Uncertainty in estuarine extreme water level predictions due to surge-tide interaction

Lyddon, Charlotte; Brown, Jenny M. ORCID: https://orcid.org/0000-0002-3894-4651; Leonardi, Nicoletta; Plater, Andrew J.. 2018 Uncertainty in estuarine extreme water level predictions due to surge-tide interaction. PLOS ONE, 13 (10). e0206200. https://doi.org/10.1371/journal.pone.0206200

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Abstract/Summary

Storm surge is often the greatest threat to life and critical infrastructures during hurricanes and violent storms. Millions of people living in low-lying coastal zones and critical infrastructure within this zone rely on accurate storm surge forecast for disaster prevention and flood hazard mitigation. However, variability in residual sea level up-estuary, defined here as observed sea level minus predicted tide, can enhance total water levels; variability in the surge thus needs to be captured accurately to reduce uncertainty in site specific hazard assessment. Delft3D-FLOW is used to investigate surge variability, and the influence of storm surge timing on barotropic tide-surge propagation in a tide-dominant estuary using the Severn Estuary, south-west England, as an example. Model results show maximum surge elevation increases exponentially up-estuary and, for a range of surge timings consistently occurs on the flood tide. In the Severn Estuary, over a distance of 40 km from the most upstream tide gauge at Oldbury, the maximum surge elevation increases by 255%. Up-estuary locations experience short duration, high magnitude surge elevations and greater variability due to shallow-water effects and channel convergence. The results show that surge predictions from forecasting systems at tide gauge locations could under-predict the magnitude and duration of surge contribution to up-estuary water levels. Due to the large tidal range and dynamic nature of hyper-tidal estuaries, local forecasting systems should consider changes in surge elevation and shape with distance up-estuary from nearby tide gauge sites to minimize uncertainties in flood hazard assessment.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1371/journal.pone.0206200
ISSN:	1932-6203
Date made live:	07 Jan 2019 14:32 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/521970

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