The flooding of New South Wales homes and businesses in the Hawkesbury-Nepean Valley is not the result of an act of God, but of bad government policy, a climate change expert says .

Much of New South Wales has been hit by torrential rains since last week, with 20 evacuation orders in place from the mid-north coast to Illawarra and west of Sydney.

Those issued for the recently developed Hawkesbury-Nepean Valley, northwest of Sydney, could have been avoided, said Professor Jamie Pittock of the Australian National University.

“The Hawkesbury-Nepean Valley is very dangerous, very prone to flooding and that’s because there are geographic bottlenecks that are causing great flooding in some of the populated areas,” he said on Monday. at ABC TV.

“There are approximately 70,000 people in the floodplain who are at risk and the NSW government intends to displace an additional 130,000 people in this area by 2050.”

A government plan to raise the Warragamba dam wall to offset the risk of flooding is “ludicrous,” he said, and will only delay the inevitable.

WaterNSW plans to raise the wall 17 meters to allow for the capture and temporary containment of additional flood water, pending federal approval.

“It only encourages further development in the direction of danger,” Professor Pittock said.

“The best approach, the kind of approach taken in countries around the world, is to prevent floodplain development, to leave floodplains as places that can be safely flooded.”

“Use this land for agriculture, recreation, and nature conservation, but don’t build more houses on it.”

A reported war of words between NSW government ministers over whether more water from the dam should have been released before the rain passed by, he said.

“Letting some water out of the dam in advance was an obvious step to take and it would have made a difference.”

“(But) whatever happens to the Warragamba Dam, there is a great risk of flooding in places like South Creek and the Grose River.

With climate change leading to extreme weather events that make major flooding more common, a decades-long plan to relocate people living in the floodplain is needed, Professor Pittock said.

Australian Associated Press