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The study's aim was to affirm the micro morphological diversity of sand grains and to uncover the relationship between morphological features of sand grains and sampling sites from various transportation environments, like wind (Aeolian), River, Lake, and beach sand samples, their surface micromorphology and geochemical analysis has been investigated using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDS/EDAX). Exoscopy of sand particles are very useful for knowing the dominant type and rate of sediment transportation. Four different environmental sand samples were collected in the Andhra Pradesh (AP) and Karnataka (KA) states in South India. Aeolian, River, and Beach sand samples were collected in the Anantapur, Nellore, and Vishakhapatnam districts of AP. Lake samples were collected in the Udupi district of KA. The importance of the study is to identify the rate of transportation of the sample in different environmental condition like water, and wind. The present study data can be utilized for special relevance to environmental scientists, research scholars, and planning agencies for monitoring geomorphological agents for the sustainable development of ecosystems in a well-organized way. Micro textures on sand grain surfaces show details about the past environment. Environmental processes such as wind and water produce distinctive micro textures on sand grain surfaces, which can be seen using a scanning electron microscope at high magnification. The analysis of quartz sand grains from various sedimentary environments using a scanning electron microscope (SEM) showed that some sedimentary processes impose distinct surface textures on the grains.

Fluvial sediment supply (FSS) is one of the primary sources of sediment received by coasts. Any significant change in sediment supply to the coast will disturb its equilibrium state. Therefore, a robust assessment of future changes in FSS is required to understand the coastal system’s status under plausible climatic variations and human activities. Here, we investigate two modelling approaches to estimate the FSS at two spatially heterogeneous river basins: the Irrawaddy River Basin (IRB), Myanmar and the Kalu River Basin (KRB), Sri Lanka. We compare the FSS obtained from a process-based model (i.e., Soil Water Assessment Tool: SWAT) and an empirical model (i.e., the BQART model) for mid- (2046–2065) and end-century (2081–2100) periods under climate change and human activities (viz, planned reservoirs considered here). Our results show that SWAT simulations project a higher sediment load than BQART in the IRB and vice versa in KRB (for both future periods considered). SWAT projects higher percentage changes for both future periods (relative to baseline) compared to BQART projections in both basins with climate change alone (i.e., no reservoirs) and vice versa when planned reservoirs are considered. The difference between the two model projections (from SWAT and BQART) is higher in KRB, and it may imply that empirical BQART model projections are more in line with semi-distributed SWAT projections at the larger Irrawaddy River Basin than in the smaller Kalu River Basin.

Core, well log and seismic data are used to investigate relationships between fan-delta facies architecture, basin margin morphology and sediment transportation into a deep-lacustrine environment o...

Various threshold curves for the sediment motion in the field of sediment transportation in fluvial hydraulics have been developed until now. These curves mostly represent the experimental data which are either from flatbed conditions or uniform sediment criteria. In this study, the two prominent bed configurational features such as non-flat bed condition and non-uniformity of bed sediment are included while developing the new empirical model in terms of critical Movability Number. It is shown that existing approximations are not accurate for large grain diameters, partly due to the large variations of the threshold values. Here, the new experimental data belonging to mentioned bed features combined with the previous data are approximated by a simple function using a technique that allows for the large variation, which gives better results.

Although the study of microplastics in the aquatic environment incorporates a diversity of research fields, it is still in its infancy in many aspects while comparable topics have been studied in other disciplines for decades. In particular, extensive research in sedimentology can provide valuable insights to guide future microplastics research. To advance our understanding of the comparability of natural sediments with microplastics, we take an interdisciplinary look at the existing literature describing particle properties, transport processes, sampling techniques and ecotoxicology. Based on our analysis, we define seven research goals that are essential to improve our understanding of microplastics and can be tackled by learning from natural sediment research, and identify relevant tasks to achieve each goal. These goals address (1) the description of microplastic particles, (2) the interaction of microplastics with environmental substances, (3) the vertical distribution of microplastics, (4) the erosion and deposition behaviour of microplastics, (5) the impact of biota on microplastic transport, (6) the sampling methods and (7) the microplastic toxicity. When describing microplastic particles, we should specifically draw from the knowledge of natural sediments, for example by using shape factors or applying methods for determining the principal dimensions of non-spherical particles. Sediment transport offers many fundamentals that are transferable to microplastic transport, and could be usefully applied. However, major knowledge gaps still exist in understanding the role of transport modes, the influence of biota on microplastic transport, and the importance and implementation of the dynamic behaviour of microplastics as a result of time-dependent changes in particle properties in numerical models. We give an overview of available sampling methods from sedimentology and discuss their suitability for microplastic sampling, which can be used for creating standardised guidelines for future application with microplastics. In order to comprehensively assess the ecotoxicology of microplastics, a distinction must be made between the effects of the polymers themselves, their physical form, the plastic-associated chemicals and the attached pollutants. This review highlights areas where we can rely on understanding and techniques from sediment research - and areas where we need new, microplastic-specific knowledge - and synthesize recommendations to guide future, interdisciplinary microplastic research.

A typical diachronous breakup developed in the South China Sea (SCS); the breakup has been unequivocally identified, and gradually decreases in age from NE to SW. To illustrate the influence of a d...

