What happens if wivenhoe dam overflows

Looking further ahead, Mr Marshall said climate predictions suggested the area would not be receiving much rainfall in the next couple of months either. The significant weather event that brought heavy showers across the region made the grid total rise by 1 per cent, but the lighter showers towards the centre meant the ground was not wet enough to start flows into Wivenhoe Dam.

Seqwater said it hoped the release would "balance lake levels" and cause a rise of more than half-a-metre of water in Wivenhoe Dam. We acknowledge Aboriginal and Torres Strait Islander peoples as the First Australians and Traditional Custodians of the lands where we live, learn, and work. Key points: Residents in south-east Queensland are being asked to conserve water despite recent falls Dams central to the Brisbane region have not received as much rainfall as their coastal counterparts There's a drier outlook for the south-east for the next seven days.

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A little-known US car maker promised the electric ute. The problem affects almost half of Seqwater's 26 large dams. Wivenhoe Dam releasing water during It's the reason Somerset and Wivenhoe have been operating for more than a year with reduced drinking water storage capacity, to provide additional space to absorb floods.

Their owner, Seqwater, insists the dams are safe. The proposal is likely to cause a political headache: money is tight and Wivenhoe doesn't appear on the state government's list of "priority infrastructure". But three independent, highly credentialled engineers have spoken to Fairfax Media saying that failure to heed the warnings would put Brisbane at unnecessary risk of disaster.

Just a few weeks ago, almost , Californians were ordered to leave their homes for three days amid fears Oroville Dam, the tallest in the US, could break. The Oroville incident put into stark relief the risks posed by large rock dams sitting above towns, not just in developing or poorly regulated countries such as China or Kazakhstan, but in one of the most safety-conscious places on Earth. In early February, with its lake brimming with snow-melt, the main spillway at Oroville, in Butte County north of Sacramento, collapsed.

When releases were slowed to limit the damage, water began flowing over an emergency spillway, causing erosion and threatening the integrity of the entire structure. At the height of the crisis helicopters dropped bags of rocks to fill the breach. Both Oroville and Wivenhoe are made of rock fill and compacted earth; both rely on secondary spillways to protect the main dam in an emergency.

Queensland's dam regulator has also identified an erosion risk at Wivenhoe. Greg McMahon, a consultant who was the chief flood expert in Queensland's local government department until the early s, says attitudes to dam safety became compromised during the late s when "political skulduggery" led to an effective lowering of standards.

He explains that when Wivenhoe was first conceived in the s, Australian design standards for large dams made of earth and rock required them to be able to contain the flood created by the largest possible rain event in the catchment, the "probable maximum precipitation". But soon after Wivenhoe was completed in , meteorologists realised they had significantly underestimated the size of this epic deluge.

But rather than raise all the dams, Mr McMahon says, authorities changed the standard. For the first time they assigned a probability to this massive rain event, even though the new national dam design manual in acknowledged a fundamental scientific problem with doing this:.

Mr McMahon believes this was an effective softening of standards and it happened because governments, including the Bjelke-Petersen regime under which he worked, balked at the cost of upgrades. At this stage it can't - and I'm not sure the population at risk has been sufficiently consulted in this decision. The Australian National Committee on Large Dams sets the guidelines for dam design across the nation, but says it does not monitor compliance of Australia's dams with them.

Wivenhoe Dam release caused Brisbane flood: report. Please try again later. The Sydney Morning Herald. By Marissa Calligeros March 11, — Save Log in , register or subscribe to save articles for later.