Beach Crest Research Articles

Deep Learning-Based Calculation Method for the Dry Beach Length in Tailing Ponds Using Satellite Images

The dry beach length determines the hydraulic boundary of tailings impoundments and significantly impacts the infiltration line, which is crucial for the tailings dam. A deep learning method utilizing satellite images is presented to recognize the dry beach area and accurately measure the length of dry beaches in tailing ponds. Firstly, satellite images of various tailing ponds were gathered and the collection was enlarged to create a dataset of satellite images of tailing ponds. Then, a deep learning method was created using YOLOv5-seg to identify the dry beach area of tailing ponds from satellite images. The mask of the dry beach region was segmented and contour extraction was then carried out. Finally, the beach crest line was fitted based on the extracted contour. The pixel distance between the beach crest line and the dry beach boundary was measured and then translated into real distance by ground resolution. This paper’s case study compared the calculated length of dry beach with the real length obtained by field monitoring. The results of the case study showed that the minimum error of the method was 2.10%, the maximum error was 3.46%, and the average error was 2.70%, indicating high precision for calculating dry beach length in tailing ponds.

Aspectos da geomorfologia costeira entre a foz dos rios Itabapoana e Paraíba do Sul, norte do estado do Rio de Janeiro

O litoral entre a foz dos rios Itabapoana e Paraíba do Sul destaca-se pela transição entre depósitos terciários da formação Barreiras e planícies fluviomarinhas quaternárias. Falésias ativas e inativas evidenciam o processo de retrogradação enquanto cristas de praia evidenciam a progradação da linha de costa. O objetivo é detalhar as características da geomorfologia costeira destacando geologia, geomorfologia e processos evolutivos. A metodologia consistiu no mapeamento de informações geológicas, geomorfológicas, perfis de praia, coleta e análise granulométrica representativas do sistema duna-praia-antepraia. Resultados apontam que perfis de praia côncavos e convexos mostram, respectivamente, áreas em erosão (ao norte) e áreas em acumulação (ao sul). As análises granulométricas indicam a presença de areia muito fina, areia fina e areia média evidenciando áreas com menor e maior energia de ondas, além da característica regional de elevado transporte de sedimentos.

Gravel beach profile response allowing for bimodal sea states

The south coast of the UK is identified as a location where significant wave swell components are present within the regional wave climate. During the winters of 2006 and 2014, several sites along the south coast of the UK were subject to significant damages where flood events were recorded. These sea states were characterised by having a double-peaked wave spectra, observing a connection between wave spectrum shape and beach response. A two-dimensional (2D) physical model study was carried out to investigate the effect of gravel beach profile response under wave spectra characterised by swell-wave and wind-wave periods in various combinations. The physical model results showed the effect of bimodal wave spectrum on beach crest erosion and were compared with the parametric model Shingle and the numerical model XBeach-G. Based on this 2D physical model study, a new parametric model, Shingle-B, was derived and an online tool developed and made available on the website for the National Network of Regional Coastal Monitoring Programmes of England. This new tool has been validated at two sites in the south of England where field data of both waves and profiles were available.

Semiautomatic Digital Clast Sizing of a Cobble Beach, Nantian, Taiwan

ABSTRACT Bujan, N.; Cox, R.; Lin, L.-C.; Ducrocq, C., and Hwung, H.-H., 2018. Semiautomatic digital clast sizing of a cobble beach, Nantian, Taiwan. Surface sediment data is scarce for beaches that are made of material close to the cobble size range, partly because of the difficulty of direct sampling for sediment size analysis. An object-detection tool for semiautomatic analysis of clast geometry, originally developed for riverbeds, was applied to the coarse-clastic beach of Nantian, Taiwan. Comparison of the software with digital point counts for the common size percentiles D5, D16, D30, D50, D70, D84, and D95 indicated an average coefficient of determination of 0.990 over 10 test pictures. The surface sediment was digitally sampled at three cross-shore locations along the beach: near the shoreline, on the steep part of the beach face, and on the beach crest. Clast-size distributions, including clast area and elongation ratio, were computed from the geometry of 1000 clasts for each location and the cros...

