Australia - and the world - will continue to dry up unless governments find a way of storing or diverting water from wet urban cities, new research suggests.
A University of NSW study, touted as the most exhaustive global analysis of rainfall and rivers to date, has found water supplies are shrinking to the point that drought-like conditions will become the new norm.
The report, released on Thursday, reveals that for every 100 raindrops that fall on land, only 36 drops enter lakes, rivers and aquifers to be used by humans.
The remaining two-thirds of rainfall is mostly retained as soil moisture and used by the landscape and the ecosystem.
But as warming temperatures cause more water to evaporate from soils, those dry soils are absorbing more of the rainfall when it does occur, leaving fewer raindrops for human use.
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Meanwhile, there are more extreme rainfall events than ever in urban cities, with the vast amount of water wasted.
"It's not really possible to tap into this water while most of our main water supply is in dry areas," Professor Ashish Sharma told reporters in Sydney on Thursday.
Prof Sharma said it was not a "pleasant situation from any angle."
"Less water is ending up where we can store it for later use. At the same time, more rain is overwhelming draining infrastructure in towns and cities, leading to more urban flooding."
While admitting the report's outlook is "pretty gloomy," Prof Sharma believes the situation is not irreversible.
The report highlights engineering interventions which could reduce urban flooding and also increase water supplies in regional areas.
Countries are already investing in green infrastructure including vertical gardens and grass rooftops to create "sponge cities" that absorb more rainfall, he said.
Noting China's south-north water transfer project - which channels water from the country's wet south to the dry north - Prof Sharma said it would be possible for Australia to similarly divert water from its wet north to the dry south.
What's missing in Australia is political will, he said on Thursday.
"There needs to be a bipartisan commitment that this is happening and something needs to be done about it.
"Open discourse about all possible options may not exist in China but at least they're doing something."
