/10.3390/w15234111.
Abstract:
The sediment transport process in watersheds is an important research component of geomorphology and surface dynamics. Previous work has inferred the spatial distribution of the sediment transport rate (STR) by the flow direction algorithm and measured topographic variation; however, the simple application of the flow direction algorithm contributes to mass non-conservation during a simulation. This study designs an improved flow direction algorithm for a sediment transport process simulation by judging the mass conservation situation in the simulation process. The specific implementation is to evaluate the existence of negative values for the STR; if they exist, the negative values of the STR are reset to stop the propagation of the negative values downstream. Experiments are conducted to improve the classical D8, MFD–se, and MFD–md flow algorithms in this paper, and the experimental results show that the method in this paper can effectively improve the simulation effect of STR. The STR simulations of the three models, D8, MFD–se, and MFD–md, improved by 1.26%, 4.17%, and 4.54%, respectively. Moreover, the MFD–se model is more suitable for the simulation of the STR when comparing the three models. The improved flow algorithm can be used to simulate the STR, sediment content, and pollutant migration in watersheds, providing a new method for the fine-grained characterization of surface processes in watersheds.
36
BITTENCOURT, ABÍLIO C. S. P., LOUIS MARTIN, JOSÉ M. L. DOMINGUEZ, IRACEMA R. SILVA, and DAIANA L. SOUSA. "A significant longshore transport divergence zone at the Northeastern Brazilian coast: implications on coastal Quaternary evolution." Anais da Academia Brasileira de Ciências 74, no. 3 (September 2002): 505–18. http://dx.doi.org/10.1590/s0001-37652002000300012.
Abstract:
By using the mean directions of the wave-fronts approaching the Brazilian northeastern coastal stretch comprised between the localities of Real river (Sergipe State) and Galinhos (Rio Grande do Norte State) - coincident with those of the main winds occurring in the area - and their periods, we have defined a wave climate model based on the construction of refraction diagrams. The resulting model of sediment transport, as obtained by numerical modelling from the refraction diagrams, taking into consideration the angle of approach and waves heights along the 10-m isobath, was capable of reproducing the patterns of sediment dispersion provided by geomorphic indicators of the longshore drift. All this coastal region, approximately 900 km in length, is characterized by a significant divergence zone in the direction of net longshore drift of sediments, the potential intensity of which increases considerably in value, in almost its entire length, continuously toward downdrift, which might explain the greater or lesser long term susceptibility to erosion, during the Quaternary, along the coastal stretch studied.
37
CONLEY, DANIEL C., SILVIA FALCHETTI, IRIS P. LOHMANN, and MAURIZIO BROCCHINI. "The effects of flow stratification by non-cohesive sediment on transport in high-energy wave-driven flows." Journal of Fluid Mechanics 610 (August 8, 2008): 43–67. http://dx.doi.org/10.1017/s0022112008002565.
Abstract:
The two-way effects of the time-varying suppression of turbulence by gradients in suspended sediment concentration have been investigated using a modified form of the Generalized Ocean Turbulence Model (GOTM). Field measurements of fluid velocities and sediment concentrations collected under high-energy conditions (mobility number ≈ 900) have been simulated both including and neglecting the feedback between sediment and turbulence. The results show that, when present, this feedback increases the wave-coherent component of transport relative to the mean component of transport, which can even change the direction of transport. Comparisons between measured and simulated time series of near-bed sediment concentrations show great coherence (0.95 correlation) and it is argued that the differences in net transport rates may be partially explained by the use of a uniform grain size in the simulations. It is seen that the effects of sediment stratification scale with orbital velocity divided by sediment setting velocity, um/ws, for all grain sizes.
38
Zhang, Xin Zhou, Xi Ping Dou, Xiao Dong Zhao, Xiang Ming Wang, and Xiang Yu Gao. "3D Numerical Simulation of Current and Sediment Transport in Estuary and Coast." Advanced Materials Research 779-780 (September 2013): 899–902. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.899.
