More rain predicted as Warragamba spills - Sydney Morning Herald

The Warragamba Dam, Sydney's main water reservoir, will continue to spill as weather forecasters tip more rain to fall across the catchment in coming days.

• Call to open dam gates earlier

Brett Dutschke, senior meteorologist at Weatherzone, said the dam's catchment was likely to receive at least 50mm of rain between now and early next week, with falls of twice that amount possible.

“Rivers that have had flooding in the past week are likely to get further flooding,” Dr Dutschke said. “I wouldn't be surprised if the flooding is a bit worse to what has just occurred and that includes the Warragamba and the Nepean-Hawkesbury areas.”

The Sydney Catchment Authority began releasing water through its central drum gate early on Monday after the dam hit capacity following recent rains. The spill, averaging about 25,000 megalitres a day, was about 17 times the amount piped to Sydney for water use.

The additional water, combined with inflows from other tributaries of the Hawkesbury-Nepean, caused minor flooding to parts of Richmond and Penrith to Sydney's north and west, a spokeswoman for the State Emergency Service said.

While the Hawkesbury-Nepean has not suffered a major flood since 1991, it remains one of Australia's most flood-prone regions, with about 120 floods recorded since European settlement.

Insurers say a major flood would potentially cost billions of dollars after Sydney's urban sprawl resulted in large-scale residential development in the valley in recent decades.

The weather bureau today downgraded the threat of more flooding for the Hawkesbury-Nepean system for now.

“The river level is receding,” the SES spokeswoman said, adding that the service will continue to remain on alert for further flood warnings.

Andrew Haigh, duty forecaster for the weather bureau, said the Warragamba catchment may receive 10-20mm on Wednesday and 20-30mm on Thursday as a rainband moves across the state.

“Localised falls could be higher,” Dr Haigh said.

The bout of showers and rain should clear by early next week, he said. Sydney's wettest days will probably come over the weekend before the weather clears up.

The SES, meanwhile, continues to join clean-up efforts across the northern coastal regions of the state, with 54 communities still isolated after the weekend's wet and wild weather, the spokeswoman said.

Weatherzone is owned by Fairfax Media, publisher of this web-site.