scholarly journals LONGSHORE TRANSPORT DETERMINED BY AN EFFICIENT TRAP

1982 ◽  
Vol 1 (18) ◽  
pp. 60 ◽  
Author(s):  
R.G. Dean ◽  
E.P. Berek ◽  
C.G. Gable ◽  
R.J. Seymour
Keyword(s):  
Sediment Transport ◽  
Field Component ◽  
Santa Barbara ◽  
Wave Characteristics ◽  
Nearshore Sediment Transport ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Correlation Constant ◽  
The Relationship ◽  
Best Fit

The Nearshore Sediment Transport Study (NSTS), sponsored by the National Sea Grant Office included a field component to quantify the total longshore sediment transport relationship. This component was conducted at Santa Barbara, California and encompassed a period of eighteen months during which ten surveys were conducted. To date, eight of these surveys have been analyzed, yielding seven intersurvey periods. A total of 288,600 m3 of net sediment transport was documented by these eight surveys. The wave characteristics are based on one of two Sxy gages located in a water depth of 7 m. The most widely used correlation constant, K, in the relationship I = KP, is 0.77. The values found from the data were 0.93 and 1.23 for linear and log best-fit values, respectively. The corresponding values of K4 relating I and S are 2.60 and 2.63 m/s, respectively.

scholarly journals LONGSHORE TRANSPORT EVALUATIONS AT A DETACHED BREAKWATER

1980 ◽  
Vol 1 (17) ◽  
pp. 86 ◽  
Author(s):  
R.O. Bruno ◽  
R.G. Dean ◽  
C.G. Gable
Keyword(s):  
Sediment Transport ◽  
Engineering Research ◽  
Pressure Transducers ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Wave Energy Flux ◽  
Correlation Constant ◽  
Wave Induced ◽  
The Relationship ◽  
The Waves

A field experiment was conducted by the Coastal Engineering Research Center (CERC) to develop correlations between wave characteristics and longshore sediment transport. The waves were measured by two near-bottom mounted pressure transducers and the average longshore sediment transport rates were determined from sequential volumetric surveys behind an offshore breakwater which was regarded as a total trap. The data analyzed herein encompass a period of nine months during which a total accumulation of 675,000 m3 occurred as documented by eight surveys. Spectral analyses of the wave data were conducted and yielded one direction per frequency. The correlations include immersed weight sediment transport rate, I, versus (1) longshore component of wave energy flux at breaking, P&Sf and (2) the onshore flux of the longshore component of wave-induced momentum, S „. The most widely used correlation constant, K, in the relationship I = KPjig is 0,77. The best-fit values found from the data were K = 0.65 and 0.92 for linear and log best-fits, respectively, as based on the p£s values directed toward the trap. The corresponding values of KA (dimensional) relating I and Sxv are 4.98 m/s and 6.37 m/s, respectively. One feature of this type of trap is the potential for overtrapping if the waves are directed nearly normal to shore.

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 APPLICATION OF A SEMI-EMPIRICAL LONGSHORE TRANSPORT FORMULATION

2012 ◽  
Vol 1 (33) ◽  
pp. 22
Author(s):  
Giuseppe Barbaro ◽  
Giuseppe Roberto Tomasicchio ◽  
Giovanni Malara ◽  
Felice D'Alessandro
Keyword(s):  
Sediment Transport ◽  
Transport Rate ◽  
Sediment Transport Rate ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Semi Empirical

The present paper deals with the determination of longshore sediment transport rate. Specifically, case study of Saline Joniche (Reggio Calabria, Italy, is discussed. This case is of interest because, in this location, an artificial basin was built in the 70’s. After few years, port entrance experienced total obstruction by sand. Actually, the area is abandoned and several projects have been proposed for revitalising port activities. This paper discusses a method for estimating the longshore sediment transport rate at Saline Joniche and complements previous methodology.

scholarly journals COASTAL ARMORING: EFFECTS, PRINCIPLES AND MITIGATION

1986 ◽  
Vol 1 (20) ◽  
pp. 135 ◽  
Author(s):  
R.G. Dean
Keyword(s):  
Sediment Transport ◽  
Adverse Effects ◽  
Field Data ◽  
Surf Zone ◽  
Local Scour ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Severe Erosion ◽  
Substantial Distance ◽  
Factual Data

