Добірка наукової літератури з теми "Einstein's sediment transport parameters"

The movement of sediment such as sand, silt or gravel by flowing water is of interest to a wide range of engineering disciplines. This study is aimed at developing models, which can be used to predict the magnitude and levels of sediment concentration in Ogbese and Owena Rivers in Ondo State S.W. Nigeria for engineering design purposes. Data were collected from field investigations conducted at the respective sampling stations on the two rivers. The live bed concept used was derived from Liu – Hwang (1954) resistance equations and that of Einstein-Brown (1981) sediment transport concept. The problem was reduced to that of a power law relationship. These data ere fitted into the power relationship to obtain the predicted model of the form: F1Q = k2k1, where the parameters F1Q is the dimensionless sediment discharge,  is the dimensionless bed shear stress, k1 and k2 are sediments transport coefficients. Calibrating the models yielded the values of k1 and k2 for Ogbese river as 0.592 and 0.865 and for Owena river as 0.335 and 1.197 respectively. When tested the predicted models for Ogbese and Owena rivers performed well in comparison with the established models such as Ackers and White (1973), Engleund and Hansen (1967), Yang (1973) a\and Karim (1998). It is concluded that the models developed would be useful for engineering design purposes for Ogbese and Owena rivers.

By the use of the binomial expansion theorem, the series expansion relations in terms of the complete gamma function are obtained for Einstein integrals arising in the hydraulic and modern sediment transport mechanics. The approach presented for Einstein integrals is accurate enough over the whole range of parameters. The computational time for calculation of the series with respect to the literature is fast. Furthermore, the comparison of the method with numerical calculations demonstrates the applicability and accuracy of the method.

The initiation of sediment transport in sewers was investigated in field and laboratory studies. From the field studies it was concluded that some deposits in sewers are permanent due to the insufficient capability of the flow to erode the deposits. From the laboratory studies it was concluded that the upper limit of the critical shear stresses for cohesive sewer sediments may not exceed 5-7 N/m2. Non-cohesive sediments are eroded at lower shear stresses than predicted by Shields' criterion. The shear stresses were calculated using the general equations of continuity and motion and Einstein's separation technique for channels of compound roughness. Experiments showed the validity of this method.

The paper concerns the movement by waves of cohesionless sediment lying on a horizontal bed. In particular it concerns the number of dimensionless parameters that are necessary to define the 2-phase motion at the bed; the specification of which would enable perfect similarity to be obtained. It is shown that in general four dimensionless parameters are necessary but that when the motion of the water at the bed can be adequately defined by an orbit length (a) and a period (T), the two-phase motion can be described by the numerical value of three dimensionless parameters. This condition is satisfied when the wave-height is low, because then the orbital motion at the bed is sinusoidal and the drift velocity is negligible. Model and prototype experiments were conducted in a wave channel, using low waves, in which the scale for depth of water and for wavelengths was -37?. The dependent parameters, three of -which are sufficient to verify similarity of all aspects of the phenomenon were chosen to be ripple height, ripple length and transport of sediment. The identity of the dimensionless numbers signifying the ripple height, ripple length and transport in model and prototype, shown in Figs, 8, 9 and 11, is proof that similarity had been obtained.

The paper discusses the problem of high errors in the design ratios proposed for assessing sediment transport in natural watercourses. The question is why numerous empirical design ratios obtained and successfully used for some watercourses can give an error of 1000% when applied to other rivers. Calculation formulas worked out on hydraulic trays and channels are found to be inappropriate for specific rivers and natural channels. The problem is caused by the complexity of the natural watercourses geometry and the heterogeneity of the bottom sediment composition. Two approaches that are currently used in assessing the transporting capacity of river flows are studied in the paper. They were laid down in river hydraulics as early as the second half of the 18th century in the works by A. Chesi and P. Dubois. The conditions and possibilities of using both methods are considered and theoretically proven in the paper. The approach developed by P. Dubois is distinguished by a detailed study of the influence of individual factors based on numerous experimental models, the construction of fairly rigorous physical models on this basis, the complication of design ratios, the inclusion of new additional parameters. A. Chesi offered the construction of a maximally simplified initial physical model, with the calibration parameters established for specific conditions on the basis of field observations or qualitative estimates, and therefore being less accurate but more stable. It is shown that despite the scientific attractiveness of the approach to constructing and using more complex calculation models containing new additional parameters, the inclusion of additional parameters entails the inclusion of additional errors associated with the estimation of these parameters. The effectiveness of both approaches is proved; the application of one or the other approach is determined by the conditions and nature of the tasks to be solved, as well as the volume and accuracy of the initial data.

