“I would like to know on what basis Melbourne Water has reduced flood mitigation measures for the tunnel’s flood wall,” Crapper said.
Civil engineer Ron Sutherland was manager of land development at Melbourne Water until he left in 2002. When asked about development in the watershed, Sutherland said flood walls were often a bad idea.
“Walls will divert currents, so overall more water will be diverted to areas that were not originally suitable for the higher currents,” he said.
Aerial photos along the Maribyrnong River over the past 20 years show the construction of thousands of new homes – each one decreasing the landscape’s ability to absorb water and subsequent runoff flowing into the river.
Associate Professor Brian Cook of the University of Melbourne said earlier this month that there should be a moratorium on development on floodplains. “We’re encroaching into the floodplain in small pieces, nibbling at the edges, and that endangers things and reduces the capacity of the river,” he said.
Liberal MP David Davis told parliament last week that planning decisions on the Maribyrnong River floodplain could potentially exacerbate flooding.
“You shouldn’t expect communities to face a flood caused in whole or in part by planning decisions that were foolishly made,” he said.
The $12.6 billion railway tunnels west entrance is on land in Kensington that was protected during last October’s flood.
Flood protection is essential for the rail tunnel, but its construction in Kensington may have affected homes and businesses nearby and elsewhere on the Maribyrnong River.
Studies completed in 2016 to assess the tunnel’s environmental impact found that its construction could increase flood levels upstream and downstream, and that compensatory flood storage of 9,000 cubic meters – approximately the entire MCG playing surface at a depth of one half a meter – would be necessary.
This requirement was revised to 2100 cubic meters in consultation with Melbourne Water and a flood storage area was established on land adjacent to the river in Kensington.
Melbourne Water guides the development of metropolitan floodplains. A spokesman for the authority said the decision to add the land needed to offset the floodplain occupied by the subway tunnel was made on the basis of a range of information and data.
A spokeswoman for Rail Projects Victoria said the Metro Tunnel project had undergone a thorough planning review to assess and mitigate impacts on surrounding neighbourhoods.
Kensington resident Denise Jury’s apartment is in a building flanked by Flemington Racecourse upstream and the entrance to the Metro Tunnel downstream.
The building’s basement flooded in October, destroying residents’ cars and belongings in storage cages, despite the fact that it was built to withstand a flood of one in 100 years.
She questioned the effect of major works such as the metro tunnel on flood levels. “Have they actually exercised due diligence to ensure that local property is not unnecessarily encroached upon because of its presence?” she said.
Speaking at a recent public forum on the Maribyrnong flood investigation, Melbourne Water’s strategic project manager Liz Nairn said the authority’s input was crucial to a project’s progress.
“Our advice is extremely important. It can often make or break an approval or denial decision,” she said.
Failures in the Flood Warning System and Planning Decisions, Revealed by The agehave raised concerns about the independence of a Melbourne Water Review in the flood.
Those concerns led last week to the upper house of the state parliament to pass a motion to hold a parliamentary inquiry into the October floods.
a community petition The plea for the government to build flood defenses for the Maribyrnong suburb has garnered more than 2,000 signatures.
Madeleine Serle, whose home in Maribyrnong was destroyed by the October flood, criticized the inconsistency of millions of dollars being poured into protecting just a few sites.
“However, for me and thousands of other residents… no mitigation and no plans for mitigation,” she said.
Greens deputy leader Ellen Sandell said successive state governments took a “scattergun approach” to planning, which meant some selected sites were protected from flooding while leaving many residents vulnerable.
The Andrews government has rejected the construction of a dam or delay basin to protect the suburb of Maribyrnong from future severe flooding.
Water Minister spokeswoman Harriet Shing said the government would await recommendations from the Melbourne Water review before making any decisions related to flood management.
Victorian MP David Ettershank, representing the Legalize Cannabis Party, is a Kensington resident who was heavily involved in the fight against the Flemington Racecourse flood wall built in 2007, and was later also involved in discussions about the Melbourne Metro Tunnel.
Ettershank was concerned that some developments in the floodplain were receiving protection, while flooding continued to affect residents and traders outside those locations.
“We are not confident that the Melbourne Water study on Melbourne Water will solve these problems,” he said.
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