International Journal of Sediment Research最新文献

Every dam or barrage construction affects the watercourse and the retention of sediment that previously was carried by the river, which can lead to siltation of the reservoir and obstruction of water intakes over time, reducing their capacities. However, the information available regarding the effect of sediment and drawdown parameters, sediment management at reservoirs, as well as different equational approaches, is scarce. The current research aims to evaluate the effect of parameters associated with numerical modeling of sediment management in reservoirs considering scenarios with different drawdowns, transport equations, sediment size distributions, and thickness of the initial sediment layer. The case study of the Aimorés Hydropower Plant (HPP) is used, applying the Delft3D-FLOW model for two-dimensional modeling. All parameters influenced the volume of mobilized sediment, among which the initial layer thickness was the parameter that resulted in the greatest changes in simulated results. In general, the results show that the uncertainties in the input parameters outweigh the uncertainties between the techniques, which found large variations in results when evaluating the use of different transport equations. These results indicate the importance of proper estimation of model parameters for predicting effects with accuracy and the need for such studies before planning and management operations are evaluated to avoid environmental harm and energy waste.

Sand waves of approximately 2 m in height were observed to migrate nearly 40 m with counterclockwise rotation between two bathymetric surveys performed three months apart near the southeastern corner of Martha's Vineyard, Massachusetts. The region is characterized by strong tidal currents, intermittent energetic surface wave events, and shallow water with local depth ranging from 2 to 7 m. This study uses the process-based model, Delft3D, with a three-dimensional approach to examine the sand wave dynamics by incorporating surface waves, winds, currents, and bathymetric observations. The model successfully simulates sand wave migration in comparisons to observations. Model sensitivity analyses show that the sand wave migration reduces by 65% with the absence of the surface waves. The modeled sand wave migration speed is correlated with the tidal current Shields parameter, and sharp increases in migration speed occur when the wave-driven Shields parameter increases in response to energetic surface wave events. The combined effect of tides, surface waves, and bathymetry is the origin of the rotational aspect of the sand wave, using the Shields parameter as an indicator of tidal currents and surface wave influence on sand wave dynamics.

The gravitational settling of a flexible, permeable circular and planktonic particle drenched in a fluid which is assumed to be Newtonian and incompressible along with being viscous was studied. A mathematical formulation and numerical simulations of the studied problem were done by applying the Immersed Boundary Method (IBM) in a two-dimensional fluid domain. Parametric studies were done for analyzing the impact of varying flexibilities and permeabilities with reference to settling velocity (terminal velocity) and shape deformation of the particle. The terminal velocity and permeability of the particle are directly proportional. It was observed that for fixed permeability, the terminal velocity increases when increasing the flexibility of the particle.

The current study utilizes a range of diagenetic fingerprints to differentiate between sandstone facies deposited in the Nile Delta before and during the Messinian salinity crisis (MSC), which is normally a challenging task considering the complex bio- and lithostratigraphic subdivisions of Messinian rock units. Subaerial exposure of the pre-MSC (Qawasim deltaic sandstone), during drawdown of the Mediterranean Sea at the time of the MSC, triggered pervasive dissolution of unstable rock fragments, kaolinization of feldspar, and meteoric dolomitization of carbonate. This was followed by mesogenetic calcite cementation and kaolinite transformation into dickite in deeply buried Qawasim sandstone. Comparatively, the Abu Madi estuarine facies, deposited during transgression after drawdown related to the MSC, is characterized by eogenetic iron (Fe)-calcite, glauconite, and pyrite (averages of 14.5%, 6%, and 2%, respectively). This facies transition is marked by abundance of mature glauconite (with potassium oxide (K₂O) at about 8%) whose content abates upward from the transgression surface. Moreover, the compositional variability of the Abu Madi sandstone gave rise to multiple diagenetic trajectories that resulted in chlorite formation presumably following smectite and kaolinite. Listed diagenetic variations in the studied Messinian sandstone resulted from a complex interplay between rocks’ compositional, depositional, and burial attributes, ultimately serving as a basis for high-resolution stratigraphic correlation in continental and marginal marine settings with poor biostratigraphic controls.