Robustness analysis of model parameters for sediment transport equation development is carried out using 256 hydraulics and sediment data from twelve Malaysian rivers. The model parameters used in the analyses include parameters in equations by Ackers-White, Brownlie, Engelund-Hansen, Graf, Molinas-Wu, Karim-Kennedy, Yang, Ariffin and Sinnakaudan. Seven parameters in five parameter classes were initially tested. Robustness of the model parameters was measured on the statistical relations through Evolutionary Polynomial Regression (EPR) technique and further examined using the discrepancy ratio of the predicted versus the measured values. Results from analyses suggest (ratio of shear velocity to flow velocity) and (ratio of hydraulic radius to mean sediment diameter) to be the most significant and influential parameters for the development of sediment transport equation.

Vegetation has been identified to play a significant role in river environments by providing a wide range of ecosystem services. For this reason, the use of plants has become relevant in river restoration projects. However, the presence of plants in channel beds increases the flow resistance and, thus, the water levels during flood conditions. Additionally, river vegetation, whether instream or riparian, influences the morphological evolution of rivers. Observations show that instream vegetation has a strong impact on bedload transport. Yet, there is a scarcity of sediment transport predictors that directly account for the effects of plants, and existing methods, based on re-calculation of roughness coefficients, may present some inconsistencies. Therefore, an approach that extends Einstein’s (1950) parameters to include the effects of vegetation geometry and spatial density on sediment transport is herein proposed. The new formulations of the dimensionless transport parameter Φ and the flow intensity parameter Ψ were derived for their implementation in existing bedload predictors of the form Φ = (Ψ). The applicability of this new approach considers the presence of submerged and emergent vegetation, but reduces to the original Einstein’s model if vegetation is absent. The research methodology was carried out in four phases. First, a comprehensive literature review for the identification of, mainly, the different effects of vegetation on river morphodynamics, the state-of-the-art knowledge on the flow-sediment-vegetation interactions, and the current approaches to bedload estimation in channels with vegetated beds. Second, the derivation of the extended Einstein’s parameters, starting from a momentum balance for a control volume of a generic channel with instream submerged vegetation (as proposed by Petryk and Bosmajian, 1975). Third, an extensive experimental program carried out on a tilting flume with a mobile bed and with plants being represented by series of aluminum cylinders. Different scenarios of vegetation spatial density were tested while measurements of bedload rate, water level, bed level and flow velocity were periodically performed in order to assess conditions of stationarity and morphodynamic equilibrium. Last, a deep analysis of experimental results allowed for the calibration of the new approach, whereas external datasets from the literature were used to assess its performance in a wide variety of conditions. A study based on four statistical measures showed that the extended Einstein’s parameters are significantly more suitable for bedload rate estimation when compared to the original ones, since predicted and measured values have, on average, the same order of magnitude. Additionally, the new approach outperformed the widely-adopted method of Baptist (2005), which consists of the re-calculation of bed roughness in vegetated settings. Finally, the experimental observations suggest that the submergence ratio and the stem spatial density are the most important traits of river plants to display influence on bedload transport, channel bed stability, and bed form dimensions and patterns. A better understanding of these traits might lead to better prediction capabilities of river evolution.
La vegetazione svolge un ruolo fondamentale negli ambienti fluviali, poiché fornisce un ampio spettro di servizi ecosistemici; per questo essa è una componente rilevante dei progetti di riqualificazione fluviale. Tuttavia, la presenza di piante in alveo aumenta la resistenza al moto e di conseguenza anche il tirante idrico durante gli eventi di piena. Inoltre, la copertura vegetale in alveo e nelle zone riparie influenza l'evoluzione morfologica dei corsi d'acqua. Nonostante le evidenze sperimentali mostrino che la vegetazione in alveo ha un forte impatto sul trasporto dei sedimenti, sono poche le formule di trasporto che tengono conto in modo esplicito dell'effetto della vegetazione e i metodi esistenti, basati sulla determinazione di un coefficiente di scabrezza, possono dare luogo a incongruenze. Per questa ragione, in questa tesi si propone un approccio che estende la formulazione di Einstein (1950) e include l'effetto della geometria e della densità spaziale della vegetazione sul trasporto solido. Sono state derivate nuove espressioni per il parametro di trasporto adimensionale Φ e il parametro di intensità del trasporto Ψ, che possono essere introdotte in modelli di trasporto esistenti del tipo Φ = f(Ψ). Questo nuovo approccio consente di considerare l'effetto della presenza di vegetazione sommersa ed emergente e si riduce al modello originale di Einstein in assenza di vegetazione. L'attività di ricerca si è svolta in quattro fasi. Nella prima fase si è svolta un'analisi approfondita della letteratura mirata soprattutto a identificare gli effetti della vegetazione sulla morfodinamica fluviale, definire lo stato dell'arte relativo alle interazioni fra flusso