Perth a growing city with declining rainfall – adapting to the new normal
Like many of us who live in Perth, our environmental scientist Vanessa Moscovis enjoys all the things that make Perth a great place to live like our bright blue skies, open spaces, beaches and relaxed lifestyle. But, while our great city is renowned for having more sunny days than any other city in Australia, we used to receive a lot more rainfall than we do today.
If we still received the average amount we used to yearly, it would be enough to supply Perth’s 2 million population with all its water needs even today.
To get a full picture of how much things have changed, we asked our expert in the field, Vanessa to share her knowledge on the level of planning and management that goes into adapting to a drying climate. After working at Water Corporation for almost 20 years, Vanessa has had firsthand experience with implementing rainfall resilient water sources and innovative technologies as we can no longer rely on rainfall as our primary water source.
It all started 50 years ago
Scientists have known for some time that Perth’s rainfall was going to continue to decrease over time, but what they didn’t see coming is the speed at which we would arrive where we are today. To put this into perspective, just over 40 years ago, our metro dams received an average of 420 billion litres of streamflow each year compared to 44 billion litres in 2019. That’s a greater than 80% reduction in just a few decades.
In response, our supply planners, including Vanessa, have spent the last 20 years diversifying our water sources which traditionally relied on rainfall alone, to now rainfall-independent sources such as seawater desalination, groundwater replenishment and wastewater recycling.
And still, the work continues as Vanessa and her team carry on with planning for future solutions in knowing that Perth’s climate is predicted to dry further. Vanessa explains, ‘Traditionally our planning was in anticipation for urban population growth, but today it has become more about ensuring sustainable sources in response to climate change.’
"Traditionally our planning was in anticipation for urban population growth, but today it has become more about ensuring sustainable sources in response to climate change."
The writing was on the wall back in the 1970s when the State Government introduced garden bores to reduce demand on scheme (drinking) water. Things continued to take a downturn and by the 1980’s warmer temperatures, and even less rainfall meant further changes and restrictions were implemented to get us through more consistent dry spells.
At the turn of the century, we started to work closely with the community to develop Australia’s first desalination plant in Kwinana. To keep up with water demand, we then built a second desalination plant in 2011 in Binningup. Today, the two desalination plants provide almost half of Perth’s drinking water.
Perth's population continues to grow, but climate change is the biggest challenge facing our water security in the future.
The lesser known impacts of climate change
One of the more hidden aspects of climate change that Vanessa’s team have recognised over the past few years is the impact climate change is having on storm events.
Have you ever thought about how storm surges in Perth that coincide with high tide impact our drainage systems and wastewater network? When storm events erode coastline, how close are our pipes and pumps in relation to a road that's right alongside the coast? These are just some of the challenges Vanessa’s team is looking to tackle in the future.
Why wastewater treatment matters
Wastewater treatment is an essential aspect of managing and protecting the environment. We are lucky to have someone like Vanessa and those in similar roles before her, who are incredibly passionate about sustainable wastewater management and improving wastewater recycling.
It’s a fine balance complying with environmental regulations while also meeting customer expectations. Every wastewater treatment plant needs to be capable of treating every litre they receive, every minute of every day.
As Vanessa puts it – ‘you can’t stop wastewater.’ We need to make sure we have the processes and plans in place to allow wastewater plants to grow as the population and flows increase.
It means thinking beyond the traditional approaches to ensure we manage wastewater sustainably – both socially and environmentally. Decades ago, we used to burn sludge and bury it. These days we’re taking a more sustainable approach.
Our processes in sludge management have adapted to a point where we now recycle 100% of our biosolids produced in Perth. Today our biosolids get sent to compost and farms to be used on crops as an effective soil improver or fertiliser. While this concept isn’t new and it’s something we’ve been doing for years, it is a change from how we treated wastewater bioproducts in the past.
Biosolids are a great idea and form part of a circular economy, but Vanessa’s team continues to innovate, asking: How can we build on this in the future?
The future of wastewater treatment
Over at our research facility, the Water Research and Innovation Precinct, our design teams and planners are surging ahead, thinking about the future and how we manage wastewater treatment sustainably in years to come.
One of the innovative solutions we’re currently trialling is membrane technology (MABR). Without getting too scientific Vanessa explains, 'It involves taking a particular type of membrane bioreactor to create more surface area for bugs to grow on, which in turn increases the treatment capacity in the same sized tanks we operate.
Historically, our treatment plants were built, and then development occurred around them, so their footprints are very constrained — we think this solution has the potential to increase the amount we can treat within these spaces.
Advanced water recycling plant.
So, we asked Vanessa what have bugs got to do with wastewater treatment? She tells us, ‘A lot actually. We rely on them entirely as part of the biological process in wastewater treatment. It’s essentially living bacteria, that when given air thrive to remove phosphorus, nitrogen, sodium, potassium, iron, calcium and compounds such as fats, sugars and proteins.’
’It’s all about looking at innovative and sustainable ways we can do more with less. Less land, less energy, less dollars,’ she says.
Now where to from here?
As Vanessa tells us, we know that our climate in Perth will continue to dry, but the one thing we don’t know is how fast. This means we need to have a number of solutions available to deploy as needed to ensure the liveability of our city and the people that sustain it.
You can learn more about how climate change is impacting our water sources and how you can help save our valuable resource. Remember we can all do something to save water—every drop of water counts and the accumulative sum can add up to big savings.