Uplift of the Qinghai-Tibetan Plateau has resulted in rapid incision of rivers along the margin of the plateau. Landslides occur frequently as a consequence of increasing bank slope and potential landslide energy due to stream bed incision or lateral bank erosion on the concave banks at bends. The Fencha Gully is on the eastern margin of the Qinghai-Tibetan Plateau and is developing on a huge landslide body. Flume experiments were conducted on the base of the field investigation to study the mechanism of landslides induced by stream bed incision. The experiments were designed with a length scale ratio of 1:20. Landslides and stream bed incision with loose sediment were observed and analyzed. The results show that landslides are induced as a result of stream bed incision. The potential landslide energy is defined, which increases quickly with an effective incision depth coupling vertical incision and lateral bank erosion. The occurrence of landslides can be attributed to increasing incision depth and potential landslide energy. Results indicate that the critical effective incision depth is 4.0–6.0 m. A critical value of the potential landslide energy is found from the experiments. Landslides occur if the potential energy exceeds the critical energy, which is 2.24×104 t·m/s2 for the Fencha Gully. The incision depth and potential energy of landslides from the Fencha Gully agree well with the results.

Rich ecosystems such as estuaries and brackish lakes are vulnerable to the effects of human activities and are prone to environmental changes. In particular, the salt environment, which is the backbone of the environment, might be affected not only by direct modifications such as dredging but also in ways that were not initially envisioned. Ichkeul Lake, located in the northern part of Tunisia, is a shallow brackish lake registered as a UNESCO World Natural Heritage Site. The construction of reservoirs upstream of the inflowing river in the 1980s reduced the amount of freshwater inflow. That only had been thought to be the cause of the increase in salinity in Ishkeul Lake. On the other hand, the sedimentation in the reservoirs upstream was remarkable, and the supply of sediment from the reservoirs upstream to the Ichkeul Lake was stopped. Changes in sediment outflow may have reduced lakebed altitude and enhanced seawater intrusion. However, the environmental protection measures for the lake so far have focused only on improving the water budget and have not been quantitatively evaluated for sediment transportation. In this study, we first estimated the water budget of the lake. Then the re-suspension by wind disturbance in the lake was estimated from the correlation with the wind speed based on laboratory experiments and field measurements. The outflow of the sediment estimated with these two models was compared with the sediment volume trapped in the upstream reservoirs that would have flowed into the lake if there had been no construction of the dams. Based on this, we evaluated whether the lake is currently erosive or cumulative. As a result, the estimated annual outflow of sediment to the sea was 4300 tons/year. It was estimated that the construction of the reservoirs upstream changed the trend of lakebed height from accumulation to erosion.

The paper studies the stochastic nature of sediment transport in rivers. Sediment transport formulas are valid only for prediction of average sediment transportation over long reaches of rivers and long periods of time. However, flow in rives is unsteady and non-uniform and failures of hydraulic works may occur because of instantaneous and local behaviour of sediment movement. An experimental study demonstrates fluctuation of the bed load transportation, which is so obvious that the maximum instantaneous transport rate is higher than 3 times of the average and the minimum is less than 5% of the average. In the upper Yangtze River, broad and shallow sections are between narrow and deep sections. Different from the normal law sediment transportation in broad sections exhibits high transport rate in low flow and low rate in high flow. Qb is approximately inversely proportional to Q. Gravel bed load moves along a so called conveying belt and there is almost no bed load movement outside of the belt. The phenomenon was investigated in a scale model and the results shows the conveying belt is relatively fixed and is of only 10% of the total width of the channel bed.

Soil erosion and sedimentation by water involve the processes of detachment, transport, and deposition of soil materials by rainfall and runoff. Major sources of sediment eroded from sloping land are interrill areas, rills, and gullies, with the relative contribution from each varying widely depending on the specific situation. Eroded sediment generally consists of both primary soil particles and aggregates, which greatly affect the size distribution, density, and stability of the sediment and, consequently, sediment transportation and deposition. The rate of soil erosion depends on various climatic, soil, topographic, and cultural factors. By identifying and quantifying such factors, erosion rates can be predicted more accurately and better soil conservation practices can be developed.

The progradation of the Nile River Delta and the thick (~1500m) Sinai-Israel shelf since the Pliocene provide a world class source to sink system feeding a deep (>1.5 km) siliciclastic basin. The general agreement that the Pliocene-to-Recent succession originates from the Nile Delta dispersing sediments via a system of counterclockwise currents does not reveal how the sediments were transported to the deep basin. Particularly, how sediments originating from the Nile Delta could have bypassed the ~50 km wide Sinai-Israeli shelf. Here, we examine the various sources that contributed to the accumulation of the Pliocene-to-Recent succession in the deep Levant basin, and the temporal and spatial contribution of each source. The analysis of a unique seismic data set covering the shelf, slope and deep basin enable us to track submarine sediment transport systems.Following attribute analysis of the seismic volumes we map channel sets, analyze their morphological features and interpret their erosional and depositional patterns. Direction flow maps indicate that sediments sources vary from eastward remnant Arabian drainage network at the onset of the Pliocene, to direct Nilotic origin during the Pliocene. Since the Late Pleistocene reworked sediments, deriving from the Israeli shelf and northern Sinai provide a major source to the deep basin. Furthermore, our results demonstrate an increase in channel’s complexity since the Early Pliocene to Recent suggesting a gradual transition from sporadic submarine flow events, carrying fewer sediments to the deep basin at the Early Pliocene, to more frequent events during the Late Pleistocene-to-Recent characterized by an increase in sediment load. The gradual increase of channel complexity from Pliocene-to-Recent is discordant to the general trend of sea-level fluctuation, suggesting that sea-level has a minor effect on sediment accumulation in the deep basin. We propose that the balance between the northward prograding Nile Cone and the longshore currents building the Sinai-Israeli shelf dictate siliciclastic accumulation in the southeastern Mediterranean basin as well as the paleogeography of its margin.

