It is estimated that up to 98% of the earth’s available freshwater is groundwater. So what do you really know about it?
When you hear ‘groundwater aquifer’ what do you picture? If you’re picturing a cavernous underground lake filled with pristine untouched water, perhaps with mysterious megafauna lurking in the darkness, well… you’re not alone.
While underground lakes do exist, like the very impressive Lake Cave in Margaret River, the reality of aquifers here in Perth is perhaps a little less mystical.
So what are our aquifers really like?
Groundwater is water located in the saturated zone below the earth’s surface and is a crucial part of the global water cycle.
An aquifer is an underground formation which transmits and contains large quantities of water. The water typically sits in tiny pores and spaces between small soil or rock particles, or within narrow fractures in the rock itself.
And how does the water get there?
Aquifers are replenished by rainfall that infiltrates through the surface – commonly referred to as groundwater recharge. Most of Perth is built on permeable sand dunes, which soak up heavy rainfall and recharge aquifers with ease. However, with urbanisation comes an increase in impervious surfaces. Which leads us to another common misconception…
We can always count on groundwater
Growing population and climate change have put enormous pressure on our traditional rainfall-fed dammed water supplies. Since the late 1970’s, Perth has increasingly used groundwater to supplement water supply. If groundwater systems are pumped too hard and by too many bores there may not be enough time for the system to recover and we can deplete our groundwater resources. Groundwater levels have been seen declining under areas of Perth.
Aside from education and water restrictions one of the leading management strategies for maintaining our groundwater resources is Managed Aquifer Recharge (MAR); a process that involves injecting treated water into the aquifers for future abstraction. The water can come from a whole range of sources including stormwater and treated wastewater!
So maybe groundwater aquifers aren’t always fantastical underground caves like Gollum’s cave in The Hobbit –
But they are still a fascinating and invaluable resource, and one that we need to stay aware of in order to preserve them long into the future.