A scenario-based approach to evaluating potential environmental impacts following a tidal barrage installation

Ian M. Kidd, A Fisher, S Chai, Jenny DAVIS

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    Total exclusion barrages have a high impact on estuarine systems as they are permanent barriers to tidal flow. The environmental impacts of five putative barrages in various locations within the Tamar River estuary in northern Tasmania, Australia were assessed by considering likely hydrological, morphological and ecological outcomes. We found that all hypothetical barrages would produce downstream silt accretion, some to the point where a major port would become unusable without ongoing dredging. The closer a barrage was located to the mouth of the estuary, the greater the loss of tidal prism, the lower the effect of flushing by floodwaters, and the greater the loss of estuarine biodiversity. Eradication of invasive rice grass (Spartina anglica) in the mid estuary is potentially a positive outcome, whilst constant headpond surface heights could cause bank erosion and subsidence. Loss of tidal wetlands would contravene the international treaties protecting the migratory waterbirds which use these habitats. Installation of a barrage at the uppermost location appears to represent the best trade-off between adverse impacts and increased recreational and visual amenity. Unfortunately, barrage installation at any site within the estuary fails to address the major anthropogenic stressors of reduced riverine inflows and tidal flushing. A wider sustainability analysis is needed in which the costs of meeting environmental, social and economic objectives are considered.
    Original languageEnglish
    Pages (from-to)9-19
    Number of pages11
    JournalOcean and Coastal Management
    Volume116
    DOIs
    Publication statusPublished - 2015

    Fingerprint

    barrage
    environmental impact
    estuaries
    estuary
    Spartina anglica
    bank erosion
    flushing
    treaties
    harbors (waterways)
    subsidence
    water birds
    Tasmania
    silt
    mouth
    wetlands
    amenity
    biodiversity
    grasses
    dredging
    habitat use

    Cite this

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    title = "A scenario-based approach to evaluating potential environmental impacts following a tidal barrage installation",
    abstract = "Total exclusion barrages have a high impact on estuarine systems as they are permanent barriers to tidal flow. The environmental impacts of five putative barrages in various locations within the Tamar River estuary in northern Tasmania, Australia were assessed by considering likely hydrological, morphological and ecological outcomes. We found that all hypothetical barrages would produce downstream silt accretion, some to the point where a major port would become unusable without ongoing dredging. The closer a barrage was located to the mouth of the estuary, the greater the loss of tidal prism, the lower the effect of flushing by floodwaters, and the greater the loss of estuarine biodiversity. Eradication of invasive rice grass (Spartina anglica) in the mid estuary is potentially a positive outcome, whilst constant headpond surface heights could cause bank erosion and subsidence. Loss of tidal wetlands would contravene the international treaties protecting the migratory waterbirds which use these habitats. Installation of a barrage at the uppermost location appears to represent the best trade-off between adverse impacts and increased recreational and visual amenity. Unfortunately, barrage installation at any site within the estuary fails to address the major anthropogenic stressors of reduced riverine inflows and tidal flushing. A wider sustainability analysis is needed in which the costs of meeting environmental, social and economic objectives are considered.",
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    A scenario-based approach to evaluating potential environmental impacts following a tidal barrage installation. / Kidd, Ian M.; Fisher, A; Chai, S; DAVIS, Jenny.

    In: Ocean and Coastal Management, Vol. 116, 2015, p. 9-19.

    Research output: Contribution to journalArticle

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