Beach Protection Research Articles

Modelling of wave climate and sediment transport patterns at a tideless embayed beach, Pirita Beach, Estonia

Nearshore sand transport patterns along the tideless, embayed Pirita beach, Tallinn, Estonia, have been investigated utilizing high-resolution modelling of wave processes combined with bathymetric surveys and sediment textural analyses of the nearshore sea floor. Textural analysis showed the mean grain size is about 0.12 mm. Fine sand (0.063–0.125 mm) accounts for about 77% of the sediments. Coarser-grained sand (0.28 mm) dominates along the waterline. Based upon the spatial distribution of the mean grain size and basic features of the local wave activity, properties of the Dean Equilibrium Beach Profile were determined. Alongshore sediment transport was calculated based upon a long-term time series of wave properties along the beach, and the CERC formula applied to about 500 m long beach sectors. The time series of wave fields and the properties of the local wave climate were modelled using a triple nested WAM wave model with an extended spectral range for short waves. The model is forced by open sea wind data from Kalbådagrund for the years 1981–2002. Results indicate that typical closure depth at Pirita is 2.5 m. The width and mean slope of the equilibrium profile are 250 m and 1:100, respectively. Southward transport dominates in the northern sections of the beach whereas no prevailing transport direction exists in the southern sections. This pattern has several nontrivial implications for the planning of beach protection activities.

Abiotic Suitability of Recycled Glass Cullet as an Alternative Sea Turtle Nesting Substrate

Because of the myriad of environmental concerns related to critically eroded shoreline areas, recycled glass (cullet) has been postulated as a potential alternative source material for beach fill. However, the newly proposed cullet beach material must uphold the nesting incubation properties of endangered species such as sea turtles. This study is the first in which the abiotic parameters of recycled glass cullet is investigated as an alternative beach fill material in relation to the nesting habitat requirements of marine turtles. By constructing a simulated sea turtle nesting hatchery and with the use of thermal/moisture logging sensors and extracted gas probe samples, we determined that recycled cullet maintains the abiotic nesting chamber properties to allow for successful sea turtle embryo development. Simulated nests containing recycled glass cullet recorded average temperatures (27.0–31.4°C) that fell within the acceptable incubation range for sea turtles and moisture content readings that showed no significant differences from the beach sand controls (p > 0.05). Similarly, gas probe samples analyzed from all the experimental cullet nests recorded high concentrations of oxygen (≥20.0%) with no significant variations from the beach sand controls (p > 0.05). Overall, this study showed that nests constructed with a portion of recycled glass cullet offered a nesting environment equal to the developmental conditions of the native beach sand. Worldwide, the nesting beaches of sea turtles are under the constant threat of erosion, which ultimately results in the loss of nesting habitat. With this research, we document that recycled glass cullet can provide a sea turtle–friendly alternative for beach protection.

Port-induced erosion prediction and valuation of a local recreational beach

This study attempts to integrate environmental economics and coastal engineering in managing port-induced coastal erosion occurring at a common beach by using Map Ta Phut port in Thailand as a case study. The existence of the port creates coastal erosion which can be considered an externality that affects local inhabitants, and a port owner and shipping companies can be seen as “polluters”. Overlaying of aerial photographs provided strong evidence that the coastline was severely eroded after the construction of the port. Coastal engineering softwares, LITPACK and MIKE 21 PMS, were utilized to predict future shoreline positions and investigate wave patterns around the port. The port alters wave climate and the port-induced erosion is jeopardizing a local recreational beach called Nam Rin, which is projected to disappear in 5 years. A valuation of Nam Rin beach using single-bounded dichotomous choice contingent valuation method revealed individual willingness to pay (WTP) for the beach, being 867.5 baht (approximately US$ 24.8) per year. Multiplying the individual WTP with the appropriate number of population to acquire the beach protection benefit and dividing such benefit by construction and maintenance costs of a particular beach protection measure, the polluters can select a proper beach protection approach that fulfills their benefit–cost requirement.

