Survey Techniques/Procedures and Data Processing for Monitoring Nearshore Sediment Transport

1982 ◽  
Author(s):  
J Zacks
Keyword(s):  
Sediment Transport ◽  
Data Processing ◽  
Survey Techniques ◽  
Nearshore Sediment Transport

scholarly journals SURVEY TECHNIQUES/PROCEDURES AND DATA PROCESSING FOR MONITORING NEARSHORE SEDIMENT TRANSPORT

1982 ◽  
Vol 1 (18) ◽  
pp. 97
Author(s):  
J. Zacks
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Survey Techniques ◽  
The Past ◽  
Bed Elevation ◽  
Innovative Methods ◽  
Survey Error ◽  
Nearshore Sediment Transport ◽  
The Many ◽  
The Cost

The cost of many coastal projects is often increased by the expensive beach repair and maintenance required to remedy the destabilising effects of structures on the adjoining coastline. Physical and/or mathematical models have been developed for use in planning these projects in order to predict and quantify the effects of marine sediment transport on the coastal topography. Such models need to be calibrated against prototype data and one method of gauging volumetric sediment movement is by successive bathymetric/ topographic profiting surveys which are performed seasonally and annually. Since large quantities of sediment are related to small changes in bed elevation it is clear that this profiling needs to be done with the utmost precision* The areas most affected extend from the beach through the surf zone to water depths of about 25 metres. The surf zone in particular is a dynamic and hostile area which falls outside the traditional activities of both the hydrographic and land surveyors. Consequently innovative methods, deficient in sound survey principle and practice, have often been pursued in this area without any attempt being made to assess the tolerance on the data. This paper attempts to show that it is possible to produce reliable and verifiable results to the required accuracy by using conventional survey equipment and techniques, also by taking the necessary precautions against the many possible sources of survey error. The procedures and techniques described have evolved from NRIO's involvement over the past decade in major projects at Richards Bay, Durban, Koeberg and in False Bay. The results of a recent verification investigation are fully reported in this paper.

Patterns of nearshore sediment transport along the Nile Delta, Egypt

1991 ◽  
Vol 15 (5-6) ◽  
pp. 409-429 ◽  
Author(s):  
Omran E. Frihy ◽  
Alfy M. Fanos ◽  
Ahmed A. Khafagy ◽  
Paul D. Komar
Keyword(s):  
Sediment Transport ◽  
Nile Delta ◽  
Nearshore Sediment Transport

scholarly journals 3D Modeling and Mechanism Analysis of Breaking Wave-Induced Seabed Scour around Monopile

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Xiaojian Liu ◽  
Cheng Liu ◽  
Xiaowei Zhu ◽  
Yong He ◽  
Qisong Wang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Laboratory Data ◽  
Suspended Load ◽  
Breaking Wave ◽  
Offshore Structure ◽  
Nearshore Sediment Transport ◽  
Wave Induced

Breaking wave-induced scour is recognized as one of the major causes of coastal erosion and offshore structure failure, which involves in the full 3D water-air-sand interaction, raising a great challenge for the numerical simulation. To better understand this process, a nonlinear 3D numerical model based on the open-source CFD platform OpenFOAM® was self-developed in this study. The Navier–Stokes equations were used to compute the two-phase incompressible flow, combining with the finite volume method (FVM) to discretize calculation domain, a modified VOF method to track the free surface, and a k−ε model to closure the turbulence. The nearshore sediment transport process is reproduced in view of shear stress, suspended load, and bed load, in which the terms of shear stress and suspended load were updated by introducing volume fraction. The seabed morphology is updated based on Exner equation and implemented by dynamic mesh technique. The mass conservative sand slide algorithm was employed to avoid the incredible vary of the bed mesh. Importantly, a two-way coupling method connecting the hydrodynamic module with the beach morphodynamic module is implemented at each computation step to ensure the fluid-sediment interaction. The capabilities of this model were calibrated by laboratory data from some published references, and the advantages/disadvantages, as well as proper recommendations, were introduced. Finally, nonbreaking- and breaking wave-induced scour around the monopile, as well as breaking wave-induced beach evolution, were reproduced and discussed. This study would be significantly helpful to understand and evaluate the nearshore sediment transport.

scholarly journals THE NEARSHORE SEDIMENT TRANSPORT STUDY

1978 ◽  
Vol 1 (16) ◽  
pp. 92 ◽  
Author(s):  
Richard J. Seymour ◽  
David B. Duane
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Surf Zone ◽  
Coastal Engineering ◽  
Predictive Tools ◽  
Transport Study ◽  
Sediment Size ◽  
Forcing Function ◽  
Nearshore Sediment Transport ◽  
Waves And Currents

The models for predicting longshore transport of sediment along straight coastlines that are presently in general use were derived empirically from very sparse measurements of both the forcing function (waves and currents) and the response function (sediment motions). A detailed treatment of these data sets is contained in Greer and Madsen (1978). In addition to the generally unsatisfactory nature of the basic measurements upon which they were based, the models may be deficient because they fail to employ such potentially significant factors as wind stress, sediment size distribution, bottom slope and spatial variations in waves and currents, including the effects of rip currents. Although these models have served certain engineering needs, there is a strong measure of uncertainty in the coastal engineering community about their general applicability. Certainly, because they are empirical rather than physically reasoned models, there is no rational means for extending their usefulness to predicting transport where coastlines are not straight -- such as the case of a tidal inlet. The economic impact of sediment transport in the nearshore regime is enormous and the need for improved predictive tools appears to be universally accepted. To be most useful, these improved models must be globally applicable. This implies very strongly that they must be based upon a thorough understanding of surf zone dynamics and the details of the response of the sediment. The surf zone flow fields are highly complex and nonlinear, implying an equally complex and difficult system of sediment responses. Characterizing the entire forcing and response functions simultaneously requires large and expensive field measurement programs that greatly exceed the present state of the art of measurement and analysis.' The approach of the last two decades of single investigators working at laboratory scale or in the ocean with a few single point measurements would not appear to ever meet these needs. However, the present costs for coastal dredging and shoreline protection, which can be measured in billions of dollars on a world scale, argue for a major undertaking to develop better predictive tools. In an attempt to satisfy these needs, an ad hoc group was formed at the Fifteenth Coastal Engineering Conference in Honolulu to plan a large scale and coordinated series of investigations leading to improved sediment transport predictive models. Less than a year later, the Nearshore Sediment Transport Study was initiated under the sponsorship of the Office of Sea Grant.

Nearshore Sediment Transport Measurement

2005 ◽  
pp. 698-701
Author(s):  
Vivian Gornitz ◽  
Nicholas C. Kraus ◽  
Nicholas C. Kraus ◽  
Ping Wang ◽  
Ping Wang ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Transport Measurement ◽  
Nearshore Sediment Transport
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