scholarly journals The erosion–deposition process and associated control mechanisms of the Nanliu River subaqueous delta, Southern China coast

2019 ◽  
Vol 2 (1) ◽  
pp. 171-192 ◽  
Author(s):  
Zhen-Kun Lin ◽  
Ai-Jun Wang ◽  
Xiang Ye
Keyword(s):  
Suspended Sediment ◽  
Southern China ◽  
Sediment Resuspension ◽  
Field Measurements ◽  
Deposition Process ◽  
Sediment Concentration ◽  
Control Mechanisms ◽  
Erosion Coefficient ◽  
Deposition Processes ◽  
Dimensional Simulation

Understanding the erosion–deposition process of sediments and the associated controlling mechanisms in subaqueous deltas is important for coastal environment protection. In this study, field observations and numerical simulations were performed for the Nanliu River subaqueous delta in Guangxi Province (Southern China) to investigate the sediment dynamic processes at the bottom boundary layer. The results show that the sediment resuspension mainly occurs during periods of spring tides and is mainly controlled by the wave action. When the seabed is free from erosion, suspended sediment settling caused by lateral transport is an important source of maintaining near bed suspended sediment concentration. It was also found that increasing the shear parameter could facilitate the formation of flocs, after which the small flocs tend to merge to large flocs. Finally, by performing a consistency analysis between the seabed erosion and deposition processes obtained from numerical simulation, and the changes of seabed level recorded by the equipment during the field observation, we determined that the local erosion coefficient was 5 × 10−5 kg/m2·s. The one-dimensional simulation is also capable of revealing the general trend at the seabed where it is first subjected to erosion and then deposition, as indicated during the field measurements.

Entrainment, dispersal, and settlement of scallop dredge sediment plumes: field measurements and numerical modelling

1999 ◽  
Vol 56 (12) ◽  
pp. 2271-2281 ◽  
Author(s):  
Kerry P Black ◽  
Gregory D Parry
Keyword(s):  
Grain Size ◽  
Suspended Sediment ◽  
Field Measurements ◽  
Sediment Concentration ◽  
Initial Value ◽  
Seabed Sediment ◽  
Southeastern Australia ◽  
Suspended Sediment Concentrations ◽  
Mean Size ◽  
Series Of Experiments

Entrainment, dispersal, and settlement of sediment plumes generated by scallop dredging were measured with an instrumented towed sled and downstream sensors during a series of experiments conducted in the main scallop grounds in Port Phillip Bay in southeastern Australia. When three 36-ha experimental plots were subjected to closely supervised, intensive dredging by commercial fishers, it was found that dredges suspend a thin layer of sediment (~0.5 cm thick) inducing initial near-bed concentrations of 2-15 kg·m-3 in a billowing turbid plume. At one field site where 30% of seabed sediment was less than 4 phi, concentrations reduced after 30 min to about 2% of the initial value and grain sizes decreased to a predominantly mud-sized sediment with a mean size of 5-6 phi. A numerical model was developed to depict plume transformations and settlement patterns. The model accurately predicted patterns of sedimentation and temporal changes to suspended sediment concentration and grain size distribution in the plume. By explicitly treating local seabed grain size, current, and water column turbulence, the model can be applied to other locations and conditions to examine suspended sediment concentrations and potential sediment-related impacts of scallop dredging.

scholarly journals Characterization of bottom sediment resuspension events observed in a micro-tidal bay

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 307-319 ◽  
Author(s):  
Manel Grifoll ◽  
Pablo Cerralbo ◽  
Jorge Guillén ◽  
Manuel Espino ◽  
Lars Boye Hansen ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Optical Sensors ◽  
Suspended Sediment Concentration ◽  
Sediment Resuspension ◽  
Ecological Status ◽  
Sediment Concentration ◽  
Strong Wind ◽  
Sedimentary Process ◽  
Sea Bottom ◽  
Wind Events

