Thank you to all our family and friends who have called or asked how we are going amongst all the flooding in Queensland. A lot has happened in the past 7 days, so let me walk you through some of it.
A series of floods hit eastern Australia in December 2010 and January 2011. Many of the affected areas have been in Queensland, but the flooding has also impacted parts of New South Wales and Victoria.
Large parts of Queensland received much heavier than usual rainfall throughout the (southern) spring and Christmas 2010 periods. Around 7 January 2011, water management authorities were forced to start release thousands of gigalitres of rainwater from the Wivenhoe Dam into the Brisbane River, in order to avoid the dam breaching its banks.
Toowoomba, in the Darling Downs area west of Brisbane, was hit by flash-flooding after more than 160mm of rain fell in 36 hours to 10 January 2011. Much of that water travelled down the range towards Brisbane, to join the water that had been released in to the Brisbane River from Wivenhoe Dam. While the controlled releases presented some risk of flooding to Brisbane, the further rainfall in the Darling Downs and Brisbane Valley made flooding a certainty.
On Tuesday morning, several office buildings in the Brisbane CBD started to evacuate. It took Anna and me more than two hours to reach home by bus in the heavy rain. We quickly packed a few clothes and important papers, and headed to higher ground. Fortunately, we were able to stay with friends far enough away from the now-raging Brisbane River.
By Tuesday evening, huge areas of Brisbane’s southern and western suburbs, including West End, Rocklea, Milton and South Bank were flooding. My friend Tyler took a number of photos of South Bank and the Brisbane CBD on January 12, January 13 and January 14 and posted them to Facebook (login required). CBC.ca also featured some of Tyler’s photos and videos (no login needed).
Bronwyn has amazing photos of the Eagle St and Riverside areas of the Brisbane CBD (Coffee Club is on the second level at Eagle St pier – the restaurants below have flooded to the ceiling), while Mike’s house was badly flooded (login required).
Our suburb of Bulimba was expected to flood, and as our house is a mere two streets from the river, we did not hold out much hope of it staying dry. On Wednesday morning, we went back to the house to put as much of our furniture up as high as possible, and snuck a few photos of the raging river.
The water started to cover the roads just before noon, so we said goodbye and good luck to the house.
On Thursday morning, we watched in frustration as the TV news helicopters buzzed all over the southern and western suburbs and the Brisbane CBD. The images were unreal! But we could not figure out why the news seemed to refuse to mention any areas beyond the CBD.
We drove to the house, and were shocked to discover that our house had been strangely and miraculously untouched! Water had flowed up to the industrial property next to us, but only soaked the grass and roads.
A number of properties upriver from us in Bulimba and Hawthorne were not so lucky. You can see in my photos from 13 January that there are a number of new “lakes” surrounding many properties and lying across roadways.
Why was our house not flooded on January 12?
The Brisbane River becomes wider and deeper when its flows reach the Bulimba area. So the main threat of flooding on our property is a storm tide. This is caused by wind and atmospheric pressure, such as tropical cyclones or storms, that produce higher than usual tide levels. In short, we are most likely to be flooded by water that has been pushed up-river by storm tides and strong winds, and less by the volume of water that flows down-river.
The storm tide scenario happened in Brisbane a big way in January 1974 and February 1893. The river’s peak in the ’74 flood measured 6.6 metres at the Port Office gauge and approximately 5.5 metres at the city gauge. That level likely meant that our house in Bulimba was under 2-3 metres of water.
The flood modeling for 13-14 January 2011 indicated that the river would exceed its 1974 levels. But very fortunately for us, the rain stopped on 11 January and we did not have a cyclone pushing water up-river.
The Big Wet 2011 is not over yet. There are a number of cyclones to the northeast of Queensland, and the next king tide is expected to hit Brisbane on Friday, 21 January. Meanwhile, the rainy season usually runs through to March. This is all the better reason to (finally) finish my disaster/storm kit!