"Inland tsunami" in Toowoomba, Queensland, Australia; floods in Brazil; Sri Lanka

AP photo from here

More than 375 people are reported dead in floods and landslides in Brazil (note added on 1/17/11: over 600 deaths now reported). A million are reported homeless due to floods in Sri Lanka. Major floods have been occurring in Australia, building up for several months and culminating last night with the flooding of Brisbane, Australia's third-largest city. In spite of individual stories of courage and heroism, there have been at least 34 deaths there. The National Post in Canada reports "Horrific picture emerges of Australia flash floods", and that Brisbane resembled a "war zone" as the flood hit 30,000 properties.

Here and here are two excellent and scary videos of the Toowoomba flood:

The water rose so quickly in Toowoomba that the event has been described as an "inland tsumani".     Perhaps this poem--one verse from a nineteenth century Queensland droving ballad, "The Overlander"  about northern Queenslan--summarizes the setting:

"I come from the northern plains

Where girls and grass are scanty;

Where the creeks run dry or ten feet high,

And it's either drought or plenty."

The whole ballad is sung on this video.

A discussion of the role of La Nina and the North Atlantic Oscillation in these weather events is here. Although there is much speculation on the WWW about the role or implications of these events and climate change, there are also lessons to be learned by looking back 150 years at the history of this part of Queensland.  It is tragically like many, many other places in the world where humans have altered their landscapes. I excerpt the following history from this reference.

For more than a century, the Queensland government had a vision, and determination, to introduce farming into this region. Australian history in the 1800's is complex.  Queensland became an independent state in 1850, with a complex history of replacing pastoralism with farming and dairying--dairying being needed to sustain the farmers until crops were sold, or in case they failed.  In the 1887 a Department of Agriculture was established in Queensland, and by World War One, the region around Toowoomba was exporting grain.

In order to meet the demand for fencing, an enormous number of trees were felled, depleting the forest resource.  Reserves and parks were established in the headwaters, but tree-clearing and increasing stock numbers caused erosion on ridges and compaction of vegetation on floodplains. In the 1870's and 180's, residents of Toowoomba changed the forest into orchards, which caused the water table to rise and swamps to developed.  Drainage became a problem, and mixing of raw sewage and groundwater wells resulted in a series of typhoid epidemics in the 1870's and 1880's. This was corrected by civil engineering and introduction of sewage systems.

However, as has been observed around the world, the replacement of vegetation with urban roads and buildings increased the rate of runoff to the main river channels. Flash flooding became a common experience in the main towns. Thus, more than a century of history preceded the tragedy of this week.

More on flash flood dynamics in a later post.