Dams and catchments video transcript

[Background music]

[Voiceover]: Here’s a question.

Why is it when Perth gets heavy rainfall, our dam levels don’t automatically rise at the same time? The answer is all to do with how much moisture is in the soil in our catchment areas. A catchment is an area where water is collected by the natural landscape, and it’s usually surrounded by high features such as hills or mountains. The soils in our catchments act like a sponge soaking up moisture and storing it in underground aquifers and gradually releasing it into our rivers and streams which then flow into our dams.

Years of below average rainfall means that Perth’s catchment areas have become drier and drier so when the rains do come, they are soaked up by the soil which leaves us needing a lot more rainfall for the water to eventually find its way into our dams.

What’s more, because Perth’s groundwater levels are dropping too it takes even longer for rainfall to seep into ground, soak the catchment and get the streams flowing. So, there’s the answer it all has to do with Perth’s dry catchment. Even if we do get decent rainfall in any one year, we’ll still get a lot less streamflow into our dams than we would have had from the same amount of rainfall several years ago.

So why do our dam levels look the same as other years? Because we’re helping our dams by using them to store water from climate independent sources like desalination. Water is stored in dams during periods of low demand, so it is available when it is most needed in the hotter months.

To find out more visit watercorporation.com.au/ourwater