The paper is focused on the design of artificial sand beaches at sheltered and exposed sites.The methodology applied includes the study of the most essential design parameters and the application of numerical models t...The paper is focused on the design of artificial sand beaches at sheltered and exposed sites.The methodology applied includes the study of the most essential design parameters and the application of numerical models to compute the beach erosion and maintenance.The computed erosion volume decreases for coarser sand(0.5 mm sand instead of 0.3 mm).Beach erosion increases for more graded sand,but the effect is small(10%–15%).The slope of the artificial beach at sheltered sites is commonly between 1 to 15 and 1 to 30 in conditions with a micro tidal range and mild waves.Slopes between 1 to 30 and 1 to 50 are used for more open exposed sites.The effect of the upper and lower beach slope(1 to 15 or 1 to 20)on beach erosion is marginal for sand in the range of 0.3 to 0.5 mm.A break in slope is quickly adjusted by transport processes.The volume of beach sand required may be reduced by constructing a submerged sill at the toe of the beach.Analysis of costs shows that the construction costs including maintenance over a period of 50 years of a submerged sill are about the same as that of beach fill including maintenance.Hence,the beach fill volume can be twice as large for a solution without a sill.Beach erosion due to alongshore transport processes is minimum if the beach line of the planform is perpendicular to the main wave direction(equilibrium beach).展开更多
Coastal ecosystems are plagued by high levels of microplastic pollution.Conducting baseline surveys is crucial to comprehend the distribution and influencing factors of this pollution.The present study investigates th...Coastal ecosystems are plagued by high levels of microplastic pollution.Conducting baseline surveys is crucial to comprehend the distribution and influencing factors of this pollution.The present study investigates the spatiotemporal variation and diversity of microplastic on the coastal beaches in Xiamen City,China,considering the combined effects of seasons,human activities,and physicochemical properties of sediments.It is detected that the abundance of microplastics in Xiamen beaches was 0.271±0.01 items/g.The abundance of microplastics in dry season was significantly higher than in rainy season.In terms of spatial variation,the beaches that attracted a larger number of tourists exhibited significantly higher microplastic abundance.The temporal pattern of microplastic distribution on different beaches varied greatly due to region-specific human activities(e.g.,mangrove restoration project)and sedimentary properties(e.g.,bulk density).When the assemblage of microplastics in the coastal area was viewed as a biological community,the Shannon-Wiener index and Pielou's index were higher in rainy season and in the beaches with high intensity of tourist activities,which suggests that the human activities and the surface runoff may contribute to the diversity of microplastics on coastal beaches.Future investigations are encouraged to combine controlled experiments and long-term monitoring at multiple scales to elucidate the underlying mechanisms and factors associated with microplastic pollution in coastal zone.展开更多
The assessment of beach quality is an important prerequisite for beach development and serves as the foundation for coastal zone management and sustainable development.This topic has attracted widespread attention,and...The assessment of beach quality is an important prerequisite for beach development and serves as the foundation for coastal zone management and sustainable development.This topic has attracted widespread attention,and various evaluation systems have been established.Given that beach quality assessment(BQA)involves multidimensional and nonlinear indicators,machine learning methods are well-suited to handling complex data relationships.However,current research utilizing machine learning for BQA often faces challenges such as limited evaluation indicators and difficulties in obtaining relevant data.in this study,a machine learning-based model for beach quality evaluation is proposed to address the limitations of existing evaluation frameworks,particular-ly under conditions of data scarcity.Simulated data were generated,and the analytic hierarchy process was integrated to extract fea-tures from 21 beach evaluation factors.A comparative analysis was conducted using the following four machine learning models:de-cision tree,random forest,XGBoost,and MLP.Results indicate that XGBoost(mean squared error(MSE)=0.1825,weighted F1=0.7513)and MLP(Pearson coefficient=0.6053)outperform traditional models.Furthermore,an ensemble learning model combining XGBoost and MLP was developed,substantially improving predictive performance(reducing MSE to 0.0753,increasing the Pearson coefficient to 0.8002,and achieving an F1 score of 0.783).Validation using real data from Yangkou Beach demonstrated that the model maintained an accuracy of 58%even when 5–10 evaluation factors had randomly missing values.展开更多
The investigation of whether sediment samples contain representative grain size distribution information is important for the accurate extraction of sediment characteristics and conduct of related sedimentary record s...The investigation of whether sediment samples contain representative grain size distribution information is important for the accurate extraction of sediment characteristics and conduct of related sedimentary record studies.This study comparatively analyzed the numerical and qualitative differences and the degree of correlation of 36 sets of the characteristic parameters of surface sediment parallel sample grain size distribution from three sampling profiles at Jinsha Bay Beach in Zhanjiang,western Guangdong.At each sampling point,five parallel subsamples were established at intervals of 0,10,20,50,and 100 cm along the coastline.The research findings indicate the following:1)relatively large differences in the mean values of the different parallel samples(0.19–0.34Φ),with smaller differences observed in other characteristic grain sizes(D_(10),D_(50),and D_(90));2)small differences in characteristic values among various parallel sample grain size parameters,with at least 33%of the combinations of qualitative results showing inconsistency;3)50%of the regression equations between the skewness of different parallel samples displaying no significant correlation;4)relative deviations of−47.91%to 27.63%and−49.20%to 2.08%existing between the particle size parameters of a single sample and parallel samples(with the average obtained)at intervals of 10 and 50 cm,respectively.As such,small spatial differences,even within 100 cm,can considerably affect grain size parameters.Given the uncertain reasons underlying the representativeness of the samples,which may only cover the area immediately surrounding the sampling station,researchers are advised to design parallel sample collection strategies based on the spatiotemporal distribution characteristics of the parameters of interest during sediment sample collection.This study provides a typical case of the comparative analysis of parallel sample grain size parameters,with a focus on small spatial beach sediment,which contributes to the enhanced understanding of the accuracy and reliability of sediment sample collection strategies and extraction of grain size information.展开更多
