滨海湿地消浪服务空间分布特征——以上海市崇明岛为例

Abstract

全球气候变化增加了滨海地区遭受侵蚀、风暴潮等灾害的风险，利用自然湿地的消浪功能增强海岸防护是当前研究的热点，但目前对消浪服务的空间分布评估研究相对匮乏。以上海市崇明岛环岛滨海湿地为例，结合GIS与Kobayashi指数形式波高衰减模型评估常规状态下湿地消浪服务的空间分布特征。结果显示，大、小潮升条件下，崇明环岛湿地消波的平均高度分别为0.94、0.54 m与效度分别为83.6%、60.4%，消波高度的空间分布表现为南岸小于北岸，消波效度的空间分布在小潮升时与消波高度相似，而大潮升时南岸的消波效度有明显提升。物理环境与生物因素空间分布及其相互作用的异质性，导致消浪服务的空间分布也具有空间异质性。实际参与消波的断面宽度与不同景观消波服务的评估结果表明，一个断面的所有景观并非都参与到消浪过程中，即使在大潮升时期，不同岸段景观的平均参与度不足71%。潮高与波高的增加并不会使参与消波的景观规模成对应比例的增加，说明消波服务在空间上具有明显的非线性特征。研究可为滨海湿地生态修复空间规划、基于生态系统的海岸带管理、自然资本核算提供科技支撑。;Global coastal zone is faced with the challenge of increasing threats from sea level rise, coastal erosion and storm surge as the result of climate change. To improve the adaptability of the coastal area to climate change, many scientists proposed to incorporate wetlands wave attenuation service into conventional coastal protection schemes, despite the knowledge gap of the spatial distribution of such service. In this study, we incorporated an exponential wave propagation model into GIS, and simulated the spatial distribution of the wave attenuation service of the coastal wetlands in Chongming island, Yangtze Estuary, under two normal scenarios (spring rise and neap rise). The results showed that coastal wetlands could reduce average significant wave heights up to 0.94 m and 0.54 m, accounting for 83.6% and 60.4% of their incoming wave heights under spring rise and neap rise, respectively. In either case, wave height reduced by the wetlands on the southern coast of Chongming island was lower than that on the northern coast. The spatial characteristics of wave attenuation rate was similar to that of the reduced wave height under neap rise. Compared to the neap rise scenario, wave attenuation rate of the wetlands along the southern coast of Chongming island showed a significant improvement under spring rise. The spatial heterogeneity of the wave attenuation service can be explained by the spatial patterns of coastal physical and biotic factors as well as their interactions. Not the whole transects of vegetation contributed to wave attenuation, even under spring rise scenario. Only a part of the transects, 70.8% in average, were engaged in wave attenuation under spring rise. This result indicates that the increased height of tide and wave may not induce the corresponding proportion increase in the width of ecosystem involved in dissipating waves due to the non-linear feature of ecosystems' wave attenuation service in space. This study can provide important support for coastal wetland restoration, ecosystem-based coastal management, and natural capital accounting.