Appreciation of Static Bay Beach Concept for Coastal Management and Protection

Sandy bay beach in static equilibrium is the only physiographic feature that could remain stable without sediment supply in a persistent swell environment anywhere around the world. With a continuing trend of erosion to sandy beaches worldwide, a conservative and practical hypothesis is not to consider the mobile dynamic wave parameters but to safeguard against a sandy beach under vanishing supply in the future. To achieve this, an empirical bay shape equation is strongly recommended as one of the best coastal management options. Combining with MEPBAY, software derived for implementing the static bay beach concept on a display unit, this empirical bay shape equation is readily applicable to verify the stability of numerous headland bay beaches in natural and man-made condition. It is also adequate for coastal managers to apply this empirical equation as a valuable tool to aid in the creation of headland bay beaches for shore protection, recreation, and coastal management before embarking on sophisticated numerical modeling.

Shape optimization of geotextile tubes for sandy beach protection

AbstractThis paper describes how to tackle new challenging coastal engineering problems related to beach erosion with a shape optimization approach. The method modifies the shape of the sea bottom in order to reduce beach erosion effects. Global optimization is shown to be necessary as the related functionals have several local minima. We describe the physical model used, the proposed protection devices against beach erosion and real case applications. Copyright © 2007 John Wiley & Sons, Ltd.

The formation of protective dune ridge along the Southeast Baltic Sea coast: historical and social aspects

This paper is based on literature-based studies, as well as material collected by the author over more than 30 years on the shores of the Southeast Baltic Sea. In order to protect roads running along the shoreline from East Prussia to Konigsberg, local shore reinforcement works commenced in the fifteenth century, although some individual attempts had been made before. In 1684, M. Ch. Hartknoch theoretically substantiated the necessity for, and methods of, shore reinforcement. The state of the shores deteriorated considerably during the Seven Years War (1756–1763), when woodlands growing along the shores were completely destroyed; hence, nearly 100 km length of the coast of the Kursių Nerija (Curonian) sand spit was left without any vegetation. Aeolian sand buried as many as fourteen settlements. This situation forced the authorities to organise maintenance of the coast and the dunes at the governmental level, and to start the formation of an uninterrupted dune ridge. The second half of the nineteenth century and the first half of the twentieth century are notable for the extensive construction of new ports. Along the shores running from the Sambian Peninsula to the Gulf of Riga, eight port engineering structures had been constructed with the intervals of approximately 26 km between the ports of Klaipėda and Liepaja, and every 13 km between Palanga and Pape. Shore management measures were being implemented simultaneously, thus ensuring the functioning of the above-mentioned coastal protection structures and the reduction of impacts upon the shores. In the second half of the twentieth century, ports were dredged and developed significantly. Their entrance channels reduced the long-shore sediment transport. Moreover, total sand reserves in the shore zone also diminished. The processes of erosion of the beaches and the dune ridge made it necessary to actively reinforce the shore. A number of countries passed legal acts governing the protection and use of the shore zone. At the turn of the twenty-first century, the incompatibility of such priorities in human activities as sea transport and recreation with nature protection has become evident. The conflict of interests in the Kursių Nerija National Park, the port of Klaipėda, and the resort of Palanga serve as good examples of such incompatibility. The conclusion that can be drawn that in twenty-first century is that the priorities in general coastal management should be as follows: harmonisation of interests among the states and individual fields of activities, as well as measures aimed at neutralisation of negative natural trends (higher frequency of storms, global rise of water level, etc.). The protective beach dune ridge will further play the role of efficient means for reducing shore erosion.

Beach Accretion and Erosion with S-Type Rubble Mound Sea Wall

The north Chennai coast, on the east coast of India, experiences severe erosion caused by waves, and an area of the beach about 600 m wide has eroded over the past 120 years. To protect the seafront, natural stones were dumped by government agencies along the coast for a distance of about 6 km, and in the process, a short beach pocket 400 m long was left unprotected for various reasons. Because the property of a chemical factory located in this 400-m stretch of beach pocket suffered damage caused by erosion, and because the need for a wide beachfront was stressed by local fishermen, an alternative method of protecting the beach was suggested. The proposal involved construction of an S-type rubble sea wall about 100 m long on the southern end of the beach pocket. This paper discusses the numerical model studies conducted to determine the configuration of the S-type rubble sea wall and its effectiveness in beach protection. The model studies suggested a length of projection of 14 m with a radius of curvature of 310 m for the S-type sea wall to achieve the desired performance. Field studies conducted on the 40-m-wide and 400-m-long beach pocket with the 100-m-long S-type sea wall indicate that the sea wall is effective in protecting the beach.