In recent years, two-dimensional sediment transportation on movable bed models have been widely used in hydraulic engineering. Because of different assumptions, each model has its own feasibility on specified issues and areas. The SRH-2D model is an implicit method of the finite-volume method without CFL stability conditions, and requires more calculations than the explicit one at each time step. On the other hand, RiverFlow2D is an explicit method of finite-volume method with CFL conditions and saves much more time. In order to compare the results from these two software, a case study of Natorsa Creek, Kaohsiung, Taiwan, is carried out on the sensitivity analysis and different structure setups associated with rainfall data, water level record and DTM. The principle results are as following: This study uses average absolute error (MAE) and mean square root error (RSML) to investigate the sensitivities of SRH-2D and RiverFlow2D models and finds out the operation time increased with shorter time interval. Although SRH-2D supports three formulas while RiverFlow2D supports ten, it takes more factors into account like secondary flow, sediment size distribution, and the bed armoring effect. The simulation of scour-and-fill condition by these two models has shown similar result. However, there still exists small discrepancy between software simulation and field investigation.

This study was undertaken with the primary objective of modeling grain velocity based on experimental data obtained under the controlled conditions of a laboratory using a rectangular hydraulic tilting channel. Soft computing approaches, i.e., support vector machine (SVM), artificial neural network (ANN), and multiple linear regression (MLR), were applied to simulate grain velocity using four input variables; shear velocity, exposed area to base area ratio (EATBAR), relative depth, and sediment particle weight. Quantitative performance evaluation of predicted values was performed with the help of three different standard statistical indices, such as the root mean square error (RMSE), Pearson’s correlation coefficient (PCC), and Wilmot index (WI). The results during the testing phase revealed that the SVM model has RMSE (m/s), PCC, and WI values obtained as 0.1195, 0.8877, and 0.7243, respectively, providing more accurate predictions than the MLR and ANN models during the testing phase.

Most public universities in Latin America and Mexico lack laboratories for measuring sediment transport or to do academic activities. The Research Center of the engineering faculty of Chiapas state university (UNACH by its acronym in Spanish) designed a portable prismatic channel for teaching and researching the sediment transportation in rivers. This paper presents the method to measure river sand transportation in a laboratory channel with a mobile bottom and presents the results of twenty-seven experiments done in the portable channel, using nine different slope inclinations and 27 flow and water speed values. The three main results are the following: 1) The construction of the channel with variable slopes, to experiment and measure sediment transportation. 2) A method developed for measuring the volume of sediment in a laboratory. 3) In a channel with a bottom slope of 0.071, a water flow of 2 l/s and a water speed of 1.77 m/s, the volume of transported sediment was 0.015 m3; in a channel with a bottom slope of 0.44, a water flow of 2 l/s and a water speed of 0.788 m/s, the volume of transported sediment was 0.006 m3; in a channel with the bottom slope of 0.024, a water flow of 2 l/s and a water speed of 0.62 m/s, the transported sediment was 0 m3.

The development of river-delta systems possesses some stochastic characteristics even under slow-varying external conditions. In this study, two sets of repeated physical modeling experiments were conducted to explore the deterministic and non-deterministic effects of the upstream river-inflow on sedimentary configurations in lacustrine shallow-water delta. The statistical analysis of the fluctuation characteristics of sedimentations indicated a commonness of the tendency of a quasi-deterministic mature state under the same sediment supply, and also deterministically, the average value, average amplitude, and average frequency of the geometrical characteristics of sedimentations were negative, positive, and positive correlated with discharge within the Runs-Averaged works respectively; non-deterministically, some outliers of average frequencies of the sedimental indicators revealed the variation of disturbance properties around the highly-active deltaic sections, and, the exceptional average amplitudes of both the indicator of sedimental height near the inlet and the indicator of sedimental width far from the inlet demonstrated the different modes of energy transformation during the process of systematic evolution. Furtherly within the Runs-Repeated works, in low-discharge cases, the unbalanced sediment transportation along the quasi-equiprobable anticlockwise-clockwise diverging directions from the polar perspective resulted in the remarkably negative relationships of both the average amplitude of the indicator of sedimental center and average frequency of the indicator of sedimental height versus the corresponding average values; in high-discharge cases, the uncertainties of the indicator of sedimental width always become prominent accompanied by the weakening of flow instability. This study innovatively interprets a new probabilistic way of understanding the deltaic sedimentations.

