Coastal Flooding

Oceans 2025 Theme 3, work package 3.6

There is a possibility that global warming may bring an increase in frequency and intensity of extreme events. In the marine context, increased flooding due to larger and more frequent storm surges (combined with larger waves and increased rainfall) could have a significant impact on economic and social systems, as well as fragile ecosystems in vulnerable areas. Understanding the risks presented by extreme events (e.g. large storm surges combined with high tides) is vital for their successful management. The December 2004 Sumatra-Andaman tsunami demonstrated the need to better quantify - and mitigate against - the consequences of very high impact, low probability events in coastal waters.

An important tool in the management of episodic flood events is an enhanced forecasting capability, with a probabilistic quantification of uncertainty. Improved operational models lead to better risk management, and inform high-level policy decisions regarding future investment in coastal defence.

Aims of the work package

• Improved forecasting tools for surges and coastal flooding, with state-of-the-art tide/surge/wave models coupled to fluvial and estuarine inundation models.
• Creation of an envelope of extreme sea levels around the UK resulting from a range of future climate scenarios.
• To predict the response of the shoreline to an increase in the frequency and intensity of storm events.
• To build upon Defra funded research (link) and quantify the risk of tsunami impact in UK coastal waters.

Deliverables

• A real-time sea level data assimilation solution for the operational modelling suite within the Storm Tide Forecasting System (STFS).
• A probabilistic ensemble forecasting system for storm surges.
• Coupled coastal-floodplain inundation models.
• Global barotropic models, driven by future atmospheric GCM scenarios, in order to assess the differing characteristic responses of continental shelves worldwide.
• Evaluation of the benefits of unstructured models for extreme events.
• Forecast tools based on artificial intelligence techniques.

Recent publications

Randon N., Lawry J., Horsburgh K.J. and Cluckie I. (2007) Fuzzy Bayesian Modelling of Sea-Level along the East Coast of Britain. IEEE Transaction on Fuzzy Systems, in press.

Horsburgh, K.J. and Wilson, C. (2007) Tide-surge interaction and its role in the distribution of surge residuals in the North Sea. Journal of Geophysical Research Oceans, 112, C08003, doi:10.1029/2006JC004033.

Butler, A., Heffernan, J.E., Tawn, J.A., Flather, R.A. and Horsburgh, K.J. (2006) Extreme value analysis of decadal variations in storm surge elevations. Journal of Marine Systems, 67, 189-200.

Figure 1. The frequency of residual (i.e. non tidal sea level) peak timing with respect to high water

Figure 2. Maximum elevation (m) obtained around Cornwall from a numerical model simulation of the Lisbon 1755 tsunami