Application of remote sensing video systems to coastline management problems

This contribution evaluates the application of coastal video systems to monitoring and management of coastal stability problems on sandy coastlines. Specifically, video-derived parameters (coastal state indicators or CSIs) are developed which facilitate the measurement of the shoreline evolution (erosion/accretion) and response to storms, seasonal cycles and anthropogenic interventions like beach/shoreface nourishment and dredging. The primary variable which forms the basis for all the CSIs discussed in this contribution is the shoreline position derived from time-averaged video images. These waterlines are used to generate secondary products including shoreline contours at a constant pre-defined level, (intertidal) beach volumes, and momentary shoreline positions which reflect the sand volume in a meter wide section of the intertidal coast. Video-derived coastal state indicators were verified via comparisons with traditional topographical/bathymetric surveying techniques and a good agreement was found in all cases. CSIs were computed for three contrasting sandy coastal environments including an unprotected natural beach, a protected beach and a spit. Firstly, results are presented which demonstrate the advantages of coastal video systems over and above infrequent traditional topographic/bathymetric surveying methods. Namely, the ability of video-derived CSIs to quantify the magnitude, accurate location, precise timing and rates of change associated with individual extreme events and seasonal variability in the wave climate. Secondly, video-derived coastal state indicators were used to monitor two different types of human intervention, including beach nourishments and a dredged pit in a navigation channel. The video-derived datasets of coastal state indicators offered significant improvement to current CZM practices, facilitating better timing of management interventions as well as more effective monitoring of the spatial impact and longevity of these actions.

Sediment Ridges on the West Florida Inner Continental Shelf: Sand Resources for Beach Nourishment

Beach nourishment requires large volumes of sand from offshore and new sources are constantly sought for development. The sediment-starved continental shelf off the central-west coast of Florida has traditionally supplied beach-quality sediments from ebb-tidal shoals and nearshore sand sheets, but as these supplies dwindle, sand searches increasingly look farther offshore for resources. Widely spaced sediment ridges, interspersed by karstified limestone seafloor (hard grounds), offer potential as sand resources that can be exploited by dredging to renourish eroded beaches for shore protection. The sand ridges, late Holocene in age, are generally shoreface detached, sediment starved, and clustered in “ridge fields.” Six sediment ridge fields identified along 285 km of coast (Anclote, Sand Key, Sarasota, Manasota, Captiva, and Collier) contain about 1.4 billion cubic meters of sediments that are potentially available for dredging. Evaluation of these sediment sources, within the purview of the USMinval Code, requires the determination of resources, reserves, and level of certainty of assessment applied to a rating of resource potential. Present research is attempting to identify the overall resource potential with an eye toward eventually determining sand volumes in reserves, which will be much less than the total sand resource volume.

Development and Utilizationin of KANSEI Design System for Designing of Coastal Landscape

This paper explores the evaluating system of coastal landscape by using the KANSEI engineering as well as the social sciences to collect data for the landscape data base. The system have been found to be useful in designing and evaluating of coastal landscape with various types of beach protection works such as detached breakwaters and submerged artificial reefs. The landscape KANSEI design systemconsists of the coastal landscape data base and Kansei designing system in whichprincipal component analysis was introduced. The system was applied to the actual castal improvement works for shore, and it was shown that the system is also very useful to get the agreement formation for the design at the citizens' participation in municipal general affairs.