Influence of Quaternary sea level changes in the littoral of Chubut, Argentina

Geomorphologic and stratigraphic studies accomplished in the littoral area between Cabo Raso and Punta Fabián, eastern Chubut Province, allowed the identification of different features and geomorphologic processes related to the modern dinamic, as well as a set of coastal units related to the different transgressive events occurred from the middle Pleistocene to the Holocene. The distribution and development of the littoral deposits displays a completely different situation from that of the area of Bahía Camarones, Bahía Bustamante, Cabo Raso and Bahía Vera (south and north of the study area), favored by a very hard substrate (Marifil Complex) at higher topographic positions. Abrasion platforms, cliffs, islands, capes and tómbolos form a broken coast in which the most relevant accumulation morphologies are gravel beaches. This situation prevailed as well in each of the high sea level event, forming beach crests in some places that corresponded to bays, wider than the modern ones. According to the altitud of these geoforms, respect to similar ones located to the south which have a significant number of numerical ages, the highest sea levels correspond to 500 k B.P., quite probably the Marine Isotopic Stage 11. This analysis includes a mean elevation of the continent of 0.12 ± 0.04 mm/yr. Although eight beach crests were clearly identified, not necessarily each of them responds to independent transgressive events. In fact, some of them may represent different positions of the same transgression during the regressive phase.

Observations of waves and currents during barrier island inundation

AbstractOverwash and inundation on barrier islands can transport sediment onshore, leading to vertical accretion. These processes could ensure barrier island growth in times of sea‐level rise, but wave and current fields during overwash and inundation are not well understood. Field data of water levels, waves, and currents were collected on a barrier island in the Netherlands to investigate the hydrodynamics during island inundation. Observations show that even in shallow water depths (<0.5 m) wave energy was not completely dissipated as waves propagated from the North Sea onshore. Additionally, locally generated wind waves entered the field area from the Wadden Sea and propagated offshore. Infragravity waves were an important part of the wave field, particularly onshore of the beach crest. They were observed to be onshore progressive and displayed a bore‐like shape when water depths were shallow. Wave breaking was the dominant dissipation mechanism for high‐frequency waves as well as for infragravity waves, which is in agreement with prior research on infragravity wave energy dissipation on mild sloping (closed‐boundary) beaches. A large‐scale offshore directed water‐level gradient between the Wadden Sea and the North Sea side, caused by elevated water levels in the Wadden Sea during the storms, frequently drove an offshore flow if it was large enough to exceed the cross‐shore gradient due to wave setup. In addition, elevated water levels in the Wadden Sea decreased current velocities due to a decrease in water‐level gradients. This study highlights the influence of back‐barrier processes on the hydrodynamics during inundation.

Coastline Zones Identification and 3D Coastal Mapping Using UAV Spatial Data

Spatial data acquisition is a critical process for the identification of the coastline and coastal zones for scientists involved in the study of coastal morphology. The availability of very high-resolution digital surface models (DSMs) and orthophoto maps is of increasing interest to all scientists, especially those monitoring small variations in the earth’s surface, such as coastline morphology. In this article, we present a methodology to acquire and process high resolution data for coastal zones acquired by a vertical take off and landing (VTOL) unmanned aerial vehicle (UAV) attached to a small commercial camera. The proposed methodology integrated computer vision algorithms for 3D representation with image processing techniques for analysis. The computer vision algorithms used the structure from motion (SfM) approach while the image processing techniques used the geographic object-based image analysis (GEOBIA) with fuzzy classification. The SfM pipeline was used to construct the DSMs and orthophotos with a measurement precision in the order of centimeters. Consequently, GEOBIA was used to create objects by grouping pixels that had the same spectral characteristics together and extracting statistical features from them. The objects produced were classified by fuzzy classification using the statistical features as input. The classification output classes included beach composition (sand, rubble, and rocks) and sub-surface classes (seagrass, sand, algae, and rocks). The methodology was applied to two case studies of coastal areas with different compositions: a sandy beach with a large face and a rubble beach with a small face. Both are threatened by beach erosion and have been degraded by the action of sea storms. Results show that the coastline, which is the low limit of the swash zone, was detected successfully by both the 3D representations and the image classifications. Furthermore, several traces representing previous sea states were successfully recognized in the case of the sandy beach, while the erosion and beach crests were detected in the case of the rubble beach. The achieved level of detail of the 3D representations revealed new beach characteristics, including erosion crests, berm zones, and sand dunes. In conclusion, the UAV SfM workflow provides information in a spatial resolution that permits the study of coastal changes with confidence and provides accurate 3D visualizations of the beach zones, even for areas with complex topography. The overall results show that the presented methodology is a robust tool for the classification, 3D visualization, and mapping of coastal morphology.

