北戴河西海滩养护工程方案研究

近年北戴河西海滩侵蚀速度显著增大,亟需治理,治理工程计划采用人工养滩辅以硬体工程措施的方法.文章阐述了一个基于一线模型开发的岸线演变模型GENESIS,首先以水工模型实验的结果验证了GENESIS模型的可靠性.并研究了主要物理参数对岸线演变模拟结果的影响;再用GENESIS模型及配套的波浪模型STWAVE预测北戴河西海滩各种养护方案下工程后10年内的岸线演变情况,比较分析模拟结果并提出最佳养护效果方案.     

基于人工补沙的海滩养护试验研究

近年来,新兴的海滩养护"软"防护方法凭借其更自然化的防侵蚀方式、环境友好程度高以及经济性合理等优势,在海岸防治和修复的工程实践中得到广泛应用。本文通过二维水槽动床试验,结合剖面识别的图像观测方法,对沙坝补沙以及滩肩补沙两种养护方案下的补沙初始剖面向平衡剖面转化的演变过程进行分析。试验发现,沙坝补沙可使外海波浪提前破碎,明显减轻了岸滩侵蚀,且在一定波浪条件下产生了向岸输沙,造成岸线前进;而滩肩补沙则为水下沙坝增长提供了足量侵蚀沙源,增强了岸滩抵御更大波浪的能力。     

黄河三角洲滩海油田岸滩防护方案探索

针对飞雁滩油田的岸滩侵蚀情况提出几种岸滩防护设想并确定防护方案.该方案充分利用自然力,通过人为干扰促使防护区外泥沙起动,借助海上潮流使高含沙海水流经防护区,实现岸滩蚀退的快速防护.     

土福湾赤岭岸线沙滩修复技术探讨

针对拦沙结构物优化问题,以土福湾赤岭岸线修复工程为例,分析了缩短拦沙堤长度而不影响航道的可行性.岸滩采用滩肩补沙方式,缩短拦沙堤长度至150 m,允许沙子绕过拦沙堤进入备用蓄沙池.实地检验近2年,期间遭受多场台风侵袭,尤其是2020年下半年台风组团影响,方案经受住了考验,证明设计效果良好.旁通输沙方案也节省了投资.研究...     

杭州湾北岸上海段水域规划线修订分析

杭州湾北岸岸线的规划和岸滩水下地形近十年发生了较大变化。通过对该地区水文测验,地形测量等勘测以及近期岸滩及海床稳定性分析和数学模型计算,并结合岸线的规划对原规划线进行了修订。     

辽宁红沿河核电厂附近海域海岸演变及沉积特征

在现场踏勘及海洋水文全潮测验的基础上,分析了辽宁红沿河核电站附近海区的海岸演变和淤积特征,重点对海岸的稳定性,岸滩与床面的淤积特征、泥沙来源等进行了探讨,认为该海区岸段与岬角上间岸滩稳定,电厂取排水口处无泥沙淤积之患,在核电取排水口设计时,可不考虑岸线侵蚀以及其它形式来沙对核电水上工程滩面发育的影响。     

拦沙堤与潜堤的布置形式对砂质海滩的影响

文中以日照港石臼港区东作业区煤码头岸线退岸还海修复整治工程为例,探讨了拦沙堤和潜堤的不同布置形式,对工程水域波浪潮流泥沙以及形成砂质海滩剖面的影响。拦沙堤可一定程度上减小泥沙输移,且海滩在拦沙堤的环抱下更接近自然平衡岸线的弧度,使淤积环境变弱。而潜堤可一定程度上减小沙滩的侵蚀程度,且对泥沙外移有一定的拦截作用。在实际的工程实践中,合理的布置潜堤和拦沙堤,可有效减少岸滩冲淤,维持稳定的海滩形态。     

陆丰海洋基地码头工程防波堤平面布置

为保障泊稳条件、减轻工程对周边岸线的影响、合理降低工程投资,对陆丰海洋基地码头工程防波堤平面布置进行研究。结合波浪和潮流观测资料、遥感影像历史资料,运用波浪、潮流泥沙及岸滩演变数值模拟手段,分析陆丰海洋基地所在地水文特性,厘清不同防波堤平面布置方案下泊稳条件、波浪荷载、流场变化、泥沙运动及岸滩演变特点,探讨工程平面布置方案的优劣。经对比分析,考虑预留更多的扩建空间及分期建设的便利性,建议采用东北开口方案,暂不延长防波堤,并对受影响岸段辅以相应的岸滩整治措施。     

潜堤平面布置和堤顶高程的研究

以斜坡式潜堤为研究对象,通过数值模拟研究和物理模型试验,研究潜堤的平面布置方案和堤顶高程。对透射系数进行分析,得出适合的计算公式和最佳离岸距离;对岸滩剖面和岸线演化进行数值模拟,分析潜堤平面环抱式布置和连续式布置方案。     