Predicting the beach response to an extreme storm is important in planning and management of beach environment and helps in hazard control. Coastal dunes and sand beaches provide protection against sea waves and risin...Predicting the beach response to an extreme storm is important in planning and management of beach environment and helps in hazard control. Coastal dunes and sand beaches provide protection against sea waves and rising water levels to many coastal communities especially during a storm event. Barrier islands along the West of Florida constantly face wave action and when a severe storm is added to the forcing, the islands face severe erosion. In this study, the numerical model CSHORE was applied to predict the short-term cross-shore profile evolution on Sand Key Beach located on the barrier islands west of Florida. The initial beach profile used in the study was measured after a beach nourishment project on the barrier islands. In a few years, the coast experienced severe storms including Hurricane Ian. Beach profiles were measured post the hurricane period and therefore this study investigated how the cross-shore beach profile was affected due to sediment transportation dynamics caused by the climate. Coastal Hazard Systems storm data sets were used as forcings on the beaches to assess the response of the beaches to the conditions. The results were compared to the field measurements taken across transects on the beach cross sections.展开更多
Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in dif...Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in different regions and the related formation mechanism were also analyzed.The results show that Dongting Lake beach expanded from 1622.17 km^(2)in 1938 to 1962.28 km^(2)in 2018.With the addition of 980.96 km^(2)of reclaimed high bay beach,the beach area increased by 1321.07km^(2).However,the change process fluctuated somewhat rather than continuously increased.Substantial expansion of the beach area occurred during 1938-1948 and 1958-1998,while slow contraction of the beach area occurred during 1948-1958 and 1998-2018.Dongting Lake beach was dominated by terrigenous debris,the sedimentary types included lacustrine deposits,river alluvial deposits,floodplain and main channel deposits,and river-lake interaction deposits.The rapid expansion occurred in the estuary delta of the east branch of the Ouchi River,which advanced 38.55 km from the estuary toward the lake over the past 90 years.The causes of the changes in the beach included beach reclamation,sediment changes,and lake sand mining.Seventy embankments(covering 2057.77 km^(2))have been enclosed in the Dongting Lake area since 1930s,of which the high bay beach covered an area of 980.96km^(2).The amount of sediment deposited in Dongting Lake has reached 230857×10^(4) m^(3) since 1950s,which is equivalent to an average deposition height of 0.85 m on the lake's bottom.The mining of lake sand caused the beach to shrink,and the proportion of the beach area decreased from 77.18%in 1998 to 72.60%in 2018.The results of this study provide objective data for protecting the lakeshore's ecosystem and biodiversity and supporting the ecological restoration and environmental protection of the Yangtze River Basin.展开更多
Conch Island is a typical artificial island at the Tanghe Estuary in Bohai Sea,China.To improve natural environment and boost local tourism,beach nourishment will be applied to its north-western shore.The projected be...Conch Island is a typical artificial island at the Tanghe Estuary in Bohai Sea,China.To improve natural environment and boost local tourism,beach nourishment will be applied to its north-western shore.The projected beach is landward and opposite to the Jinmeng Bay Beach.Nowadays,with climate changes,frequent heavy rainfalls in Hebei Province rise flood hazards at the Tanghe Estuary.Under this circumstance,potential influences on the projected beach of a flood are investigated for sustainable managements.A multi-coupled model is established and based on the data from field observations,where wave model,flow model and multifraction sediment transport model are included.In addition,the impacts on the projected beach of different components in extreme events are discussed,including the spring tides,storm winds,storm waves,and sediment inputs.The numerical results indicate the following result.(1)Artificial islands protect the coasts from erosion by obstructing landward waves,but rise the deposition risks along the target shore.(2)Flood brings massive sediment inputs and leads to scours at the estuary,but the currents with high sediment concentration contribute to the accretions along the target shore.(3)The projected beach mitigates flood actions and reduces the maximum mean sediment concentration along the target shore by 20%.(4)The storm winds restrict the flood and decrease the maximum mean sediment concentration by 21%.With the combined actions of storm winds and waves,the maximum value further declines by 38%.(5)A quadratic polynomial relationship between the deposition depths and the maximum sediment inputs with flood is established for estimations on the potential morphological changes after the flood process in extreme events.For the uncertainty of estuarine floods,continuous monitoring on local hydrodynamic variations and sediment characteristics at Tanghe Estuary is necessary.展开更多
Major differences in beach erosion between two neighboring artificial beaches Xiangluwan Beach(XL beach)and Meiliwan Beach(ML beach)in Zhuhai,China,were studied after Super Typhoon Hato.In this study,a fully nonlinear...Major differences in beach erosion between two neighboring artificial beaches Xiangluwan Beach(XL beach)and Meiliwan Beach(ML beach)in Zhuhai,China,were studied after Super Typhoon Hato.In this study,a fully nonlinear Boussinesq wave model(FUNWAVE)-Total Variation Diminishing(TVD)was used to distinguish the main impact factors,their relative contributions,and the hydrodynamic mechanisms underlying the different beach responses.Results show that compared to the ML beach,the main reason for the relatively weak erosion on Xiangluwan(XL)beach was the smaller beach berm height(accounting for approximately 75.9%of the erosion response).Regarding the beach with a higher berm,the stronger wave-induced undertow flow,along with the higher sediment concentration,led to a higher offshore sediment transport flux,resulting in more severe erosion relative to the beach with a smaller berm height.The second most important reason explaining the weak erosion on XL beach was the absence of seawalls(accounting for approximately 17.9%of the erosion response).Wave reflection induced by the seawall could cause higher suspended sediment concentration,resulting in a toe scouring near the seawall.The offshore submerged breakwater protected XL beach slightly(accounting for approximately 6.1%of the erosion response).Due to the higher water level induced by storm surge,most of the wave energy could penetrate through the submerged breakwater.The effect of the larger berm width of XL beach was negligible.Compared to the beach with a larger berm width,the erosion/deposition regions in the beach with a narrower berm width showed shoreward migration,without significant changes in the erosion/deposition extent.Despite of this,the larger berm width could reduce the wave energy reaching the shoreline.This study of the storm stability of artificial beaches may be applied to beach restoration design.展开更多
