Numerical Modelling of Tropical Cyclone Storm Surge

The Great Barrier Reef Region which constitutes the north-eastern continental shelf waters of Australia, is an area that is subject to both large astronomical tides and the passage of tropical cyclones (hurricanes). One section of this area, centred on Mackay, is characterised by particularly high tides, with a springs range of order 10 metres. Numerical hydrodynamic modelling is used in the present study to: (a) simulate the M tide to investigate possible effects of the reef barrier on tidal amplification; (b) simulate the passage of a tropical cyclone across the continental shelf; (c) investigate the effect and consequences of non-linear surge/tide interactions. The recent discovery of a major shipping route through the reef in this area and the continuing development of natural resources makes a much more detailed understanding of the region's hydrodynamics essential for coastal engineering.

Section: Sia^mentioning

confidence: 87%

“…Further details of the model can be found in Refs. (1,7,11,12). The equations of motion to be solved are: it + 5x<iT> + S?<I-> + CT " " H i?…”

Section: Methods Op Solutionmentioning

confidence: 99%

Simulation of Tides and Storm Surges in the Great Barrier Reef Region

Stark

Bode

Mason

1984

“…Numerical solutions of these equations are readily y accomplished under quite general conditions of bathymetry, coastal detail and meteorological forcing. One such example is the numerical hydrodynamic model SURGE described by Sobey, Harper and Mitchell (14) and Sobey,Harper and Stark (13) .…”

Section: Hindcasting the Sea Responsementioning

confidence: 99%

Synthesis Op Hurricane Response Hydrographs

Sobey

1982

Self Cite

A hindcasting methodology is described for the total water level and wave hydrographs at a coastal site during a hurricane. It accommodates phasing of the separate components of the sustained water level (astronomical tide, storm tide, breaking wave setup) , as well as storm variability and coastal bathymetry. Complete hindcast models are utilised, but an intermediate cost and precision is achieved by compromising the number of complete hindcast storms, rather than the precision of the hindcast model. A synthesis technique is developed to predict the response hydrographs of the remaining storms in the historical data set.

“…The meteorological characteristics of a tropical cyclone and Australian data on the statistics of the various cyclone parameters are discussed in detail in Ref. 10. The tropical cyclone is essentially an atmospheric phenomenon, developing over tropical seas in mid to late summer.…”

Section: Tropical Cyclone Wind Fieldmentioning

confidence: 99%

“…In formal terms the probability of a landfalling tropical cyclone crossing the coast a distance y from a nominated coastal site with equal probability over a length of coast extending a distance L both sides of the site is described by the PDF 1 for -L « y S L f(y) = { 2L (17) 0 elsewhere. The remaining decision concerns storm direction and here some very subjective assumptions are necessary as the Card 13 data is very inconclusive (10). It has been assumed that only one-half of all tropical cyclones passing within 200 n miles of the site actually cross the coast in this region and that these storms cross essentially at right angles to the general line of coastline; the remaining storms are assumed to move away from the site and not to unduly influence the coastal wave climate.…”

Section: Tropical Cyclone Wind Fieldmentioning

confidence: 99%

Wind Wave Frequencies in a Tropical Cyclone Region

Sobay

1978

Australia's Coral Sea coast from Bundaberg north to Cape York has a wind wave climate that is almost unique. The coastline is afforded unparalleled protection from the 1900 km Great Barrier Reef, yet it lies in a tropical cyclone region and must expect recurrent intense wind and wave conditions. The Great Barrier Reef is a continuous chain of quite separate coral reef clusters located near the edge of the continental shelf. The separate reefs are often exposed at low tide, the inner fringe of the clusters ranges from 10 km offshore north of Cairns to 200 km offshore south of Rockhampton and the outer fringe is typically some 50 km further offshore, beyond which the ocean bed drops rapidly away. Incident wave energy from the Coral Sea is invariably dissipated on the outer edge of the Reef and wave conditions on the continental shelf can reasonably be considered due to local wind conditions. The Reef imposes an effective fetch limitations on wave generation over the continental shelf and there is, as a consequence, a moderately rapid response of wave conditions to changes in local wind conditions. A pronounced diurnal variation in the wind climate is reflected also in the wave climate and the stability of the region's tropical climate leads to frequent calm to slight sea conditions. This stability however is occasionally exploded by the generation and passage of a tropical cyclone in mid to late summer. Large waves can be generated by the intense winds of the tropical cyclone (hurricane or typhoon), often an order of magnitude greater than those in response to non-cyclonic events. The rational design of coastal structures and the rational pursuit of coastal zone management requires appropriate estimates of the frequency of occurrence of waves of various heights. Ideally such information is obtained from an extreme value analysis of long term wave records at the particular site in question. Permanent wave recording programs unfortunately have only become common practice in the present decade and wave records, if they exist at all for a particular site, are rarely long enough to allow a satisfactory extreme value analysis. It is clear, in the Australian context at least, that historical wave data alone is not yet sufficient to derive satisfactory estimates of long term wave frequencies. The alternative is system modelling. Wind is a major meteorological variable and its long term recording has been a standard meteorological practice now for over half a century.