Living in the shadow of a great flood

In June 2016, Launceston experienced its most damaging floods in nearly 50 years, with similarities to the city’s worst ever flooding in 1929. Thankfully, the city’s recently rebuilt flood levees, a project costing nearly $60 million and taking over six years to complete, proved their worth.

The people of Launceston have lived in the shadow of a great flood for nearly a century. In 1929 torrential rains fed destructive floodwaters that claimed more than 20 lives across Northern Tasmania, caused widespread damage and forced 4,000 people in low lying areas of Launceston from their homes.

Launceston’s Flood Risk Management Project, completed in late 2015, is managed by the Launceston Flood Authority and was built to withstand a one-in-two-hundred-year flood. The city’s original system of flood levees were built in the 1960s, the dominant feature being a huge concrete ‘training’ wall along Royal Park.

They, too, had only just been completed when tested by a major flood in May 1969. The flood of 2016 ranks behind 1969 and 1929 in terms of water flow but again demonstrated how quickly and devastating heavy rainfall events can be despite the best of planning and flood mitigation technology.

After drought conditions across much of Tasmania throughout 2015, heavy rainfall in the catchments of the North and South Esk rivers in June 2016 occurred in a sequence similar to 1929, forcing deadly floodwaters to converge simultaneously into the Tamar Estuary. Elsewhere in Tasmania, the floodwaters claimed three lives, destroyed public and private infrastructure, and wiped out livestock and crops worth millions of dollars.

It happened with deadly speed. At the end of the first week of June, the Bureau of Meteorology warned that a southward moving complex low pressure system was working its way down the Eastern seaboard of Australia producing heavy rains, damaging winds and widespread flooding.

BOM records show that moderate to heavy falls were recorded over much of the eastern half of Tasmania but some places in the north had record high daily rainfall totals. Pyengana, to the north-east of Launceston, recorded 129 mm on Sunday 5 June and 211 mm on Monday 6 June. At Loongana, behind Ulverstone, the weekly total was 338 mm, with 248 mm on 6 June, and at Yolla the weekly total was 318mm with 248 mm recorded on 6 June.

The Bureau of Meteorology predicted that the flood peak in the North Esk River would exceed the levels of 1929 and residents of some areas of Invermay and Newstead were advised to evacuate. As in 1929, an evacuation centre was established in the Albert Hall but this was later relocated to the Silverdome at Prospect and another evacuation centre was opened at the Newnham campus of the University of Tasmania.

As the Launceston Flood Authority installed the city’s floodgates, the ABC reported that about 3,000 residents and 800 businesses had been advised to evacuate from the low-lying suburb of Invermay. When the roaring floodwaters swept through the Launceston section of the North Esk on the morning of 7 June about 50 homes were inundated, mostly in Newstead.

The flood peak in the South Esk River didn’t reach the 1929 level but West Tamar Road was cut north of Paterson Bridge and with the Charles St Bridge flood gates in place there was traffic chaos in Launceston on Tuesday and Wednesday (7 and 8 June).

At the historic Duck Reach Power Station in the Cataract Gorge, site of the first publicly owned hydro-electric power station in Australia, the flood crest came close to the suspension footbridge, a replacement for the one destroyed in 1969, which in turn was a replacement of one swept away in 1929.

Across Tasmania the floods inundated about 200 homes, destroyed numerous bridges and damaged more than 100 roads. The damage bill for public infrastructure was reported to have exceeded $100 million.

At the Trevallyn Power Station the floodwaters in 2016 peaked at 2,248 cubic metres a second (cumecs) while Hydro Tasmania records put the flow in the South Esk in May 1969 at 2,670 cumecs. The flow in 1929 was recorded as 3,964 cumecs.

All these flood events however fall short of the Launceston flood of December 1863. On that occasion it has been calculated that the floodwaters raging down the Cataract Gorge peaked at 4,625 cumecs. The Examiner said the floodwaters almost touched the new Gorge Bridge.

(Written for the book THE FABRIC OF LAUNCESTON: A Collaborative Community History, to be launched on 6 August 2016)