Abstract:The‘14th Five-Year Plan’has provided robust policy support for the integrated development of offshore wind power and marine ranching and such an integrated development is a marine economic model with broad prospects and enormous potential.However,the integrated development of offshore wind power and marine ranching in the urban cluster of the Beibu Gulf is still in an exploratory stage,especially in the coastal area of Guangxi such integrated development is relatively backward.In this article,the concept of the integrated development of offshore wind power and marine ranching and its current status and development models at home and abroad are summarized.And in order to provide scientific guidance and reference basis for intensive development and utilization of marine resources in the Beibu Gulf,the integrated construction of offshore wind power and marine ranching in the Beibu Gulf is expected based on the characteristics of marine resources and environments in the Beibu Gulf region and the necessity and feasibility of the integrated construction are explained.

Abstract:In the context of global climate change,national dual-carbon strategies and green low-carbon transitions have created a clear need for the development of marine carbon sinks.The marine ecological restoration is the most feasible and important way to increase ecological sinks.In order to guide the carbon sink development for marine ecological restoration,the main carbon sink resources for marine ecological restoration in the offshore areas of China are analyzed,the distribution characteristics of carbon sink resources are clarified and the mechanisms on which marine carbon sink development projects for marine ecological restoration can be based are proposed.The applicability of four main mechanisms(including the Verified Carbon Standard(VCS)mechanism,the China Carbon Emission Reduction(CCER)mechanism,the local carbon inclusive mechanism and the industry group standard specifications)to the development of ocean carbon sinks is analyzed.The mechanisms of carbon sink development for marine ecological restoration can be determined by comprehensive evaluations based on the actual situation of ecological restoration projects and carbon sink application scenarios.On this basis,the main collaborative development pathways of carbon sink for marine ecological restoration is proposed based on the current situation of marine carbon sink methodology and the development potential of marine sink increase technology.These pathways include increasing sinks by protection and restoration of coastal ecosystems and by marine shellfish and algae proliferation and release,etc.The development of marine carbon sinks through ecological restoration can be also achieved by close cooperation with the ecosystem protection and restoration implementation units,and by designing,in the project of ecological restoration compensation,schemes in which the benefits of enhancing sinks should be taken into account.Finally,suggestions for the coordinated development of carbon sink in marine ecological restoration are proposed,which include to open up actively a road of the coordinated development of carbon sinks for marine ecological restoration in the aspects such as giveing full play to the supporting role of science and technology,jointing superior resources to reduce development costs,exploring deeply the application scenarios and promoting the development of typical projects.

Abstract:Marine geophysical exploration methods can be used for external detection of submarine pipelines.By starting with the in-situ states of the submarine pipelines,the existance characteristics,causes and treatment requirements of the buried,exposed and suspended states of the submarine pipelines are described and the functions and characteristics of various traditional marine geophysical exploration methods commonly used for the submarine pipeline detection in China at the present are introduced in the aspects of the basic principle and application process of instruments.The images of side scan sonar,sub-bottom profiler and multibeam bathymetry system obtained in the cross-sea water pipeline inspection project in Zhoushan are investigated.The results indicate that the methods of side scan sonar and multibeam system have better detection effects on the direction and shape of the exposed and suspended pipeline,the sub-bottom profiler can detect accurately the buried depth and surrounding strata of the submarine pipelines and the magnetometer is suitable for detecting the existance and position of the pipelines.Combined with the interference factors possibly encountered in the detection process and the principle limitations of the instrument itself,the capabilities and characteristics of the marine geophysical exploration methods are analyzed and compared,and the applicability and the advantages and disadvantages of these methods to the submarine pipelines with different states are summarized,in order to guarantee and improve the accuracy of the pipeline state discrimination.In addition,new marine geophysical exploration techniques are listed and the current situation and future development trend of submarine pipeline detection methods are discussed.

