Postcard of Launceston's Cataract Gorge in flood, undated (Tasmaniana Library, SLT)
Floods were first recorded as widespread throughout Van Diemen's Land in September 1828, when most bridges in the Midlands were carried away. The Ross bridge survived, although it was completely covered by water in the first of many such instances. The South Esk basin, Tasmania's largest water catchment area, has experienced many major floods since, including 1852, 1863, 1872, 1889, 1893, 1921, 1929, 1969 and 1970. In order of magnitude, the major flood was that of 1863 with 4625 cusecs of water in the South Esk, followed by 1852 with 4190 cusecs. Flooding may occur at any time of year, but most significant flood events have been in late summer, when warm sea surface temperatures bring ex-tropical low pressure systems off the east coast. River levels in the Huon can also rise quickly, especially in the spring with snow-melt.
In terms of lives lost, Tasmania's most severe flood occurred in 1929 after heavy rains covered the whole of the state. The once prosperous tin mining centre of Derby was practically wiped out when the Cascade Dam (containing 188 million gallons of water) burst on 5 April and flooded the Briseis Tin Mine. Fourteen lives were lost in the only dam-burst in Australia's history to have taken human life. Houses were crushed like matchsticks as a twelve-foot wave of water swept through the town. A ten-ton granite boulder which had travelled two miles was among the mountain of debris left in its wake. The influx of water caused the Ringarooma River above Derby to run uphill for nearly six hours.
In Launceston, the post office bells rang out in the early morning to warn residents of Inveresk and Invermay to evacuate their homes immediately. Volunteers in boats transported thousands of refugees to the shelter of the Albert Hall. All this occurred in pitch darkness, as power supplies to the city were cut off when the Duck Reach power station was washed away. Floodwaters caused thundering torrents through Cataract Gorge, wrenching away iron railings from the pathway. For two days, the city was without transport, gas or electricity – forcing the Examiner to use power supplied by a Deere tractor.
Hobart was isolated, with the main road and railway flooded at Tunbridge. The death toll of 22 included deaths when a vehicle plunged into a flooded river near Ulverstone. Numerous bridges were destroyed or damaged and there were great stock losses. To aid recovery, primary producers were offered interest-free loans for up to ten years under the Flood Sufferers' Relief Act.
Widespread and extreme flooding throughout the state occurred also in 1960, with the Macquarie, Elizabeth, Lake and Liffey Rivers particularly affected. Longford was isolated and families were evacuated at Ross and Liffey. Part of the Lake Highway bridge was carried away by a rapid river rise of 1 metre in 30 minutes. The Macquarie Plains–New Norfolk area saw the greatest damage with several people rescued from rooftops, twelve houses destroyed and an estimated 650 rendered homeless. Hobart sustained record losses estimated at £3 million as the Hobart Rivulet flooded. Water ran knee-high in Liverpool Street, and the Army was called to help in the rescue.
Further reading: www.dpiwe.tas.gov.au/inter.nsf; www.bom.gov.au/lam/climate; Examiner, 8 April 1929; Weekly Courier, 10 April 1929.