liquido, sedimenti e vegetazione, ed analizzare gli approcci esistenti per la stima del trasporto di fondo in alvei vegetati. Nella seconda fase si sono derivati i parametri della formulazione di Einstein estesa a partire dal bilancio di quantità di moto per un volume di controllo di un canale generico con vegetazione sommersa (come proposto da Petryk e Bosmajian, 1975). Nella terza fase è stato condotto un esteso set di esperimenti, utilizzando un modello fisico costituito da una canaletta di laboratorio a pendenza variabile e fondo mobile, in cui le piante sono state simulate tramite cilindri in alluminio. Sono stati riprodotti diversi scenari di densità spaziale della vegetazione e sono stati misurati periodicamente la portata solida, la quota della superficie libera e del fondo e la velocità della corrente per valutare le condizioni di stazionarietà ed equilibrio morfodinamico. Infine, il nuovo approccio è stato calibrato sulla base di un'analisi approfondita dei risultati sperimentali e quindi applicato a set di dati di letteratura per valutarne l'accuratezza in un ampio intervallo di condizioni. Un'analisi statistica basata su quattro indicatori ha mostrato che i parametri della formulazione di Einstein estesa producono stime di trasporto solido sensibilmente più accurate rispetto ai parametri originali, in quanto i valori calcolati sono, in generale, dello stesso ordine di grandezza dei valori misurati. Inoltre, il nuovo approccio dà risultati migliori rispetto al metodo di Baptist (2005), ampiamente adottato, che consiste nel ricalcolo della scabrezza per gli alvei vegetati. Infine, le osservazioni sperimentali suggeriscono che il rapporto di sommergenza e la densità spaziale delle piante sono i parametri che influenzano in modo più significativo il trasporto solido, la stabilità del fondo dell'alveo, la scala delle forme di fondo e la loro organizzazione spaziale. Una conoscenza più approfondita di questi aspetti può contribuire a una maggiore capacità di prevedere l'evoluzione dei corsi d'acqua.
Se ha identificado a la vegetación como un actor importante en ambientes fluviales al proporcionar una amplia gama de servicios ecosistémicos. Por esta razón, el uso de plantas se ha vuelto cada vez más relevante en proyectos de restauración de ríos. Sin embargo, su presencia en lechos fluviales impacta la resistencia al flujo, aumentando los niveles del agua en condiciones de inundación. Además, este tipo de vegetación, ya sea que esté en el lecho o en las márgenes, influye en la evolución morfológica de los ríos. Diversas observaciones han mostrado que la vegetación fluvial tiene un fuerte impacto en las tasas de transporte sólido de fondo. A pesar de ello, hay una escasez de métodos confiables para la estimación de este tipo de sedimentos que tome en consideración el efecto de las plantas y, aquéllos que existen, los cuales se basan en la corrección del coeficiente de rugosidad del canal, suelen presentar resultados inconsistentes. Por tanto, se propone aquí un método que extiende las definiciones fundamentales de Einstein (1950) en modo que se incluyan los efectos de la geometría y la densidad espacial de las plantas sobre el transporte sólido. Las nuevas ecuaciones del parámtero de transporte, Φ, y el parámetro de movilidad, Ψ, fueron obtenidas para su implementación en métodos predictores de transporte de fondo de la forma Φ = (Ψ). La aplicabilidad de este nuevo enfoque considera la posibilidad de vegtación fluvial tanto emergente como sumergida, y se reduce a las ecuaciones originales de Einstein si ésta fuera inexistente. La metodología de investigación se llevó a cabo en cuatro fases. Primero, una revisión exhaustiva de la literatura para la identificación, principalmente, de los diferentes efectos de la vegetación en la morfodinámica de ríos, los avances más recientes en el conocimiento sobre las interacciones flujo-sedimento-vegetación, y los métodos actualmente existentes para la estimación del transporte sólido de fondo en canales naturales vegetados. En segundo lugar, la obtención de los parámetros de Einstein extendidos a partir de un balance de momentum para el volumen de control de un canal genérico con vegetación sumergida (según lo propuesto por Petryk y Bosmajian, 1975). En tercer lugar, un extenso programa experimental realizado en un canal de fondo móvil y pendiente variable, con las plantas siendo representadas por series de cilindros metálicos. Se probaron diferentes escenarios de densidad espacial de vegetación, mientras que periódicamente se realizaron mediciones transporte sólido, niveles del agua, topografía del fondo y velocidad del flujo con el objeto de evaluar las condiciones de flujo uniforme y equilibrio morfodinámico. Por último, un análisis profundo de los resultados experimentales permitió la calibración del nuevo método, mientras que se utilizaron datos externos disponibles en la literatura para evaluar su desempeño bajo diversas condiciones. Un estudio basado en cuatro medidas estadísticas mostró que los parámetros extendidos de Einstein son mucho más adecuados para la estimación del transporte de fondo en comparación con los originales, ya que los valores estimados y los medidos muestran, en promedio, el mismo orden de magnitud. Además, el nuevo método superó al propuesto por Baptist (2005), ampliamente utilizado, el cual consiste en la corrección de la rugosidad del canal en presencia de vegetación. Finalmente, las observaciones experimentales sugieren que la sumergencia de las plantas y la densidad espacial de los tallos son las variables más influyentes en el transporte sedimentos de fondo, la estabilidad del lecho, y las dimensiones y patrones de la forma de fondo. Una mejor comprensión de estas variables puede significar una mejor capacidad para predecir la evolución de un río.

