scholarly journals Simulation of Sediment Discharges during an Outfall Dredging Operation

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Anton Purnama ◽  
Mahad S. Baawain ◽  
Dongdong Shao
Keyword(s):  
Suspended Sediment ◽  
Input Data ◽  
Single Port ◽  
Muddy Sediment ◽  
Fine Silt ◽  
Horizontal Angle ◽  
Marine Outfall ◽  
Near Shore ◽  
Water Depths ◽  
Dredging Operation

CORMIX-GTS simulations are carried out to study suspended muddy sediment plumes following the discharge of the spoils taken from the seabed during a marine outfall pipeline dredging operation. Single port discharges are considered at three different locations at 400 m, 800 m, and 1200 m from the shoreline with water depths ranging from 3.5 m to 10.5 m. For discharges in the shallow near-shore region at 400 m offshore, most of the dredge materials are deposited at the seabed and the simulated suspended sediment plumes are found to be carrying a concentration of less than 1 kg/m3 of mainly fine silt and clay. For discharges in the deeper far-shore region at 1200 m offshore, the sediment plumes are more elongated and carrying a concentration of more than 3 kg/m3. Iterative simulations are also conducted to analyse the inherent uncertainty in the input data by varying the ambient velocity and the port’s horizontal angle of discharge.

scholarly journals Wave Energy Estimation in Four Italian Nearshore Areas

2013 ◽  
Author(s):  
Valentina Vannucchi ◽  
Lorenzo Cappietti
Keyword(s):  
Time Series ◽  
Deep Water ◽  
Hot Spots ◽  
Water Wave ◽  
Wave Power ◽  
Energy Estimation ◽  
Power Maps ◽  
Near Shore ◽  
Deep Water Wave ◽  
Water Depths

In this work, a set of analyses concerning the deep water wave power of the whole Mediterranean Sea has been carried out. These analyses cover the period from July 2009 to March 2012. Processes affecting waves as they propagate towards the coasts can modify the wave power, leading to reductions or, sometime, local enhancements due to focusing mechanisms. To quantify these processes, and thus to select the most energetic locations, numerical simulations were used to propagate the offshore time series into four selected near-shore areas. Monthly and yearly mean wave power maps are presented. Moreover some hot-spots, located at water depths in the range of 50 m to 15 m, are highlighted.

scholarly journals Suspended sediment concentration distribution in an alluvial channel flow

1994 ◽  
Vol 16 (1) ◽  
pp. 15-19
Author(s):  
Dang Huu Chung
Keyword(s):  
Mathematical Model ◽  
Suspended Sediment ◽  
Channel Flow ◽  
Concentration Distribution ◽  
Input Data ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Concentration Gradients ◽  
Alluvial Channel ◽  
The Finite Difference Method

In this paper a numerical solution for the problem on suspended sediment concentration distribution in an alluvial channel flow has been computed on the base of PROFILE model proposed by L. C. Van Rijn for the case of uniform flow. Although, in the present case, mathematical model is quite simple, but it is exact enough to apply to Somme problems in practice. The aim of the paper is that the author would like to use the finite difference method for the same problem. The input data was used from experiment flume. The result showed that the concentration distribution fast decreased along the channel and concentration gradients became very small at the sections situated far enough from the upstream. Besides, a computing program me with the ability of graphic expression was established. 

scholarly journals Hydrodynamics Sabang Bay and Its Influence on Near Shore Sediment Transport, Weh Island, Indonesia

Jurnal Segara ◽  
2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Ulung Jantama Wisha ◽  
Ilham Ilham
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Marine Pollution ◽  
Acoustic Doppler Current Profiler ◽  
Andaman Sea ◽  
Hydrodynamic Characteristics ◽  
Marine Tourism ◽  
Current Profiler ◽  
Near Shore ◽  
Wave Induced