The capacity of the Gunderboom® in Mamaroneck Harbor on the reduction of E. coli and coliform bacteria from water and soft-shelled clams (Mya arenaria)

Harbor Island Park of Mamaroneck Harbor is one of the beaches that has been frequently closed to the public due to unsanitary swimming conditions. In 2002, a Gunderboom® BPS™(Beach Protection System) was reinstalled in Harbor Island Park to lower bacterial levels in swimming areas. The first Gunderboom® had been destroyed by an oil spill several years before. The current Gunderboom® is an 800 foot curtain made of a treated polypropylene/polyester fabric and the company claims a 99.1% coliform reduction with its use. In this study, water inside and outside the Gunderboom® was tested weekly from June to August 2005, and bi-weekly from September to December 2005. Coliscan® Membrane Filtration plates were used to recover the relative amounts of Escherichia coli and coliform bacteria from the water. Soft-shelled clams (Mya arenaria) living in both these areas were also tested for their E. coli and coliform bacteria level using 3M Petrifilm™ plates. Water was also tested from Hudson Park in New Rochelle, a frequently closed beach due to high levels of coliform bacteria, as well as from Read Sanctuary in Rye, a “pristine” beach. Our results showed the amount of E. coli and coliform bacteria recovered from the water inside the Gunderboom® were significantly lower (P < 0.05) compared to outside the Gunderboom® and Hudson Park. There was 81.9% reduction in E. coli and 51.6% reduction in coliform bacteria inside the Gunderboom® as compared to the outside. In addition, significant differences (P < 0.05) were found with lower numbers of E. coli and coliform bacteria recovered from the clams inside the Gunderboom® compared to outside the Gunderboom®. In conclusion, the Gunderboom® system installed in Mamaroneck Harbor resulted in a significant reduction of E. coli and coliform bacteria in the water and clam samples, thus proving its efficiency as a water filter.

Hurricanes 2004: An overview of their characteristics and coastal change

Four hurricanes battered the state of Florida during 2004, the most affecting any state since Texas endured four in 1884. Each of the storms changed the coast differently. Average shoreline change within the right front quadrant of hurricane force winds varied from 1 m of shoreline advance to 20 m of retreat, whereas average sand volume change varied from 11 to 66 m3 m−1 of net loss (erosion). These changes did not scale simply with hurricane intensity as described by the Saffir-Simpson Hurricane Scale. The strongest storm of the season, category 4 Hurricane Charley, had the least shoreline retreat. This was likely because of other factors like the storm's rapid forward speed and small size that generated a lower storm surge than expected. Two of the storms, Hurricanes Frances and Jeanne, affected nearly the same area on the Florida east coast just 3 wk apart. The first storm, Frances, although weaker than the second, caused greater shoreline retreat and sand volume erosion. As a consequence, Hurricane Frances may have stripped away protective beach and exposed dunes to direct wave attack during Jeanne, although there was significant dune erosion during both storms. The maximum shoreline change for all four hurricanes occurred during Ivan on the coasts of eastern Alabama and the Florida Panhandle. The net volume change across a barrier island within the Ivan impact zone approached zero because of massive overwash that approximately balanced erosion of the beach. These data from the 2004 hurricane season will prove useful in developing new ways to scale and predict coastal-change effects during hurricanes.

Dynamic Pressure Evaluation NearSubmerged Breakwaters

The increasing use of submerged breakwaters is not only due to their important role in beach protection, but also because of their low environmental impact. In their design process, an analysis of the pressure fields (near and along the structure slope) under wave flow is needed. Although a considerable amount of research has been conducted in order to improve our understanding of these structures behaviour and establish reliable formulae for design purposes, several outstanding questions remain. This paper aims to present the evolution of dynamic pressure fields when the structure is submitted to the action of regular incident waves. These pressure fields are obtained by indirect means, through the measured horizontal wave flow velocity component as a function of the wave phase and water depth.

Shoreline response to submerged structures: A review

Submerged coastal structures are widely perceived to be capable of providing beach protection, without the adverse impacts (including loss of beach amenity and aesthetic considerations) often associated with more conventional structures such as revetments and groynes. In addition, there is growing interest in the concept that the layout and cross-section of submerged coastal protection structures can be optimised to also enhance local surfing conditions. However, as submerged structures have only rarely been adopted for beach protection, the shoreline response to these structures is not well understood at present. Therefore, this review of the available published literature was undertaken with the aim of investigating the environmental and structural parameters governing shoreline response to submerged structures, gleaned from the results of field, laboratory and numerical studies undertaken to date. The review reveals that, contrary to expectations, a majority of the submerged structures constructed to date have resulted in shoreline erosion in their lee. Furthermore, the key environmental and structural parameters governing the mode (i.e. erosion or accretion) and the magnitude (i.e. size of salient) of shoreline response to submerged structures are yet to be identified. Although submerged coastal structures offer the potential for low aesthetic impact incorporating multi-function design, until the response of the adjacent shoreline to submerged structures is better resolved, their use is likely to remain relatively limited.

