Improving shore protection design

1990 ◽  
Vol 17 (2) ◽  
pp. 142-147
Author(s):  
J. William Kamphuis
Keyword(s):  
Sediment Transport ◽  
Key Words ◽  
Physical Parameters ◽  
Shore Protection

The construction of shore protection is expensive, but the alternative of permitting erosion is also expensive. Yet any design of shore protection is based mostly on intuitive concepts. This paper presents an overview of what is lacking in our knowledge, a possible methodology for improving shore protection design and discussions about some of the most important (and often ignored) physical parameters to be considered if shore protection is to perform its task without interfering with the littoral environment. Key words: erosion, groins, seawalls, sediment transport, shore protection.

scholarly journals LONGSHORE TRANSPORT AT A TOTAL LITTORAL BARRIER

1976 ◽  
Vol 1 (15) ◽  
pp. 70 ◽  
Author(s):  
Richard O. Bruno ◽  
Christopher G. Gable
Keyword(s):  
Sediment Transport ◽  
Accurate Determination ◽  
Coastal Engineering ◽  
Channel Islands ◽  
Shore Protection ◽  
Material Transport ◽  
Engineering Research ◽  
Longshore Sediment Transport ◽  
Longshore Transport

Analysis of longshore transport at a littoral barrier is presented. Channel Islands Harbor, California was selected as the study site because its offshore breakwater and jetties form a unique complete littoral barrier. Through repetitive surveys an accurate determination of longshore material transport in one direction was made. Measured transport rates ranged from 160,000 to 1,284,000 cubic meters per year. Utilizing visual observations of surf parameters, estimates of longshore wave thrust were computed. The range of wave thrust was 145 to 1,988 Newtons per meter. Comparison of the relation of wave thrust and longshore sediment transport is made. This study indicates that in an environment of high transport, nearly twice as much transport is predicted tinder corresponding wave thrust as that of the data summarized in the Coastal Engineering Research Center's Shore Protection Manual.

scholarly journals Bedforms in a turbulent stream: ripples, chevrons and antidunes

2011 ◽  
Vol 690 ◽  
pp. 94-128 ◽  
Author(s):  
Bruno Andreotti ◽  
Philippe Claudin ◽  
Olivier Devauchelle ◽  
Orencio Durán ◽  
Antoine Fourrière
Keyword(s):  
Free Surface ◽  
Sediment Transport ◽  
Flow Direction ◽  
Linear Instability ◽  
Physical Parameters ◽  
Flow Depth ◽  
Supercritical Regime ◽  
Free Surface Waves ◽  
Alternate Bars ◽  
Flooding Events

AbstractThe interaction between a turbulent flow and a granular bed via sediment transport produces various bedforms associated with distinct hydrodynamical regimes. In this paper, we compare ripples (downstream-propagating transverse bedforms), chevrons and bars (bedforms inclined with respect to the flow direction) and antidunes (upstream-propagating bedforms), focusing on the mechanisms involved in the early stages of their formation. Performing the linear stability analysis of a flat bed, we study the asymptotic behaviours of the dispersion relation with respect to the physical parameters of the problem. In the subcritical regime (Froude number $\mathscr{F}$ smaller than unity), we show that the same instability produces ripples or chevrons depending on the influence of the free surface. The transition from transverse to inclined bedforms is controlled by the ratio of the saturation length ${L}_{\mathit{sat}} $, which encodes the stabilizing effect of sediment transport, to the flow depth $H$, which determines the hydrodynamical regime. These results suggest that alternate bars form in rivers during flooding events, when suspended load dominates over bedload. In the supercritical regime $\mathscr{F}\gt 1$, the transition from ripples to antidunes is also controlled by the ratio ${L}_{\mathit{sat}} / H$. Antidunes appear around resonant conditions for free surface waves, a situation for which the sediment transport saturation becomes destabilizing. This resonance turns out to be fundamentally different from the inviscid prediction. Their wavelength selected by linear instability mostly scales on the flow depth $H$, which is in agreement with existing experimental data. Our results also predict the emergence, at large Froude numbers, of ‘antichevrons’ or ‘antibars’, i.e. bedforms inclined with respect to the flow and propagating upstream.