Problems of soil erosion and sedimentation are issues of global concern. With the intensification of global change and the impacts of human activities, many countries are facing severe challenges from wide-ranging sediment-related problems. The prevention and control of sediment disasters and the rational use of soil and sediment resources are important requirements for the sustainable development strategies of all countries. As sediment problems are closely related to social, economic, and other human activities, the effective solution of sediment problems requires the concerted efforts of experts in different fields and thus an interdisciplinary approach is essential. In view of the increasing recognition of sediment as a topic of global significance and the need to promote interdisciplinary research in this field, the World Association for Sedimentation and Erosion Research (WASER) was inaugurated in 2004. In this paper the history of the establishment of WASER is reviewed and its main activities are briefly summarized. The series of International Symposia on River Sedimentation (ISRS) has served as the official symposium of WASER since 2004. These triennial technical events have been held in China, Russia, Japan, South Africa, and Germany with about 2,000 participants. In addition to sponsoring the ISRS, WASER has to date also sponsored/organized or co-sponsored/co-organized over 30 other international conferences, workshops, training courses, and study tours besides sponsoring the ISRSs. The adoption of the International Journal of Sediment Research (IJSR) as the official journal of WASER in 2004 has also played an important role in increasing the exposure of the Association. These activities have served to raise WASER's profile as well as promoting collaboration with agencies and other organizations working in the field of erosion and sedimentation. Three types of prizes and honors are awarded by WASER. These include the International Qian Ning Prize for Erosion and Sedimentation Technology, the IJSR Award for Distinguished Contributions to Sediment Research and Honorary Membership. Through its activities, WASER aims to strengthen the development of education and capacity building in the field of sustainable sediment management in global water management, promote sharing of information, on related data, the results of scientific research, and management methods, and advances in the study of erosion and sedimentation.

Flocculation-settling of cohesive fine sediment is the main cause of sediment deposition and changes in topography and geomorphology in estuaries. However, studies on estuary morphology have often focused on a single influencing factor, and sediment deposition characteristics under disturbances in sediment concentration, moisture content, and external forces have rarely been considered simultaneously. The authors propose an ultrasound-assisted flocculation-settling method to analyze the various factor affecting cohesive sediment. The current study examined the sedimentation patterns of cohesive sediment with a sediment content concentration of 30%–80% through ultrasound experiments. The results show that when the sediment concentration is 40%–50%, the best effect on flocculation and sedimentation is induced by ultrasound waves. The corresponding settling height at the clear-muddy water interface is 3.05–3.45 cm, and the settling rate is 0.161–0.173 cm/min. Finally, using ultrasound waves, a moisture content of the sediment concentration of 30%–80% was analyzed based on wet and dry conditions. Taking a sediment concentration of 50% as an example, the maximum values of the variation in the water contents of the upper, middle, and lower layers of the wet basis were 0.82%, 0.51%, and 0.37%, respectively, whereas those of the upper, middle, and lower layers of the dry basis were 4.77%, 1.07%, and 0.60%, respectively. Thus, the moisture content of dry and wet sediment varied as follows: W_upper > W_middle > W_lower. The current research results can provide a theoretical basis and technical reference for siltation in channels, harbors, and reservoirs; the evolution of submarine deltas and coastal beaches; transportation of fluid mud; and the treatment of hyper-concentrated sediment flows.