Abstract:As an important coastal space,the sandy coasts provide multiple ecosystem services.However,issues like coastal squeeze,habitat fragmentation,ecological degradation triggered by global climate change and human activities pose new challenges in protecting and managing sandy coasts.This study uses CiteSpace to visualize literature from the As an important coastal space,sandy coasts can provide multiple ecosystem services.However,problems such as coastal squeeze,habitat fragmentation and ecological degradation triggered by global climate change and human activities have posed new challenges to the protection and management of the sandy coasts.In this paper,the English literatures retrieved from the"Web of Science"core collection database are visualized by using software CiteSpace and the efforts,hotspots and trends of the research on the protection and management of sandy coasts are analyzed and reviewed.The results show that the researches on the protection and management of sandy coasts were conducted generally in the globle coastal countries from 1979 to March,2024.Among them,the United States,the United Kingdom and France started earlier and held a leading advantage in this field.The number of the publications in this field shows a rapid growth and the scope of the study covers more than 60 disciplines,of which the hotspots of the research are mostly environmental science and ecology and the research themes are primarily concentrated on the geomorphological characteristics and ecological environments of the sandy coasts.By now,the sandy coast study has been gradually developed into a systematic research on coastal monitoring,shoreline evolution,protection and restoration,habitat quality,community dynamics,ecological functions,disaster warning and adaptive management.It is in the future a frontier direction of the research on the protection and management of the sandy coasts to carry out a research on the deep integration with emerging technologies such as artificial intelligence,big data and GIS.

Abstract:After the Yellow River returned to the north,the sources of the sediments in the northern part of the radiant sand ridge area in the South Yellow Sea have been lacking.As a result,the evolution pattern of the radiant sandbar area is bound to change.Based on the nautical charts of different periods in the radiant sand ridge area,and combining with the large scale underwater topographic data of typical areas obtained in winter ana summer and the grain-size analysis of sediment samples,the spatiotemporal variation characteristics of seabed scouring and siltation in the northern part of the radiant sand ridge area in the South Yellow Sea and the scour risk of pile foundation and submarine cable of offshore wind power plant are analyzed.The results indicate that the Xiyang Deep Trough on the west side of the radiant sand ridge area expands toward the south side and the east and west sides and is still deepened and adjusted constantly by scouring under the action of tidal currents.The Xiaojia Trough,the Xiaobei Trough,the Dabei Trough,the Chenjiawu Trough and the underwater sand ridges between the deep troughs are all swing markedly and have a trend to move westward as a whole.The Liangyue sand ridge,the Taiping sand ridge and the Niluoheng sand ridge are in a scattered distrtibution.The change and disappearance of these ridges indicate that the changes in terrain of the area are active under the action of tidal dynamics.In the typical areas,the changes of terrain in the areas of sand ridges and deep troughs range from-0.5 m to 1.4 m in winter and summer of a year.The sand ridges also tend to migrate toward the steep slope located on the west side.According to the analysis,there are three areas currently in a scouring state in the northern part of the radiant sand ridge area in the South Yellow Sea.This will have a certain impact on the safety of pile foundation and submarine cable of offshore wind farm.

Abstract:Local scour of offshore wind power pile foundation is an important research content in the design,operation and maintenace of wind farm.The depth and range of scour are complex and changeable due to the actions of superposition of seafloor topography,seabed sediment types,waves and tidal currents.By selecting an offshore wind farm in the Beibu Gulf of Guangxi as the study area,the applicability of the empirical formulas is analyzed and comparied based on the data of seafloor topography,surface sediments and one-year-long in-situ observations of waves and tidal currents,and the formula for local scouring which is suitable for the seabed features in the study area is selected to study the scouring characteristics of the pile foundation under the conditions of different ocean dynamics and different fan layout schemes.The results show that because the seabed sediments in the engineering area of the study area are mainly composed of silty sand,the Wang Rukai formula of the empirical formulas is recommended to be used for calculatng the local scour.Considering the reduction coefficient of the reciprocating tidal flow to the unidirectional flow,the maximum scouring depth of the representative pile foundation of the wind farm ranges from 5.86 m to 6.88 m and the scouring radius is 14.15 to 15.91 m.To reflect the specific geometric patterns of the pile foundation in the offshore wind farm,a numerical model is established for sediment movement and seabed scour of the pile foundation and verfied by hydrological and scouring parameters.Through carrying out erosion and siltation simulation for three fan layout schemes of 12.5,13.7 and 14.0 MW,the scouring characteristics of the pile foundation under the case of these fan layout schemes are analyzed and comparied respectively,indicaing that the fan layout scheme of 14.0 MW is the recommended scheme.