An attempt is made to conduct a rational assessment of the potential adverse effects of coastal armoring on adjacent shorelines and to propose methodology for mitigation, where appropriate. Specific attention is directed toward claims that armoring causes: profile steepening, increased longshore sediment transport, intensified local scour, transport of sand to substantial offshore distances, etc. The assessment presented here is based on a combination of sound principles and the availability or lack, of laboratory and field data to either support or refute the claims. Although it is found that data relating to coastal armoring effects are sparse, conclusions can be drawn. There seems to be no factual data to support the contentions that armoring causes profile steepening, increased longshore transport, transport of sand to a substantial distance offshore, or significantly delayed profile recovery following a severe erosion event. Armoring does have the potential to cause intensified local scour both in front of and at the ends of an armored segment. Reasons for these effects, based on knowledge of response of a natural profile, are presented. Additionally, armoring which projects into the active surf zone can act as a partial barrier to the net longshore sediment transport, thereby causing downdrift erosion. Methodology is presented for quantifying the appropriate mitigation for a particular armoring situation. The proposed mitigation is the annual placement of sand in the vicinity of the armoring to offset its potential adverse effects. The two potential adverse effects addressed in the methodology include the reduction of sediment supplied to the system as a result of the armoring and the blockage of longshore sediment transport by a protruding armoring installation.

scholarly journals MODELING SEDIMENTATION AT INLET AND COASTAL REGION

1972 ◽  
Vol 1 (13) ◽  
pp. 44
Author(s):  
Pang-Mou Lin
Keyword(s):  
Sediment Transport ◽  
Coastal Region ◽  
Shear Stresses ◽  
Wave Steepness ◽  
Coastal Regions ◽  
Longshore Sediment Transport ◽  
Flume Tests ◽  
Bed Materials ◽  
The Relationship ◽  
Fluid Characteristic

Sediment transport In the vicinity of inlets and coastal regions depends on the combined bottom shear stresses due to both currents and waves. The modeling of the movement of bedload is controlled by the Proude law, bottom shear stress, wave steepness, and friction factor. Assuming Einstein's theory of bedload function can be applied to this study, an analysis was performed after conducting experiments in the flume and model basin. A series of results obtained from the flume tests is to Insure the relationship between the fluid characteristic and the movement of bedload. The final results concerning the longshore sediment transport appeared satisfactory with the estimated curves. The bottom configurations in the Inlet after each test were also shown satisfactorily similar. The sedimentologlcal time scale for the three bed materials were not In satisfactory agreement, however, more discussion of the results was presented in this paper.

scholarly journals NEARSHORE SEDIMENT TRANSPORT STUDY EXPERIMENTS

1980 ◽  
Vol 1 (17) ◽  
pp. 87
Author(s):  
R.J. Seymour ◽  
C.G. Gable
Keyword(s):  
Sediment Transport ◽  
Large Data ◽  
Data Sets ◽  
General Description ◽  
Institutional Research ◽  
Santa Barbara ◽  
Transport Study ◽  
Similar Work ◽  
Nearshore Sediment Transport ◽  
Waves And Currents

The Nearshore Sediment Transport Study (NSTS) is a multi-institutional research program with the objective of developing improved engineering predictive models for transport of sediment. both longshore and cross shore, by waves and currents. The program is sponsored by the Office of Sea Grant (OSG), an agency of the National Oceanic and Atmospheric Administration (NOAA). A general introduction to the objectivesi schedule and organization of the NSTS program was presented at the 16th ICCE by Seymour and Duane (1979). Shortly after the Hamburg Conference, the first major field experiment was conducted at Torrey Pines Beach. California, in November, 1978. The second major experiment was conducted 14 months later in February, 1980 at Leadbetter Beach, in Santa Barbara, California. Each of these experiments involved levels of measurement intensity that appear to exceed by a large factor those of any similar work. Because of the large data sets obtained and the importance of these data to other investigators in coastal processes, the NSTS project is making them available promptly. In the following sections, a general description will be given for each of these experiments and information supplied on how the data may be obtained.

scholarly journals CAPACIDAD DE TRANSPORTE POTENCIAL LONGITUDINAL DE SEDIMENTOS A ESCALA INTRAANUAL EN PUNTA YARUMAL, DELTA DEL RÍO TURBO, GOLFO DE URABÁ, A PARTIR DE LA SIMULACIÓN DE UN CLIMA MARÍTIMO