The present work analyzes the effectiveness of windbreaks against wind erosion through the study of streamline patterns and turbulent flow by means of sonic anemometry and sediment traps. To this end, windbreaks composed of plastic meshes (7.5 m long and 0.7 m tall) were used. Windbreaks are a good means to reduce wind erosion, as they produce a positive effect on the characteristics of air currents that are related to wind erosion processes. Due to their ease of installation and dismantling, plastic meshes are widely used in areas where they are not required permanently. In our study, the use of a mesh of 13 × 30 threads cm−2 and 39 % porosity resulted in an average reduction of 85 % in face velocity at a height of 0.4 m and a distance of 1 m from the windbreak. The turbulence intensity i increased behind the windbreak because the reduction of mean of air speed on the leeside caused by the flow of air through the windbreak. Fluctuation levels, however, remained stable. The mean values of turbulence kinetic energy k decreased by 65 % to 86 % at a distance of 1 m from the windbreak and at a height of 0.4 m. The windbreak reduces erosion and sediment transportation 2 m downwind (2.9 times the windbreak height). Nevertheless, sediment transportation was not reduced at a height of 1.0 m and the effect of the windbreak was not observed at a distance of 6 m downwind (8.6 m times the windbreak height).

This study shows hill slope process of Mt. Ovoot in the northeast of Khangai Mountain Range, Mongolia. This work is mainly focused on sediment transportation by surface and subsurface flows in Mt. Ovoot based on movement of microelements within soil profiles along the mountain slopes and measurement of particle sizes and shapes of the soils. The main purpose is (1) to determine the chemical and physical properties of soils, and (2) to reveal hill slope process with movements of microelements. Movement of the microelements show intensive slope processes in the Mt. Ovoot. Each surface soil on upper slope contains microelements less than those on lower slope of the mountain, where sediments have been more round and finer. It infers that more soils are eroded and accumulated on upper and lower slopes, respectively, these transport and deposition of the soil particles are caused by the surface and subsurface flows.

Introduction: Bridge scour is one of the major causes of bridge failure. Prediction of the maximum depth and shape of local scour plays an important role in bridge design and maintenance. In this paper, k-ε turbulent model combined with wall function was employed and complex flow fields are exhibited. The bed load transport model summarized by Qian and Wan [1] was applied to evaluate the development of local scour. Besides, σ-grid module was developed and embedded into the commercial solver FLUENT to fit the change of channel-bed. Method: In this module, the change of the elevation of the channel bed is calculated through using user defined functions(UDF), and the motion of the grid system is realized based on a program developed through C++ language, which extends the applications of FLUENT. The evolution of local scour hole for two cases, i.e., local scour around a cylindrical pier and a semicircular abutment, was simulated. Results and Conclusion: The depth and the shape of local scour as well as the flow fields were predicted. Numerical result conforms well to the experimental measurement. Especially, it provides fairly reasonable prediction on the key issue of the maximum scour depth. The satisfactory agreement validates the numerical method developed in the present study. In addition to the validation purpose, the different performance of this method for predicting local scour around the cylindrical pier and the semicircular abutment was discussed.

Flooding events in wetlands transport sediment particles landwards and can increase accretion in some areas of the wetland or resuspend the sediment in other areas. In this study a flooding event with different water discharges was analyzed in a laboratory simulated wetland to determine the effect stem density has on particle trapping. The discharge that entered the simulated wetland was a particle laden barotropic current that initially produced a pulse that traveled through the wetland. After the first pulse, a baroclinic current, with a different timescale to the initial pulse, developed. Three stem densities, along with the ‘without plant case’, were considered. A semi-empirical model was formulated to explain the propagation of the water pulse. The model predicted the velocity of the pulse dampening in the presence of the simulated vegetation, by using the roughness parameter that had been found to increase with stem density. The baroclinic current propagated at a lower velocity than the pulse did, and its velocity decreased with stem density. As less sediment was found in the wetland with denser canopies, this indicates that the presence of a canopy acts as a barrier to sediment transportation. Furthermore, a greater amount of sediment was deposited in regions at the foot of the denser vegetated wetland zone and the sediment deposition also increased with the water discharge.

The characterization of wave transformation processes in the nearshore is of paramount importance when it comes to assessing storm and flooding impacts, sediment transportation and deposition, harbors safety or design of coastal protective structures. This study analyzes nonlinear wave parameters on Ofir sandy beach. This beach is located along the northwest Portuguese coast which is a highly energetic coast exposed to waves generated far away in the Atlantic Ocean. Despite the existence of rocky outcrops in the nearshore and intertidal zones at the study site, reducing the wave energy that reaches the beach, the study site exhibits pronounced erosive processes. Field observations of six near-bottom pressure records collected at the intertidal zone help to characterize the evolution of wave nonlinearities which are directly associated with sediment transport mechanisms. Data results show that there is an interrelation between the characteristics of the waves and the local morphology. It is also possible to ascertain, more clearly, the level of asymmetry present in the waves propagated at different depths, contributing to a better understanding of the local morpho-hydrodynamics.

In order to cover the crop water requirements, flow control structures such as gates and weirs are used to transfer the desired amount of water from the canals to the field canals. This paper examines the impact of gate operation and the selection of gates on the deposition of non-cohesive sediment. The Delft3D model is used to simulate the effects of different scenarios regarding gate operation and the location of the gate that is opened. The model results showed that the gate selection affects not only hydraulic parameters but also morphological parameters. It was found that opening the gates closer to the offtake resulted in less sediment deposition at the entrance of the branch canal when compared to opening the gates further away. Gate selection can be used as a tool in sediment management. By alternating the opening of different gates sediments that are already deposited after opening one gate can be eroded when another gate is operated, thus minimizing the additional cost of sediment removal. The use of Delft3D proved beneficial as the selection of different gates leads to asymmetric sediment deposition patterns which would be missed when using a 1D model.

