This blog is not about Climate Change, which is complex, long- term, important and in the future. It is about weather, which is simpler, short- term, urgent and happening now.
The Swan and Canning Rivers are loved by this community and are key attractions of Perth. Riverside infrastructure of the freeway and rail line is a vital part of WA’s economy.
Most riverside infrastructure was built in the 1950's to 70's through the Public Works Dept, which no longer exists. The state of our infrastructure is aging, under- capacity and not up to current standards. Basic maintenance costs are increasing with age. The walls are already under stress during high tides, strong winds and storm surges.
Winter storms have long been recognised as a major hazard in WA. The Noongar people moved inland during the cooler months, partly to avoid the weather.
In June 1801, the French explorer Nicholas Baudin felt the full force of a winter gale as he rounded Cape Leeuwin en route to Rottnest Island.
Early settlers were quickly made aware of the dangers of winter gales. The loss of a ship and damage to others during a gale in 1830 threatened the existence of the colony.
In 1934, the Swan River rose almost 6 metres in less than 8 hours at Guildford in response to heavy rain upstream.
In 1955 storms caused massive coastal erosion on Perth's beaches. At Cottesloe not a bit of sand was left anywhere along the seaward side of the main promenade.
In 1963 a strong front caused wind gusts of 150 km/h in Perth.
In 1981 a storm with heavy rain produced widespread damage, Perth being littered with fallen trees, power lines and debris from damaged buildings.
In 1994 one of the most destructive weather events to affect Perth brought a damage bill of $37 million
In 2003 Fremantle recorded a storm surge of 0.8 m, causing the highest tide ever recorded there.
Storms with severe winds can cause heavy rain, but cold fronts with slow- moving cloud bands cause the heaviest total rainfall.
A worst case scenario is to have a peak in gale-force winds coinciding with a high tide, causing a storm surge, pushing East against floodwaters coming down the Swan River.
Our last major floods occurred in 1963 and 1964. In recent decades this has not occurred, thank goodness, because Perth's infrastructure is just not designed to cope with it.
This plot, from the Bureau of Meteorology, shows the frequency of heavy rain in Perth since 1883, in 15- year blocks. It highlights the sudden decrease in heavy rainfall events in the 1960s. It was in this peaceful era that we built our riverside infrastructure. In hindsight, we built in all the wrong places.
Our rainfall pattern is trending towards that of the period when we experienced our worst storms, floods and damage. Our built and natural environments and our economic links are under threat.
These matters affect all 21 Councils on the river banks. Management requires a combined approach of all members. It is not appropriate that it be handled by each Council separately. It is a big issue, it affects the economy of the whole State and we require support from both State and Federal Governments.
WALGA has recognised this and has formed the "C21" group of Councils, chaired by James Best, our Mayor. The Perth Natural Resources Management Group, with which I serve, also acts to coordinate the actions of individual local councils.
These two groups have prepared a business case for combined and effective management of our rivers.
The Swan River Trust budget allocated by State is just way too small for the task ahead.
City of South Perth has presented an Infrastructure Australia submission on behalf of the 21 councils for $83M, based on priorities set by Swan River Trust. We need support of State Cabinet for this.
A further approach will be made for Commonwealth funding later today. An additional submission is being made for $3.5M for repair of seriously deteriorated river walls.
We are calling for support for our combined submission to manage these rivers that we love, that are part of our economy and part of our social fabric.
I hope that when the Commonwealth Heads of Government visit our city next year, 2011, we can demonstrate with pride the management of our rivers.
Please feel free to have your say; it makes a difference. Just click on “Comments” below and log in as Name (preferred) or Anonymous, or email me and I’ll post your comments for you.