The oscillatory turbulent flow over fixed two dimensional ripples is numerically solved by using an appropriate turbulence closure. The aim of the contribution is that of detecting features of the flow field which influence the ripple shape and the sediment transport. The flow depends on three dimensionless parameters: the Reynolds number (Re), the ripple steepness (h/L) and the ratio between the amplitude of fluid excursion close to the sea bed and ripple wavelength (a/L). The results suggest that for increasing values of a/L, the vortex shed on one side of the ripple crest is no longer the mirror image of the vortex shed on the other side of the ripple during the following half oscillation cycle. This suggests, for ripples forming in an erodible bottom, an uneven degree of sediment entertainment from the two sides of the ripple crest. Moreover, steady recirculating cells form. The number of cells which form per ripple length can be either one or two, depending on the values of the parameters. The presence of steady recirculating cells is expected to influence the equilibrium shape of the ripples. The evaluation of the plane and time averaged velocity component shows the formation of a horizontal steady streaming, which is directed either onshore or offshore. Such steady streaming is bound to influence the cross-shore sediment transport.

La Nouvelle-Calédonie, île située au Sud-Ouest de l’Océan Pacifique et actuel 6e producteur mondial de nickel, est confrontée à une pollution sédimentaire sans précédent de ses cours d’eau. En effet, l’exploitation minière débutée dès les années 1880 a fortement amplifié les processus d’érosion des sols et de transport sédimentaire. Une hyper-sédimentation des hydro-systèmes calédoniens a notamment été constatée suite au déploiement de l’activité minière sur l’archipel. Bien que ce phénomène constitue un facteur aggravant les problèmes d’inondation caractéristiques de ces régions tropicales, les contributions sédimentaires générées par l’exploitation minière restent encore inconnues à ce jour et sont pourtant importantes pour guider la mise en œuvre de mesures visant à réduire ces apports sédimentaires.À cette fin, une étude de traçage sédimentaire qualifiée de fingerprinting a été menée sur un bassin « pilote » : le bassin versant de Thio (397 km²), considéré comme le « berceau » de l’activité minière en Nouvelle-Calédonie. Différents marqueurs tels que les radionucléides, la géochimie élémentaire ou la « couleur » ont été testés pour quantifier les contributions des sources minières aux apports sédimentaires générés par deux crues cycloniques récentes (dépression tropicale en 2015, cyclone Cook en 2017). Une carotte sédimentaire a également été prélevée dans la plaine inondable de la rivière Thio afin de reconstruire l’évolution temporelle des contributions des sources minières. Les résultats de cette étude montrent que les contributions des sources minières dominent, avec une contribution moyenne comprise entre 65-68% pour la crue de 2015 et entre 83-88% pour celle de 2017. L’impact de la variabilité spatiale des précipitations a notamment été mis en évidence pour expliquer les variations des contributions de ces sources. Les variations temporelles des contributions des sources minières déduites de l’analyse de la carotte sédimentaire ont, quant à elles, pu être associées aux différentes périodes historiques de l’exploitation minière sur le bassin versant de Thio (pré-mécanisation, mécanisation, post-mécanisation de l’activité minière). Les contributions des sources minières restent, là encore, dominantes avec une contribution moyenne le long du profil sédimentaire de 74%. La méthode de traçage validée a ensuite été testée sur quatre autres bassins versants de Nouvelle-Calédonie afin d’évaluer la transposabilité de cette approche