Shipwreck sites often occur in highly dynamic intertidal environments, posing major challenges in terms of preservation and coherence of the archaeological record. These sites typically consist of widely scattered materials located either in the intertidal zone or above the high waterline. Exposure to winds, waves, surges, tides, currents, and sediment transportation occurs continuously across space and over time, and within various significant spatial-temporal scales, resulting in natural cycles of flood, burial and exposure of stranded wrecks. Ultimately, however, the survival of shipwrecks in the archaeological record in these environments will depend on an array of interactions with natural and cultural post-depositional processes. The following chapter presents the current knowledge regarding the archaeology of intertidal shipwreck sites in South America, based on case studies from highly dynamic settings in Southern Brazil, Argentina and Uruguay. It aims at highlighting regional themes and defining the gaps which need to be filled towards a more systematic macro-regional approach.

In the recent survey, the thickness of the floating sludge layer in the outer channel of Shenhua Huanghua Port is obviously larger than that in the inner channel, which is different from the law of historical survey. Based on analysis of the sediment survey, this paper first describes the distribution characteristics of surface sediment in the surveyed area, and draws the conclusion that silt is the dominant distribution, and that the area with the coarsest sediment should be the accumulation area of sediment with medium sediment environment. The strong overflow outside the entrance has a strong effect on the sediment reconstruction, and the south side of the entrance is a weak flow area, and the hydrodynamic environment is weak for the sediment reconstruction. Then, through Gao. Collins model analysis and calculation of sediment transport trend, it is concluded that the south section of the breakwater entrance of Shenhua Huanghua Port is a "sink" of sediment, and the surrounding sediment accumulates to it under the action of hydrodynamic force. As the accumulation area is close to the channel, the finer components of the sediment particles enter the channel with the rising tide current during the process of the sediment transportation to this area, which increases the thickness of the floating sludge layer formed on the basis of other dynamic forces.

The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd > Pb > Ni > Zn > Cu > Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd > Pb > Ni > Cu > Zn > Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.

Sediment transport is an important aspect of all fluvial systems like river flows. Sediment transportation depends on the flow conditions, ratio of densities of sediment and fluid, and the size of the particle. Analysis of sediment yield data is helpful in understanding the distributional characteristics of sedimentation in river basins. Evolving a sediment distribution relationship over the region, consisting of different catchments, may facilitate in estimating sedimentation rates at non-sampling locations. Such estimates based on geostatistical analyses would be better estimates of mass fluxes compared to those obtained through conventional methods. As processes like river sedimentation, with time-space variation, may be considered as regionalized variables, geostatistical techniques can be effectively utilized in analyzing such variables to bring out their spatial structure. In the present study, geostatistical analysis of sediment yield data from sixteen river basins of the State of Kerala has been undertaken with a view to reveal the spatial and temporal distribution pattern of sedimentation in the region. The mean annual rainfall in the region is above 3000 mm, and it varies from west to east as well as from south to north. Therefore, the sedimentation behavior also is expected to vary. Geostatistical analysis has been carried out for distinct cases based on regional and seasonal variations. Northern and southern regions were treated separately. Also, seasonal variations with regard to SW and NE monsoons were also considered. The geostatistical analyses revealed that the sedimentation characteristics in Kerala river catchments tend to increase from north to south during NE monsoon. However, during SW monsoon, northern region yielded more sediment. The quantitative increment in sediment yield toward the southern parts of the state may be attributed to the rainfall characteristics.

Sediment load of the Yangtze River is mainly from the upper reaches. The mean annual runoff of the Yichang hydrometric station, where the Three Gorges Project locates, is 436.4 billion m3, and the annual sediment discharge is 470 billion kg. The suspended sediment mainly comes from the Jinshajiang River and the Jialingjiang River. The total mean annual sediment load of these two rivers occupies about 75% of the Yichang station. Compared with the years before 1990, the region composition of the runoff at Yichang station has no obvious variations, while the composition of the sediment source changes distinctly. Due to a large number of hydraulic constructions, the sediment transportation of the Jialinjiang River reduced greatly, whose proportion of the Yichang station has dropped from about 27% to around 10%. The Jinshajiang River basin has become the major area, from which the sediment into the Three Gorges Project comes. In this paper, a long time series of runoff and sediment observations from 1955 to 2011 of the Jinshajiang River is used for characteristics analysis, including trend, jumpy point and the sediment transportation properties. Besides descriptive statements, some statistical analysis techniques, such as Mann Kendall rank correlation test, Fisher ordered clustering, and double mass curves analysis are applied. The results illustrate that the sediment discharge varies with the runoff, displaying a decrease tendency over long time, especially in recent years, the sediment load drops significantly. Meanwhile, the sediment transportation efficiency reduces obviously in recent 10 years, which means much less sediment load can be carried with the same runoff. The construction of the large-scale water conservancy project is the main reason for such drastic change.

