Attenuation of high water levels over restored saltmarshes can be limited. Insights from Freiston Shore, Lincolnshire, UK
Attenuation of high water levels over restored saltmarshes can be limited. Insights from Freiston Shore, Lincolnshire, UK
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DOI：
10.1016/j.ecoleng.2019.06.009
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发表时间：
2019-10-01
影响因子：
3.8
通讯作者：
Vafeidis, Athanasios
中科院分区：
文献类型：
--
作者：
Kiesel, Joshua;Schuerch, Mark;Vafeidis, Athanasios
对低洼海岸的防洪进行有管理的调整（MR），以及在新旧更向内陆的海上防线之间创建或重建潮间带盐沼栖息地是一项干预措施，旨在帮助保护沿海基础设施和社区免受风暴浪和海潮的影响。然而，此类方案的有效性很少在现场得到证实。环境监测一般局限于实施后的最初几年，重点关注沉积物堆积和地表高程变化、植被建立和栖息地利用，而忽视了生物物理过程的研究，例如波浪能量耗散和高水位（HWL）衰减。我们通过分析弗莱斯顿海岸（英国林肯郡）开放海岸 MR 站点内部和前面盐沼中的 HWL 衰减率来解决这一知识差距。为此，沿着相同设置的四个部分（MR 内两个，MR 外两个）部署了一套 16 个压力传感器，以测量 2017 年最高春季期间的水位变化。我们的结果表明，对于现场监测期间遇到的条件， Freiston Shore MR 站点提供的 HWL 衰减有限。 HWL 衰减率明显高于天然盐沼（MR 前面），其中 HWL 衰减范围在 0 至 101 cm km(-1) 之间（平均 46 cm km(-1)）。在 MR 站点内，速率在 - 102 至 160 cm km(-1) 之间变化（平均值为（-3） cm km(-1)），甚至大约一半的测量潮汐出现负衰减（即放大）。我们认为 MR 站点在 HWL 衰减方面的弱性能是方案设计和气象条件引起的内部水动力的结果。后者可能抵消了由恢复的盐沼提供的额外浅水区域引起的 HWL 衰减效应。
The managed realignment (MR) of flood protection on low-lying coasts, and the creation, or re-creation, of intertidal saltmarsh habitat between old and new, more landward sea defence lines is an intervention designed to help protect coastal infrastructure and communities against the impact of storm waves and surges. However, the effectiveness of such schemes has rarely been proven in the field. Environmental monitoring has generally been limited to the first few years after implementation and has focussed on sediment accretion and surface elevation change, vegetation establishment and habitat utilization, to the neglect of the study of biophysical processes, such as wave energy dissipation and High Water Level (HWL) attenuation. We address this knowledge gap by analysing HWL attenuation rates in saltmarshes from within, and in front of, the open coast MR site of Freiston Shore (Lincolnshire, UK).For this purpose, a suite of 16 pressure transducers was deployed along four sections (two within and two outside the MR) of identical setup to measure water level variations during the highest spring fides of the year 2017.Our results show that for the conditions encountered during the field monitoring period, the capacity of the Freiston Shore MR site to provide HWL attenuation was limited. HWL attenuation rates were significantly higher over the natural saltmarsh (in front of the MR), where HWL attenuation ranged between 0 and 101 cm km(-1) (mean 46 cm km(-1)). Within the MR site, rates varied between - 102 and 160 cm km(-1) (mean(-3) cm km(-1)), with even negative attenuation (i.e. amplification) for about half of the measured tides.We argue that the weak performance of the MR site in terms of HWL attenuation was a result of internal hydrodynamics caused by scheme design and meteorological conditions. The latter may have counteracted the HWL attenuating effect caused by the additional shallow water area provided by the restored saltmarsh.