GEOG10001 Lecture Notes - Lecture 10: Climate Change Mitigation, Stormwater, Bass Strait
28 Jul 2018
School
Department
Course
Professor
Water Crisis: Water supply options for a growing Melbourne after the
Millennium Drought
The Millennium Drought: the problems of relying on river flows for our water supply
Melbourne’s water supply: 2006 - a fateful turning point
What coul dhave been and what might be: a more sustainable approach to urban water supply
The Millennium Drought (2001-2009)
“Worst drought on record for SE Australia”
- Natural flows into the river dropped by 45%
- We kept extracting water at much the same rate as normal
- 2001-2006; 18% less rain over the Murray Darling Basin
- Gross Regional Product dropped by 16%
- Flows in the lower Murray dropped by 82%
Why does 18% less rainfall result in 45% less river flow?
-Most rainfall ends up back in the air; much is stored in the soil and transpired by vegetation
back to the atmosphere.
-The longer it is dry, the more capacity soils have to hold back water for uptake by vegetation
-Years of soil water deficit increase the probability of forest fires
Melbourne’s water supply and wastewater disposal and treatment system
Dams with capacity for ~10 year demand in a severe drought (with no augmentation)
Water flowing into Melbourne’s reservoirs 1912-2006 (GL/y)
- 2006: a very dry year after 10 quite dry years
- An unprecedented decade of demand mainly exceeding inflows
- Worst-case climate-change and demand predictions pointed to demand exceeding long-
term supply by 2020-2030
- A short-term augmentation of 50-100 GL/y was needed
Recycled wastewater: the 2006 augmentation proposal
- A pipeline from Eastern Treatment Plant to Cardinia:
- Cheap because an upgrade to near-potable effluent was already planned and
budgeted for.
- Energy requirement per kL ~ 30% that required for desal
- Politically unpalatable…influence of the Toowoomba referendum?
The Wonthaggi desalination plant: the successful proposal
Extract seawater from Bass Strait at Wonthaggi
Extract the salt (return concentrated brine to the sea),
Pump desalinated water to Cardinia (a service reservoir)
● The dominant water industry advice in 2006 was to develop a ‘portfolio’ of different water
sources that included a 50 GL/y desalination plant.
● But desal was attractive to the politicians because it was sold as ‘climate independent’
● A 150 GL/y plant was ordered.
● A new energy-intensive industry when climate change mitigation requires reduction of
energy consumption
● And the cost of the water that it provides?...
Document Summary
Water crisis: water supply options for a growing melbourne after the. The millennium drought: the problems of relying on river flows for our water supply. Melbourne"s water supply: 2006 - a fateful turning point. What coul dhave been and what might be: a more sustainable approach to urban water supply. Natural flows into the river dropped by 45% We kept extracting water at much the same rate as normal. 2001-2006; 18% less rain over the murray darling basin. Flows in the lower murray dropped by 82% Most rainfall ends up back in the air; much is stored in the soil and transpired by vegetation back to the atmosphere. The longer it is dry, the more capacity soils have to hold back water for uptake by vegetation. Years of soil water deficit increase the probability of forest fires. Melbourne"s water supply and wastewater disposal and treatment system. Dams with capacity for ~10 year demand in a severe drought (with no augmentation)