Comparison between the macroinfauna of urbanized and protected beaches in Rio de Janeiro State, Brazil

The intertidal macroinfauna of five sandy beaches with similar morphodynamics conditions was studied to compare composition and structure between beaches near urbanized centers and protected beaches located in Rio de Janeiro State. The beaches were sampled in winter 1996 and summer 1997 according to a systematic design with stratification. A total of nine species were identified with the crustaceans being the most abundant and frequent animals. Species richness showed little variation between beaches while density of some species such as Emerita brasiliensis (Crustacea) and Phaleria testacea (Insecta) were lower at urbanized beaches when compared to protected ones. At the most urbanized beaches, Pseudorchestoidea brasiliensis was absent during both sampling periods. The negative relationships between human recreational activities (e.g., trampling) and density of macroinfaunal species was recently gained support and in Barra da Tijuca beach these relation is very clear. In the developed and most-visited sector, Barra (Alvorada), the amphipod Pseudorchestoidea brasiliensis was never collected whereas in the protected portion, Barra (Reserva), the same species occurred in high densities. Thus, our results suggested that the amphipod Pseudorchestoidea brasiliensis is more vulnerable to trampling than are other species.

Increase of a Caribbean leatherback turtle Dermochelys coriacea nesting population linked to long-term nest protection

The leatherback turtle Dermochelys coriacea is considered to be at serious risk of global extinction, despite ongoing conservation efforts. Intensive long-term monitoring of a leatherback nesting population on Sandy Point (St. Croix, US Virgin Islands) offers a unique opportunity to quantify basic population parameters and evaluate effectiveness of nesting beach conservation practices. We report a significant increase in the number of females nesting annually from ca. 18–30 in the 1980s to 186 in 2001, with a corresponding increase in annual hatchling production from ca. 2000 to over 49,000. We then analyzed resighting data from 1991 to 2001 with an open robust-design capture–mark–recapture model to estimate annual nester survival and adult abundance for this population. The expected annual survival probability was estimated at ca. 0.893 (95% CI: 0.87–0.92) and the population was estimated to be increasing ca. 13% pa since the early 1990s. Taken together with DNA fingerprinting that identify mother–daughter relations, our findings suggest that the increase in the size of the nesting population since 1991 was probably due to an aggressive program of beach protection and egg relocation initiated more than 20 years ago. Beach protection and egg relocation provide a simple and effective conservation strategy for this Northern Caribbean nesting population as long as adult survival at sea remains relatively high.

Gauntlet Fisheries for Elasmobranchs - the Secret of Sustainable Shark Fisheries

The longevity and low fecundity of sharks make them particularly vulnerable to over-exploitation. Previous studies have emphasized the range of natural productivities observed across elasmobranch species and have used this to explain the sustainability of some elasmobranch fisheries and the deple - tion of others. This paper discusses the assessment of the two principal species fished by the Southern Shark Fishery of Australia, school shark (Galeorhinus galeus) and gummy shark (Mustelus antarcticus). The modeled simulations presented here show that shark behaviour patterns and fishing techniques which restrict fishing mortality to a few juvenile age-classes may be equally or more important than the productivity of different species in determining their relative robustness under exploitation. Counter- intuitively concentrating a fishery on a few year-classes of pups, juveniles or sub-adults proves to be a robust management strategy for elasmobranch fisheries, as long as the means exist for protecting adults from fishing mortality. Furthermore this management strategy proves to be most effective with the species considered to be least productive, those with greatest longevity. The obverse of this finding is to highlight the damaging impact on elasmobranch fisheries of human activities such as by-catch, finning, sport fishing and beach protection that cause even low levels of adult mortality .

