Flood hazard assessment for a hyper-tidal estuary as a function of tide-surge-morphology interaction

Lyddon, Charlotte; Brown, Jennifer ORCID:; Leonardi, Nicoletta; Plater, Andrew J.. 2018 Flood hazard assessment for a hyper-tidal estuary as a function of tide-surge-morphology interaction. Estuaries and Coasts, 41 (6). 1565-1586.

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Astronomical high tides and meteorological storm surges present a combined flood hazard to communities and infrastructure. There is a need to incorporate the impact of tide-surge interaction and the spatial and temporal variability of the combined flood hazard in flood risk assessments, especially in hyper-tidal estuaries where the consequences of tide and storm surge concurrence can be catastrophic. Delft3D-FLOW is used to assess up-estuary variability in extreme water levels for a range of historical events of different severity within the Severn Estuary, southwest England as an example. The influence of the following on flood hazard is investigated: (i) event severity, (ii) timing of the peak of a storm surge relative to tidal high water and (iii) the temporal distribution of the storm surge component (here in termed the surge skewness). Results show when modelling a local area event severity is most important control on flood hazard. Tide-surge concurrence increases flood hazard throughout the estuary. Positive surge skewness can result in a greater variability of extreme water levels and residual surge component, the effects of which are magnified up-estuary by estuarine geometry to exacerbate flood hazard. The concepts and methodology shown here can be applied to other estuaries worldwide.

Item Type: Publication - Article
Digital Object Identifier (DOI):
ISSN: 1559-2723
Date made live: 14 Mar 2018 11:29 +0 (UTC)

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