The Ba Lang sand beaches, located north of the Nha Trang Bay in Central Vietnam, are famous tourist attractions. However, they are experiencing shoreline and coastal erosion retreat, which is attributed to natural cau...The Ba Lang sand beaches, located north of the Nha Trang Bay in Central Vietnam, are famous tourist attractions. However, they are experiencing shoreline and coastal erosion retreat, which is attributed to natural causes (such as tropical depressions, storms, and monsoons) as well as human impacts (such as hydropower generation, sand dredging, and coastal works). According to the forecast of the Vietnam Ministry of Natural Resources and Environment, global climate change will cause the sea level to rise by 74 cm along the coast from the Dai Lanh Cape to the Ke Ga Cape (including the Ba Lang beaches) by the end of this century in the representative concentration pathway (RCP) 8.5 scenario. Sea level rise (SLR) due to global climate change is expected to aggravate the coastal erosion and shoreline retreat problems. In this study, coupled numerical models with the spectral wave module (MIKE 21 SW), hydrodynamic module (MIKE 21 HD), and sand transport module (MIKE 21 ST) in the MIKE 21 package were used to simulate waves, current fields, and sediment dynamics along the Ba Lang beaches considering the impact of SLR. These models were calibrated with the field data measured in December 2016. The results showed that SLR caused the wave height to increase and reduced the current speed and total sediment load in monsoon conditions. The increase in wave height was even intensified under the joint impact of SLR and extreme events.展开更多
Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, howeve...Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, however, low-frequency GPR survey to investigate fault-related depositional systems at greater depths. The Quinta-Cassino area in the Rio Grande do Sul Coastal Plain (RGSCP, Brazil) shows a wide strandplain that is made off by very long, continuous, and linear geomorphic features (beach ridges). This strandplain extends for ~70 km southward. The beach ridges show low-angle truncations against the Quinta escarpment, and also truncations in the strandplain. The traditional approach points that RGSCP was developed by juxtaposition of four lagoons/barrier systems as consequence of sea level changes;previous model assumes that no deformational episode occurred in RGSCP. The geophysical and geological surveys carried out in this area showed the existence of listric fault controlling the beach ridges in the escarpments and hanging-wall blocks. The radargrams could distinguish Pleistocene basement unit anticlockwise rotation, thickening of beach ridges radarfacies close to listric normal faults, and horst structures. These deformational features indicate that the extensional zone of a large-scale gravity-driven structure controlled the mechanical subsidence, the Holocene sedimentation and its stratigraphic and geomorphic features in the Quinta-Cassino area to build up an asymmetric delta. The results point to a new approach in dealing with RGSCP Holocene evolution.展开更多
The problem of human overload in many habitats is becoming increasingly urgent, as it is the driving force that destroys ecosystems beyond repair. This paper describes a possible workflow for beach surveillance, using...The problem of human overload in many habitats is becoming increasingly urgent, as it is the driving force that destroys ecosystems beyond repair. This paper describes a possible workflow for beach surveillance, using a deep learning solution available online that runs on a standard laptop with RGB images acquired with a standard camera. The software is YOLO v7, a state-of-the-art real-time object detection model presently used for autonomous driving, surveillance, and robotics. The workflow and parametrization needed for building a model are described, along with examples of the results over 180 test images that ensures an overall precision of 0.98 and recall of 0.94 (F1 = 0.96). The model was parametrized to focus on a minimum number of false positives;from the 5672 possible detections identified by human curation, 5285 were correctly identified and located, 387 missed and there are 116 mistakes. A minimum of computational skills is needed to reproduce this implementation in any user data of the same kind.展开更多
This study aimed to determine variations in water quality index(WQI)and physicochemical properties of surface water and bottom sediments of selected coastal beaches of Niger Delta,Southern Nigeria.The water quality of...This study aimed to determine variations in water quality index(WQI)and physicochemical properties of surface water and bottom sediments of selected coastal beaches of Niger Delta,Southern Nigeria.The water quality of the river is categorized into five classes,which are classes I,II,III,IV and V based on the WQI(derived from the determination of DO,BOD,COD,TSS and ammonia and pH).Water and bottom sediment samples were analysed using standard procedures.During the wet season,physicochemical parameters such as potential hydrogen(pH),electrical conductivity(EC),dissolved oxygen(DO),total dissolved solids(TDS)and salinity showed significant difference(p<0.05)across all the locations.During the dry season,parameters like EC,EA,pH,sodium(Na),sulphate(SO4),chloride(Cl-),potassium(K),effective cation exchange capacity(ECEC)and calcium(Ca)showed significant difference(p<0.05)across all the six sampled beaches while phosphate(PO4)did not show any clear significant difference across all the sampled locations.The general trend in the levels of physicochemical parameters revealed that temperature and pH were within those recommended by World Health Organization(WHO)and United States Environmental Protection Agency(USEPA)for both wet and dry season but EC and TDS were above the WHO and USEPA limit.Twenty one(21)water quality parameters from six sampling locations were studied and by applying WQI,the state of the six beach water was very unsuitable for drinking,swimming and recreational activities as at the time of this study.The water is only suitable for irrigation purpose.展开更多
The coast of the Dapeng Peninsula has been honored as one of “the eight most beautiful coasts in China”. The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong...The coast of the Dapeng Peninsula has been honored as one of “the eight most beautiful coasts in China”. The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong on the southern coast of the peninsula is the longest and the most important one. The information of the stability, sedimentary source and shape change of the beach is very important for maintaining the beach in terms of sustainable development of the peninsula. Heavy minerals in the sand of the beach and the inland stream at Xichong are compared with those of a nearby beach on the same coast to determine the beach sand source; with help of a computer software, MEPBAY, the equilibrium planforms of the beaches on the peninsula are compared with those of an island without rivers to evaluate the stream＇s effects on the beach stability; cross shore profiles along the Xichong beach are also surveyed in different seasons of a year to assess the annual shore normal beach changes affected by the stream input, and the relation between the equilibrium planform state and cross shore changes of the beach. It is shown that （1） stream is the main sedimentary source of the beach and the weathering materials of the rocky headlands on both sides of the bay transported by waves are the second source for the beach but it is limited, sand from an inner shelf is not the sedimentary source for the beach at present and was not even during the Holocene transgression; （2） the Xichong beach cannot reach static equilibrium around the entire bay shoreline, the segment of the shore-line where a stream outlet is located is in dynamic equilibrium, and the unstable section occurs in the wave shadow region in the lee of an offshore island; （3） no matter whether the section of the beach shoreline at Xichong is in an equilibrium state or not, it is eroded in the typhoon season and recovered after the season, the maximum change in erosion and accretion occurs in the unstable segment; （4） the Xichong beach can only have small sand body since it is supplied with sand mainly form inland streams, resulting in a possible danger in which sand loss induced by human activities or huge storms cannot be replenished naturally.展开更多