The processes of rill erosion and overland flow are significantly affected by freeze-thaw cycles. Meltwater concentrated flow laboratory experiments were carried out to assess the soil erosion of different frozen conditions based on the runoff energy consumption process which own to runoff energy against the sediment transportation and terrain evolution. The experiments were performed over frozen, shallow-thawed, and unfrozen soil-filled flumes under 1, 2, and 4 L/min flow rates with the temperature around 5 °C. The results imply that soil erosion became more severe with increasing flow rate. Variation rate of the soil erosion rate of frozen slope was highest under 1 and 2 L/min flow rates due to lower infiltration of water into soil. Variation in runoff energy consumption variation with flow time presented significant differences under unfrozen, shallow-thawed, and frozen slopes at equal runoff rate (p

Sediment samples from the foreshore and backshore regions between Thottappally and Kayamkulam, (Thottappally – Trikkunnapuzha = Northern; Trikkunnapuzha – Arattupuzha = Central; Arattupuzha – Kayamkulam = Southern), which are enriched with heavy minerals, were subjected to detailed textural evaluation. Through frequency curves, bivariate and CM pattern, the textual characteristics of black sand deposits have been brought out and their provenance has been discussed. Beach sands of the study area mainly comprise fine sand, moderately well- to well-sorted, with near symmetrical skewness in all three sectors. Kurtosis is platykurtic in the northern sector, whereas mesokuritic sediments in the central and southern sectors show a characteristic playtkuritc nature. In the Trikkunnapuzha – Arattupuzha and Aratupuzha – Kayamkulam sectors, sediments are mesokurtic to platykurtic, which shows that low energy conditions and high wave energy conditions must have prevailed. Sediment transportation is mainly by saltatio...

Between 1995 and 2011 a global positioning system survey of 13 boulders and three ablation stakes (long stakes frozen in the ice) on the frozen surface of Lake Hoare was undertaken. Data interpretation illustrates complexities of post-depositional transport dynamics of boulders. Earlier studies on comparable datasets have suggested linear ‘conveyor’ type transport mechanisms for lake surface boulders. Yet explanations for non-linear boulder displacements or ‘walks’ and the mechanisms responsible for movements are inadequate. Two modes of boulder specific movement were observed. First, localized changes in the ice surface promote individual boulder movement (rolling). Second, ice rafting, which indicates the displacement of ‘plates’ of lake ice on which the boulder is located. Ablation stakes used as fixed survey control points support the hypothesis that ice cover moves as discrete plates rather than as a single homogenous mass. Factors that create the conditions to generate either of the two modes of movement may be related to location specific energy budgets. A relationship between average orientations and prevailing wind direction was also observed. The investigation describes the local-scale behaviour of surveyed boulders, and offers methodologies and interpretive frameworks for additional studies of modern and ancient sediment transportation dynamics in Antarctic lacustrine environments.

Suspended particulate matter concentration (SPM) in coastal waters is of great importance for studying sediment resuspension and sediment transportation, especially for the profile distribution in bodies of water. The traditional SPM profile-obtaining method that uses a turbidity meter introduces large uncertainty for pigment particle-dominated waters. This research used a large amount of profile data on optical properties and hydrological measurements parameters (conductivity-temperature-depth (CTD), chlorophyll and turbidity), which were measured synchronously in the Bohai Sea and Yellow Sea; the data were used to analyze the relationships between the vertical distribution of the particulate backscattering ratio and the vertical distribution of pycnocline, chlorophyll and turbidity and to distinguish pigment particles and sediment particles in the vertical distribution. After considering the particle types, we also developed a novel method that exclusively depended on conventional hydrological measurements. The results show that the new method is simplified and effective and could significantly improve the accuracy of SPM estimations in coastal waters.

The assessment of the eco-environmental benefits of rivers has important guiding significance for improving water resource management, establishing water resource protection mechanisms, and maintaining river health. In view of the current imprecise quantitative methods of determining the eco-environmental benefits of rivers and based on the viewpoint of ecology, the significance and composition of river eco-environmental benefits were discussed. An emergy theory was introduced to quantify both the solar transformity of subtypes of water bodies and the sediment transportation benefit, which improved the indicator system of eco-environmental benefits. Applying the indicator system to the management practice of the Yellow River Basin, the eco-environmental benefits in 2015 were calculated by dividing the Yellow River into 66 sections. A Geographic Information System (GIS) atlas was then used to describe their spatial distribution. Eight typical cities were selected for the key analysis. Among these eight cities, the eco-environmental benefit inside the river in Xi’an section is the largest with a total emergy benefit of 1.08 × 1021 solar equivalent joules (sej) and a corresponding monetary benefit of 28.03 Chinese Yuan (¥)/m3. The eco-environmental benefit outside the river in Jinan section is the largest with a total emergy benefit of 1.37 × 1020 sej and a corresponding monetary benefit of 12.39 ¥/m3. This study proposed that rivers have great eco-environmental benefits, and the harmonious development of economy, society, and environment should be pursued in water resources management.

A forma dos perfis longitudinais dos cursos d’agua associada a distribuicao das planicies aluviais adjacentes permitem identificar trechos com predominio de processos agradacionais e denudacionais nos sistemas fluviais. Este trabalho identifica trechos dos perfis longitudinais dos rios a montante do Parque Estadual de Terra Ronca, no nordeste do estado de Goias, que possuem tendencias diferentes para transferencia de sedimentos para jusante. Os rios cujos perfis longitudinais mais atenuam o potencial de transferencia de sedimentos sao: o Sao Vicente, da Lapa e Angelica. A forma dos perfis e a distribuicao das planicies aluviais estao intrinsecamente ligados aos compartimentos geomorfologicos da area do Parque Estadual de Terra Ronca e a evolucao do relevo regional, influenciando o transporte de sedimentos da rede de drenagem. The Role of the Longitudinal Profile in the attenuation of the Potential of Transport of Sediments in Watersheds: the case of the Terra Ronca State Park (GO), Brazil A B S T R A C T The shape of the longitudinal profiles of rivers associated with the distribution of the adjacent floodplains allows identifying sections with predominance of aggradational and denudational processes in the fluvial systems. This paper identifies stretches of the longitudinal profiles of the rivers upstream of the Terra Ronca State Park, in the northeast of the state of Goias, which have different trends to transfer of sediments to downstream. The rivers whose longitudinal profiles more attenuate the sediment transfer potential are: Sao Vicente, Lapa and Angelica. The shape of the profiles and the distribution of alluvial plains are intrinsically linked to the geomorphological compartments of the Terra Ronca State Park’s area and the evolution of the regional relief, influencing the sediment transportation of the fluvial drainage network. Keywords: sediment transportation, alluvial plains, geomorphological compartmentation.