Détermination au champ de la conductivité hydraulique saturée à l'aide de l'infiltromètre à charge constante de Côté: théorie et approximations mathématiques

1991 ◽  
Vol 71 (1) ◽  
pp. 119-126 ◽  
Author(s):  
O. Banton ◽  
D. Côté ◽  
M. Trudelle
Keyword(s):  
Hydraulic Conductivity ◽  
Key Words ◽  
Groundwater Table ◽  
Physical Parameters ◽  
Large Area ◽  
Conductivité Hydraulique ◽  
Potential Sources ◽  
Constant Head ◽  
A Charge ◽  
High Level

Saturated hydraulic conductivity is one of the most difficult physical parameters of soil to measure. The most accurate methods are those used in the field in the presence of a groundwater table. However, in many cases, these cannot be used, primarily when no groundwater table is present. The Côté constant head infiltrometer method proves useful in such cases, because the measurement is made on soil which is not necessarily saturated beforehand. The constant head of water used by the infiltrometer is low (3.5 cm), and so representative of precipitation and irrigation conditions. The device (which is 10 cm in diameter) performs the measurement on a large area of soil (roughly 200 cm2), and can therefore integrate varying heterogeneity and macroporosity, rendering the measurement more reliable and representative. The quantity of water needed for a measurement is about 1 L, making operation in the field easier. The Côté constant head infiltrometer is an unsophisticated device which is easy to use. Different mathematical approximations of the saturated flow of water around the infiltometer are described according to the various forms of flow taken into account. The corresponding coefficients may be used to quickly determine this parameter with a high level of confidence. However, one problem and some potential sources of error remain in the evaluation of hydraulic conductivity in the field, due principally to cases in which the soil is not totally saturated, to compaction or smoothing of the hole during digging, and to the variability of the parameter on the site. Key words: Hydraulic conductivity, infiltrometer, permeameter

scholarly journals Coupled Delft3D-Object Model to Predict Mobility of Munition on Sandy Seafloor

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 330
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan ◽  
Joseph Calantoni
Keyword(s):  
Experimental Data ◽  
Sediment Transport ◽  
Time Series Data ◽  
Major Axis ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Rolling Moment ◽  
Object Mobility

The coupled Delft3D-object model has been developed to predict the mobility and burial of objects on sandy seafloors. The Delft3D model is used to predict seabed environmental factors such as currents, waves (peak wave period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) physical parameters such as diameter, length, mass, and rolling moment; (b) dynamics of the rolling cylinder around its major axis; (c) an empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 13 May 2013 off the coast of Panama City, Florida. The experimental data contain both object mobility using sector scanning sonars and maintenance divers as well as simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly shows the model’s capabilities and limitations.

scholarly journals Coupled Delft3D-Object Model to Predict Mobility and Burial of Munition on Sandy Floor

2021 ◽  
Author(s):  
Peter C. Chu ◽  
Vinicius S. Pessanha ◽  
Chenwu Fan
Keyword(s):  
Sediment Transport ◽  
Time Series Data ◽  
Development Program ◽  
Environmental Research ◽  
Series Data ◽  
Physical Parameters ◽  
Object Model ◽  
Wave Direction ◽  
Peak Period ◽  
Rolling Moment

Coupled Delft3D-object model has been developed to predict object’s mobility and burial on sandy seafloor. The Delft3D model is used to predict seabed environment such as currents, waves (peak period, significant wave height, wave direction), water level, sediment transport, and seabed change, which are taken as the forcing term to the object model consisting of three components: (a) object‘s physical parameters such as diameter, length, mass, and rolling moment, (b) dynamics of rolling cylinder around its major axis, and (c) empirical sediment scour model with re-exposure parameterization. The model is compared with the observational data collected from a field experiment from 21 April to 23 May 2013 off the coast of Panama City, Florida funded by the Department of Defense Strategic Environmental Research and Development Program. The experimental data contain both objects’ mobility using sector scanning and pencil beam sonars and simultaneous environmental time series data of the boundary layer hydrodynamics and sediment transport conditions. Comparison between modeled and observed data clearly show the model capability.