Through investigating ten recreational marine beaches in China, we aimed to detect the occurrence of human enteric viruses in coastal bathing beaches and find a correlationship, if any, between the presence of enteric...Through investigating ten recreational marine beaches in China, we aimed to detect the occurrence of human enteric viruses in coastal bathing beaches and find a correlationship, if any, between the presence of enteric viruses in surface seawater and the concentrations of fecal coliforms, the conventional indicator of fecal pollution. In this study, twenty seawater samples were assayed for fecal coliforms and human pathogenic enteric viruses （hepatitis A viruses, rotaviruses, polioviruses） analysis. Enteric viruses were detected by RT-PCR, in 20 sample sites, 5%, 40%, 40% were positive for the presence of human hepatitis A viruses, rotaviruses, polioviruses, respectively. Seven of 20 sites are suffering from severe fecal contamination, based on traditional plate counts of fecal coliform outnumbering the established thresholds for recreation. Additionally, statistical analysis presented that no correlation was found between bacterial indicators and viruses in surface seawaters. The data confirmed that indicator bacteria in water are not reflective of the presence of enteric viruses in marine waters. Thus, current recreational water quality standards of both bacterial and viral indices should be reevaluated.展开更多
By use of a shorehne-change numerical model （GENESIS） based on one-line theory, a preliminary modeling study on shoreline changes caused by a beach nourishment project in Beidaihe, China, is presented in this paper....By use of a shorehne-change numerical model （GENESIS） based on one-line theory, a preliminary modeling study on shoreline changes caused by a beach nourishment project in Beidaihe, China, is presented in this paper. Firstly, the GENESIS model is verified and model sensitivity to the major parameter changes is discussed by simulating a hydraulic model test. The beach nourishment project, after that the shoreline change is kept being monitored, is a small-scale emergency one carried out to use two bathing places on the west beach in the summer, 2008. In this paper the shoreline changes caused by the beach nourishment project are modeled by the GENESIS model, and the computed results fit well with the measured shorelines. With the same model and parameters, a long-term performance of the project is predicted, and the result shows that the bathing places only can be suitable for bathing in 2 to 3 years without subsequence nourishment project. Therefore, it is proposed to nourish the beaches in time to keep the service life of the beach in recent years and carry out the beach nourishment project for the whole west beach as soon as possible.展开更多
This paper, after briefly reviewing the experimental research on sediment transport on muddy beach since the 1950s, improves and perfects the method for forecasting siltation in navigation channels and harbour basins ...This paper, after briefly reviewing the experimental research on sediment transport on muddy beach since the 1950s, improves and perfects the method for forecasting siltation in navigation channels and harbour basins which was first put forward in China by the authors. In consideration of silty sediment and sand, some factors in forecasting methods have been changed and modified. Consequently, the modified methods can be used either to compute siltation in navigation channels and harbour basins on muddy beach or to compute siltation and scouring in navigation channels and harbour basins on both silty beach and sandy beach. The verification of field data from eleven large, medium and small natural harbours shows a good agreement between the forecasting by the modified method and the natural conditions. Finally, the paper deals with the rational utilization of water area after the construction of the West Dyke in Lianyungang, the maintenance of water depth of the navigation channel at the entrance, siltation distribution, siltation in the navigation channel and harbour basin for ships of 100 thousand tonnnage. Results once again prove that the prospect of constructing Lianyungang Harbour into a deepwater harbour is bright.展开更多
On average,five to six storms occur in the Qiongzhou Strait every year,causing significant damage to coastal geomorphology and several property losses.Tropical Storm Bebinca is the most unusual and complex storm event...On average,five to six storms occur in the Qiongzhou Strait every year,causing significant damage to coastal geomorphology and several property losses.Tropical Storm Bebinca is the most unusual and complex storm event that has occurred in this region over the last 10 years.To detect the high-frequency beachface responses to the storm,a pressure sensor was deployed in the surf zone to record the free sea surface height,and the heights of grid pile points on the beachface were measured manually to determine beach elevation changes during this storm.Empirical Mode Decomposition and related analysis techniques were used to analyze the high-frequency topography and wave data.The results showed that:(1)the beachface response process occurred in three stages.The first stage was the rapid response stage,wherein the spring tide berm began to erode significantly,and the front edge of the beach berm reacted closely.The two beach sections resisted the harmful energy of the main storm.In the second stage,the beach slope increased after a large sediment loss on the beach berm and its front edge.To adapt to the storm energy,the beach at the low tide line began to erode,and the beach slope decreased.In the third stage,after the storm turned,the wave energy was significantly attenuated,and the beach berm eroded to resist the residual wave energy.The beachface began to oscillate and recover.(2)The main wave surface was the superimposed product of a few internal mode functions.Similar results were observed in beachface changes.High-frequency driving factors determine the local characteristics of beach evolution,and low-frequency driving factors determine the beach evolution trend.(3)The response of sediment to the storm was not a single sea-transportation,but a single-or two-way conversion driven by factors such as wave energy,swash flow,and secondary wave breaking.(4)TheΩ-RTR model is not completely applicable to beach states that undergo rapid changes during storms.Therefore,it is necessary to carry out further research on beach state identification during storms.展开更多
文摘The paper is focused on the design of artificial sand beaches at sheltered and exposed sites.The methodology applied includes the study of the most essential design parameters and the application of numerical models to compute the beach erosion and maintenance.The computed erosion volume decreases for coarser sand(0.5 mm sand instead of 0.3 mm).Beach erosion increases for more graded sand,but the effect is small(10%–15%).The slope of the artificial beach at sheltered sites is commonly between 1 to 15 and 1 to 30 in conditions with a micro tidal range and mild waves.Slopes between 1 to 30 and 1 to 50 are used for more open exposed sites.The effect of the upper and lower beach slope(1 to 15 or 1 to 20)on beach erosion is marginal for sand in the range of 0.3 to 0.5 mm.A break in slope is quickly adjusted by transport processes.The volume of beach sand required may be reduced by constructing a submerged sill at the toe of the beach.Analysis of costs shows that the construction costs including maintenance over a period of 50 years of a submerged sill are about the same as that of beach fill including maintenance.Hence,the beach fill volume can be twice as large for a solution without a sill.Beach erosion due to alongshore transport processes is minimum if the beach line of the planform is perpendicular to the main wave direction(equilibrium beach).