Abstract:Gravity anchor,serving to offshore mooring systems,is suitable for offshore shallow waters.Due to its advantages of simple and convenient construction and low maintenance cost,it is preferable in the field of offshore engineering.In the current design specifications,a semi-analytical and semi-empirical method is used for estimating the holding capacity of gravity anchor in the single layer soils and for the complex layered soils the finite element method is recommended to be used for checking.For the geological conditions of actual stratified soils at a floating photovoltaic site,the bearing mechanism of rectangular gravity anchors under actions of dragging load and dead weight is studied by using the finite element analysis,and the load bearing properties in the spaces of vertical-horizontal,vertical-bending moment and horizontal-bending moment loads are quantitatively analyzed respectively by using the method of failure envelope surface of bearing capacity.Through specific design cases,it is explained how to use the obtained failure envelopes of bearing capacity for carrying out checking,in which the mooring point position and dragging angle are take into acount.The results indicate that under the case of layered soils,there is significant coupling between the combined loads on the gravity anchor and the changing tendency of the bearing capacity exhibits different characteristics under the failure modes dominated by different loads.The method for calculating the bearing capacity of the gravity anchor proposed in the study can provide technical support for the design and optimization of offshore mooring anchor foundation.

Abstract:Two main cooling methods,i.e.once-through cooling and secondary circulation cooling,currently applied in coastal nuclear power plants and their characteristics are introduced,and the drainage engineering environment and economic effect induced by using these two cooling methods are analyzed,which include subsurface pipe drainage and open channel drainage and their advantages and disadvantages as well.In addition,a comparative analysis is carried out by combining the comparison and optimization of the cooling method and drainage scheme of a nuclear power project in Shandong.The results demonstrate that after using the secondary circulation cooling system the volume of warm-water discharge is significantly less than that by using the once-through cooling method and the area of 4℃temperature rise envelope is only 3%of the sea area used by the once-through cooling scheme.This not only makes the sea area used by warm-water drainage reduce significantly,but also greatly reduces the loss of marine organisms caused by the water intake and drainage of the nuclear power plant,meeting the requirements of saving and intensive use of the sea of the project.Therefore,it can effectively reduce the impact of coastal nuclear power plant on marine ecological environment and realize a harmonious development of economy,society and environment to use the secondary circulation cooling method and its drainage engineering optimization scheme in the coastal nuclear power plants.

Abstract:Different types of deep-water anchors can all be used for mooring floating oil and gas platforms or wind turbines,of which the drag anchor becomes one of the most commonly used forms due to its simple structure,low overall cost and high anchor efficiency.When the drag anchor is installed in sandy soils,its penetration depth is usually shallow and there is a soil heave gradually formed in front of the dragged anchor.Because the soil heave has a significant impact on the penetration depth and holding capacity of the dragged anchor,it is nessenary to take the accumulative situation of the soil heave into acount when making the prediction analysis of the drag anchor installation.For this reason,an accumulation model of the soil heave has been proposed:First is to determine the calculation boundary of the soil heave,and then is to take the self-weight of the gradually accumulated soil heave as the soil pressure overlapping the anchor,which is used for the process of the anchor holding capacity developed with the drag and penetration.The applicability of the proposed soil heave accumulation model is verified by the theoretical analysis framework as well as the comparison with the published centrifuge tests.Then small-scale model tests are carried out and the influences of the soil heave on the holding capacity and motion trajectory of the drag anchor are quantitatively evaluated.

