A black sand beach littered with huge chunks of glistening(闪亮的)ice has become one of the most visited attractions in Iceland,and for good reason,it looks like something out of a fantasy movie.Known as Breiðame...A black sand beach littered with huge chunks of glistening(闪亮的)ice has become one of the most visited attractions in Iceland,and for good reason,it looks like something out of a fantasy movie.Known as Breiðamerkursandur in Icelandic,Diamond Beach takes its name from the chunks of pristine ice scattered across the black volcanic sand and glistening like giant,uncut diamonds.展开更多
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
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
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
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
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
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
This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coasta...This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coastal segments of a headland-bay beach in west Guangdong, South China, and explores the physical significances of those parameters in the models. The results indicate that：（1） Bodge＇s model is more in line with the equilibrium beach profile of the tangential or transitional segment, whereas Lee＇s model is more consistent with the shadow profile;（2） most of the parameters in three models have clear physical significances in accordance with the actual characteristics of this headland-bay beach; and（3） both the selections for the equilibrium beach profile from different segments and significances of most of the parameters in three models are in essence correlated with the morphodynamic states at various coastal locations.展开更多
River training walls have been built at scores of locations along the NSW coast and their impacts on shoreline change are still not fully understood. In this study, the Brunswick River entrance and adjacent beaches ar...River training walls have been built at scores of locations along the NSW coast and their impacts on shoreline change are still not fully understood. In this study, the Brunswick River entrance and adjacent beaches are selected for examination of the impact of the construction of major training walls. Thirteen sets of aerial photographs taken between 1947 and 1994 are used in a GIS approach to accurately determine the shoreline position, beach contours and sand volumes, and their changes in both time and space, and then to assess the contribution of both the structures and natural hydrodynamic conditions to large scale (years-decades and kilometres) beach changes. The impact of the training walls can be divided into four stages: natural conditions prior to their construction (pre 1959), major downdrift erosion and updrift accretion during and following the construction of the walls in 1959～1962 and 1966, diminishing impact of the walls between 1966 and 1987, and finally no apparent impact between 1987～1994. The impact extends horizontally about 8 km updrift and 17 km downdrift, and temporally up to 25 years.展开更多
Beach erosion has occurred globally in recent decades due to frequent and severe storms.Dongsha beach,located in Zhujiajian Island,Zhejiang Province,China,is a typical embayed sandy beach.This study focused on the mor...Beach erosion has occurred globally in recent decades due to frequent and severe storms.Dongsha beach,located in Zhujiajian Island,Zhejiang Province,China,is a typical embayed sandy beach.This study focused on the morphodynamic response of Dongsha beach to typhoon events,based on beach topographies and surficial sediment characteristics acquired before and after four typhoon events with varying intensities.The four typhoons had different effects on the topography and sediment characteristics of Dongsha beach.Typhoons Ampil and Danas caused the largest(-51.72 m3/m)and the smallest erosion(-8.01 m3/m),respectively.Remarkable alongshore patterns of beach profile volumetric changes were found after the four typhoon events,with more erosion in the southern and central parts of the beach and few changes in the northern part.Grain size coarsening and poor sorting were the main sediment patterns on the beach influenced by different typhoons.Typhoons that occurred in the same year after another typhoon enhanced the effect of the previous typhoon on sediment coarsening and sorting variability,but this cumulative effect was not found between typhoons that occurred during different years.A comparison of the collected data revealed that the topographic state of the beach before the typhoon,typhoon characteristics,and tidal conditions were possible reasons for the difference in the responses of Dongsha beach to typhoon events.More severe beach erosion was caused by typhoons with higher intensity levels and longer durations,and high tide levels during typhoons can determine the upper limit of the beach profile erosion site.Taken together,these results can be used to improve beach management for storm prevention.展开更多
The beach of the Shengli oilfield, as the prospect for steady continuous development of the Shengli oilfield, has a large area, special geographic and geological conditions, and other technical difficulties so that ex...The beach of the Shengli oilfield, as the prospect for steady continuous development of the Shengli oilfield, has a large area, special geographic and geological conditions, and other technical difficulties so that exploration has been slow. Seismic acquisition methods in the beach area and very shallow water have been investigated and, with the introduction of new equipment, given rise to more sophisticated acquisition geometries. A series of improved seismic exploration methods in the beach area and very shallow water are established by analyzing different shot and receiver parameters. As a result, S/N ratio and resolution of seismic data have been improved significantly to identify subsurface structures, improve reservoir description, and increase reserves and production.展开更多
The headland-bay beach is one of the most common coastal types in the world.Its morphology reflects the changes that occurred during long-term evolution of the sandy coast.Several headland-bay beach models have been p...The headland-bay beach is one of the most common coastal types in the world.Its morphology reflects the changes that occurred during long-term evolution of the sandy coast.Several headland-bay beach models have been proposed to simulate the coastline’s configuration in equilibrium.In this paper,a new elliptical model is proposed,described,and applied.On the east coast of Laizhou Bay in Shandong Province from Longkou Port to Diaolongzui,four typical headland-bay beaches have developed,and four headland-bay beach models are used in this paper to simulate the morphology of these beaches to assess the applicability of each model.The simulation results of the elliptical model verify that it is applicable to the study area.In addition,the elliptical model is easy to use.Through simulation and field investigations,we concluded that most of the coastal segments in this area will remain in an erosion state,and the human activity has a significant impact on the shoreline’s evolution.展开更多
文摘A black sand beach littered with huge chunks of glistening(闪亮的)ice has become one of the most visited attractions in Iceland,and for good reason,it looks like something out of a fantasy movie.Known as Breiðamerkursandur in Icelandic,Diamond Beach takes its name from the chunks of pristine ice scattered across the black volcanic sand and glistening like giant,uncut diamonds.