Turbidity current is produced when a particle-laden fluid flows under lighter ambient fresh fluid. The streaming of particle-laden fluid is called a turbidity current and this kind of current is an important mechanism for sediment transportation in lakes and oceans. In the present research, the main concentration is on the effect of obstacle with an isosceles right triangular cross section on the behavior of turbidity current. A series of laboratory experiments were carried out with various obstacle heights and different inlet densimetric Froude numbers. In each experiment, velocity profiles upstream and downstream of the obstacle were measured, using an acoustic Doppler velocimeter. Kaolin was used as the suspended material. Experiments showed that the density current with lower inlet Froude number, reacts to the presence of the obstacle more rapidly compared to the currents with higher values of inlet Froude number. At the upstream section of the obstacle, an increase in the height of the obstacle resulted in a reduction in the current inertia and the maximum velocity. Also the local Froude numbers had an abrupt increase when the dense layer passed the obstacle.

Sand nourishments are presently widely applied to maintain or enhance coastal safety and beach width. Over the last decades, global sand nourishment volumes have increased greatly, and the demand for nourishments is anticipated to increase further in coming decades due to sea level rise. With the increase in nourishment size and the request for more complex nourishment shapes, an adequate prediction of the morphodynamic evolution is of major importance. Yet, neither the skill of current state-of-the-art models for such predictions nor the primary drivers that control the evolution are known. This article presents the results of a detailed numerical modelling study undertaken to examine the model skill and the processes governing the initial morphological response of the Sand Engine and the adjacent coastline. The process-based model Delft3D is used to hindcast the first year after completion of the mega-nourishment. The model reproduces measured water levels, velocities and nearshore waves well. The prediction of the morphological evolution is consistent with the measured evolution during the study period, with Brier Skill Scores in the ‘Excellent’ range. The model results clearly indicate that the sand eroded from the main peninsular section of the Sand Engine is deposited along adjacent north and south coastlines, accreting up to 6 km of coastline within just one year. Analysis of model results further show that the erosional behaviour of the Sand Engine is linearly dependent on the cumulative wave energy of individual high energy wave events, with the duration of a storm event being more dominant than the maximum wave height occurring during the storm. The integrated erosion volume due to the 12 events with the highest cumulative wave energy density accounts for about 60% of the total eroded volume of the peninsula, indicating that the less energetic wave events, with a higher probability of occurrence, are also important for the initial response of the Sand Engine. A structured model experiment using the verified Delft3D model indicates that wave forcing dominates the initial morphological response of the Sand Engine, accounting for approximately 75% of the total erosion volume in the first year. The vertical tide is the second most important factor accounting for nearly 17% of the total erosion volume, with surge, wind and horizontal tide playing only a minor role.

This chapter presents a numerical investigation of submerged debris flows using the DEM–CFD coupling model. The same DEM model configuration for granular column collapse as that discussed in Chap. 3 has been used in this research to simulate the mechanical behaviour of solid particles, while an incompressible, viscous fluid flow model has been introduced to capture the hydraulic behaviour of fluid flow in the submerged environment. This research aims to shed light on the fluid–solid interaction and the hydraulic properties of submerged debris flows. Conclusions are drawn with regard to the ability of the DEM–CFD coupling algorithm to model the sediment transportation and deposition processes.

The application of GOCI data in the research of sediment transportation is introduced in the paper..Compared with traditional ways to verify the simulated results, remote sensing data can contain a huge observation scope and a longer observing time.In. The computed results of water level and suspended sediment concentration were compared with processed GOCI data and had an acceptable result.

Based on a method stochastic processes, two new bedload transport models for the ith size fraction nonuniform sediment are theoretically developed by using a stochastic model of sediment exchange and the probabilistic distribution of fractional bedload transport rates. The relations, proposed recently by Yang, for the probability of fractional incipient motion and for the average velocity of particle motion are introduced to bedload formulas. Plenty of experimental data for the bedload transport rate of uniform sediment are used to determine parameters. Finally, the two models are verified with natural data expressing the transport of nonuniform sediment under full motion in laboratory flume. The result shows that the experimental observations agree well with the predicted fractional bedload transport rates. Comparison of the theory with field data shows that the proposed formula still applies to uniform sediment transportation condition as long as the relevant parameters for uniform sediment are taken into account.