Abstract:The island ecosystem has received wide attention in recent years due to its ecological fragility and significant values in environment,economy and humanity.With the climate change and irrational human activities,however,the structures and functions of the island ecosystem have severely disrupted,so that to carry out the island ecological protection and restoration becomes an important way for improving the island ecology.The nature-based solution(NbS)is an innovative strategy for addressing ecological and environmental challenges and plays an important role in the island ecological protection and restoration.In this paper,the latest research progress on NbS in the context of island ecological protection and restoration is reviewed and the characteristics of NbS are summarized.It is indicated that the NbS can not only simulate the ecological functions of the natural ecosystem,but also enhance biodiversity and thus to improve effectively the stability and sustainability of the island ecosystem.In addition,the concept and principles of NbS are elaborated,the differences between NbS and traditional infrastructure are highlighted,the advantages of the application of NbS in island environment are analyzed and the actual effects of NbS in island ecological protection and restoration are evaludated.It is found that the NbS can not only improve the resilience ability of the ecosystem,but also fosters the sustainable development of local communities.It is pointet out that the potential challenges and limitations of NbS in island ecosystems mainly include aspects such as technological innovation,resource investment,and social participation.Finally,some suggestions are proposed,which include enhancing the cross-scale and multi-system collaborative management and international cooperation in order to generalize and implement the NbS and establishing the diversified financing mechanisms and scientific restoration technical standards as well as implementing the interdisciplinary integration and multi-party participation in order to realize a broader application of NbS in island ecological protection and restoration,and thus to contribute more for constructing a healthy and sustainable island ecosystem.

Abstract:With the rapid development of photovoltaic power technology,the construction of offshore photovoltaic electric field becomes more prevalent.However,the complex offshore environment,especially the problem of the scour of group pile foundations,poses a severe challenge to the stability and safety of the offshore photovoltaic electric field.It is,therefore,necessary to apply effective monitoring technologies for ensurng the safe operation of the offshore photovoltaic electric field.The results of scour monitoring studies in recent years are overviewed,the status of scour monitoring technology is analyzed and the advantages and disadvantages of the existing scour monitoring techniques such as sonar,fiber Bragg grating sensors,resistivity detection and magnetic measurement are discussed.Subsequently,the status of the scour monitoring technologies for marine pile foundations is further discussed in detail and some suggestions are put forward for the scour monitoring of the offshore fixed photovoltaic pile foundation in order to provide effective solutions for solving the scouring of group pile foundations in the offshore photovoltaic electric field.

Abstract:To investigate tourists'awareness of beach safety and rip current,a questionnaire survey was conducted on six recreational beaches in South China.The survey covered five parts,including demographic characteristics,beach visit information,swimming ability,and awareness of beach safety and rip current.During the survey,educational strategies were implemented to enhance tourists'understanding of rip currents,and the effectiveness of these strategies was scientifically evaluated.The findings indicate that:Beachgoers lack awareness of beach safety and rip currents in China.After the implementation of educational interventions,there is a significant improvement in the accuracy of respondents'choices of safe swimming areas,identification of rip currents in images,and selection of correct escape routes.Implementing educational interventions can greatly increase tourists'awareness of beach safety and rip currents,and it is recommended that local governments and management agencies strengthen public education and outreach efforts regarding knowledge of rip currents,as well as enhance beach safety management capabilities.These measures can reduce accidents caused by rip currents and ensure the safety of beach tourism.

Abstract:Due to the long-term scouring by water flow,the effective buried depth of the Donghai Bridge pile foundation has been diminishing year by year,thus leading to the decreasing of the pile foundation stability and even to the endangering of the entire building safety.For the protection project of bridge pile groups,the stabilized soil slurry ratio is investigated and determined,the high flow stabilized soil protection construction is successfully completed and the underwater pumping construction process and the outcomes and long-term protective effects of the stabilized soil protection construction are analyzed.The results indicate that with the increasing of curing agent dosage,the strength of the stabilized soil increases while its fluidity decreases,whereas with increasing in water content of the soil slurry,the strength of the stabilized soil decreases while its fluidity increases.The underwater high-definition sonar is used for observing real-time the relative positions between the underwater pile foundations and the pumping pipe.It is found that the underwater ejection distance of the stabilized soil slurry is approximately 2.5 meters and its flowing distance and width are both over 3 meters.The lowest point of the centre-line projection of Pier PM123 has upraised by approximately 4.3 meters and that of Pier PM230 by approximately 5.4 meters.Obviously,the construction of the stabilized soil protection can effectively backfill the gaps of pile groups and the depressions at the bottom,forming a smooth stabilized soil protective layer with excellent erosion resistance and long-term durability.This engineering practice can accumulate experiences and provide data support and technical reference for similar projects.