岱山西北海域海床冲淤演变分析*

根据不同年份的水深地形资料及遥感影像,采用GIS技术对近30 a来岱山西北岸线变化及海床冲淤进行数字化分析。同时,结合该海域的水文泥沙特征及人类活动因素,研究海底冲淤变化的主要影响因素。综合分析表明：2011年以前岱山西北海岸岸线稳定,岸滩经历了由滩淤槽冲转为滩冲槽冲的动态演变过程,除岱山西部与大鱼山之间的槽沟局部地形变化较大外,其它海区冲淤速率不到10 cm/a,整个海域的侵蚀速率有加速趋势。2011年之后,岱山北部开始实施大规模围涂工程,岱山西北近岸5 m等深线以浅的岸滩发生1.75 m/a的淤积,而计算范围内的其它海区仍以微侵蚀为主。岱山西北海域泥沙主要以过境输移为主,长江来沙量的减少和近年围垦活动的增加是该海域海床冲淤演变的两个主要影响因素。     

Synergies between Adjacent Beach-Nourishing Communities in a Morpho-Economic Coupled Coastline Model

Beach “nourishment” consists of placing sand on an eroding beach. The widened beach provides increased storm protection to adjacent structures and improved recreational benefits, but is most often transient, requiring on-going, repeated nourishment episodes. Numerical models of beach nourishment typically address such questions as how long a widened beach will last; economic models compare the benefits and costs of preserving a stretch of beach without regard to its geomorphic evolution. Neither have addressed the physical nor economic interactions between adjacent nourishing communities. Here, we couple a numerical model of coastline evolution and a cost-benefit model of beach nourishment, allowing adjacent communities to make dynamic nourishment decisions. Beach nourishment benefits adjacent communities both “updrift” and “downdrift.” The total amount of money spent on nourishment activities can decrease by as much as 25% when adjacent communities both conduct on-going nourishment projects, as opposed to the case where each community nourishes in isolation.     

Comparison of Beach Nourishment along the U.S. Atlantic,Great Lakes,Gulf of Mexico,and New England Shorelines

The U.S. national beach nourishment experience is summarized for the East Coast barrier islands, the Gulf of Mexico, New England, and the Great Lakes. A total of 1,305 nourishment episodes on 382 beaches are recorded at a total estimated cost of approximately $1.4 billion ($2.5 billion in 1996 dollars). In terms of both volume and costs, nourishment has been the most extensive by far on the East Coast barrier islands. Depending on the region, between 65% and 85% of all nourishment projects have a federal funding component. Annual expenditures and sand volumes for beach nourishment are increasing, especially on East Coast barriers. At present, total annual national beach nourishment costs (excluding the Pacific Coast) are on the order of $100 million per year. The cost per cubic yard of nourishment sand as expressed in 1996 dollars has remained more or less constant over time. Additionally, the volumes of sand needed for subsequent nourishment episodes on individual beaches do not decrease, despite contrary assumptions in the shoreface-profile-ofequilibrium concept that subsequent nourishment volumes should diminish. In light of the historical experience of beach nourishment identified in this study, individual state and local coastal communities should reevaluate their plans for future beach nourishment programs. The complete listing of all the data on nourished beaches from this survey is available at www.geo.duke.edu/Research/psds/psds.htm     

Visitor Preferences for Public Beach Amenities and Beach Restoration in South Florida

Coastal erosion threatens many sandy beaches and the ecological, economic, social and cultural amenities they provide. The problem is especially chronic in South Florida. A frequent solution for beach restoration involves sand replacement, or nourishment, but is temporary, expensive, and has usually been funded by governmental sources. However, as such agencies reduce their share and require more local funding, beach nourishment must rely on other funding sources, including beach recreationists. Our study characterized three South Florida beaches and probed visitor willingness-to-pay for beach nourishment. We found that even beaches within close proximity attract different user types. Users are amenable to higher fees if they lead to greater resource protection.     

The Potential of a Legislative Approach to Managing Beach Use: The Case of Beach Bylaws in the Republic of Ireland

This article examines the use of inland mined sand and offshore dredged sand for beach nourishment projects in North Carolina, focusing on the question of whether inland mined sand is economically preferential for hot‐spot erosion control. Excavation, processing, and transport costs are presented, and cost efficiencies of hypothetical beach nourishment projects are compared. Cost analyses indicate that inland mined sand is economical for small projects (10,000–50,000 cubic yards), given that a clean sand source can be located within 15 miles of the nourishment site. The two factors primarily influencing per cubic yard costs of inland sand are overland transportation expenses and processing costs. The use of dredged offshore sand is less expensive for large projects (> 100,000 cubic yards) due to the economies of scale affecting dredge mobilization. Large beach nourishment projects in North Carolina will most likely continue to utilize offshore dredged sand.     