A numerical model for beach profile development

1985 ◽  
Vol 12 (1) ◽  
pp. 231-234 ◽  
Author(s):  
A. Swain ◽  
J. R. Houston
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Key Words ◽  
Laboratory Tests ◽  
Field Data ◽  
Time Dependent ◽  
Water Level Fluctuations ◽  
Beach Profile ◽  
Sediment Size ◽  
Profile Development

A time-dependent numerical model that calculates beach profile development due to offshore sediment transport is developed. The model allows variable wave conditions, water level fluctuations due to tide, arbitrary bathymetry, and sediment size. The accuracy of the model is tested by comparison of calculations with laboratory and with field data. The agreement between calculated and measured beach profiles is good. Key words: numerical model, beach profile, laboratory tests, field data.

Fluctuations of Chlorophyll and Related Physical Parameters in British Columbia Coastal Waters

1979 ◽  
Vol 36 (2) ◽  
pp. 113-121 ◽  
Author(s):  
R. C. Wiegand ◽  
S. Pond
Keyword(s):  
British Columbia ◽  
Key Words ◽  
Physical Parameter ◽  
Power Law ◽  
Surface Waters ◽  
Coastal Waters ◽  
Physical Parameters ◽  
Vertical Profiles ◽  
Turbulent Environment ◽  
Phase Data

Continuous horizontal profiles of chlorophyll, temperature, salinity, and oxygen were made at three depths and in three locations in British Columbia coastal waters, and spectra and cross spectra calculated. Generally, fairly strong relationships exist between chlorophyll and temperature and salinity, especially at scales of order 10–1000 m. However, the relationships are not always expressed through the same physical parameter. It is apparent from coherence and phase data that in a turbulent environment the vertical profiles of the parameters are important in determining the nature of the relationships. Average spectra show power law relationships similar to the results of other authors. Key words: chlorophyll, temperature, salinity, oxygen fluctuations; surface coastal waters; T, S, O2, chlorophyll fluctuations; spectra and cross-spectra of T, S, O2, chlorophyll; measurements of T, S, O2, chlorophyll in surface waters

scholarly journals LONGSHORE SEDIMENT TRANSPORT DATA: A REVIEW

1978 ◽  
Vol 1 (16) ◽  
pp. 93 ◽  
Author(s):  
Matthew N. Gree ◽  
Ole Secher Madsen
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Empirical Relationship ◽  
The United States ◽  
Transport Processes ◽  
Coastal Engineering ◽  
Shore Protection ◽  
Engineering Research ◽  
Longshore Sediment Transport ◽  
Predictive Relationship

Siltation rates anticipated at harbor entrances, in navigation channels and at inlet structures as well as possible adverse effects caused by these and other coastal engineering constructions are often assessed based on considerations of longshore sediment transport rates. The ability to predict the longshore sediment transport rate is consequently of considerable importance in many coastal engineering problems. The engineering need for an ability to predict longshore sediment transport rates is evidenced by the fact that the development of empirical relationships preceeded, by decades, any attempts at rigorous analyses of the mechanics of sediment transport processes in the surf zone. A predictive relationship for longshore sediment transport rates, which enjoys considerable popularity in the United States, is the empirical relationship suggested by the U.S. Army (1973), Coastal Engineering Research Center (CERC) in their Shore Protection Manual (SPM-73).

Sign in / Sign up

Export Citation Format

Share Document