Abstract:With the rapid construction and deployment of offshore wind farms,large number of wind power related facilities such as wind turbines,substation platforms and power collection systems can generate electromagnetic interference to the surrounding environment during their operation.To mitigate the negative impacts of such interference,it is crucial to focus on the electromagnetic characteristics of wind turbines.Therefore,the analysis of electromagnetic scattering characteristics of offshore wind farms is focused on and the main methods currently used for this analysis are systematically reviewed.These methods include experimental measurement methods,high-frequency approximation methods(such as method of moments,physical optical method,physical diffraction method,geometrical optical approach and geometric diffraction method)and full-wave numerical methods(such as finite element method and time-domain finite-difference method).Through comparative analysis of the applicable characteristics of several methods and for improving the computing efficiency as well,it is proposed to introduce multipath effect analysis,expand the scope of model application and combine deep learning techniques,and it is also proposed that the future research direction should be to combine multiple methods to achieve more accurate electromagnetic characteristic analysis.All these can provide important references for the optimization of offshore wind farm deployment and the study of electromagnetic compatibility,thus facilitating the intelligent and sustainable development of offshore wind power technology.

Abstract:The wharf is a basic component of the marine infrastructure.With the increasing of old wharves,the requirements of health monitoring of the wharf operation and maintenance stage have been higher.In order to monitoring real-time the wharfl Operation and Maintenance(O&M),emerging technologies such as the Building Information Modeling(BIM),the Internet of Things(IoT)and the Artificial Intelligence(AI)are integrated and a BIM-based Wharf Structural Health Monitoring(BIM-WSHM)System has been developed in the ports of various regions in China.The accurate evaluation of the monitoring systems is favourable for exploring the rationality of these systems and for feedbacking correctly the potential issues as well.The factors for evaluating the BIM-basedWharf Structural Health Monitoring(BIM-WSHM)System are sumarrized and analyzed,an evaluation system for this system is built up and furthermore an evaluation model is established based on the Analytic Network Process(ANP)and the Matter-Element Extension Analysis(MEEA).The feasibility of this model has been verified through an engineering example.This study provides a scientific method of combining quantitative and qualitative methods for the evaluation of the BIM-based Wharf Structural Health Monitoring(BIM-WSHM)System,thus promoting effectively the digital intelligence development of the wharf Operation and Maintenance.

Abstract:This study performs a numerical simulation and analysis of tidal currents in the adjacent waters of Cook Strait using the Finite-Volume Community Ocean Model(FVCOM),a three-dimensional finite-volume hydrodynamic ocean numerical model.At the same time,the tidal level data of the tidal station and its tidal harmonic analysis data are collected to compare and verify the model results.The results reveal significant tidal discrepancies on both sides of Cook Strait.On the north side,the amplitude gradually decreases from the New Zealand coast to the Tasman Sea,and on the south side,the amplitude gradually increases from the southern wide sea area to the southern coastline of New Zealand.The tidal process in this area is greatly affected by topography and coastline.This typical reciprocating flow exists in the central part of Cook Strait,and mainly flows southward.The presence of uplift topography and trenches on the south side of Cook Strait is an important influence on tidal processes in the area beyond the strait,as evidenced by the significant increase in tidal current velocities and change in current direction in the uplift region in the southern ocean.By comparing with the measured data,the numerical simulation results of this study are basically consistent with the measured data,which can accurately simulate the hydrodynamic conditions in the adjacent sea area of Cook Strait and provide important experimental basis for related marine engineering construction and scientific research.

Abstract:Many empirical formulas and models for soil classification based on Cone Penetration Test(CPT)data have been developed.However,the conclusions from different scholars vary in terms of the classification model of soils and the distinguishment of soil types due to the differences in geographical locations,standards and research objectives.In this study,the CPT data of 60 boreholes obtained in the Yinggehai Basin in the South China Sea and the samples taken from the adjacent boreholes are studied.Firstly,based on the data of boreholes located nearby,the CPT data corresponding to five common types of soils(i.e.clay,silty clay,silt,silty sand and fine sand)are selected and then processed interpretively.Secondly,soil behavior classification models suitable for using in the Yinggehai Basin are built up by using the normalized frictional ratio and the normalized cone tip resistance as the classification indicators and applying various machine learning techniques including Random Forest,Artificial Neural Networks,Decision Trees,Bayesian Learning,Support Vector Machines and Linear Perceptions.Thirdly,the metrics such as confusion matrix,overall accuracy and Kappa coefficient are used to evaluate the classification accuracy of the models.Finally,the developed models are applied to automatically interpret CPT data in the surrounding and distant sea areas,and then validated using borehole samples adjacent to the CPT data.The results indicate that the soil behavior classification models developed in this study demonstrate high accuracies in interpreting CPT data in the northern part of the South China Sea,providing valuable insights for geotechnical engineering applications in offshore wind energy projects and other marine construction activities.