Particulate matter, such as sediment and microplastics (MPs), in aqueous environments has comparable micro-interfacial characteristics. However, the micro-interfacial characteristics of heterogeneous particulate matter are complex and are not fully understood. In this study, micro-interfacial kinetics and the interactions governing copper (Cu) ion adsorption to PP–sediment were investigated using micro-interfacial characterization experiments and kinetic experiments for Cu ion absorption to sediment, polypropylene (PP), and PP–sediment particles. The results show that (1) a pseudo-second-order model can be used to accurately describe the micro-interfacial kinetics of Cu ion adsorption to PP–sediment, indicating that chemical adsorption dominates the process. For Cu, the adsorption capacity, q_e, of PP–sediment is approximately 0.4808 mg/g, between that of sediment and PP. (2) Film diffusion is the rate-controlling process in the early adsorption stage. Intraparticle diffusion gradually becomes the controlling process as the film diffusion constant (k_fd) decreases and the film diffusion model becomes less applicable, but intraparticle diffusion is weaker in the PP–sediment system than in the sediment-only system. (3) The applicability of the intraparticle diffusion model for Cu ion adsorption to PP–sediment in the later stage of adsorption is between that of the sediment and PP systems. Furthermore, the heterogeneous aggregation of sediment and PP affects the micro-interfacial interactions of both types of particulate matter. The current study contributes to a better understanding of the micro-interfacial interactions of heterogeneous particulate matter (such as fine-grained sediment and MPs) with heavy metal ions in aqueous environments.

The existing incipient sediment motion models typically apply conventional regression methods considering either velocity or shear stress. In the current study, incipient sediment motion is analyzed through a simultaneous and joint analysis of velocity and shear stress using the robust low-rank learning (RLRL) multi-output regression technique. Moreover, the experimental data compiled from five different channels are utilized to develop a generic incipient sediment motion model valid for a channel of any cross-sectional shape. The efficiency of the developed method is examined and compared against the available conventional regression models. The experimental results indicate that the RLRL model yields better results than its counterparts. In particular, while cross-section specific models fail to provide accurate estimates for shear stress or velocity for other cross sections, the proposed model provides satisfactory results for all channel shapes. The better performance of the recommended approach can be attributed to the joint modeling of the shear stress and the velocity which is realized by capturing the correlation between these parameters in terms of a low rank output mixing matrix which enhances the prediction performance of the approach.

Local scour is a phenomenon leading to the localized lowering of the channel bed due to the imbalance of sediment transport. As spur dikes protrude into the natural channels, local scour could be triggered. Accurate estimation of local scour around spur dikes is crucial for the effectiveness of erosion control and prevention and habitat enhancement measures. In the current study, the correlations between the maximum scour depth and the overtopping ratio, spur dike dimensions, ice cover roughness, and grain size of the bed material are investigated. Under both open channel and ice-covered flow conditions, a variety of experiments were done in a large-scale outdoor flume with different experimental setups. The results revealed that the scour depths around submerged spur dikes increased with increases in the densimetric Froude number and the decreases in the overtopping ratio and alignment angle. The maximum scour depth around a submerged angled vertical wall spur dike is significantly affected by the presence of an ice cover on the water surface, namely, the rougher the cover, the deeper the scour hole. Based on data collected from the laboratory experiments, an existing maximum scour depth estimation equation has been modified to consider the influence of the cover condition and the submergence level. The calculated results showed high accuracy in estimation of the measured data.

Hyperconcentrated turbidity currents typically display non-Newtonian characteristics that influence sediment transport and morphological evolution in alluvial rivers. However, hydro-sediment-morphological processes involving hyperconcentrated turbidity currents are poorly understood, with little known about the effect of the non-Newtonian rheology. The current paper extends a recent two-dimensional double layer-averaged model to incorporate non-Newtonian constitutive relations. The extended model is benchmarked against experimental and numerical data for cases including subaerial mud flow, subaqueous debris flow, and reservoir turbidity currents. The computational results agree well with observations for the subaerial mud flow and independent numerical simulations of subaqueous debris flow. Differences between the non-Newtonian and Newtonian model results become more pronounced in terms of propagation distance and sediment transport rate as sediment concentration increases. The model is then applied to turbidity currents in the Guxian Reservoir planned for middle Yellow River, China, which connects to a tributary featuring hyperconcentrated sediment-laden flow. The non-Newtonian model predicts slower propagation of turbidity currents and more significant bed aggradation at the confluence between the tributary Wuding River and the Yellow River in the reservoir than its Newtonian counterpart. This difference in model performance could be of considerable importance when optimizing reservoir operation schemes.