Abstract:
In estuarine and coastal area, due to the colligated function of tide, runoff, wind and wave, suspended sediment profile in main flow direction varies from the inland river. Thus, combined with massive data sets from experiments in flume and observations in field, the study on the profile of concentration of suspended sediment are carried out in the thesis. Finally, 3D numerical model of turbulent sediment is established in estuarine and coastal area to carry out a simulation research on current and sediment movement in Yangtze River estuary.
39
Dionísio António, Sara, Jebbe van der Werf, Erik Horstman, Iván Cáceres, José Alsina, Joep van der Zanden, and Suzanne Hulscher. "Influence of Beach Slope on Morphological Changes and Sediment Transport under Irregular Waves." Journal of Marine Science and Engineering 11, no. 12 (November 27, 2023): 2244. http://dx.doi.org/10.3390/jmse11122244.
Abstract:
This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves.
40
Muñoz-Pérez, Juan J., Isabel Caballero, Begoña Tejedor, and Gregorio Gomez-Pina. "Reversal in Longshore Sediment Transport without Variations in Wave Power Direction." Journal of Coastal Research 264 (July 2010): 780–86. http://dx.doi.org/10.2112/08-1141.1.
41
Strypsteen, Houthuys, and Rauwoens. "Dune Volume Changes at Decadal Timescales and Its Relation with Potential Aeolian Transport." Journal of Marine Science and Engineering 7, no. 10 (October 8, 2019): 357. http://dx.doi.org/10.3390/jmse7100357.
Abstract:
Long-term changes in dune volume at the Belgian coast are analyzed based on measured data by airborne surveys available from 1979. For most of the 65 km long coastal stretch, dune volume increases linearly in time at a constant rate. Dune growth varies between 0–12.3 m³/m/year with an average dune growth of 6.2 m³/m/year, featuring large variations in longshore directions. Based on a wind data set from 2000–2017, it is found that potential aeolian sediment transport has its main drift from the west to southwest direction (onshore to oblique onshore). Based on a modified Bagnold model, onshore potential aeolian sediment transport ranges to a maximum of 9 m³/m/year, while longshore potential aeolian sediment transport could reach up to 20 m³/m/year. We found an important correlation between observed and predicted dune development at decadal timescales when zones with dune management activities are excluded. Most of the predicted data are within a factor of two of the measured values. The variability in potential transport is well related to the variability in dune volume changes at the considered spatial–temporal scale, suggesting that natural dune growth is primarily caused by aeolian sediment transport from the beach. It also suggests that annual differences in forcing and transport limiting conditions (wind and moisture) only have a modest effect on the overall variability of dune volume trends.
42
Boix-Fayos, C., E. Nadeu, J. M. Quiñonero, M. Martínez-Mena, M. Almagro, and J. de Vente. "Coupling sediment flow-paths with organic carbon dynamics across a Mediterranean catchment." Hydrology and Earth System Sciences Discussions 11, no. 5 (May 15, 2014): 5007–36. http://dx.doi.org/10.5194/hessd-11-5007-2014.