基金Supported by the Natural Science Foundation of Fujian Province(No.2022J05278)the Marine and Fishery Development Special Fund of Xiamen(No.23YYST064QCB36)。
文摘Coastal ecosystems are plagued by high levels of microplastic pollution.Conducting baseline surveys is crucial to comprehend the distribution and influencing factors of this pollution.The present study investigates the spatiotemporal variation and diversity of microplastic on the coastal beaches in Xiamen City,China,considering the combined effects of seasons,human activities,and physicochemical properties of sediments.It is detected that the abundance of microplastics in Xiamen beaches was 0.271±0.01 items/g.The abundance of microplastics in dry season was significantly higher than in rainy season.In terms of spatial variation,the beaches that attracted a larger number of tourists exhibited significantly higher microplastic abundance.The temporal pattern of microplastic distribution on different beaches varied greatly due to region-specific human activities(e.g.,mangrove restoration project)and sedimentary properties(e.g.,bulk density).When the assemblage of microplastics in the coastal area was viewed as a biological community,the Shannon-Wiener index and Pielou's index were higher in rainy season and in the beaches with high intensity of tourist activities,which suggests that the human activities and the surface runoff may contribute to the diversity of microplastics on coastal beaches.Future investigations are encouraged to combine controlled experiments and long-term monitoring at multiple scales to elucidate the underlying mechanisms and factors associated with microplastic pollution in coastal zone.
基金supported by the National Natural Science Foundation of China(Nos.82202299,62203060,62403492).
文摘The assessment of beach quality is an important prerequisite for beach development and serves as the foundation for coastal zone management and sustainable development.This topic has attracted widespread attention,and various evaluation systems have been established.Given that beach quality assessment(BQA)involves multidimensional and nonlinear indicators,machine learning methods are well-suited to handling complex data relationships.However,current research utilizing machine learning for BQA often faces challenges such as limited evaluation indicators and difficulties in obtaining relevant data.in this study,a machine learning-based model for beach quality evaluation is proposed to address the limitations of existing evaluation frameworks,particular-ly under conditions of data scarcity.Simulated data were generated,and the analytic hierarchy process was integrated to extract fea-tures from 21 beach evaluation factors.A comparative analysis was conducted using the following four machine learning models:de-cision tree,random forest,XGBoost,and MLP.Results indicate that XGBoost(mean squared error(MSE)=0.1825,weighted F1=0.7513)and MLP(Pearson coefficient=0.6053)outperform traditional models.Furthermore,an ensemble learning model combining XGBoost and MLP was developed,substantially improving predictive performance(reducing MSE to 0.0753,increasing the Pearson coefficient to 0.8002,and achieving an F1 score of 0.783).Validation using real data from Yangkou Beach demonstrated that the model maintained an accuracy of 58%even when 5–10 evaluation factors had randomly missing values.
基金supported by the Innovation Driven Development Foundation of Guangxi(No.AD22080035)the Open Project Funding of the Key Laboratory of Tropical Marine Ecosystem and Bioresource,Ministry of Natural Resources(No.2023-QN04)+1 种基金the Guangdong Provincial Ordinary University Youth Innovative Talent Project in 2024(No.2024KQNCX134)the Guangdong Provincial Special Fund Project for Talent Development Strategy in 2024(No.2024R3005).
文摘The investigation of whether sediment samples contain representative grain size distribution information is important for the accurate extraction of sediment characteristics and conduct of related sedimentary record studies.This study comparatively analyzed the numerical and qualitative differences and the degree of correlation of 36 sets of the characteristic parameters of surface sediment parallel sample grain size distribution from three sampling profiles at Jinsha Bay Beach in Zhanjiang,western Guangdong.At each sampling point,five parallel subsamples were established at intervals of 0,10,20,50,and 100 cm along the coastline.The research findings indicate the following:1)relatively large differences in the mean values of the different parallel samples(0.19–0.34Φ),with smaller differences observed in other characteristic grain sizes(D_(10),D_(50),and D_(90));2)small differences in characteristic values among various parallel sample grain size parameters,with at least 33%of the combinations of qualitative results showing inconsistency;3)50%of the regression equations between the skewness of different parallel samples displaying no significant correlation;4)relative deviations of−47.91%to 27.63%and−49.20%to 2.08%existing between the particle size parameters of a single sample and parallel samples(with the average obtained)at intervals of 10 and 50 cm,respectively.As such,small spatial differences,even within 100 cm,can considerably affect grain size parameters.Given the uncertain reasons underlying the representativeness of the samples,which may only cover the area immediately surrounding the sampling station,researchers are advised to design parallel sample collection strategies based on the spatiotemporal distribution characteristics of the parameters of interest during sediment sample collection.This study provides a typical case of the comparative analysis of parallel sample grain size parameters,with a focus on small spatial beach sediment,which contributes to the enhanced understanding of the accuracy and reliability of sediment sample collection strategies and extraction of grain size information.
