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North-west flows in early 2020

Response of groundwater resources

How groundwater resources responded to rainfall during the North-west flows in 2020.

Response of groundwater resources to rainfall

Monitoring helps us to find out what impact the recent rain and surface water flows have had on groundwater levels. The data has been reviewed for 20 groundwater sources so far. Early results confirm that shallow systems, such as the Peel Alluvium, show a clear but relatively minor response to the rains and flows. Dry soil profiles from the prolonged drought have soaked up much of the recent rainfall resulting in only a small amount of this reaching the groundwater systems.

Watch the video

This video demonstrates just how reactive some groundwater systems can be to rainfall. In it, a pink ribbon flutters as the groundwater level in the bore rises rapidly in response to significant rainfall and pushes the air out of the bore.

Larger, deeper systems show some recovery in water levels following the recent rain. However, this response is more than likely due to a reduction in groundwater pumping as surface water is available and used preferentially. It takes a much longer time for rainfall to reach the deep groundwater systems than the small shallow systems.

More rain and flood events are needed for significant groundwater recharge to occur. The department and WaterNSW will continue to monitor groundwater levels to see how the different groundwater systems respond to significant rainfall and flood events.