Abstract:
Abstract. Terrestrial sedimentation buries large amounts of organic carbon (OC) annually, contributing to the terrestrial carbon sink. The temporal significance of this sink will strongly depend on the attributes of the depositional environment, but also on the characteristics of the OC reaching these sites and its stability upon deposition. The goal of this study was to characterise the OC during transport and stored in the depositional settings of a medium sized catchment (111 km2) in SE Spain, to better understand how soil erosion and sediment transport processes determine catchment scale OC redistribution. Total Organic Carbon (TOC), Mineral-Associated Organic Carbon (MOC), Particulate Organic Carbon (POC), Total Nitrogen (N) and particle size distributions were determined for soils (i), suspended sediments (ii) and sediments stored in a variety of sinks such as sediment wedges behind check-dams (iii), channel bars (iv), a small delta in the conjunction of the channel and a reservoir downstream (v) and the reservoir at the outlet of the catchment (vi). The data show that the OC content of sediments was approximately half of that in soils (9.42 ± 9.01 g kg−1 vs. 20.45 ± 7.71 g kg−1, respectively) with important variation between sediment deposits. Selectivity of mineral and organic material during transport and deposition increased in a downstream direction. The OC mineralisation, burial or formation occurred in sediments depending on their transport process and on the post-sedimentary conditions. Upstream sediments showed low OC contents because they were partially mobilised by non-selective erosion processes affecting deeper soil layers. We hypothesise that the relatively short transport distances, the effective preservation of OC in micro-aggregates and the burial of sediments in the alluvial wedges give rise to low OC mineralisation, with C : N ratios similar to those in soils. Deposits in middle stream areas (fluvial bars) were enriched in sand, selected upon deposition and had low OC concentrations. Downstream, sediment transported over longer distances was more selected, dominated by silt and clay fractions and associated with OC. Overall, the study shows that OC redistribution in the studied catchment is highly complex, and that transport and deposition processes have a strong effect on the concentration and quality of OC found at the different depositional settings, with important consequences for the temporal stability of the buried OC and in turn for the OC budget.
43
Ruol, Piero, Barbara Zanuttigh, Luca Martinelli, Peter Kofoed, and Peter Frigaard. "NEAR-SHORE FLOATING WAVE ENERGY CONVERTERS: APPLICATIONS FOR COASTAL PROTECTION." Coastal Engineering Proceedings 1, no. 32 (January 27, 2011): 61. http://dx.doi.org/10.9753/icce.v32.structures.61.
Abstract:
Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency and transmission characteristics are approximated to functions of wave height, period and obliquity. Their order of magnitude are 20% and 80%, respectively. It is imagined that an array of DEXA is deployed in front of Marina di Ravenna beach (IT), a highly touristic site of the Adriatic Coast. Based on the CERC formula, long-shore sediment transport is evaluated in presence and in absence of this array of DEXAs. The sediment transport in this site is quite large and frequently changes directions during the year. The larger North directed contribution and the more persistent South directed one are similar in magnitude and almost compensate each other, with the latter only slightly prevailing. It is shown that the DEXA could be designed so that the effect on sediment transport becomes quite significant and the direction of the net transport can be reversed.
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Brand, Evelien, Lars De Sloover, Alain De Wulf, Anne-Lise Montreuil, Sander Vos, and Margaret Chen. "Cross-Shore Suspended Sediment Transport in Relation to Topographic Changes in the Intertidal Zone of a Macro-Tidal Beach (Mariakerke, Belgium)." Journal of Marine Science and Engineering 7, no. 6 (June 1, 2019): 172. http://dx.doi.org/10.3390/jmse7060172.
Abstract:
Sediment transport is a key element in intertidal beach morphodynamics, but measurements of sediment transport are often unreliable. The aim of this study is to quantify and investigate cross-shore sediment transport and the resulting topographic changes for a tide-dominated, sandy beach. Two fortnight-long field experiments were carried out during which hydrodynamics and sediment dynamics were measured with optical and acoustic sensors, while the beach topography was surveyed with a permanent terrestrial laser scanner. Suspended sediment was generally well-mixed and currents were largest at approximately 1.5 m above the bed, which resulted in a peak in sediment transport at 1/3 of the high tide level. The mean transport direction was onshore during calm conditions (wave height <0.6 m) thanks to tidal currents and offshore during energetic conditions due to undertow. Oscillatory transport was always onshore because of wave asymmetry but it was subordinate to mean transport. The intertidal zone showed an alternation of erosion and accretion with formation of morphological features during energetic (no storm) conditionsand smoothening of the morphology during calm conditions. A good qualitative and quantitative agreement was found between the daily cross-shore suspended load and beach volume changes, especially during calm conditions.