Paleoenvironmental Reconstruction and Timeline of a Dorset-Thule Settlement at Quaqtaq (Nunavik, Canada)

ABSTRACTA geoarchaeological and paleobotanical study of a Paleoeskimo and Neoeskimo site was undertaken in order to reconstruct site-formation processes. The study site JfEl-10 is located on Igloo Island, in Diana Bay, on the southern shore of Hudson Strait. It contains a peat-mineral deposit situated between two successive beach crests, close to a small marsh. Samples from the edge of the site, which consists of a remarkable section of stratigraphy 60 cm thick that contains alternating brown organic beds and light-colored sand beds, were examined in the laboratory. Macrofossil data and pollen data were used to reconstruct the local and regional vegetation and to determine climatic changes over the past 1200 years. The geoarchaeological study includes the stratigraphy and the sedimentology of archaeological sediments. The evolution of the site followed three successive environmental phases, and the site was home to two distinct cultures. The first phase (from ca. 1200 to ca. 950 cal. yr B.P.) was characterized by cold and mesic conditions and the Dorset occupation. In the second phase, conditions became more humid beginning ca. 950 cal. yr B.P. and lasted for approximately 450 years. This period is marked by the arrival of Thule Inuit, who hunted marine mammals in the vicinity. Zooarchaeological information indicated a fall/winter occupation during the Thule Inuit period. The third phase corresponds with the onset of the Little Ice Age (A.D. 1500–1850) and associated cooling. During this time, the Thule Inuit abandoned the site. If the increased cooling caused an earlier freeze-up of Diana Bay, this may have prevented the movement of walrus to their haul-out island during fall. Additionally, the faster accumulation of thick ice would have limited the hunting of seals through their breathing holes.

Flavonoids of Calophyllum inophyllum Linnaeus. C. von

Calophyllum inophyllum Linnaeus C.von (Syn.) Calophyllum bintagar Roxb of Guttifereae (Clusiaceae) is commonly known as ‘ Indian laurel’ or ‘Alexandhian laurel’ a broad-leaved evergreen tree occurring as a littoral species along the beach crests, sometimes seen inland. It is widely distributed and cultivated throughout tropics from West Africa to Pacific islands (as far) East-as Tahiti. It blossoms during March to October. Fresh flowers of Calophyllum inophyllum have been treated for their flavonoids contents. They are rich flavonol quercetin and flavonol glycosides quercitrin. They have been characterized with the help of modern physical methods like UV, H-1 NMR, C-13 NMR, chemical reactions, chromatographic techniques and hydrolytic studies.

Stratigraphy and chronology of Provo shoreline deposits and lake‐level implications, Late Pleistocene Lake Bonneville, eastern Great Basin, USA