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.
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.
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 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 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.
基金financially supported by the National Natural Science Foundation of China(Grant No.41301005)Postdoctoral Science Foundation of China(Grant No.2014M552118)
文摘This study introduces three typical models on equilibrium beach profile, and discusses the application limitations of these models. Then this study examines the selections for applying these models on different coastal segments of a headland-bay beach in west Guangdong, South China, and explores the physical significances of those parameters in the models. The results indicate that：（1） Bodge＇s model is more in line with the equilibrium beach profile of the tangential or transitional segment, whereas Lee＇s model is more consistent with the shadow profile;（2） most of the parameters in three models have clear physical significances in accordance with the actual characteristics of this headland-bay beach; and（3） both the selections for the equilibrium beach profile from different segments and significances of most of the parameters in three models are in essence correlated with the morphodynamic states at various coastal locations.
文摘River training walls have been built at scores of locations along the NSW coast and their impacts on shoreline change are still not fully understood. In this study, the Brunswick River entrance and adjacent beaches are selected for examination of the impact of the construction of major training walls. Thirteen sets of aerial photographs taken between 1947 and 1994 are used in a GIS approach to accurately determine the shoreline position, beach contours and sand volumes, and their changes in both time and space, and then to assess the contribution of both the structures and natural hydrodynamic conditions to large scale (years-decades and kilometres) beach changes. The impact of the training walls can be divided into four stages: natural conditions prior to their construction (pre 1959), major downdrift erosion and updrift accretion during and following the construction of the walls in 1959～1962 and 1966, diminishing impact of the walls between 1966 and 1987, and finally no apparent impact between 1987～1994. The impact extends horizontally about 8 km updrift and 17 km downdrift, and temporally up to 25 years.
基金The Zhejiang Provincial Natural Science Foundation of China under contract No.LHZ22D060001the Scientific Research Funds of the Second Institute of Oceanography,Ministry of Natural Resources under contract Nos JG2315 and XRJH2309the National Key R&D Program of China under contract No.2022YFC3106200.
文摘Beach erosion has occurred globally in recent decades due to frequent and severe storms.Dongsha beach,located in Zhujiajian Island,Zhejiang Province,China,is a typical embayed sandy beach.This study focused on the morphodynamic response of Dongsha beach to typhoon events,based on beach topographies and surficial sediment characteristics acquired before and after four typhoon events with varying intensities.The four typhoons had different effects on the topography and sediment characteristics of Dongsha beach.Typhoons Ampil and Danas caused the largest(-51.72 m3/m)and the smallest erosion(-8.01 m3/m),respectively.Remarkable alongshore patterns of beach profile volumetric changes were found after the four typhoon events,with more erosion in the southern and central parts of the beach and few changes in the northern part.Grain size coarsening and poor sorting were the main sediment patterns on the beach influenced by different typhoons.Typhoons that occurred in the same year after another typhoon enhanced the effect of the previous typhoon on sediment coarsening and sorting variability,but this cumulative effect was not found between typhoons that occurred during different years.A comparison of the collected data revealed that the topographic state of the beach before the typhoon,typhoon characteristics,and tidal conditions were possible reasons for the difference in the responses of Dongsha beach to typhoon events.More severe beach erosion was caused by typhoons with higher intensity levels and longer durations,and high tide levels during typhoons can determine the upper limit of the beach profile erosion site.Taken together,these results can be used to improve beach management for storm prevention.
文摘The beach of the Shengli oilfield, as the prospect for steady continuous development of the Shengli oilfield, has a large area, special geographic and geological conditions, and other technical difficulties so that exploration has been slow. Seismic acquisition methods in the beach area and very shallow water have been investigated and, with the introduction of new equipment, given rise to more sophisticated acquisition geometries. A series of improved seismic exploration methods in the beach area and very shallow water are established by analyzing different shot and receiver parameters. As a result, S/N ratio and resolution of seismic data have been improved significantly to identify subsurface structures, improve reservoir description, and increase reserves and production.
基金supported by the Marine Public Benefit Scientific Research Special Fund Project of the State Oceanic Administration (Nos. 200905008 and 201405037)
文摘The headland-bay beach is one of the most common coastal types in the world.Its morphology reflects the changes that occurred during long-term evolution of the sandy coast.Several headland-bay beach models have been proposed to simulate the coastline’s configuration in equilibrium.In this paper,a new elliptical model is proposed,described,and applied.On the east coast of Laizhou Bay in Shandong Province from Longkou Port to Diaolongzui,four typical headland-bay beaches have developed,and four headland-bay beach models are used in this paper to simulate the morphology of these beaches to assess the applicability of each model.The simulation results of the elliptical model verify that it is applicable to the study area.In addition,the elliptical model is easy to use.Through simulation and field investigations,we concluded that most of the coastal segments in this area will remain in an erosion state,and the human activity has a significant impact on the shoreline’s evolution.
