摘要
2017-2020年,由于广西铁山港码头吹填导致高浓度悬沙输入红树林,发生了大片红树林死亡事件,引发了社会的广泛关注.在红树林海岸日益受到人类活动影响的背景下,为了给海岸工程建设期间的红树林保护工作提供参考数据,研究红树林致死悬沙浓度十分必要.本研究基于悬沙扩散方程推导和计算,基于现场实测和室内实验获取的关键参数,计算分析了在铁山港榄根码头吹填施工期间,一处死亡红树林斑块内的涨潮流中的悬沙沉降速率和悬沙浓度特征.结果表明:施工期间潮沟边缘的涨潮流悬沙浓度介于2.7～5.9 g/L,而死亡红树林-幸存红树林边界的涨潮流悬沙浓度介于2.0～4.6 g/L,因此2.0 g/L可以作为研究区内红树林致死悬沙浓度的一个保守参考值.在其他区域,在分析当地红树林植株淹没时间以及悬沙粒径特征与铁山港死亡红树林差异的基础上,该数值也可以为分析海岸工程施工期间红树林的安全性提供保护工作参考依据.
Abstract
Large patches of mangrove forest have died between 2017 and 2020 due to the suspended sediment concentration(SSC)in high level caused by reclamation project at the Tieshan harbour of Guangxi province,China.This case reminds us that it is very necessary to determine the lethal SSC level for mangrove,which is helpful in mangrove protection in context of coastal engineering construction increasing.In this study,based on a one-dimensional diffusion equation and the parameters obtained from field survey,we calculated the settling speed of suspended sediment in flood tide in the died mangrove forest during reclamation project and determined the SSC in flood tide at the edge of died mangrove forest according to a SSC-settling speed curve.The result show that the average SSC within the dead mangrove patch is 2.7～5.9 g/L during reclamation project and the SSC is 2.0～4.6 g/L at the border of died mangrove forest-survival mangrove forest.This value(or a value adjusted from this value)is a conservative reference for the estimation or the the monitoring which is conducted to protect the mangrove forest under the threat of coastal engineering construction.
NETL
NSTL
万方数据