The Provo shoreline of Lake Bonneville formed following the Bonneville flood, and, based on previous dating, was formed during a period of overflow from about 17.5 to 15.0 cal. ka. In many places the Provo shoreline consists of a pair of distinct shorelines, one ∼3 m higher than the other. We present data from two cuts through double beaches to show that the upper beach is younger and represents sedimentation after a lake‐level rise. In addition, the lower beach deposits are internally stratified by beds that suggest three more lake‐level rises during its development. The Provo beach complex thus appears to have been built during rising lake levels, which can be explained by rises in the overflow threshold by sequential landslide deposition. Evaluation of beach altitudes demonstrates that the two beach crests throughout the Bonneville basin experienced equivalent rebound from removal of the lake load, and therefore they formed after the rebound associated with the Bonneville flood occurred in early Provo time. However, radiocarbon ages on gastropods collected within the beach deposits suggest both that the sequence of five beach deposits formed from c.18.1 to c. 17.0 cal. ka, and that the Bonneville flood occurred before 18 cal. ka. These ages are discordant with previous dates on shells within offshore sands, and raise questions about the validity of radiocarbon ages for shells in Lake Bonneville as well as about the age of the Bonneville flood and Provo shoreline. The timing for maximum Provo lake depths and its association with climate stages during deglaciation remain unresolved.

Dating High Arctic Holocene relative sea level changes using juvenile articulated marine shells in raised beaches

High Arctic raised beaches provide evidence for changes in relative sea-level (RSL), sea-ice extent, storminess, and variations in sediment supply. In many High Arctic areas, driftwood and whale bone are usually the preferred targets for radiocarbon dating, with marine shells a third choice because of their often large age and height uncertainties with respect to former sea level. Here we detail a new approach to sampling marine shells that reduces these problems by targeting juvenile, articulated specimens of Astarte borealis that are washed onto the beach under storm conditions and become incorporated into the beach crest. Radiocarbon dates from articulated valves of A. borealis from eight raised beaches from Billefjorden, Svalbard, provide a chronology for Holocene beach ridge formation and RSL change that compares favourably to the most precise records developed from elsewhere in Svalbard using driftwood or whale bone. We demonstrate the value of this new approach by comparing our record with previously published RSL data from eastern Svalbard to test different models of Late Weichselian ice load in this region. We find support for a major ice dome centred south and east of Kong Karls Land but no evidence for a significant ice dome located over easternmost Spitsbergen or southern Hinlopen Strait as proposed from recent marine geophysical survey. The approach is potentially applicable elsewhere in Svalbard and the High Arctic to address questions of RSL change and beach ridge chronology, and hence wider questions regarding palaeoclimate and ice load history.

LABORATORY EXPERIMENT ON CROSS-SHORE BARRIER SPIT EVOLUTION BY STORM DYNAMICS

Every year there are many severe storms occurring around the world, in general, and in Japan, in particular. The occurrence of storms is expected to increase because of the global warming effects. An increasing wave height together with a rising mean water level during a storm create a high possibility for waves to overtop the beach crest causing a lot of sediment to be eroded to offshore areas or deposited in the inland direction. The study of the barrier island response to storms has therefore become very important in terms of sediment transport and beach morphology change, as well as damage to nearshore structures due to runup overwash and inundation overwash. However, changes in the beach profile and prevailing sediment transport mechanisms during a real event are difficult to obtain. Thus, laboratory studies are necessary to conduct. This study presents a laboratory experiment on the impact of storms on a sandy barrier islands. The main aim is to investigate the entire barrier island (or sand spit) response due to storm conditions considering the increase in water level due to storm surge. Also, further development of an analytical model for barrier profile change caused by runup overwash is presented and obtained results overall captured order-of-magnitude barrier face retreat and volume changes after the storm.

Beach Morphological Change Caused by Wave Overtopping and Verification of Hard Structure to Prevent the Overwashing

Rising of sea level together with the increase of wave height during a single extreme storm event might give storm waves more possibility to get over the beach crest and bring the sediment further inland direction especially at a low barrier island. Therefore, it is important to estimate the total amount of deposited sediment on a barrier island after storm and propose any suitable countermeasures to prevent the sand deposition into the bay or lagoon. From 8th to 10th of October 2009, an extreme typhoon number 18 attacked the Nanakita River mouth area and there was a lots of sediment deposited inland. This study is to analyze the deposited sediment and to evaluate the effectiveness of present overwash prevention construction in the Nanakita River mouth area by using the field observation data. The estimated sediment deposition shows well agreement with the result of empirical overwash formula.