Sabang Bay is one of areas of significance in Weh Island that becomes a center of marine tourism. Recently, massive urban development in coastal areas impacts on the increase of marine pollution and sedimentation issues within the bay. This study aimed to determine hydrodynamic characteristics and its influence on evoking sedimentation within the bay. Acoustic Doppler Current Profiler (ADCP) was installed within the bay for 30 days, which recorded surface elevation, waves, and sea currents. Sediment transport along the coast was determined by comparing the sediment transport and waves energy component in the form of flux equation. Tidal current speed ranging from 0-0.2 m/s moves predominantly southeastward and northwestward during flood and ebb tides, respectively. Significant wave height (Hs) ranges from 0.18-1 m with the period span of 3.5 seconds propagates toward within the bay, resulting in enhanced sedimentation within the bay caused by the wave-induced scour and turbulence. Sediment budget transported within the bay reaches 1586.18 m3/year. This proves that the sediment movement extremely occurs within the bay wherein the concentration of suspended sediment ranges from 5-35 mg/L and 2-25 mg/L during the high tidal and low tidal conditions, respectively. Scour and turbulence events are strongly induced by internal solitary waves generated from the Andaman Sea that results in increased coarse-sized sediment deposition when the flood tide takes place. While, during ebb tide, the widespread distribution of suspended sediment will occur over the bay.

scholarly journals Hindcasting and Forecasting Total Suspended Sediment Concentrations Using a NARX Neural Network

2021 ◽  
Vol 13 (1) ◽  
pp. 363
Author(s):  
Vladimir J. Alarcon
Keyword(s):  
Neural Network ◽  
Suspended Sediment ◽  
Urban Areas ◽  
Input Data ◽  
Suspended Sediments ◽  
Efficiency Index ◽  
Open Loop ◽  
Model Parameters ◽  
Creek Watershed ◽  
Suspended Sediment Concentrations

Estimating and forecasting suspended sediments concentrations in streams constitutes a valuable asset for sustainable land management. This research presents the development of a non-linear autoregressive exogenous neural network (NARX) for forecasting sediment concentrations at the exit of Francia Creek watershed (Valparaiso, Chile). Details are presented on input data selection, data splitting, selection of model architecture, determination of model structure, NARX training (optimization of model parameters), and model validation (hindcasting and forecasting). The study explored if the developed artificial neural network model is valid for forecasting daily suspended sediment concentrations for a complete year, capturing seasonal trends, and maximum and baseflow concentrations. Francia Creek watershed covers approximately 3.24 km2. Land cover within the catchment consists mainly of native and exotic vegetation, eroded soil, and urban areas. Input data consisting of precipitation and stream flow time-series were fed to a NARX network for forecasting daily suspended sediments (SST) concentrations for years 2013–2014, and hindcasting for years 2008–2010. Training of the network was performed with daily SST, precipitation, and flow data from years 2012 and 2013. The resulting NARX net consisted of an open-loop, 12-node hidden layer, 100 iterations, using Bayesian regularization backpropagation. Hindcasting of daily and monthly SST concentrations for years 2008 through 2010 was successful. Daily SST concentrations for years 2013 and 2014 were forecasted successfully for baseflow conditions (R2 = 0.73, NS = 0.71, and Kling-Gupta efficiency index (K-G) = 0.84). Forecasting daily SST concentrations for year 2014 was within acceptable statistical fit and error margins (R2 = 0.53, NS = 0.47, K-G = 0.60, d = 0.82). Forecasting of monthly maximum SST concentrations for the two-year period (2013 and 2014) was also successful (R2 = 0.69, NS = 0.60, K-G = 0.54, d = 0.84).

Distribution Patterns of Suspended Sediment in Radial Sand Ridges Area, South Yellow Sea, China

2013 ◽  
Vol 368-370 ◽  
pp. 1640-1643 ◽  
Author(s):  
Hui Ming Huang ◽  
Yi Gang Wang ◽  
Cheng Chen ◽  
Ji Bin Sun ◽  
Chun Guang Yuan
Keyword(s):  
Grain Size ◽  
Spatial Distribution ◽  
Suspended Sediment ◽  
Yellow Sea ◽  
Sediment Concentration ◽  
South Yellow Sea ◽  
Sand Ridges ◽  
Tidal Current Velocity ◽  
Radial Sand Ridges ◽  
Near Shore

