台风过程影响下的滨海湿地物理变量观测及湿地系统响应

如何研究台风等极端天气事件影响下的湿地系统响应过程，进而提出有效的生态完整性维护和管理方案，对关键区域的湿地管理及生态安全维护具有重要意义。本文于2021年9月“灿都”台风期间在南汇东滩南岸设置水动力观测点，采集表层沉积物、测量滩面高程并用无人机获得植被影像，运用ArcGIS空间分析，探讨了台风过程影响下的南汇东滩水动力、滩面沉积变化与植被分布面积响应。结果表明:台风中，观测点近底层平均流速为0.23 m/s，植被边缘平均有效波高和波能是台风前后的1.54倍和2.14倍，近底层1 m的滩面出现“高悬沙浓度层”（>10 g/L）且存在时长为8.13 h。台风后高程低于4 m的稀疏海三棱藨草和互花米草滩面侵蚀0～4.8 cm，高程高于4 m的茂盛互花米草和芦苇滩面淤积0～14.7 cm；研究区植被分布面积共减少1 827.67 m2，减少量占台风前植被总量的1.63%，其中侵蚀滩面植被分布面积减少31.9%，淤积滩面减少68.1%。对台风过程影响后的湿地管理，可以总结为:（1）湿地在台风过程后滩面基本表现为明显的侵蚀、淤积区域共存的特征；（2）对高程低于4 m的侵蚀滩面，建议确定植被适宜生长的高程，结合台风过程冲淤变化通过“微生物膜”和植被斑块移植的方法消浪、固滩和促淤，加速湿地在台风过程影响后的修复。

Observation of physical variables of coastal wetland and response of wetland system under the influence of typhoon process

How to study the response process of wetland system under the influence of extreme weather events such as typhoon, and then put forward effective ecological integrity maintenance and management schemes is of great significance to wetland management and ecological security maintenance in key areas. In this paper, during the process of “Chanthu” Typhoon in September 2021, hydrodynamic observation points were set up on the South Bank of Nanhui east tidal flat, surface sediments were collected, tidal flat surface elevation was measured, and vegetation images were obtained by unmanned aerial vehicle. Using ArcGIS spatial analysis, the hydrodynamic and sedimentary changes of Nanhui east tidal flat and the response of tidal flat surface elevation, surface sediments and vegetation distribution area were discussed. The results show that the average effective wave height and wave energy at the edge of the vegetation are 1.54 times and 2.14 times in the typhoon, the average current velocity near the bottom layer is 0.23 m/s, and a “high suspended sediment concentration layer” (>10 g/L) with a thickness of more than 1 m appears on the tidal flat for 8.13 h. After the typhoon, the tidal flat surface of Scirpus mariqueter and Spartina alterniflora distributed sparsely below 4 m eroded 0?4.8 cm, and the tidal flat surface with lush growth of Spartina alterniflora and Phragmites australis above 4 m deposited 0?14.7 cm. The distribution area of vegetation in the study area decreased by 1827.67 m2, accounting for 1.63% of the total vegetation before the typhoon, including 31.9% of the eroded tidal flat vegetation and 68.1% of the deposited tidal flat vegetation. The wetland management after the typhoon process can be summarized as follows: (1) The wetland basically shows the characteristics of coexistence of erosion and accretion areas after the typhoon process; (2) For the tidal flat surface with an elevation lower than 4 m, it is suggested to determine the elevation suitable for vegetation growth, combine the erosion and deposition changes during the typhoon process, and use the “microbial film” and vegetation patch transplantation to dissipate waves, consolidate the tidal flat and promote accretion, so as to accelerate the rapid restoration of the wetland after the impact of the typhoon process.