A numerical model of coastal overwash

Overwash, the flow of water and sediment over the crest of a beach, contributes to flooding and the deposition of sand landward of the beach crest. Washover, the sand deposited by overwash, contributes to the sediment budget and migration of barrier islands. The ability to predict the occurrence, location, and thickness of overwash deposits is important for coastal residents, coastal town planners, environmental planners, and engineers alike. In this study, a numerical model that simulates the sediment transport and one-dimensional barrier profile change caused by overwash was developed. The magnitude of overwash and the morphology of washovers are dependent on the overwash regime. New formulae are developed to estimate the sediment transport rate over the beach crest for both run-up overwash, using ballistics theory, and inundation overwash, treating flow over the crest as weir flow. Two-dimensional flow is described on the back barrier by considering the continuity of a block of water at steady state, taking into account lateral spreading, friction, and infiltration. The model is tested against 26 different beach profile sets from several different locations, and several different storms, exhibiting a variety of initial morphologies. The model is capable of reproducing varying overwash morphology responses including dune crest erosion, dune destruction, barrier rollback, the thinning of a washover deposit on the backbarrier, and overwash over a multiple dune system.

Analytical model of beach erosion and overwash during storms

During severe storms high waves and water levels may greatly impact the sub-aerial portion of the beach inducing significant morphological change at elevations that the waves can not reach under normal conditions. Morphological formations such as dunes and barrier islands may suffer from direct wave impact and erode. Overwash occurs if the wave run-up and/or the mean water level are sufficiently high allowing for water and sediment to pass over the beach crest, which in turn causes flooding and deposition of sediment shoreward of the crest. An analytical model of sub-aerial beach response to storms was developed based on impact theory, including overwash, and the evolution of schematised dunes was investigated. Furthermore, the analytical model was applied to the case of schematised barrier islands exposed to extensive overwash. After validation using field data, the analytical model was employed at two coastal sites, namely Ocean City on the United States east coast and the Ebro Delta on the Spanish Mediterranean coast, in order to calculate quantities for assessing the storm impact on beaches, such as eroded volume, overwash volume, beach crest reduction, and contour-line retreat. These quantities were subsequently analysed to derive empirical probability distribution functions to be utilised in different types of risk assessment concerning flooding and erosion in coastal areas.

Assessing Anthropogenic and Natural Impacts on Ghost Crabs (Ocypode quadrata) at Cape Hatteras National Seashore, North Carolina

This study explores impacts of off-road vehicles on ghost crab populations as a measure of impact from recreational beach use on two beaches of the Cape Hatteras National Seashore and assesses the effectiveness of several alternatives for the use of off-road vehicles (ORVs) on the beach. Ghost crab population size and density have been used as indicators of the environmental quality of beaches and dunes. Data on the creation of an “ORV corridor” in which ORVs can drive on the landward portion of the berm, but not on the beach crest, indicate that it may be possible to preserve ghost crab populations on the beach while still permitting the use of ORVs. Closing the beach crest 24 hours a day may be the optimal solution for preservation of ghost crab populations. High-energy weather events, however, resulted in larger changes to the population dynamics of the ghost crabs. After storms, ghost crabs were able to (re)inhabit areas where their numbers previously had been reduced by the operation of ORVs. While temporary closures of the beach crest may be used to reduce the short-term impacts of ORVs on ghost crab populations on the outer banks of North Carolina, long-term impacts ultimately are controlled by the strength and frequency of storms that reset the system.

