Melbourne will be at risk of running dry by 2050 if no measures are taken to slow global warming and improve water security, a study has found.
The city ranked fifth in a list of global cities that will be most affected by climate change in 30 years’ time.
The list – which measures sea-level rising, water shortages and weather changes – was compiled by accommodation website Nestpick based on existing climate data.
Perth ranked 56th and Sydney was 66th but no other Australian cities were in the top 100.
The Victorian Desalination Plant (pictured) at Dalyston on the Bass Coast in southern Victoria opened in 2012 after the Millennium Drought and now supplies one third of Melbourne’s water
Melbourne’s total storage capacity is at 62.6 per cent and its largest reservoir, the Thomson Dam (pictured) which can hold 1,069 litres of water, is 55.8 per cent full
Melbourne was so high because its demand for water is predicted to vastly outweigh current supply as its population soars.
In 2018, the Australian Bureau of Statistics predicted that Melbourne will become the largest city in Australia by 2031 – and will have a population of 12.2million by 2066.
Jono La Nauze, CEO of Environment Victoria, said Nestpick’s results are roughly accurate – but that drought in Melbourne can be avoided by sensible policies.
‘It certainly stacks up with what the climate science is showing will happen, if you don’t do anything about it,’ he told radio 3AW on Thursday.
Cities most at risk from climate change
1. Bangkok (sea-level rising)
2. Ho Chi Minh City (sea-level rising)
3. Amsterdam (sea-level rising)
4. Shenzhen (climate shift)
5. Melbourne (water shortage)
‘But the key messages is that these are risks we can manage – both in terms of stopping the planet getting any hotter but also by making sure we have secure drinking water supplies whatever happens.’
Melbourne’s water is supplied from ten reservoirs which are topped up by rain and a desalination plant that removes salt from seawater.
The Victorian Desalination Plant at Dalyston on the Bass Coast in southern Victoria opened in 2012 after the Millennium Drought and now supplies one third of the city’s water.
For the 2019-20 financial year, the Minister for Water ordered 125 billion litres from the Desalination Plant, the largest order that has been made to date.
At the moment, Melbourne is not in danger of drought.
The city’s total storage capacity is at 62.6 per cent and its largest reservoir, the Thomson Dam which can hold 1,069 litres of water, is 55.8 per cent full.
But experts are generally agreed that the city will need to shore up its water security as its population expands.
Melbourne (pictured) ranked fifth in a list of global cities that will be most affected by climate change in 30 years’ time
There are three main ways to do this: by building more dams, creating more desalination plants, and by recycling water for drinking purposes.
Recycling water for drinking is already done in Namibia, South Africa and the US but the only Australian city that currently follows suit is Perth.
Melbourne has two recycling plants but the recycled water is not used for drinking.
State ministers could follow Brisbane’s lead after the city in 2010 designed the Western Corridor Recycled Water Scheme to recycle almost all of its water.
The scheme has not been needed but if stores drop below 40 per cent it could be recommissioned.
In September federal Water Resources Minister David Littleproud said more dams should be built – but Victorian ministers rejected the idea.
He said the federal government has offered $1.3bn for new infrastructure projects but state governments are too reluctant to build dams due to cost and environmental issues.
But Victorian Water Minister Lisa Neville hit back, saying there was no point building new dams because there is very rarely enough rain to fill them.
‘The dams we have already are in the best places to collect a high yield of water – any new dams would be unlikely to capture enough water to be worth it,’ she told the newspaper.
‘For Minister Littleproud to suggest otherwise demonstrates a complete lack of understanding when it comes to water and climate change, especially in Victoria.’
Ms Neville pointed out that Victoria’s Thomson Dam has only filled three times since it was built in 1984, most recently in 1996.
She said a better alternative is to expand the state’s desalination plant even though this would increase water bills by at least $10 per household because desalination uses lots of electricity.
How good is each state capital at recycling water?
Adelaide has a very big agricultural irrigation scheme, known as the ‘Bolivar Scheme’. It sends most of its wastewater from its largest treatment plant north to irrigate market gardens and vineyards. It’s always been the leading city in Australia for reuse, due primarily to this very large scheme.
Perth now has the Groundwater Replenishment Scheme which puts recycled water back into the drinking supply. At the moment the scheme is not big but it aims to recycle 45 per cent of wastewater by 2030.
Brisbane in 2010 designed the Western Corridor Recycled Water Scheme to recycle almost all of its water. It has not been needed but if stores drop below 40 per cent it could be recommissioned, meaning the city will be able to recycle the vast majority of the wastewater it produces.
Canberra pumps most of its wastewater into the Molonglo River which flows into the Murray River. It is not recycled in Canberra but used by towns downstream such as Adelaide.
Sydney has some important recycling schemes but they account for less than 10 per cent of waste water. The same goes for Melbourne, Hobart and Darwin.
Source: Professor Stuart Khan, UNSW