Abstract. In this study we investigate the variability in near-bottom turbidity in Alfacs Bay (in the northwestern Mediterranean Sea). The bay is characterized by a micro-tidal environment and seiching activity that may lead to flow velocities of more than 50 cm s−1. A set of current meters and optical sensors were mounted near the sea bottom to acquire synchronous hydrodynamic and optical information from the water column. The time-series observations showed an evident relation between seiche activity and sediment resuspension events. The observations of turbidity peaks are consistent with the node–antinode location of the fundamental and first resonance periods of the bay. The implementation of a coupled wave–current numerical model shows strong spatial variability of the potential resuspension locations. Strong wind events are also a mechanism responsible for the resuspension of fine sediment within the bay. This is confirmed by suspended sediment concentration maps derived from Sentinel-2 satellite imagery. We suggest that the sequence of resuspension events plays an important role in the suspended sediment concentration, meaning that the occurrence of sediment resuspension events may increase the suspended sediment in subsequent events. The suspended sediment events likely affect the ecological status of the bay and the sedimentary process over a long-term period.

scholarly journals Modeling and Simulation of a Chemical Vapor Deposition

2011 ◽  
Vol 2011 ◽  
pp. 1-25 ◽  
Author(s):  
J. Geiser ◽  
M. Arab
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Real Life ◽  
Chemical Vapor ◽  
Single Species ◽  
Deposition Process ◽  
Control Mechanisms ◽  
Metallic Bipolar Plates ◽  
Complicated Model ◽  
Deposition Processes

We are motivated to model PE-CVD (plasma enhanced chemical vapor deposition) processes for metallic bipolar plates, and their optimization for depositing a heterogeneous layer on the metallic plate. Moreover a constraint to the deposition process is a very low pressure (nearly a vacuum) and a low temperature (about 400 K). The contribution of this paper is to derive a multiphysics system of multiple physics problems that includes some assumptions to simplify the complicate process and allows of deriving a computable mathematical model without neglecting the real-life processes. To model the gaseous transport in the apparatus we employ mobile gas phase streams, immobile and mobile phases in a chamber that is filled with porous medium (plasma layers). Numerical methods are discussed to solve such multi-scale and multi phase models and to obtain qualitative results for the delicate multiphysical processes in the chamber. We discuss a splitting analysis to couple such multiphysical problems. The verification of such a complicated model is done with real-life experiments for single species. Such numerical simulations help to economize on expensive physical experiments and obtain control mechanisms for the delicate deposition process.

Characteristics of Suspended Sediment and Resuspension Process in Wendeng Coastal Area, Shandong Peninsula

2013 ◽  
Vol 807-809 ◽  
pp. 1595-1599 ◽  
Author(s):  
Xiao Liu ◽  
Xiu Li Feng ◽  
Jie Liu
Keyword(s):  
Suspended Sediment ◽  
Coastal Area ◽  
Tidal Cycle ◽  
Suspended Sediment Concentration ◽  
Sediment Resuspension ◽  
Analysis Data ◽  
Sediment Concentration ◽  
Velocity Variation ◽  
Shandong Peninsula ◽  
Maximum Value

Based on the field observations and laboratory analysis data of the suspended sediment of Wendeng coastal area, this paper studied the change process of suspended sediment concentration and characteristics of surface sediment resuspension in the study area. In results: (1) In vertical, the suspended sediment concentration of each station increased gradually from surface to bottom, and the maximum value could reach 0.11 kg/m3; (2) Suspended sediment concentration is well correlated with velocity variation in a tidal cycle, and the peak of suspended sediment concentration occurs four times in a tidal cycle, indicating that there are four resuspension processes during a tidal cycle in the study area; (3) According to the suspended sediment concentration at different times and the content of the previous time, the maximum settlement is between 0.063~0.092kg/m3, and the maximum resuspension is between 0.057~0.125kg/m3 in the study area.

scholarly journals Characterization of bottom sediment resuspension events observed in a micro-tidal bay