Financing Beach Improvements: Comparing Two Approaches on the Georgia Coast

Fifty-five percent of Georgia's developed coastline has been armored with various types of erosion protection devices. This article is about beach improvement projects at Jekyll Island that would operate under (a) a nourishment policy or (b) a retreat policy. Benefits are calculated from an intensive, on-site survey of beach visitors and the costs are calculated from observable sources. Two financing methods are considered: general revenue and user fee financing. The analyses imply recommending beach improvement as an effective policy within the considered time frame.     

Coastal erosion and sea level rise: Implications for ocean beach and San Francisco's westside transport project

Abstract

One of the consequences of sea level rise resulting from the greenhouse effect is increased coastal erosion. This article discusses a model of erosion that can be used to estimate the response of beaches to sea level rise. The model is applied to Ocean Beach, California, with particular attention to the consequences of accelerated erosion for the San Francisco Westside Sewer Transport. Results obtained show that erosion produced by accelerated sea level rise could cause substantial damage to the structure. Large expenditures on beach nourishment will be required to protect the transport and the recreational value of the beach.     

Evolution of coastal hazards policies in the United States

The ocean and Great Lakes coasts of the United States are experiencing widespread economic and environmental damage from coastal flooding and erosion. During this century, public response to such coastal hazards has evolved haphazardly in response to particular disasters. Over time, however, the range of response has broadened as research has helped to refine public understanding of physical coastal processes, and specific disasters have been studied before longer term forms of institutional response have been formulated. Earlier reliance on engineered shoreline protection has been supplemented by beach nourishment, flood insurance, building and land use regulations, coastal zone planning, and other approaches. This article interprets the evolution of such public policy innovations in terms of a model that depicts the interaction of spatially differentiated systems of physical, legal, and cultural phenomena in the coastal context.     

An Interdisciplinary Analysis of Beach Management in the Catalan Coast (North-Western Mediterranean)

This article presents a comprehensive analysis of beach management in the Catalan coast (NW Mediterranean) by introducing and integrating results from different partial projects. They analyzed the legal, political, and administrative framework of beach management, the quality tools available, the practices of management, the processes of beach use, and beach waste/litter dynamics. The information obtained served to create a new beach management tool referred to as the Beach Quality Index, which was developed by an interdisciplinary team of academics from the natural/physical sciences and social sciences that worked together during the course of four years. Information obtained from users and key stakeholders served to create the index. The study demonstrated that as a consequence of the shortcomings in the legal and administrative system as well as inadequate practices of beach managers, beach management in the area experiences coordination problems, insufficient information and lack of proactive management, pollution, and in general problems associated with the satisfaction of short-term user demands.     

Surfer and Beachgoer Responsiveness to Coastal Water Quality Warnings

Fecal contamination of coastal waters has led local public health agencies to issue tens of thousands of beach advisories annually and to advise against ocean swimming and surfing for 72 hours following a rain. The responsiveness of recreationists to beach advisories and the “72 hour rule” is estimated by merging four years of multi-daily surfer and beachgoer counts at one beach in Southern California with hourly data on beach advisories, recent precipitation, meteorological conditions, and the UCSB academic calendar. Both surfing and beach-going decreased significantly following rainfall in response to the 72 hour rule, showing that recreationists are willing to engage in health risk-reducing avoiding behavior. However, neither surfing nor beach-going decreased significantly during beach advisories. Surfers were significantly more responsive to beach advisories during dry periods than during wet periods, consistent with the hypothesis that recreationists are most likely to respond to a risk warning that they believe provides accurate and additional health risk information beyond what they can observe personally. Additional studies of beach advisories elsewhere could clarify whether responsiveness to beach advisories varies by recreationist demographic, recreational activity, frequency of advisories, or frequency of repeat visitation. Increasing the accuracy and additional information provided by beach advisories, as proposed by numerous authors, could lead to increased responsiveness.     

The First Step for the Environmental Management of Australian Beaches: Establishing an Effective Policy Framework

Beach management and coastal management are interwoven and scale-dependent activities in Australia. Present coastal policies are broad and designed for large, national, and statewide scales. They specify ecologically sustainable development as the overarching goal for coastal management and provide the context for beach management. On smaller scales, an approach focusing on the reduction of geomorphic hazards as the basis of beach management was established by the Coastline Hazard Policy, with nonhazard aspects of beach management such as ecological, economic, and social concerns assuming secondary importance. Although beach management can occur effectively under these coastal management arrangements, better guidance is required to make this process as effective and efficient as possible. This guidance - the policy framework - could be better developed for beach management and better integrated with existing coastal management arrangements. While this policy development is not strictly necessary to achieve positive outcomes from beach management, it is necessary to effectively guide implementation of the existing broad coastal policies. Effective goals for beach management are yet to be thought out and clearly articulated in Australia. A good start would be to couple the present goals of ecologically sustainable development and hazards reduction into a coherent goal for beach management. A specific policy for beaches should be developed given the importance of beaches in Australia.