海岸线变化研究综述

受全球及海岸带区域环境过程与人类活动的综合影响,海岸线发生剧烈的变化,对生态、环境及经济社会的影响不容忽视,海岸线变化相关研究因此得到普遍的关注。在讨论海岸线的定义和分类的基础上,介绍岸线信息提取的方法与技术,总结国内外海岸线变化的特征、机制与影响方面研究的进展,并指出未来研究的趋势,包括:对海岸线变化过程进行动态监测仍将是普遍关注的研究重点之一;对海岸线变化特征、规律与机理的认识已经日益深化,基于大量高精度数据和机理模型的研究已成为热点和前沿问题;针对不同的海岸带区域,聚焦海岸线变化的原因和机制及其对环境和生态的影响,以及不同区域之间的相互联系与影响特征,这将是未来研究的重点之一;中国海岸线变化的独特性、复杂性突出,促进和支撑中国的海岸带综合管理实践,提高决策者与管理者对岸线变化所带来的灾害风险的重视,为中国海岸带的科学规划与发展提供依据,这应该是我国海岸线变化研究的重要目标。

Review of research on coastline changes

Because of the combined effects of global and coastal environmental processes and human activities, dramatic changes to coastlines have had significant effects on the environment, ecosystems, and human society in the coastal zone, and the issue has increasingly become a major socio-economic concern to countries along the coast. Consequently, coastline changes have drawn great attention in the academic community, and numerous studies on this issue have been conducted and results subsequently published. Following the definition of proxy-based coastlines and rules of coastline classification, in this paper, we review the methodologies and technologies of coastline interpretation, quality calculation, and estimation of coastlines extracted from remote sensing imageries and topographic maps, as well as analytical methodologies and technologies related to coastline change. Driving factors and the effects of coastline changes are also summarized and analyzed in this paper. Progress and directions of expected research are presented in the last part of this paper. A coastline is a wet-dry boundary or ocean-land boundary. In this paper, individual shoreline indicators generally fall into two categories: visually discernible coastlines (e.g., wet-dry line, debris line, vegetation line), or intersection lines of the coastal profile with a specific vertical elevation defined by the tidal constituents of a particular area (e.g., mean high-low water line, mean sea level line). Methodologies and data sources of coastline data extraction are reviewed in the second part, and the methodologies are classified into three categories based on whether they involve human assistance (automatic extraction, semi-automatic extraction, and visual interpretation). Calculation of quality and estimation of coastlines are discussed in the second part of this paper, and include line-based evaluation, point-based evaluation, and deduction evaluation. In the third part, methods for analysis of coastline change are reviewed and explained, from simple methods to more complicated ones, and from qualitative methods to more quantitative ones. The driving factors are reduced to three categories: global environmental processes (e.g., global warming, sea level rise), coastal environmental processes (e.g., ocean dynamic, sediment movement), and human activities (e.g., coastline hardening, sea reclamation). In the last part of this paper, we discuss research progress and expected research on coastline change around the world. We put forward the following views. Dynamic monitoring of coastline changes remains one of the highest research priorities, as our understanding of features, laws, and mechanisms of coastline change deepens, and as research based on high-accuracy data and advanced mechanistic models develops. Studies focus on causes and mechanisms of coastline changes, impacts on coastal environments and ecosystems of various coastal zones, as well as on the characteristics of interrelations and mutual influences of different coastal regions, are another major area of focus of studies on global coastline change. Furthermore, coastline changes in China have distinct characteristics and complexity; therefore, studies of the Chinese coastline should be used to set the primary goals for improving and supporting the practices of ICZM (Integrated Coastal Zone Management). These studies will increase the awareness of decision-makers and stakeholders of the risks of hazards caused by coastline change, and will provide key information for coastal scientific planning and development.