Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tropical cyclone-induced storm surges

• Published in: Climate dynamics Vol. 42; no. 1-2; pp. 139 - 157
• Main Authors: Haigh, Ivan D., MacPherson, Leigh R., Mason, Matthew S., Wijeratne, E. M. S., Pattiaratchi, Charitha B., Crompton, Ryan P., George, Steve
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2014; Springer; Springer Nature B.V
• Subjects: Annual variations; Australia; climate; Climatology; coasts; continental shelf; Continental shelves; Cyclones; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; engineering; Engineering and environment geology. Geothermics; engineers; Environment; Environmental aspects; Exact sciences and technology; External geophysics; Fluid mechanics; Geophysics/Geodesy; Hurricanes; Hydrodynamics; Hydrofoil boats; Internet; land use; Land use planning; managers; Meteorology; Natural hazards: prediction, damages, etc; Oceanography; Physics of the oceans; planning; researchers; risk; Sea level; Storm surges; Storms; Surface waves, tides and sea level. Seiches; Tidal analysis; Tidal waves; tides; Tropical cyclones; United States; wastes; Water levels; Australia; United States; Extra-tropical cyclones; Tropical cyclones; Storm surges; Hurricanes; Extreme water levels; Return levels; Australia; Tides; Return periods; Century 21st; Extreme event; Australasia; Forecast model; tides; coastal zone; hurricanes; Return period; Severe weather; Sea surge; Tropical cyclone; Risk assessment; Storm surge; Risk management; Natural hazards; sea level
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-012-1653-0

The incidence of major storm surges in the last decade have dramatically emphasized the immense destructive capabilities of extreme water level events, particularly when driven by severe tropical cyclones. Given this risk, it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood and erosion management, engineering and for future land-use planning and to ensure the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. Australia has a long history of coastal flooding from tropical cyclones. Using a novel integration of two modeling techniques, this paper provides the first estimates of present day extreme water level exceedance probabilities around the whole coastline of Australia, and the first estimates that combine the influence of astronomical tides, storm surges generated by both extra-tropical and tropical cyclones, and seasonal and inter-annual variations in mean sea level. Initially, an analysis of tide gauge records has been used to assess the characteristics of tropical cyclone-induced surges around Australia. However, given the dearth (temporal and spatial) of information around much of the coastline, and therefore the inability of these gauge records to adequately describe the regional climatology, an observationally based stochastic tropical cyclone model has been developed to synthetically extend the tropical cyclone record to 10,000 years. Wind and pressure fields derived for these synthetically generated events have then been used to drive a hydrodynamic model of the Australian continental shelf region with annual maximum water levels extracted to estimate exceedance probabilities around the coastline. To validate this methodology, selected historic storm surge events have been simulated and resultant storm surges compared with gauge records. Tropical cyclone induced exceedance probabilities have been combined with estimates derived from a 61-year water level hindcast described in a companion paper to give a single estimate of present day extreme water level probabilities around the whole coastline of Australia. Results of this work are freely available to coastal engineers, managers and researchers via a web-based tool ( www.sealevelrise.info ). The described methodology could be applied to other regions of the world, like the US east coast, that are subject to both extra-tropical and tropical cyclones.