Radial sand ridges area is located in south Yellow Sea, China, which is a valuable area for tidal flat reclamation and port construction. To rationally develop and protect this resource, the spatial distribution of tidal current velocity, grain size and suspended sediment concentration was studied based on measured data in August 2006. Result shows that the velocity in study area has a decreasing tendency with the Tiaozini water area being centered towards surrounding areas. The grain sizes near shore are smaller than ones offshore. At the same time ,the spatial distribution of grain size appears Λ pattern from north to south. The high value of mean sediment concentration appears in near shore area as well as the center of radial sand ridges.

scholarly journals Dispersion Plumes in Open Ocean Disposal Sites of Dredged Sediment

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 808
Author(s):  
Elisa Helena Fernandes ◽  
Pablo Dias da Silva ◽  
Glauber Acunha Gonçalves ◽  
Osmar Olinto Möller
Keyword(s):  
Suspended Sediment ◽  
Ecological Impact ◽  
Rio Grande ◽  
Open Ocean ◽  
Dredged Material ◽  
Dredged Sediment ◽  
Anthropogenic Pressures ◽  
Patos Lagoon ◽  
Dredging Operation ◽  
Ocean Disposal

Management of estuarine systems under anthropogenic pressures related to port settlement and development requires thorough understanding about the long-term sediment dynamics in the area. In an era of growing shipping traffic and of ever larger ships; millions of tons of bottom sediments are dredged annually all over the world and the major question concerning dredging operations is not whether they should be done, because it is obvious that they are extremely important and necessary, but where the dredged sediments can be disposed of with the least possible ecological impact. The present study involves the evaluation of transport trends of dredged material from a turbid estuary disposed of in four different open ocean disposal sites using numerical model techniques, aiming to contribute to minimizing potential environmental impacts and maximizing efficiency of the dredging operation. The study is carried out in southern Brazil, investigating the fate of dredged material from the Port of Rio Grande, located inside the Patos Lagoon estuary. Simulations were carried with the TELEMAC-3D model coupled with the suspended sediment (SEDI-3D) module and incorporating results from the wave module (TOMAWAC) to evaluate the dispersion of the suspended sediment plume and its interaction with coastal currents. This modeling structure proved to be a valuable tool to study the hydrodynamics and sediment transport pathways in estuarine and coastal areas. Results indicate that the natural Patos Lagoon coastal plume was observed under the predominant ebb flows and NE winds, promoting fine sediment entrapment south of the mouth of the lagoon (in front of Cassino Beach). The dispersion plumes in the disposal sites responded to the wind intensity and direction and did not present any transport tendency towards Cassino Beach. Part of the dredged sediment disposed of in the proposed alternative sites located in deeper areas (Sites B and C) left the site and was transported parallel to the coast (SW–NE direction) according to the wind direction (NE–SW). The area where the disposal sites were located took around 4 days to recover from the dredging operation and reach the usual suspended sediment concentrations and the actual Port of Rio Grande Licensed Site for dredged material proved to be the best alternative among the investigated options

Transmission Electron Diffraction Analysis by Computer

1970 ◽  
Vol 28 ◽  
pp. 40-41
Author(s):  
R.A. Ploc ◽  
G.H. Keech
Keyword(s):  
Electron Diffraction ◽  
Input Data ◽  
Reciprocal Lattice ◽  
Computer Programme ◽  
Transmission Electron Diffraction ◽  
Usual Procedure ◽  
Transmission Electron ◽  
Complex Shapes ◽  
Computer Input ◽  
Diffraction Effects

An unambiguous analysis of transmission electron diffraction effects requires two samplings of the reciprocal lattice (RL). However, extracting definitive information from the patterns is difficult even for a general orthorhombic case. The usual procedure has been to deduce the approximate variables controlling the formation of the patterns from qualitative observations. Our present purpose is to illustrate two applications of a computer programme written for the analysis of transmission, selected area diffraction (SAD) patterns; the studies of RL spot shapes and epitaxy.When a specimen contains fine structure the RL spots become complex shapes with extensions in one or more directions. If the number and directions of these extensions can be estimated from an SAD pattern the exact spot shape can be determined by a series of refinements of the computer input data.

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