Internal structure of a barrier beach as revealed by ground penetrating radar (GPR): Chesil beach, UK

Chesil Beach (Dorset) is one of the most famous coastal landforms on the British coast. The gravel beach is over 18 km long and is separated for much of its length from land by a tidal lagoon known as The Fleet. The beach links the Isle of Portland in the east to the mainland in the west. Despite its iconic status there is little available information on its internal geometry and evolutionary history. Here we present a three-fold model for the evolution of Chesil Beach based on a series of nine ground penetrating radar (GPR) traverses located at three sites along its length at Abbotsbury, Langton Herring and at Ferry Bridge. The GPR traverses reveal a remarkably consistent picture of the internal structure of this barrier beach. The first phase of evolution involves the landward transgression of a small sand and gravel beach which closed upon the coast leading to deposition of freshwater peat between 5 and 7 k yr BP. The second evolutionary phase involves the ‘bulking-out’ of the beach during continued sea level rise, but in the presence of abundant gravel supplied by down-drift erosion of periglacial slope deposits. This episode of growth was associated with a series of washover fans which accumulated on the landward flank of the barrier increasing its breadth and height but without significant landward transgression of the barrier as a whole. The final phase in the evolution of Chesil Beach involves the seaward progradation of the beach crest and upper beach face associated with continued sediment abundance, but during a still-stand or slight fall in relative sea level. This phase may provide further evidence of a slight fall in relative sea level noted elsewhere along the South Coast of Britain and dated to between 1.2 and 2.4 k yr BP. Subsequently the barrier appears to have become largely inactive, except for the reworking of sediment on the beach face during storm events. The case study not only refines the evolutionary picture of Chesil Beach, but illustrates the importance of the subtle interplay between relative sea level and sediment supply in the evolution of a barrier system. In addition, it also illustrates the potential of GPR in resolving the evolutionary history of gravel-rich coastal landforms such as Chesil Beach.

Verification of New Washover Formula with Field Measurements Data

Prediction of overwash occurrence can provide valuable planning information for local authorities, emergency services, and coastal residents. Based on those proposes a new empirical formula for predicting deposited washover volume was derived. The new formula was developed by modifying the assumptions of previous empirical models using new assump-tions based on the governing physical processes by taking into account the excess runup height over the beach crest and the duration of the overwash event. The empirical coefficient was calibrated using field data sets from United States. Verification of the model with a further fourteen field data sets was shown that the formula yields predictions are comparable to the measured field data with most of predicted overwash volumes falling within a factor of two.

Predicting the crest height of a gravel beach

The beach crest is a common morphological feature formed by the deposition of sediment carried up-slope by wave swash. The elevation to which waves can pile gravel is a function of the size and density of the material relative to the hydraulic components of swash velocity, wave frequency and runup height. Two equations ((17) and (21)) that predict the height of the beach crest to the wave forces and the beach material are derived. The first derivation compares the wave force acting to move a stone up the beach face with a weight force acting to hold the stone in place. The second derivation relates the potential energy per unit area of the beach crest to the total wave energy that lifted and deposited the material above a given sea-level datum. As a test of the derived equations, the actual crest height of one natural gravel beach was accurately estimated by both equations derived. Further research and testing on other natural beaches are needed to fully verify Eqs. (17) and (21). A comparison of other equations (Eqs. (2), (3) and (4)) that predict crest height is also made. The poor fit of the other equations are a result of using values for the coefficients that were established in wave tank experiments. Another shortcoming of Eqs. (3) and (4) is that they do not include variables related to the beach material. Hence, they predict that all particle sizes from sand to boulders would be piled to the same elevation by the same wave forcing. Eq. (2) includes a particle size variable but predicts increasingly higher beach crests for larger particles. More realistic results for all three equations (Eqs. (2), (3) and (4)) would be expected with field-tested values for the coefficients, but a range in values for each different beach would be necessary. The advantage of Eqs. (17) and (21) is that equations are not dependent on coefficients whose values come from correlation with other data sets.

Recent shingle beach renourishment schemes in the UK: Some preliminary observations

Experience gained during shingle beach replenishment from offshore sources is described. Schemes undertaken along the Southern coastline of England reveal that the presence of fine-grained material in the sediments can lead to the formation of a more compact beach which has a lower permeability. This (generally) leads to the formation of a hard vertical face around high water mark as opposed to a mobile beach crest. Such features could reduce the sea defence and amenity values of beach replenishment schemes.