Is there a risk that there will be insufficient water supplies in Melbourne to meet the needs of the predicted future population growth? If so, when? Melanie Collett (MC): The recently released
Do we have enough water?
Melbourne Water System Strategy suggests that water supplies will need to be supplemented sometime within the next 50 years to meet the growing population in Melbourne. Water supply is dependent on two things: the
Sustainability Matters asked AECOM’s Water Resource Practice leader, Melanie Collett, about future urban water security challenges from a local perspective.
amount of water (supply) and the use of water (demand). Insufficient water supply occurs when the demand is greater than the supply. There are many ways to mitigate this problem including increasing supply or decreasing demand. Melbourne’s current water is mostly sourced from rainfall in the water supply catchments, which is stored in our large reservoirs. One of the biggest risks to supply going forward is the impact of climate change, which may reduce runoff in the catchment, which may reduce water supplies. Land use changes such as urbanisation, natural rainfall variability (droughts) and degraded water quality (due to bushfires) can also impact on water supplies. The demand for water increases with population growth, but can be reduced through education campaigns and the use of alternative water sources for non-potable water requirements such as toilet flushing and outdoor use. On the supply side, alternative water sources may be used to supplement the current potable water from catchments. These alternative sources include desalination, stormwater harvesting and recycled water from treatment plants. With each of these alternative water sources, treatment is required to improve the quality of water to make it suitable for use. When will we run out of water? — We can’t say for certain. This will depend on both the supply and demand of potable water. Water authorities such as Melbourne Water are constantly modelling different scenarios of both supply and demand to predict what could happen in the future and plan for any eventuality. Monitoring of the catchment conditions, supply and demand against the plan can help decision-makers to refine the plans as
10 Sustainability Matters - Oct/Nov 2017
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