The role of fringing coral reef in beach protection of Hurghada, Gulf of Suez, Red Sea of Egypt

The coral-reef system fronting most of the coastline of the Red Sea provides natural protection to the aquatic system. Its pronounced morphologic features protect coastal recreation facilities located behind the reef. To provide a basis for evaluating the role of the fringing coral reef in protecting marinas and sandy beaches against waves and currents, a two-dimensional (2D) numerical model “SIMulating COastal PROcess” (SIMCOPRO) was applied with its three main modules including wave, current and sediment. The selected study area is located at Sahl Hasheesh coast south of Hurghada on the west coast of the Red Sea at a site proposed for the construction of a marina. The model offers insight in how the reef system modifies the wave and current fields. The application of the model in the presence of a marina reveals insignificant erosion on the downdrift side of the marina breakwaters (south of the southern breakwater). The erosion is expected to be 1 m after the first year, 2 m after the next 5 years and no further change for a period of 10 years. This is because the rocky reefal beachface will be exposed and erosion of sand will be diminished. The minor local erosion is controlled by the protective response of coral reef, the very limited coarse sand on the beachface (<0.5 m thick), the weak current induced by waves (0.13 m/s) and other topographic protective elements in the region. The submerged/emerged geometric nature of the reefal system, both reef flat and reef crest, allow wave dissipation and thus behaves as a submerged breakwater to protect marinas or artificial beaches in the shelter zone of this reef. An important lesson to be learned from this study is that improper construction practices of building marinas can seriously hurt the environment. The dredging of artificial reef lagoons is one improper practice that would create unexpected beach erosion.

Intensive beach management as an improved sea turtle conservation strategy in Mexico

We evaluate the role of intensive beach management, meaning intense patrolling and nest reburial to a central hatchery, as a strategy for improving the success of sea turtle conservation at nesting sites in Mexico. We report the results of an experimental program at Playa Cuixmala, Jalisco, western Mexico. Sea turtle conservation efforts in Mexico have, in general, poor results because of lack of funds, which leads to insufficient beach protection and severe negative effects of nest removal on hatching success and sex ratios. Alternative strategies are needed to optimize limited resources. We predicted that intensive beach management, which included intense patrolling and careful nest reburial, could be an effective way to maximize nest survival and hatchling release under limited financial and human resources. The results of our 9-year study were very positive. Survival rate increased several fold during the study period. Hatching success and sex ratios were not significantly different between in-situ and removed nests. Survival in removed nests was, however, much higher that in-situ nests, because of predation and beach erosion. In total, the small (3 km length) Playa Cuixmala became the second most productive sea turtle nesting beach in the region because of these concentrated efforts. Intense beach management can be an important technique for sea turtle conservation, and can be properly applied to small beaches or the most productive sections of large beaches.

Influence of coastal structures on the beaches of southern Karnataka, India

Eight beaches of Dakshina Kannada and Udupi districts were regularly surveyed and monitored between 1985 and 1999 to understand morphological changes. During SW monsoon the wide summer beaches of this coast experience erosion. Eroded beaches start growing during post-monsoon period and are fully developed by April/May. These erosional and accretional trends are cyclic and annual in nature. Minimum sediment is stored on the beaches during July/August and maximum during April/May. Sediment budget estimates reveal a net gain and hence, there is an accretional trend along this coast. Wherever erosion becomes severe, construction of seawalls is taken up as a preventive measure. In fact, these structures enhance erosion or shift erosional sites towards adjacent areas or they undergo destruction. Occupation of protected beaches is an added problem. Material from cliff erosion of northern coast and that contributed by rivers of these districts are the major sources of littoral drift and beach sediments. Net littoral drift is towards south and any construction as barrier to this results in erosion on downdrift side. Three case studies conducted at Old Mangalore Port, New Mangalore Port and Kapu-Mulur areas exemplify this trend. Significant morphological changes have taken place at Old Mangalore Port area after the recent construction of breakwaters. The shoreline has prograded by about 225 m on updrift side and retreated by 165 m on downdrift side between December 1993 and July 1995.