文摘Predicting the beach response to an extreme storm is important in planning and management of beach environment and helps in hazard control. Coastal dunes and sand beaches provide protection against sea waves and rising water levels to many coastal communities especially during a storm event. Barrier islands along the West of Florida constantly face wave action and when a severe storm is added to the forcing, the islands face severe erosion. In this study, the numerical model CSHORE was applied to predict the short-term cross-shore profile evolution on Sand Key Beach located on the barrier islands west of Florida. The initial beach profile used in the study was measured after a beach nourishment project on the barrier islands. In a few years, the coast experienced severe storms including Hurricane Ian. Beach profiles were measured post the hurricane period and therefore this study investigated how the cross-shore beach profile was affected due to sediment transportation dynamics caused by the climate. Coastal Hazard Systems storm data sets were used as forcings on the beaches to assess the response of the beaches to the conditions. The results were compared to the field measurements taken across transects on the beach cross sections.
基金supported by the Hunan Provincial Natural Science Foundation Project(No.2024JJ8320)the Hunan Province Natural Resources Science and Technology Plan Project(No.20230151ST)+1 种基金the Hunan Province Science Popularization Special Plan(Science and Technology Talent Support Project)(No.2023TJ-N16)the Open Fund of Hunan Provincial Key Laboratory for Remote Sensing Monitoring of Ecological Environment in Dongting Lake Area(No.DTH Key Lab.2021-28)。
文摘Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in different regions and the related formation mechanism were also analyzed.The results show that Dongting Lake beach expanded from 1622.17 km^(2)in 1938 to 1962.28 km^(2)in 2018.With the addition of 980.96 km^(2)of reclaimed high bay beach,the beach area increased by 1321.07km^(2).However,the change process fluctuated somewhat rather than continuously increased.Substantial expansion of the beach area occurred during 1938-1948 and 1958-1998,while slow contraction of the beach area occurred during 1948-1958 and 1998-2018.Dongting Lake beach was dominated by terrigenous debris,the sedimentary types included lacustrine deposits,river alluvial deposits,floodplain and main channel deposits,and river-lake interaction deposits.The rapid expansion occurred in the estuary delta of the east branch of the Ouchi River,which advanced 38.55 km from the estuary toward the lake over the past 90 years.The causes of the changes in the beach included beach reclamation,sediment changes,and lake sand mining.Seventy embankments(covering 2057.77 km^(2))have been enclosed in the Dongting Lake area since 1930s,of which the high bay beach covered an area of 980.96km^(2).The amount of sediment deposited in Dongting Lake has reached 230857×10^(4) m^(3) since 1950s,which is equivalent to an average deposition height of 0.85 m on the lake's bottom.The mining of lake sand caused the beach to shrink,and the proportion of the beach area decreased from 77.18%in 1998 to 72.60%in 2018.The results of this study provide objective data for protecting the lakeshore's ecosystem and biodiversity and supporting the ecological restoration and environmental protection of the Yangtze River Basin.
基金The National Key Research and Development Program of China under contract No.2022YFC3106205the National Natural Science Foundation of China under contract Nos 41976159 and 41776098.
文摘Conch Island is a typical artificial island at the Tanghe Estuary in Bohai Sea,China.To improve natural environment and boost local tourism,beach nourishment will be applied to its north-western shore.The projected beach is landward and opposite to the Jinmeng Bay Beach.Nowadays,with climate changes,frequent heavy rainfalls in Hebei Province rise flood hazards at the Tanghe Estuary.Under this circumstance,potential influences on the projected beach of a flood are investigated for sustainable managements.A multi-coupled model is established and based on the data from field observations,where wave model,flow model and multifraction sediment transport model are included.In addition,the impacts on the projected beach of different components in extreme events are discussed,including the spring tides,storm winds,storm waves,and sediment inputs.The numerical results indicate the following result.(1)Artificial islands protect the coasts from erosion by obstructing landward waves,but rise the deposition risks along the target shore.(2)Flood brings massive sediment inputs and leads to scours at the estuary,but the currents with high sediment concentration contribute to the accretions along the target shore.(3)The projected beach mitigates flood actions and reduces the maximum mean sediment concentration along the target shore by 20%.(4)The storm winds restrict the flood and decrease the maximum mean sediment concentration by 21%.With the combined actions of storm winds and waves,the maximum value further declines by 38%.(5)A quadratic polynomial relationship between the deposition depths and the maximum sediment inputs with flood is established for estimations on the potential morphological changes after the flood process in extreme events.For the uncertainty of estuarine floods,continuous monitoring on local hydrodynamic variations and sediment characteristics at Tanghe Estuary is necessary.
基金Supported by the National Natural Science Foundation of China(Nos.42006176,42330406,U1706220,41901006)the Basic Research Project of the Science and Technology Innovation Development Program of in Yantai(No.2022JCYJ028)。
文摘Major differences in beach erosion between two neighboring artificial beaches Xiangluwan Beach(XL beach)and Meiliwan Beach(ML beach)in Zhuhai,China,were studied after Super Typhoon Hato.In this study,a fully nonlinear Boussinesq wave model(FUNWAVE)-Total Variation Diminishing(TVD)was used to distinguish the main impact factors,their relative contributions,and the hydrodynamic mechanisms underlying the different beach responses.Results show that compared to the ML beach,the main reason for the relatively weak erosion on Xiangluwan(XL)beach was the smaller beach berm height(accounting for approximately 75.9%of the erosion response).Regarding the beach with a higher berm,the stronger wave-induced undertow flow,along with the higher sediment concentration,led to a higher offshore sediment transport flux,resulting in more severe erosion relative to the beach with a smaller berm height.The second most important reason explaining the weak erosion on XL beach was the absence of seawalls(accounting for approximately 17.9%of the erosion response).Wave reflection induced by the seawall could cause higher suspended sediment concentration,resulting in a toe scouring near the seawall.The offshore submerged breakwater protected XL beach slightly(accounting for approximately 6.1%of the erosion response).Due to the higher water level induced by storm surge,most of the wave energy could penetrate through the submerged breakwater.The effect of the larger berm width of XL beach was negligible.Compared to the beach with a larger berm width,the erosion/deposition regions in the beach with a narrower berm width showed shoreward migration,without significant changes in the erosion/deposition extent.Despite of this,the larger berm width could reduce the wave energy reaching the shoreline.This study of the storm stability of artificial beaches may be applied to beach restoration design.
