Growing population and less intense weather in recent decades has led to relaxation of Australian planning laws

Andrew Ash in the Courier-Mail (Brisbane): In the aftermath of Tropical Cyclone Oswald, questions are being asked about urban planning strategies and approaches to rebuilding. The risks have been growing for decades, especially in southeast Queensland, but until the last few years we have been dealt some kind cards when it comes to intense weather.

Consequently, we have not been paying attention to these risks as they have been gradually ramping up. By far the greatest increase in risk has been the growing population and the concentration of these increasing numbers of people on flood plains, mostly close to the coast.

Since 1950, southeast Queensland's population has grown from 660,000 to more than 3,000,000 people. In parallel, there has been a shift in the type and size of houses. Classic high-set Queenslanders have been replaced largely by low-set houses on concrete slabs. Compounding this is the increase in capital now invested in our homes. Today's dwelling price-to-income ratios are more than double levels of 40 years ago.

When you put these three factors of population growth in vulnerable locations, more vulnerable dwellings and higher capital tied up in houses, there has been a dramatic increase in risk.

However, the cyclical nature of our weather and climate has meant southeast Queensland has been exposed to less intense weather in the past 30 years than the three decades prior to that, when 17 tropical cyclones crossed the east coast of Queensland.

The past three decades have seen a greater frequency of El Nino events in which only two cyclones crossed the coast in the southeast region. (Indeed, it is more than 20 years since a cyclone has crossed - near Byron Bay). For most people there is little memory or understanding of what damage these cyclones can cause....

NASA image of Tropical Cyclone Oswald, January 21, 2013