2018 ◽  
Author(s):  
Manel Grifoll ◽  
Pablo Cerralbo ◽  
Jorge Guillén ◽  
Manuel Espino ◽  
Lars Boye Hansen ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Optical Sensors ◽  
Sediment Resuspension ◽  
Ecological Status ◽  
Sediment Concentration ◽  
Strong Wind ◽  
Sedimentary Process ◽  
Node Location ◽  
Nw Mediterranean ◽  
Wind Events

Abstract. In this contribution we investigate the origin of the variability in near-bottom turbidity observations in the Alfacs Bay (NW Mediterranean Sea). This bay is characterized by a micro-tidal environment and a relevant seiching activity which may lead to flow velocities of more than 50 cm s−1. A set of current meters and optical sensors mounted near the sea bottom were used to acquire synchronous hydrodynamic and optical information of the water column. The time-series observations showed an evident relation between seiche activity and sediment resuspension events. The observations of turbidity peaks are consistent with the node/anti-node location for the fundamental and first resonance periods of the bay. The implementation of a coupled wave-current numerical model shows a strong spatial variability of the potential resuspension locations. Strong wind events are also a mechanism responsible of the resuspension of fine sediment within the bay. This is confirmed using retrieval of suspended sediment concentration from Sentinel-2 data. We suggest that the sequence of resuspension events plays a relevant role in SSC, in such a way that previous sediment resuspension events may influence the increase of suspended sediment in subsequents events. The suspended sediment events likely affect the ecological status of the Bay and the sedimentary process at long-term period.

scholarly journals Suspended sediment transport map for disaster mitigation in the upper course of Jangkok River

2021 ◽  
Vol 331 ◽  
pp. 08005
Author(s):  
Yusron Saadi ◽  
IB Giri Putra ◽  
Agus Suroso
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
River Flow ◽  
Rapid Change ◽  
Field Measurements ◽  
Sediment Concentration ◽  
Disaster Mitigation ◽  
Suspended Sediment Transport ◽  
Preventive Action ◽  
Two Parameters

Jangkok River, a very important river for irrigation purposes in Lombok Island Indonesia is experiencing a rapid change in the land use of its watershed. The conversion of trees into seasonal crops in the watershed causes a decrease in the carrying capacity of the watershed and reduces its ability to prevent soil erosion. Environmental damages such as erosion and sedimentation along the river are becoming increasingly difficult to control. This paper proposed an idea to identify river conditions based on suspended sediment concentration. A series of field measurements of suspended sediment concentrations and river flow discharges were carried out to obtain the relationship between these two parameters. A resulting watershed map contains information on the rate of suspended sediment transport in the form of a suspended sediment-flow discharge rating curve is designed as a sediment conservation health indicator of the watershed. The map allows the authority to observe the condition of each river order in the upper course of the Jangkok River since the nearby tributaries are most likely to have their pattern of suspended sediment transport rate. The finding from this preliminary study can facilitate the drafting and implementation of the right policy in watershed conservation management planning which leads to preventive action and better preparedness in disaster mitigation.

scholarly journals Impact of Sea Ice on the Hydrodynamics and Suspended Sediment Concentration in the Coastal Waters of Qinhuangdao, China

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 611
Author(s):  
Man Jiang ◽  
Chongguang Pang ◽  
Zhiliang Liu ◽  
Jingbo Jiang
Keyword(s):  
Sea Ice ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Resuspension ◽  
Parabolic Type ◽  
Bottom Layer ◽  
Sediment Concentration ◽  
Shielding Effect ◽  
Strong Wind ◽  
Seabed Sediment