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Song, Dan, Kaihang Cheng, Bo Li, Xuefeng Xu, Longci Deng, and Cong Liu. "Estimation of Tidal Current Asymmetry in an Archipelagic Region: The Zhoushan Islands." Water 14, no. 9 (May 5, 2022): 1485. http://dx.doi.org/10.3390/w14091485.
Abstract:
Tidal current asymmetry (TCA) often occurs in coastal regions. It can significantly influence bedload sediment transport. Recently, the statistical skewness of the tidal current velocity was calculated to represent the TCA. In archipelagic region, the tidal current directions vary temporally and spatially from channel to channel. This creates complexity in finding the flood–ebb axis about which to discuss the axial dissymmetry of tidal currents. In the present work, a method that involves taking the main flood direction (MFD) as the axis to split the tidal current was suggested. The MFD is the most probable direction of the strongest flood flow during each tidal cycle. The method was applied in an archipelagic region: The Zhoushan Islands. The results show that the calculated skewness well represented the TCA in waters around islands, and the degree of the TCA was mainly determined by the residual current. When the direction of the residual current was the same as the MFD, the skewness was positive, which indicated flood dominance. On the contrary, when the direction of the residual current was opposite to the MFD, the skewness was negative, which indicated ebb dominance. The stronger a residual current is, the more significant the TCA will be. Islands play an important role in forming residual circulations. Large ones force flows to move offshore around headlands or along curved channels, because of centrifugal forcing, while small ones often cause segregated flood/ebb conduits and form residual circulations. In the waterways between the Zhoushan Islands, the ebb current generally carries more sediment than the flood current. Therefore, ebb dominance always means sediment is more likely to be deposited, and vice versa. Further research into sediment transport modeling is suggested.
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Boldreel, L., O. Kuijpers, A. Madsen, E. B. ,. Hass, S. Lindhorst, R. Rasmussen, M. G. Nielsen, J. Bartholdy, and J. B. T. Pedersen. "Postglacial sedimentary regime around northern Sylt, South-eastern North Sea, based on shallow seismic profiles." Bulletin of the Geological Society of Denmark 58 (April 8, 2010): 15–27. http://dx.doi.org/10.37570/bgsd-2010-58-02.
Abstract:
During the past 5 years the coastal zone offshore the northern part of the island of Sylt, has been investigated by sparker seismics and high-resolution subbottom profiling. The North Sea sector of the area is characterized by northward-directed sediment bypass as a result of strong long-shore (tidal) currents heading towards the Lister Tief. The southern part of Lister Tief is characterized by the presence of a major dune field with up to 8 m high compound dunes with wavelengths up to 350 m indicative of easterly-directed sediment transport (flood dominated). Further to the northwest, in the outer delta, a dune field suggesting westerly-directed sediment transport is identified. The two dune fields appear to be separated by minor indefinite bed forms. The northern part of the Lister Tief is characterised by the presence of a channel with a depth of 20-30 mbsf (meter below sea level) (30-40 msec TWT (Two Way Traveltime)) and displaying erosion towards the north. At the western termination of the channel the sediment transport pathway appears to be divided into two directions; one towards the outer delta, and one towards the sediment depocenter SW of Rømø. The Lister Ley is characterized by the presence of minor dunes, indicative of flood-current control, apart from a central zone where ebb-tide is responsible for northward-directed sediment transport. Sparker seismic and Chirp III data are consistent with processes having been persistent throughout the Holocene. Based on the study a model for the current direction and sedimentation regime is suggested.
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Li, Yan, Jinliang Zhang, Haijue Xu, and Yuchuan Bai. "Experimental Study on the Characteristics of Sediment Transport and Sorting in Pressurized Pipes." Water 13, no. 19 (October 7, 2021): 2782. http://dx.doi.org/10.3390/w13192782.