文摘The Ba Lang sand beaches, located north of the Nha Trang Bay in Central Vietnam, are famous tourist attractions. However, they are experiencing shoreline and coastal erosion retreat, which is attributed to natural causes (such as tropical depressions, storms, and monsoons) as well as human impacts (such as hydropower generation, sand dredging, and coastal works). According to the forecast of the Vietnam Ministry of Natural Resources and Environment, global climate change will cause the sea level to rise by 74 cm along the coast from the Dai Lanh Cape to the Ke Ga Cape (including the Ba Lang beaches) by the end of this century in the representative concentration pathway (RCP) 8.5 scenario. Sea level rise (SLR) due to global climate change is expected to aggravate the coastal erosion and shoreline retreat problems. In this study, coupled numerical models with the spectral wave module (MIKE 21 SW), hydrodynamic module (MIKE 21 HD), and sand transport module (MIKE 21 ST) in the MIKE 21 package were used to simulate waves, current fields, and sediment dynamics along the Ba Lang beaches considering the impact of SLR. These models were calibrated with the field data measured in December 2016. The results showed that SLR caused the wave height to increase and reduced the current speed and total sediment load in monsoon conditions. The increase in wave height was even intensified under the joint impact of SLR and extreme events.
文摘Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, however, low-frequency GPR survey to investigate fault-related depositional systems at greater depths. The Quinta-Cassino area in the Rio Grande do Sul Coastal Plain (RGSCP, Brazil) shows a wide strandplain that is made off by very long, continuous, and linear geomorphic features (beach ridges). This strandplain extends for ~70 km southward. The beach ridges show low-angle truncations against the Quinta escarpment, and also truncations in the strandplain. The traditional approach points that RGSCP was developed by juxtaposition of four lagoons/barrier systems as consequence of sea level changes;previous model assumes that no deformational episode occurred in RGSCP. The geophysical and geological surveys carried out in this area showed the existence of listric fault controlling the beach ridges in the escarpments and hanging-wall blocks. The radargrams could distinguish Pleistocene basement unit anticlockwise rotation, thickening of beach ridges radarfacies close to listric normal faults, and horst structures. These deformational features indicate that the extensional zone of a large-scale gravity-driven structure controlled the mechanical subsidence, the Holocene sedimentation and its stratigraphic and geomorphic features in the Quinta-Cassino area to build up an asymmetric delta. The results point to a new approach in dealing with RGSCP Holocene evolution.
文摘The problem of human overload in many habitats is becoming increasingly urgent, as it is the driving force that destroys ecosystems beyond repair. This paper describes a possible workflow for beach surveillance, using a deep learning solution available online that runs on a standard laptop with RGB images acquired with a standard camera. The software is YOLO v7, a state-of-the-art real-time object detection model presently used for autonomous driving, surveillance, and robotics. The workflow and parametrization needed for building a model are described, along with examples of the results over 180 test images that ensures an overall precision of 0.98 and recall of 0.94 (F1 = 0.96). The model was parametrized to focus on a minimum number of false positives;from the 5672 possible detections identified by human curation, 5285 were correctly identified and located, 387 missed and there are 116 mistakes. A minimum of computational skills is needed to reproduce this implementation in any user data of the same kind.
文摘This study aimed to determine variations in water quality index(WQI)and physicochemical properties of surface water and bottom sediments of selected coastal beaches of Niger Delta,Southern Nigeria.The water quality of the river is categorized into five classes,which are classes I,II,III,IV and V based on the WQI(derived from the determination of DO,BOD,COD,TSS and ammonia and pH).Water and bottom sediment samples were analysed using standard procedures.During the wet season,physicochemical parameters such as potential hydrogen(pH),electrical conductivity(EC),dissolved oxygen(DO),total dissolved solids(TDS)and salinity showed significant difference(p<0.05)across all the locations.During the dry season,parameters like EC,EA,pH,sodium(Na),sulphate(SO4),chloride(Cl-),potassium(K),effective cation exchange capacity(ECEC)and calcium(Ca)showed significant difference(p<0.05)across all the six sampled beaches while phosphate(PO4)did not show any clear significant difference across all the sampled locations.The general trend in the levels of physicochemical parameters revealed that temperature and pH were within those recommended by World Health Organization(WHO)and United States Environmental Protection Agency(USEPA)for both wet and dry season but EC and TDS were above the WHO and USEPA limit.Twenty one(21)water quality parameters from six sampling locations were studied and by applying WQI,the state of the six beach water was very unsuitable for drinking,swimming and recreational activities as at the time of this study.The water is only suitable for irrigation purpose.