New Caledonia, an island located in the south-western Pacific Ocean and currently the world's sixth largest producer of nickel, is facing unprecedented sedimentary pollution of its river systems. Indeed, nickel mining that started in the 1880s accelerated soil erosion and sediment transport processes. Hyper-sedimentation of the Caledonian hydro-systems has been observed after the deployment of mining activities on the archipelago. Although this phenomenon exacerbates the flooding problems experienced in these tropical regions, the sediment contributions generated by nickel mining remain unknown and are nevertheless required to guide the implementation of control measures to reduce these sediment inputs.To this end, a sediment fingerprinting study was carried out in a "pilot" catchment: the Thio River catchment (397 km²), considered as one of the first areas exploited for nickel mining in New Caledonia. Different tracers such as radionuclides, elemental geochemistry or "colour" properties were tested to trace and quantify the mining source contributions to the sediment inputs generated during two recent cyclonic flood events (tropical depression in 2015, cyclone Cook in 2017). A sediment core was also collected in the floodplain of the Thio River catchment to reconstruct the temporal evolution of these mining source contributions. The results of this study show that mining sources dominated sediment inputs with an average contribution ranging from 65-68% for the 2015 flood event to 83-88% for the 2017 flood event. The impact of the spatial variability of precipitation was highlighted to explain the variations in the contributions of these sources across the catchment. The temporal variations in the contributions of the mining sources deduced from the analysis of the sediment core were interpreted at the light of the mining history in the Thio River catchment (pre-mechanization, mechanization, post-mechanization of mining activity). The contributions of mining sources were again dominant with an average contribution along the sedimentary profile of 74 %. Once validated, this tracing method has been tested in four other catchments of New Caledonia in order to evaluate the validity of the approach in other contexts

碩士
國立臺灣大學
農業工程學研究所
89
Sediment deposition in gravel-bed rivers has great influence on salmonid embryo survival and it could be solved by flushing flow to remove fine sediment out of the substrate. Therefore, understanding the mechanism of partial transport of nonuniform sediment bears important ecological meaning for protection of salmonid. This study applies stochastic theory with the mechanism of partial transport to develop a bedload transport model of nonuniform sediment for gravel-bed rivers. The parameters of the model are derived from flume experiments. This study establishes an experimental procedure based on digital image processing so that the parameters could be obtained from flume experiments. 　　The experimental study is divided into two parts, which are color-bed experiments and non color-bed experiments. The color bed experiments are mainly to investigate the mobility of sediment. We could estimate the number and position of sediment for any size fraction in the bed by applying blob analysis of image processing software and compare the initial image with the final image to determine the mobility of each size fraction. The non color-bed experiments are set to the dimensionless mean velocity and moving-static time ratio of sediment. We could obtain the moving distance of sediment by using the function of particle tracking from sequent images so that the mean velocity of sediment can be calculated. 　　The preliminarily experimental results of this study verify that digital images of particle motion and image processing technology could be applied to determine the needed model parameters. We also confirm that the moving time and static time of sediment particles are exponentially distributed which are the corresponding presumption of the Markov chain process. There exist obvious relationships between the dimensionless mean velocity and moving-static time ratio of sediment particles with the dimensionless shear stress. We could predict partial transport of nonuniform sediment and use the model as a tool for flushing flow planning after the functional relationship of the model parameters with the dimensionless shear stress are determined.

