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The Australian Coastal Zone and Global Change: Research Needs

Australian Academy of Science, Becker House, Canberra. Friday 16 December 1994

Coastal impacts of tropical cyclones, techniques, social and economic aspects

Dr Greg Holland

What I would like to talk about is a project that is fairly new but is definitely going to grow to be one of the major components of my group in BMRC, and that is tropical cyclone impact on coastal communities. This is a highly multidisciplinary study which is coordinated by us in BMRC, by the Brisbane Tropical Cyclone Warning Centre, in particular Rex Falls, and by Ann's group at Macquarie University.

It is multidisciplinary with a wide range of disciplines, from town planners through city engineers to demographic people to people who are specialists in buildings and such involved in the project. Our objectives are to, firstly, quantify the impact of tropical cyclones on coastal communities under current climatic conditions, as well as demographic trends. Development of improved techniques for assessing and forecasting coastal impacts: what we are currently doing is having a good hard look at storm surge models, for example, mainly to convince ourselves that they are the most accurate and the best that we can use, and then we will be going on to develop some speciality techniques from that. Another aspect is boundary layer modelling of what happens when a tropical cyclone comes ashore. There has been no work done in that area at all, so we are starting on virgin ground.

The third objective is assessing the potential impact trends arising from climate change and, since I did not want to just give an advertisement here, that is actually what the last half of my talk will be. The fourth one is, given all of that, development of improved risk and counter-disaster methods, both at the time scale of, 'The storm is out there right now. What do we do with the people on the coast?', and also at the time scales of planning and longer term activities. I have to acknowledge that it was the NGAC, the National Greenhouse Advisory Committee, that helped us get this project up and running. I am very grateful to them for that. I have since obtained substantial support also from the US Office of Naval Research, and we have in the pipeline funding from other areas. But we never have enough money for those things so if you have any extra funds we would be most grateful to help you spend them.

Overhead 1 - Tropical Cyclone Impact on Coastal Communities

Overhead 1

Let me put the project in the context. This is a slide made up by Rex Falls. It is a little bit old now but it gives the generic aspects. Essentially what we are trying to do is say, 'We have one problem, which is tropical cyclone hazard modelling; we have another problem, which is vulnerability assessment; and we have another problem, which is counter-disaster type methods'. To attack all of this in some sort of logical fashion we have centred on the Queensland coast but because we need a coastal stretch to work with, it is generic work that we are doing. We have picked within that area a set of specific sites. Those sites were selected either because of their vulnerability, their meteorological or oceanographic interest or other reasons. This gives us a perfect laboratory to test out our techniques and work away at improving the overall system. All of the techniques that are being developed are generically useful anywhere on earth.

Overhead 2

Overhead 2

In perhaps more of a summary fashion, 'Why do we want to do this?'. This cartoon was found by Ann Henderson-Sellers. Basically we have Captain MacIntyre who has been off for his nightly beer at the pub and he, in this thing, is killed by a following sea which is coming around the corner. The aspects of the project are as follows. Firstly, storm surge and high wind damage are an extremely important component of not just the population, the effects on the natural geography of the area. Storm surges can be horrific. The highest storm surge in Australia is actually higher than the roof of this building, and that is blue water; that is not waves. You might like to think of your favourite coastal site and imagine something like 14 metres of water coming past and how you would survive that. So, there is a terrific social and other problem involved here.

We could stop Captain MacIntyre going to the pub altogether, but he likes his beer at night and also the pub owner would get a bit upset about not having the economic return. So, that is not a viable answer. The whole idea of the project is to let him go to the pub, or the tourist come to the tourist facility, or whatever, as often and whenever they like, and to finetune the techniques so that we get them out of that region only when we actually have to. So, we save the economy substantial amounts of money in addition to loss of life and safety aspects.

Studies done within the Bureau of Meteorology indicate that the cost of the current system, just for the operational warning part of it, is of the order of $200-$300 million a year. That is what the warning system costs the country, forgetting about the cyclones coming ashore.

I will go into a little bit of advertisement about some of the aspects that we have been working with. Firstly, we are looking at observational components, and this is only peripherally involved in the particular project that I am talking about here but I would like to pass information to some of the people here that need observations. This is a small aircraft that is being developed in Australia in conjunction with some US interests. I would like to just read the statistics: 3-metre wingspan; between 12 and 15 kilograms all up weight; 20cc motor; its range, fully autonomous, is 8,000 kilometres, and it can stay in the air at low levels five days or at high levels three days. The aircraft is currently flying in a test mode and we expect over the next three years to have that at its full operational capacity, which means that essentially anywhere you want to go, on the Australian coastline in particular, you can actually go and take observations. Indeed, we will be taking observations directly inside tropical cyclones.

Many of you will know about the site that we run in northern Australia at Darwin. It is the most heavily instrumented atmospheric observing site in the southern hemisphere and has operated for several years with a very good record of the changing year-to-year aspects of the weather in the Darwin region. As a part of this project we have a site just off Western Australia, on North West Cape, where there is a Navy communications array, with the highest tower being at 1,400 feet. We are currently instrumenting two of the towers in that array with a full suite of atmospheric observations. This area happens to be frequented by tropical cyclones, and our aim is to be able to get the first set of proper observations in the lower levels of tropical cyclones in the vicinity of a coast. I think over the next few years we will be able to use that to go on and finetune our techniques even further.

Coming down to a local community level, one township that was on that list was Mackay, it is about half way up the Queensland coast. Mackay is the best documented storm surge on an actual built-up area that we have. The 1914 storm surge actually covered much of the current city area. Should that be repeated - and that was not a particularly big storm surge - approximately one-third of Mackay would be destroyed.

The city knows about the risk and are very happy to work with us; so we will be working very closely with this community on the storm surge, the windfield modelling, and, having done all of that, what is the real threat to this community and how can we get the community to respond to that threat - both in a sense of what they should do in planning in the future, but also what they will do when the cyclone is physically sitting off the shore and they need to do something immediately about it.

This is the first bit of real research that has come out of the project, which has only been going for the last six months or so. This is some work by myself in conjunction with Ann and her group at Macquarie University. I am going to just look at the maximum potential intensity of tropical cyclones from a thermodynamic viewpoint and some of its implications for climate change.