MAR: Storing water underground

MAR: Storing water underground


[Music plays] (Narrator) We all need water. But rapid population growth and changes in climate may mean we have to do more with less. Or, we could tap into some of the water around us that we just don’t use, excess surface water, treated wastewater and urban stormwater. Of course, if we save this water we need somewhere to bank it for a not so rainy day. Rather than giant, unsightly, above-ground storage tanks, we can use large, naturally occurring underground reservoirs called aquifers. They hold water in porous or fractured rock or loose, unconsolidated sediment. Less permeable layers, like clay, help to contain the stored water. The CSIRO focuses its research on how best to use aquifers to store, convey and treat water. Storing water like this is known as Managed Aquifer Recharge. Most agricultural areas have a wet season, so let’s start there. There’s high rainfall and less demand for irrigation. In other words, a perfect time to capture excess runoff. Water is simply filtered through the soil and “banked” in a shallow aquifer. It’s then ready as an economic irrigation supply when the dry season returns. And as a bonus, storing water this way means no algal blooms, no mosquito problems and reduces the water lost to evaporation when things inevitably heat up and dry off. In urban settings, storm water can be collected in a wetland area and injected into a well to reach a deeper aquifer. The stored water can then be recovered via the same well and used in the irrigation of crops or ovals, or for non-potable water in households or industry, or even treated to become drinking water. Urban centres also produce significant volumes of waste water. This can also be used to recharge deeper aquifers and unlike storm water is available for recycling all year round. And in fact, Managed Aquifer Recharge helps us recycle urban waste water without the disruption to natural environments that waste discharge can sometimes cause. Once banked in the aquifer storage periods can vary from short term irrigation support to long term insurance against drought. Of course, there are a whole raft of important social, health, environmental and economic considerations whenever and wherever we use these processes. CSIRO helps assess and enable these projects with research into the fate of pathogens and chemicals, protect human health and the environment and answer fundamental questions like, “Where are the suitable aquifers?” and “How natural processes affect the quality of water during storage?”. More and more demand will, inevitably, be placed on our water supply. With appropriate research support from the CSIRO, Managed Aquifer Recharge can help us create a diversity of water supply options that will meet our future water needs. [Music plays]

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