Flow-through porous media is concerned with the term hydraulic conductivity (K), which imparts a crucial role in the groundwater processes. The present work examines the impact of key parameters i.e., grain size and porosity on the K of four borehole soil samples (Gravelly, Coarse, Medium, and Fine sands) and evaluates the applicability of seven empirical relationships for K estimation. Experimental investigations postulate that an increase in the grain size and porosity value increases the K value. Further, the K values computed using the Kozeny–Carman relationship proved to be the best estimator for Coarse, medium, and fine sands followed by Beyer and Hazen relationships. However, the Beyer relationship had a closer agreement with experimentally obtained value for Gravelly sand. Alyamani and Sen relationship is very sensitive toward the grain-size curve pattern, hence it should be used carefully. Whereas other relationships considered in this study underestimated the K of all samples.

Sediment transport (ST) in unsteady flows is a complex phenomenon that the existing formulae are often invalid to predict. Almost all existing ST formulae assume that sediment transport can be fully determined by parameters in streamwise direction without parameters in vertical direction. Different from this assumption, this paper highlights the importance of vertical motion and the vertical velocity is suggested to represent the vertical motion. A connection between unsteadiness and vertical velocity is established. New formulae in unsteady flows have been developed from inception of sediment motion, sediment discharge to suspension’s Rouse number. It is found that upward vertical velocity plays an important role for sediment transport, its temporal and spatial alternations are responsible for the phase lag phenomenon and bedform formation. Reasonable agreement between the measured and the proposed conceptual model was achieved.

The present study contributes to the evaluation of the impact of the various activities developed around the Bay of Dakhla in Morocco through the study of the physico-chemical quality of the waters and sediments of the Bay. For this purpose, a spatial and temporal monitoring of the physicochemical and metallic pollution indicator parameters was conducted between May 2014 and March 2015. The main physicochemical descriptors of water quality were monitored, namely: temperature, salinity, pH, dissolved O2, nutrients (ammonium, nitrites, nitrates, phosphates) and chlorophyll (a). A qualification of the waters of the Bay was drawn up based on water quality assessment grids. The quality of the sediments was assessed through the determination of granulometry, the total organic carbon content and the contents of the main metallic trace elements (cadmium, lead, mercury, chromium, copper and zinc). The results of the present study show the beginning of nutrient enrichment of the water bodies of the bay, especially the stations located near the urban area, where 1.83 mg l−1 of nitrates, 0.37 mg l−1 of phosphate and 7.42 μg l−1 of chlorophyll (a) were recorded. For the sediment, the maximum concentrations of metallic trace elements were recorded in the station near the harbour basin. These results allowed to establish a quality grid for the waters of the bay, generally qualified as “Good”, except for the sites located near the urban area for which the quality is qualified as “Average”. The sediment quality of the bay was assessed according to the criteria established by the Canadian Council of Ministers of the Environment. The levels of metallic trace elements remain below the toxicity thresholds, except for the sediments taken from the harbour basin.

The transport and fate of chemicals in the environment comprise one of the most pertinent issues in environmental chemistry. Physical and chemical interactions between the chemical of interest (sorbate) and the various components present in soil, water, and sediment (sorbent) can dramatically influence the transport and fate of the chemical. For example, organic material such as humic acids or surfactants, when bound to the surface of soil, sediment, and clay particles, can enhance sorption of chemicals to the particle surface, immobilizing the chemicals and possibly protecting them from degradation. The term “sorption,” as used in this chapter, refers to any physical or chemical association between the sorbate and sorbent. Thus, this definition includes molecular associations ranging from hydrophobic partitioning processes to covalent binding. It has also been observed that sorbents can act as a “buffer system” for the sorbate by taking up the sorbate when it is present at high concentrations and then slowly releasing it back into solution during periods of low or zero sorbate concentration. This type of behavior is important when the environmental presence of the chemical is episodic, such as in seasonal application of pesticides and herbicides. A dramatic example of this is presented by Steinberg et al., who detected the volatile, soil fumigant 1,2-dibromoethane in agricultural topsoils up to 19 years after the last application. On the other hand, soluble organic matter such as dissolved humic and fulvic acids can dramatically increase the apparent solubility of many hydrophobic chemicals in soil and sediment pore water. In this manner, the mobility of the chemical is increased. Thus, the nature and presence of organic material can strongly influence the transport properties of many chemicals in the environment. It is well known that sorption processes are a function of numerous parameters: the chemical characteristics of the sorbate (e.g., hydrophobicity, polarity), and the identity and chemical characteristics of the mineral phase and its organic coating. Other parameters important to sorption processes are the porosity of the sorbent particles, the presence of dissolved organic matter, and the solution pH and ionic strength.