The influence of sea ice on the hydrodynamics, sediment resuspension, and suspended sediment concentration (SSC) in the coastal area of Qinhuangdao was systematically investigated using 45-day in situ measurements at two stations (with ice at station M1 and without ice at station M2) in the Bohai Sea in the winter of 2018. It was found that the daily fluctuations of temperature and salinity at M1 are more significant than those at M2. During a typical seawater icing event on January 28, the temperature and salinity of the bottom water at M1 were decreased by 1.77 °C and increased by 0.4 psu, respectively. Moreover, due to the shielding effect of the sea ice, the residual current was much less affected by the wind at M1 than at M2. For the vertical distribution of current velocity, it changed from a traditional logarithmic type under ice-free conditions to parabolic type under ice-covered conditions due to the larger drag coefficient of the water body on the solid ice surface. For the SSC and turbidity at the bottom layer, the average values were 4.9 μL/L and 8.6 NTU at M1, respectively, approximately half of those at M2. The smaller SSC and turbidity at M1 can be attributed to the lower near-bottom turbulent kinetic energy (TKE). At M2, however, the larger SSC is closely related to the strong wind forcing, which could induce higher TKE without sea ice cover, and hence stronger turbulent resuspension. The seabed sediment analysis results showed that in the study area, fine sand is most likely to resuspend, while cohesive particles would resuspend only under strong hydrodynamic conditions.

scholarly journals Aerial Photo Utilization in Estimating Suspended Sediment in the Wuryantoro Watershed, Wonogiri

2004 ◽  
Vol 17 (2) ◽  
Author(s):  
Sugiharto Budi Santoso ◽  
Kuswaji Dwi Priyono ◽  
Alif Noor Anna
Keyword(s):  
Remote Sensing ◽  
Suspended Sediment ◽  
Field Measurements ◽  
Sediment Concentration ◽  
Rainfall Data ◽  
Remote Sensing Imagery ◽  
Remote Sensing Technique ◽  
Physical Data ◽  
Result Show ◽  
Imagery Data

Suspended sediment load flowing out from a watershed is normally predicated by analysis os suspended sediment of water sample, and the volume of suspended sediment be calculated based on sediment concentration and river discharge. Such field measurements need a lot of field data and they are time consuming. Another method for prediction of suspended sediment by using remote sensing imagery data and recorded rainfall data. The objective of this research is to 1) examine the capability of remote sensing technique to obtain the parameters of the physical data of land in the prediction of suspended sediment; 2) examine the accuracy of the model for prediction suspended sediment. This research is carried out in Wuryantoro watershed, Wonogiri. The main data to obtain the parameters of the physical data of land is infrared aerial photograph on scale 1 : 10.000. the method that used in this research is interpretation of remote sensing imagery data, combined with rainfall data. The result show that the accuracy of landuse is 88.5%, the accuracy of slope is 87.67%. the accuracy of the prediction of suspended sediment by model A3 87.07%, model C1 86.63%, model C2 90.57%, model A8 84.13%, model A9 80.1%, and model C4 78.6%.

Tide-induced fine sediment resuspension in the well-mixed Hangzhou Bay, East China Sea, China

2011 ◽  
Vol 102 (1) ◽  
pp. 25-34 ◽  
Author(s):  
John Z. Shi
Keyword(s):  
Suspended Sediment ◽  
East China Sea ◽  
Suspended Sediment Concentration ◽  
Sediment Resuspension ◽  
Sediment Concentration ◽  
Fine Sediment ◽  
East China ◽  
Hangzhou Bay ◽  
China Sea ◽  
Suspended Sediment Concentrations

ABSTRACTHangzhou Bay is a typical funnel-shaped high turbid estuary along a mesotidal coast of the East China Sea. In this paper, field studies are undertaken in an attempt to better understand tide-induced fine sediment transport processes in the Bay. Field observations were made mainly of current velocities (speeds and directions) and suspended sediment concentrations at six different relative depths and two stations in September 1992. Results show that (1) high near-bed suspended sediment concentrations varied from 1·81 to 4·00 kg m−3 during the spring tide and from 1·04 to 8·00 kg m−3 during the neap tide; (2) tide-induced near-bed fine sediment resuspension processes are indicated by several periodic suspended sediment concentration peaks; and (3) a hysteresis effect, or suspension-lag, occurs in suspended sediment concentration and resuspension events. Tide-induced fine sediment processes are mainly responsible for very high concentration suspensions of fine sediments in Hangzhou Bay. The occurrence of the suspension-lag phenomenon is likely to be common in other similar muddy tidal environments.

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