Floods have long taken a deep toll

Of course, there have been floods for millennia in the Canberra area, and many have been recorded during the 200-odd years of European settlement. The major rivers and creeks of the region, like the Murrumbidgee, Cotter, Queanbeyan, Molonglo and Ginninderra, all have flood stories to tell.

The Murrumbidgee rose with terrific power in 1852. Local grazier James Wright, founder of Lanyon, in 1847 moved with is wife and five children to Cuppacumbalong, adjacent to present-day Tharwa near the junction of the Murrumbidgee and Gudgenby rivers. The property's name is Aboriginal and means "meeting of the waters".

The 1852 flood inundated the property and caused great anxiety for the family and employees (24 people in total) who luckily survived by sheltering in a barn. The homestead was never the same again and the Wrights sold in 1856 to the De Salis family, who held the property until the 1890s depression.

But worse was to come further downstream. The original town of Gundagai had been built too close to the river. When the Murrumbidgee rose during the night of June 24, 1852 after weeks of rain, it wiped away most of the town's buildings and 89 people lost their lives. It was one of Australia's worst natural disasters.

The death toll would have been much higher had it not been for four Wiradjuri men, including Yarri and Jacky Jacky, who in their canoe and a rowboat paddled amongst stranded villagers on rooftops and trees and conveyed nearly 70 people to safety. Both men were awarded metal breastplates in recognition of their amazing deeds of bravery. Yarri's was on display in the Gundagai Museum until it was stolen in 2010. Yarri is buried in the Gundagai cemetery, though his grave was unmarked until a headstone was installed in 1990. In 2017 a bronze sculpture of the two men and their bark canoe was unveiled in the town.

Creek and river crossings were always risky during times of flood in the colonial period when bridges were not as widespread as today (and indeed today lives are all too often lost when people try to drive though crossings that are unsafe). At Ginninderra Creek in September 1892, 48-year-old pastoralist Edward Crace was attempting to cross the creek with his groom George Kemp. Crace was impatient to get the coach across the creek and unwisely tried to hurry through an unsafe crossing point. Kemp drowned after trying to calm the horses, and Crace died when the coach was swept away.

The Cotter River was one of the reasons for siting Canberra where it is today. This river too has risen with force. In 1949 the federal government decided to increase the height of the Cotter Dam wall to provide more water for an expanding post-WWII population. During construction, a big flood came down, overtopping the incomplete wall and providing a dramatic view from nearby Mount Macdonald, captured in a photo held in The Canberra Times archive of the time. Fortunately no great damage was caused to the dam works.

Further upstream, Corin Dam was built in the mid 1960s. Though the river did not flood at the time (in fact drought enabled completion ahead of schedule), heavy rains brought drama just as the job finished in winter 1968. A butterfly valve in the diversion tunnel could not be closed as water started to rise behind the dam. Desperate Thiess workers spent five hours in dangerous conditions, eventually closing the valve and stopping the ferocious jet of water shooting through it.

Floods in the Molonglo River have had their impact on Canberra. In the 1920s a major flood undermined the early railway line crossing the river and caused other damage. In 1939 and 1942 floods caused mine tailings and slimes dams at Captains Flat to collapse, resulting in catastrophic pollution of the Molonglo which devastated native fish and other river species downstream of the mining town. Remediation works were carried out in 1976.

Googong Dam was built on the Queanbeyan River in the 1970s to provide more water for Canberra and Queanbeyan. The river flooded before the dam was completed. For an earth and rockfill (not concrete) dam this was very serious as floodwaters can rip away the wall material. Luckily dam workers had enough notice and fixed steel protection mesh on the rockfill, avoiding a disaster.

The 1974 Queanbeyan River flood had a grisly consequence. The river tore away part of Riverside Cemetery. Several graves were washed away and witnesses saw coffins and bodies floating downstream in the raging waters for several days. About 100 of the cemetery's graves were hit by the flood.

Despite humans seeing floods as dangerous times, floods do perform important roles in the natural environment. They refresh waterways and high waters act as triggers to fish breeding. They bring food down waterways for riverine creatures, create new shelter via undermined trees, spread silt across floodplains, and are needed at intervals by various plants, including River Red Gums in particular.

What Australia's future floods will look like is difficult to tell. The extreme nature of the current rainfall amounts and flood heights point to climate change as a powerful force on rivers. With more heat and thus energy in the meteorological system, plus the fact that warmer air can hold greater amounts of water vapour, just where the boundary between flood-free and flood-prone land will be in coming years is a quandary for us all.