Abstract:ICESat-2(Ice,Cloud,and Land Elevation Satellite-2)is one of the most advanced laser altimetry satellites currently available.Using a laser wavelength of 532 nm,it can effectively acquire bathymetric data in the shallow water areas,thus greatly promoting the development of shallow water bathymetry.However,the raw data from ICESat-2 are often clouded by noisy point clouds so that great challenges can be brought to the post-processing of the data.To improve the accuracy and efficiency of data processing,a denoising algorithm based on Multilayer Perceptron(MLP)is developed to address the feature that ICESat-2 point clouds are denser in horizontal direction than in vertical direction.This algorithm takes into account comprehensively the feature values such as point density,average distance between points,and distance between the nearest neighbors(respectively 3 and 5)within a horizontal elliptical search area,thus realizing the effective identification and removal of noise points.The developed denoising model has been validated by selecting the ICESat-2 data from an reef island region in Australia as the training set and also using the data from the Jade Bangle Reef and the East Island in the Xisha Islands of China.The experimental results show that the denoising method developed in the study has an accuracy rate of over 90%,which is significantly better than the existing OPTICS denoising algorithm and the denoising results extracted by the official ATL03 algorithm.This achievement not only provides a new solution for the noise removal from ICESat-2 data,but also provides reliable data support for the research in related fields.

Abstract:The design flow velocity is an important parameter in ocean engineering.The design tide pattern,as one of the commonly used drive conditions,plays an important role in the calculation of design flow velocity.However,there is currently no universal and mature method for calculating the design tide patterns.In this study,a two-dimensional tidal flow model used in the sea area of the Dalian Changshan Archipelago is built up by numerical simulation and validated by using the current data measured in the Dalian Changhai Bridge area.By using this model,the changes of tidal flow field and the values of design flow velocity in the Changhai Bridge area are simulated under different boundary conditions of the design tide pattern,and the influences of the different drive conditions on the simulated results are studied.The results show that compared to the results worked out using the tide patterns such as'astronomical tide+increase water in different recurrence period'and'tidal range in different recurrence period',the design flow velocities worked out using'tidal range in different recurrence period+wind-driven current in corresponding recurrence period are even more close to those calculated out by using the empirical harmonic analysis methods and can provide more valuable reference for the ocean engineering.

Abstract:A two-dimensional CFD model for local scour of submarine pipelines is established based on SST k-ω model,Herschel-Bulkley clay model and VOF two-phase flow model.The inflow velocity U and soil strength τ0 are used as the variable parameters for the study of numerical simulation.By using this model,the law of the influence of different inflow velocities U and soil strength τ0 on local scour characteristics of the submarine pipelines is studied by analyzing the bed surface pressure characteristics,shape of scouring pit,duration curve of scouring depth and local flow speed distribution on both sides of the pipeline.The results show that the local scour of the submarine pipelines in the clay seabed environment is affected significantly by inflow velocity.With the increase of the inflow velocity,both the local limit equilibrium scour depth and the width of scour pit increase,and the ratio of the increase in equilibrium scour depth to the increase in flow velocity tends,as a whole,to slow down.The local scour of submarine pipelines in the clay seabed environment is affected significantly by soil strength.With the increase of the soil strength,the seepage force of the seabed is weakened,the limit equilibrium scour depth of the pipeline decreases and the mound downstream of the pipeline is closer to the pipe axis.When the soil strength is greater than or equal to 300 Pa,it is more difficult to form a gap between the bottom of the pipe and the seabed.