基金Shenzhen Dapeng Peninsula National Geopark Project of China under contract No.340775the Natural Science Foundation of Guangdong Province of China unde contract No.S2012010008610the National Natural Science Foundation of China under contract No.40871020
文摘The coast of the Dapeng Peninsula has been honored as one of “the eight most beautiful coasts in China”. The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong on the southern coast of the peninsula is the longest and the most important one. The information of the stability, sedimentary source and shape change of the beach is very important for maintaining the beach in terms of sustainable development of the peninsula. Heavy minerals in the sand of the beach and the inland stream at Xichong are compared with those of a nearby beach on the same coast to determine the beach sand source; with help of a computer software, MEPBAY, the equilibrium planforms of the beaches on the peninsula are compared with those of an island without rivers to evaluate the stream＇s effects on the beach stability; cross shore profiles along the Xichong beach are also surveyed in different seasons of a year to assess the annual shore normal beach changes affected by the stream input, and the relation between the equilibrium planform state and cross shore changes of the beach. It is shown that （1） stream is the main sedimentary source of the beach and the weathering materials of the rocky headlands on both sides of the bay transported by waves are the second source for the beach but it is limited, sand from an inner shelf is not the sedimentary source for the beach at present and was not even during the Holocene transgression; （2） the Xichong beach cannot reach static equilibrium around the entire bay shoreline, the segment of the shore-line where a stream outlet is located is in dynamic equilibrium, and the unstable section occurs in the wave shadow region in the lee of an offshore island; （3） no matter whether the section of the beach shoreline at Xichong is in an equilibrium state or not, it is eroded in the typhoon season and recovered after the season, the maximum change in erosion and accretion occurs in the unstable segment; （4） the Xichong beach can only have small sand body since it is supplied with sand mainly form inland streams, resulting in a possible danger in which sand loss induced by human activities or huge storms cannot be replenished naturally.
基金provided by the National High Technology Research and Development Program("863"Program)of China,grant no.2006AA09Z162the National Key Scientific and Technological Project,grant no.908-01-ZH3
文摘Through investigating ten recreational marine beaches in China, we aimed to detect the occurrence of human enteric viruses in coastal bathing beaches and find a correlationship, if any, between the presence of enteric viruses in surface seawater and the concentrations of fecal coliforms, the conventional indicator of fecal pollution. In this study, twenty seawater samples were assayed for fecal coliforms and human pathogenic enteric viruses （hepatitis A viruses, rotaviruses, polioviruses） analysis. Enteric viruses were detected by RT-PCR, in 20 sample sites, 5%, 40%, 40% were positive for the presence of human hepatitis A viruses, rotaviruses, polioviruses, respectively. Seven of 20 sites are suffering from severe fecal contamination, based on traditional plate counts of fecal coliform outnumbering the established thresholds for recreation. Additionally, statistical analysis presented that no correlation was found between bacterial indicators and viruses in surface seawaters. The data confirmed that indicator bacteria in water are not reflective of the presence of enteric viruses in marine waters. Thus, current recreational water quality standards of both bacterial and viral indices should be reevaluated.
基金supported by two funds from the Department of Land and Resources of Hebei Province,China(Grant Nos.HEBEIGT2006ZT and HEBEIGT2008-2903)two grants from the Ministry of Science and Technology,China(Grant Nos.2008BAJ08B14 and 2007FY110300-03)
文摘By use of a shorehne-change numerical model （GENESIS） based on one-line theory, a preliminary modeling study on shoreline changes caused by a beach nourishment project in Beidaihe, China, is presented in this paper. Firstly, the GENESIS model is verified and model sensitivity to the major parameter changes is discussed by simulating a hydraulic model test. The beach nourishment project, after that the shoreline change is kept being monitored, is a small-scale emergency one carried out to use two bathing places on the west beach in the summer, 2008. In this paper the shoreline changes caused by the beach nourishment project are modeled by the GENESIS model, and the computed results fit well with the measured shorelines. With the same model and parameters, a long-term performance of the project is predicted, and the result shows that the bathing places only can be suitable for bathing in 2 to 3 years without subsequence nourishment project. Therefore, it is proposed to nourish the beaches in time to keep the service life of the beach in recent years and carry out the beach nourishment project for the whole west beach as soon as possible.
文摘This paper, after briefly reviewing the experimental research on sediment transport on muddy beach since the 1950s, improves and perfects the method for forecasting siltation in navigation channels and harbour basins which was first put forward in China by the authors. In consideration of silty sediment and sand, some factors in forecasting methods have been changed and modified. Consequently, the modified methods can be used either to compute siltation in navigation channels and harbour basins on muddy beach or to compute siltation and scouring in navigation channels and harbour basins on both silty beach and sandy beach. The verification of field data from eleven large, medium and small natural harbours shows a good agreement between the forecasting by the modified method and the natural conditions. Finally, the paper deals with the rational utilization of water area after the construction of the West Dyke in Lianyungang, the maintenance of water depth of the navigation channel at the entrance, siltation distribution, siltation in the navigation channel and harbour basin for ships of 100 thousand tonnnage. Results once again prove that the prospect of constructing Lianyungang Harbour into a deepwater harbour is bright.
基金The National Natural Science Foundation of China under contract Nos 42176167 and 41676079the Project of Enhancing School with Innovation,Guangdong Ocean University under contract No.Q18307.
文摘On average,five to six storms occur in the Qiongzhou Strait every year,causing significant damage to coastal geomorphology and several property losses.Tropical Storm Bebinca is the most unusual and complex storm event that has occurred in this region over the last 10 years.To detect the high-frequency beachface responses to the storm,a pressure sensor was deployed in the surf zone to record the free sea surface height,and the heights of grid pile points on the beachface were measured manually to determine beach elevation changes during this storm.Empirical Mode Decomposition and related analysis techniques were used to analyze the high-frequency topography and wave data.The results showed that:(1)the beachface response process occurred in three stages.The first stage was the rapid response stage,wherein the spring tide berm began to erode significantly,and the front edge of the beach berm reacted closely.The two beach sections resisted the harmful energy of the main storm.In the second stage,the beach slope increased after a large sediment loss on the beach berm and its front edge.To adapt to the storm energy,the beach at the low tide line began to erode,and the beach slope decreased.In the third stage,after the storm turned,the wave energy was significantly attenuated,and the beach berm eroded to resist the residual wave energy.The beachface began to oscillate and recover.(2)The main wave surface was the superimposed product of a few internal mode functions.Similar results were observed in beachface changes.High-frequency driving factors determine the local characteristics of beach evolution,and low-frequency driving factors determine the beach evolution trend.(3)The response of sediment to the storm was not a single sea-transportation,but a single-or two-way conversion driven by factors such as wave energy,swash flow,and secondary wave breaking.(4)TheΩ-RTR model is not completely applicable to beach states that undergo rapid changes during storms.Therefore,it is necessary to carry out further research on beach state identification during storms.
