Changes in Spring Flows
Aquifers are topped up during the Wet season, raising watertables. Spring flows are at a maximum at that time. As the Dry season proceeds groundwater drains out of the aquifer via springs and the watertable progressively falls. If the watertable falls below ground level at the spring it will stop flowing.
Some springs are permanent but the majority dry up at some time before the next Wet season. Even some apparently permanent springs can dry under extended drought conditions.The example below shows stream flow in a river that is spring fed in the Dry season.
During the mid to late Dry season all the water is sourced from springs. In most years, flow continues throught the year but in 1996 and 2002 it stopped flowing due to below average rainfall in the previous wet seasons.
Springs draining aquifers with limited storage space will only be affected by the previous years rainfall while those from aquifers with large storage capacity may be affected by the rainfall from a series of previous years.
For example after a long drought spring flow from a limited aquifer will return to normal after one good seasons rain. In an aquifer with large storage however it may take several years for spring flows to return to normal.