Abstract:
Sediment transport in pipes is an effective engineering measure used to reallocate water–sediment resources and is widely used in reservoir flooding and sediment discharging, river dredging, floodplain area deposition, as well as other projects. An experimental investigation of sediment transport in pressurized pipes, with heterogeneous sediment (d50 = 107 μm) of the lower Yellow River as the experimental material, is presented. This study mainly explored the change law of sediment transport and sorting in pressure pipes with an internal diameter of 0.08 m. The experimental results reveal that the presence of sediment significantly changed the distribution of the flow velocity field. At the same flow rate, the velocity of the lower water body with a high sediment concentration decreased, while that of the upper water body increased. At a low water flow rate, the increase in sediment concentration caused an asymmetric distribution of the cross-sectional velocity. The vertical concentration decreased in height, and the obvious stratification of vertical sediment particles was observed. With the increase in the flow rate, the asymmetry of the velocity distribution significantly decreased, the concentration profile tended towards being uniformly distributed along the vertical direction, and the separation effect of the sediment particles weakened.
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Frank-Gilchrist, Donya P., Allison Penko, and Joseph Calantoni. "Investigation of Sand Ripple Dynamics with Combined Particle Image and Tracking Velocimetry." Journal of Atmospheric and Oceanic Technology 35, no. 10 (October 2018): 2019–36. http://dx.doi.org/10.1175/jtech-d-18-0054.1.
Abstract:
AbstractAccurately assessing the response of sediments to oscillatory flows requires high-resolution fluid velocity and sediment transport measurements at the fluid–sediment interface. Fluid and sediment grain velocities were measured simultaneously with combined particle image and tracking velocimetry under oscillatory flows over movable sand ripples. Three high-speed cameras equipped with varying optical filters were used to distinguish between fluorescent fluid tracers and the grains, from which the fluid and grain velocities were determined, respectively. Individual grains were tracked during transport to determine velocities and trajectories. Sediment grains were first mobilized by a vortex impacting the bed during flow reversal and suspended into the water column just prior to vortex ejection from the ripple crest, similar to previous observations. During phases of maximum flow velocity, additional grains were mobilized by the shear stress and were subsequently suspended. The flow reversed and similar observations were made in the opposite direction. Consequently, four peaks in suspended sediment concentration were observed throughout the flow cycle, consistent with previous observations. However, some previous researchers attributed peaks in suspended sediment concentration occurring during phases of maximum flow velocity to sediment-laden vortices that were shed from adjacent ripples. The measured sediment grain velocities were of similar magnitude and phase to the near-bed fluid velocities when the grains were being advected with the flow. Measurements of suspended sediment concentration agreed well with semiempirical formulations having an average root-mean-square deviation of approximately 4 × 10−5 m3 m−3. Predictions of settling velocity also compared well with the laboratory estimates, agreeing to within 90%.
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Kostaschuk, R. A., J. L. Luternauer, J. V. Barrie, P. H. Leblond, and L. Werth Von Deichmann. "Sediment transport by tidal currents and implications for slope stability: Fraser River delta, British Columbia." Canadian Journal of Earth Sciences 32, no. 7 (July 1, 1995): 852–59. http://dx.doi.org/10.1139/e95-071.
Abstract:
Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.
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Leo, Annalisa De, Greg Collecutt, Mitchell Smith, Alessandro Stocchino, and Bill Syme. "ANISOTROPIC EDDY VISCOSITY A BENCHMARK CASE STUDY IN AN IDEALISED TIDAL ESTUARY." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 30. http://dx.doi.org/10.9753/icce.v37.sediment.30.
Abstract:
Numerical schemes for solving the full shallow water equations require a turbulence closure model to represent the momentum diffusion caused by turbulence that the velocity fields do not explicitly capture. Typical models include Smagorinsky, depth-U*, Prandlt, and k-epsilon. All of these models predict isotropic eddy viscosity – i.e. the diffusion of momentum acts equally in all directions. However, it is known that when modelling saline transport within an estuary with a 2D scheme, mass dispersion is present in the longitudinal direction due to the depth velocity profile. In a 2D numerical scheme, should diffusion of momentum also be applied anisotropically? In this paper we present a benchmark case study between laboratory measured velocity results and those from numerical simulations using TUFLOW.