Altered seasonal stream flow

Impact

In this context, stream flow refers to the discharge of water that occurs in a waterway, where discharge is the volume of water that passes through a given section of the waterway within a specified time.  Under natural conditions stream flow increases and decreases with seasonal fluctuations in precipitation (mainly snowmelts and rainfall).  These seasonal flow patterns are important for a range of ecological functions, such as the successful reproduction of many plant and animal species.  When waterways are regulated, e.g. through the construction of dams and weirs, the seasonal flow regime is disrupted and sometimes reversed as water is released to meet irrigation needs during naturally dry periods.  Increased stream flow during naturally dry periods can degrade natural habitats, change aquatic ecosystems and encourage exotic pest species, such as carp.

Suggested indicator: Water flow*

Altered seasonal stream flow may be associated with:

Potential associated impacts	Suggested indicators
Changed in-stream habitat	In-stream habitat* River & wetland fauna* Aquactic macro-invertebrates* Microalgae in water*
Disrupted plant and animal breeding cycles and subsequent reduction in some species leading to: Reduced food supply for dependant species resulting in organism deaths	Fish* River & wetland fauna* Aquatic macro-invertebrates* Native land fauna* Fauna behaviour* Exotic pest fauna*
Invasion of pest animals and weeds	Weed species* Weed cover*  Exotic pest fauna*

* Yet to be developed

Last updated: 27 August 2008

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