Accurate estimation of the amount of sediment in rivers; determination of pollution, river transport, determination of dam life, etc. matters are very important. In this study, sediment estimation in the river was made using Interaction Regression (IR), Pure-Quadratic Regression (PQR) and Support Vector machine (SVM) methods. The observation station on the Patapsco River near Catonsville was chosen as the study area. Prediction model was developed by using daily flow and turbidity data between 2015- 2018 as input parameters. Models were compared to each other according to three statistical criteria, namely, root mean square errors (RMSE), mean absolute relative error (MAE) and determination coefficient (R2 ). These criteria were used to evaluate the performance of the models. When the model results were compared with each other, it was seen that the IR model gave results consistent with the actual measurement results.

The main objective of this paper is to study the protection of sediment siltation and shoreline evolution in Taichung harbor using two numerical models of SMC (Coastal Modeling System) and GENESIS (GENEralized model for SImulating Shoreline change System). Numerical results of wave height in the vicinity of groins were compared to validate the capability of SMC model. In addition, the transport parameters, K1 and K2 in GENESIS are calibrated. Some numerical cases were runned to simulate the nearshore hydrodynamics, the sediment transportation and siltation on the north area with siltation of Taichung harbor. In particular, a beach nourishment measure is proposed based on GENESIS simulations of shoreline change on southern eroded coast.

Ulza Dam is one of the oldest hydropower infrastructures in Albania. The water capacity of the reservoir has been reduced because of the accumulation of the sediments coming from Mat River. The bathymetric measurements and river sediment transport are used for quantifying the water storage change up to nowadays. Analyzing the future climate change impact in the sediment transport from the river is very important for understanding the Ulza Dam lifespan. In order to analyze the sediment regime in the future, the climate change projection from the EURO-CORDEX has been downscaled for Mat River catchment and used as input for the HEC-HMS hydrological model considering also the erosion and sediment module. The hydrological model was also calibrated with the MUSLE parameters, and it reproduces the average value of the total sediment transport. The analysis of climate change impact on erosion and sediment transported at the reservoirs was done considering the mean annual load for the different 30-year simulated periods related to values from the historical period 1981-2010. Considering the impacts of climate change, the mean annual sediment siltation could increase for RCP4.5 and RCP8.5 scenarios. Over this hypothesis, the remaining lifespan can be reduced drastically in both scenarios. Different land-use scenarios were analyzed in order to evaluate the impact of erosion and, because the current land use scenario doesn’t produce any impact on the hydrological process, but only effects at a small scale, two hypothetical scenarios were defined at large scale and applied for Mat River catchment. Extensive management of land use and reforestation produce a positive effect on the hydrological process and reducing the erosion rate. The change of land use significantly counteracts the negative effects of climate change by 15% and a 24% reduction in the case of these land-use scenarios.

Deposition of sediment by means of discharging via the bottom doors of a Trailing Suction Hopper Dredge is a method often used. This method can be deployed for land reclamation and backfilling of trenches for pipelines or outfalls. The sediment will leave the hopper as a mixture of sand and water. Sand will settle from this mixture. The shape of the under water body is governed by the dynamic settling process from a (sometimes highly concentrated) density current. Slopes angles and density of the sand body and possible segregation is depending on the discharge production, sediment characteristics, water depth and ambient current. In the paper the discharge process is simulated using a 2 dimensional numerical model based on the Reynolds Averaged Navier-Stokes equations. In this model the momentum and sediment transport equations are solved. The model includes a morphological module therefore slopes angles can be predicted. The computational results are validated using laboratory tests. The efficiency of the backfilling process, expressed as the ratio between the volumes of settled sediment in the trench and the discharged sediment, is determined as a function of the domination process parameters.