2016 ◽  
Vol 43 (2) ◽  
Author(s):  
Luis Gabriel Molina Flórez ◽  
Andrés Fernando Osorio Arias ◽  
Luis Jesús Otero Díaz
Keyword(s):  
Sediment Transport ◽  
Eastern Margin ◽  
Area Of Interest ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Del Rio

In this article we estimate the rate of intra-annual and annual longshore sediment transport, inflenced by waves in the delta formed by the mouth of the Turbo river, located on the eastern margin of the Gulf of Urabá, specifially Punta Yarumal, from three equations proposed by various authors. The article contains an overview of the area of interest, a summary of the chosen methodology to develop this study, and fially, once the estimated longshore transport rates are calculated, the results, discussion and conclusions are presented.

scholarly journals FIELD INVESTIGATION OF LONGSHORE TRANSPORT DISTRIBUTION

1982 ◽  
Vol 1 (18) ◽  
pp. 98 ◽  
Author(s):  
E.P. Berek ◽  
R.G. Dean
Keyword(s):  
Sediment Transport ◽  
Active Contours ◽  
Field Investigation ◽  
Wave Direction ◽  
Change Analysis ◽  
Incoming Wave ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
The Cross ◽  
Water Depths

Following a change in wave direction, the active contours in an idealized pocket beach respond by rotating such that they approach a perpendicular orientation relative to the incoming wave rays. Assuming that cross-shore sediment transport does not contribute to this contour rotation, and that the contours are in the early stages of this equilibration process, the amount of contour rotation can be interpreted as the cross-shore distribution of the longshore sediment transport. As part of the Nearshore Sediment Transport Study, detailed nearshore profile measurements were conducted at Santa Barbara, California. Twenty-two of these profile lines were located on Leadbetter Beach, which is a quasi-pocket beach. To explore the concept described above, two of the nine intersurvey periods were selected due to their strong indications of wave direction change. Analysis of these data sets yielded two estimates of cross-shore distribution of longshore sediment transport which were compared with those presented by Komar, Fulford and Tsuchiya. Although these three distributions differ significantly, the effect of the tidal variations is to "smear" the differences in the inferred distributions as evident in the contour displacements. It was found that none of the relationships for longshore transport distribution predicted the amount of transport inferred in water depths greater than one meter. It is possible, especially for one of the intersurvey periods that the changes in contour locations were so extreme that substantial crossshore sediment transport was induced and would be interpreted as longshore transport occurring in water depths greater than had actually occurred. The method introduced here should be useful in other field and laboratory programs to investigate the cross-shore distribution of longshore sediment transport.

scholarly journals CRITERION FOR STABILITY OF SHORELINE PLANFORM

1980 ◽  
Vol 1 (17) ◽  
pp. 77
Author(s):  
John D. Wang ◽  
Bernard Le Mehaute
Keyword(s):  
Sediment Transport ◽  
Deep Water ◽  
Water Wave ◽  
Shoreline Evolution ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Long Time ◽  
Wave Angle ◽  
Deep Water Wave ◽  
Offshore Transport

The problem of beach planform stability has been known for a long time: When does a small perturbation on a straight beach tend to grow with time and when does it tend to be flattened out? The interest in this problem arises from evidence of instabilities occurring in nature, but perhaps more importantly it is a problem that must be taken into account when formulating models for beach evolution and erosion. Existing mathematical models describing shoreline changes assume that the beach planform is stable and in equilibrium. It is therefore important to establish the range of wave conditions for which instabilities could occur, thereby invalidating such models. In the present case our interest is specifically directed towards determining conditions for which a model for shoreline evolution is intangible because of development of local instability. Grijm (1960) gave an approximate mathematical analysis indicating that at the point where the longshore sediment transport Q as a function of wave angle is maximum the shoreline must either be straight or form a cusp. Under his assumption that Q is proportional to sin 2a the maximum occurs for a = 45°. Le Mehaute and Soldate (1977) summarizes other studies that essentially arrive at the same results, viz. when the deep water wave angle is greater than 45° the shoreline is unstable. This result did not seem to be substantiated by field or laboratory observations. In this study of shoreline planform we first derive a criterion for instability of straight beaches. Then assuming that longshore sediment transport is proportional to the alongshore wave energy flux component at the point of breaking we determine the range of deep water wave characteristics and beach slopes which would cause unstable situations to occur. We consider only the longshore transport and exclude effects of on-offshore transport.

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