Wakes, S., 2013. Three-dimensional Computational Fluid Dynamic experiments over complex dune topography In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) For modeling coastal dune systems the topography is often complex with complicating factors such as dune vegetation, sediment transport and the sand properties. Strategies such as simplifying the geometry and vegetation and no sediment transportation have been applied and provided insight into mechanisms of flow over the coastal dunes at Mason Bay, Stewart Island, New Zealand. Simulations building on the complexity of this modeling process are undertaken with a targeted mesh. Included was surface roughness signifying areas of vegetation but no Aeolian sediment transportation. Comparing preliminary results against the existing two and three-dimensional simulations and field data shows that although the strategy of splitting the domain in order to achieve three-dimensional results originally is workable simulating the whole do...

To ensure the secure buried depth of the subway tunnel which was routed underneath the Fenghuahe River, a two-dimensional tidal current and sediment transportation model was established to simulate the maximum scour depth of the riverbed. The conclusions were shown as follows: the most disadvantageous hydrologic condition was a combination of the 200-year return period flood in the Fenghuahe River and the 5-year highest tide in the Yonghe River. The maximum scour depth of the riverbed above the subway tunnel was 1.19 m and the lowest elevation of the riverbed cross-section was -8.56m. The results could provide technical support for the safety of subway design.

The Brazilian Law stipulates that water is a limited natural resource doted of economic value, thus it is necessary to develop mechanisms for its adequate management. Actions that encourage the farmers to apply soil conservation practices with the purpose of increase water yield from springs and to promote improvement of its quality, reducing production of sediment transportation, is being encouraged by governments, even with financial compensation for owners. From these assertions, this study aims to quantify the benefits of the conservation actions of the management units and to characterize a Water Yield Indicator (WYI) to support sustainable actions in the watershed of Alto Rio Grande region, in the state of Minas Gerais (MG). To assess the impact of actions it were identified four scenarios of land use and occupation of the watershed from Marcela stream which is located in Alto Rio Grande Region. After analyzing the results, it can be stated that the scenarios simulation has demonstrated important changes in water yield and that the definition of the Water Yield Index from the junction of the erosion potential with the water storage potential, has proved effective, as it integrate quantity and quality of water. A legislação brasileira estabelece que a água é um recurso natural limitado e dotado de valor econômico; logo, há necessidade de se criar mecanismos para sua adequada gestão. Medidas que estimulam os produtores rurais a adotarem práticas conservacionistas, visando a maior produção de água, melhoria de sua qualidade e redução da produção de sedimentos, vêm sendo estimuladas pelos governos, utilizando para isso até mesmo uma compensação financeira. A partir destas asserções, objetivou-se quantificar os benefícios das ações de conservação nas unidades de gestão e definir um Indicador de Produção de Água (IPA) para a tomada de decisão em uma bacia hidrográfica da região Alto Rio Grande-MG. Para avaliar o impacto das ações, foram definidos 4 cenários de uso e ocupação do solo da bacia hidrográfica do Ribeirão Marcela, localizada na UPGRH-GD1 (Alto Rio Grande). Após a análise dos resultados obtidos, chegou-se à conclusão de que as simulações de diversos cenários demonstraram alterações na produção de água e que a definição do Indicador de Produção de Água, a partir da junção do potencial de erosão com o potencial de armazenamento, demonstrou ser eficaz, pois integrou quantidade e qualidade de água.

Debris flow sabo dam is one of the most widely used debris flow control engineering. Its stability and safety operation is a key to controlling the effect of hazard prevention and avoiding secondary hazard. Because of the particularity of debris flow, it’s very hard to observe the process and morphology directly by field investigation. Although the scouring depth calculation method in hydraulic engineering provide an idea for debris flow sabo dam, but it can’t be used directly for the calculation of scouring depth downstream of debris flow sabo dams and foundation designation of the control engineering. This paper analyzed the influence factors of scouring laws downstream of debris flow sabo dams and the research status home and abroad. It suggests studying the scouring process and laws downstream of debris flow sabo dams by theoretical analysis, mechanical analysis and energy method combined with simulation experiments, establishing quantitative relationship between the scouring laws, limited depth, morphology, sediment transportation characteristics and the feature parameters of debris flow.

The map Series of surface suspended sediment distribution of Yangtze Estuary by remote sensing interpretation has been worked out based on the US Landsat TM and ETM images of the past two decades.In the map series,we revealed the spatial distribution pattern of surface suspended sediment at Yangtze Estuary,described the impact of the variation of tide,the construction of Three Gorges Dam and the variations of water and sediment discharges on sediment distribution,discussed the diffusion mechanism of surface suspended sediment at Yangtze Estuary during flood and dry seasons,the variation trend of high turbidity zone,the morphological change caused by sediment transportation from the river to the sea,and the variation of surface suspended sediment concentration.

Since the 92.2km-long , 350m-wide and -12.5m-deep draft channel was successfully achieved in the South Channel and the North Passage in the year 2010 , high siltation was found to temporally take place in the wet seasons , and spatially concentrate in the middle reach of the North Passage, where is consistent with the location of the traditional turbidity maximum zone (TMZ) of the Yangtze Estuary. The data from 2011 to 2015 show that the average annual siltation in the draft channel reached 80 Million m3 per year. With systematic analysis of the sediment source and comprehensive investigation on the mechanism of the flow and sediment transportation and siltation in the North Passage, this paper reveals a major cause of the back-siltation in the middle reach and subsequently discusses several engineering measures proposed to reduce the siltation . The final-selected engineering measure has been implemented quite recently , and the preliminary study shows that desired effect has been produced by the engineering measure.