Bovilla reservoir is the main source of water supply for around 1 million inhabitants in Tirana, the capital of Albania. The reservoir was created in 1998 from Bovilla Dam and belongs to the upper part of the Terkuza River catchment. The dam previously was planned in a smaller size for irrigation purposes. Intense erosion due to large deforestations followed by increasing nutrient run-off from cultivated land is a challenge for the Bovilla Dam management authority because it is influencing the water quality in daily use and decreasing the dam lifespan in long term. Zall Bastari stream transports high amounts of solid materials. Other streams show also a strong torrential character, after rainfall events the water level suddenly rises which leads to massive erosion. Daily meteorological parameters and 30 meters Digital Terrain Model is used together with Land Cover Map in the HEC-HSM hydrological model which is designed to simulate the complete hydrologic processes of watershed systems, including the erosion and sediment transport. The lack of water level and discharge data made impossible the calibration of the hydrological model. The creation of a new data series for the daily discharges was crucial for further analyzes of the sediment transport and accumulation into the reservoir. Bovilla basin has been divided into many sub-basins in order to better calculate the inflow at the reservoir. The lack of previous bathymetric data caused the usage of alternative ways to calculate total accumulated sediment into the reservoir instead of the classical way in lifespan analysis. The characteristics of the sediment in the sub-basins and in the riverbed have been defined through gradation curves got from some available data. Sediment yield has been evaluated based on the conditions of the previous 21 years, from the construction of the dam in 1996 to nowadays. The old storage curve has been interpolated to be compared with the one defined after the survey specifically done in 2017. The analysis was very important to understand the way haw are accumulated sediment into the reservoir but also their distribution through the reservoir bed.

The interest to study the processes in the Imeretinka lowland increases in the last years due the few reasons. The main structures of so-called “coastal cluster” of Olympic Games 2014 built in this area. Some of planned structures effected significantly the coastal processes; they are the seaport near the river Mzimta mouth and coastal protection. The natural coastal processes in the area complicated by the effects of the underwater canyons. The natural-technogenic system requires the study with using the methods of modeling and monitoring. Wave climate of Imeretinka lowland coast estimated based on long-term data of meteorological fields above Black Sea with modeling of wave transformation in nearshore zone by the gentle slope equations. Such approach provides possibilities to assess the effect of the designed coastal protection structures on the changes of the wave parameters in nearshore zone. Numerical modeling of currents in the Black Sea using 3D circulation model with refinement in the region of canyons of the Imeretinka coast obtained. To estimate the sediment transport, 3D Lagrangian multifraction sediment transport model LagrSed is used. 2D flow fields, free-surface level and wave characteristics calculated, using 2D hydrodynamic model of the coastal zone. It has presented the few years story of modeling and monitoring of the coastal processes with the important lessons.

Estuaries trap much of the fine sediment delivered to them by rivers. This phenomenon presents challenges to the US Army Corps of Engineers (USACE) navigation mission, which maintains navigable waterways for waterborne commerce through estuarine regions. The USACE Regional Sediment Management Program and the USACE Norfolk District are conducting a regional sediment transport modeling study to identify cost-effective sediment management schemes in the James River, a tributary estuary of Chesapeake Bay. A key element of the sediment transport modeling study is the definition of cohesive sediment transport processes, such as erosion and settling velocity. This report describes field-based measurements of cohesive sediment erosion and settling velocity conducted in November 2017. The team conducted erosion testing on 15 cores collected throughout the tidal system. Additionally, two anchor stations were occupied to measure tidal variations in vertical distributions of suspended sediment concentration, particle size, and settling velocity. Recommended cohesive sediment transport parameters were developed from the field measurements.

Navigation channels, turning basins, and other US Army Corps of Engineers (USACE)–managed navigation infrastructure often serve as repositories for contaminated sediment from off-site sources. As much as 10% of the material that USACE dredges on an annual basis is contaminated such that it requires additional and more costly management (for example, rehandling and placement in managed confined disposal facilities). Presence of contaminated sediments constrain potential management options resulting in additional costs and opportunity loss from the inability to beneficially use the material. One potential solution is applying clean dredged material to stabilize and isolate contaminated sediment sources, preventing further transport and introduction to USACE-managed infrastructure. This document summarizes a comprehensive literature review of laboratory and field case studies relevant to using clean dredged material to isolate or stabilize contaminated sediments, focusing on the physical, chemical, and biological parameters critical to establishing its feasibility and long-term effectiveness. Potentially effective engineering control measures were also reviewed where erosion and site hydrodynamics are facilitating the transport of contaminated sediments to USACE-maintained navigation infrastructure. This literature review documents and summarizes those factors considered in establishing feasibility and long-term effectiveness of the approach as well as the applicable engineering tools employed and constraints encountered.