Impact of Barrier Breaching on Wetland Ecosystems under the Influence of Storm Surge, Sea-Level Rise and Freshwater Disc
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WETLANDS AND CLIMATE CHANGE
Impact of Barrier Breaching on Wetland Ecosystems under the Influence of Storm Surge, Sea-Level Rise and Freshwater Discharge Xiaorong Li 1 & Nicoletta Leonardi 1 & Andrew J. Plater 1 Received: 30 May 2019 / Accepted: 27 August 2019 # The Author(s) 2019
Abstract Coastal wetland ecosystems and biodiversity are susceptible to changes in salinity brought about by the local effects of climate change, meteorological extremes, coastal evolution and human intervention. This study investigates changes in the salinity of surface water and the associated impacts on back-barrier wetlands as a result of breaching of a barrier beach and under the compound action of different surge heights, accelerated sea-level rise (SLR), river discharge and rainfall. We show that barrier breaching can have significant effects in terms of vegetation die-back even without the occurrence of large storm surges or in the absence of SLR, and that rainfall alone is unlikely to be sufficient to mitigate increased salinity due to direct tidal flushing. Results demonstrate that an increase in sea level corresponding to the RCP8.5 scenario for year 2100 causes a greater impact in terms of reedbed loss than storm surges up to 2 m with no SLR. In mitigation of the consequent changes in wetland ecology, regulation of relatively small and continuous river discharge can be regarded as a strategy for the management of coastal back-barrier wetland habitats and for the maintenance of brackish ecosystems. As such, this study provides a tool for scoping the potential impacts of storms, climate change and alternative management strategies on existing wetland habitats and species. Keywords Wetland ecosystem . Barrier breach . Climate change . Accelerated sea level rise . Storm surge . Freshwater discharge . Wetland loss . Reedbeds . Mitigation strategies . Coastal wetland management strategies
Introduction Wetlands are commonly found along low energy coastal environments, and provide important ecosystem services and economic benefits (e.g., Gedan et al. 2009, 2011; Ndebele and Forgie 2017; Li et al. 2018). The resilience of these coastal ecosystems under a changing climate is uncertain, as they are under pressure from accelerated sea-level rise (SLR) and
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-019-01219-x) contains supplementary material, which is available to authorized users. * Xiaorong Li [email protected]; [email protected] 1
Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Roxby Building, Chatham Street, Liverpool L69 7ZT, UK
changes in the frequency and/or magnitude of storms (e.g. Leonardi and Fagherazzi 2014; Chambers et al. 2016; Leonardi et al. 2017). Indeed, a recent study shows a high probability for salt marsh retreat under projected future sealevel rise (Horton et al. 2018), whilst Leonardi et al. (2017) stresses the critical importance of storms in determining the long-term response. Depending on the
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