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How does groundwater interact with the environment?

How does groundwater interact with the environment?

Where groundwater occurs close to the surface it can interact with the surface environment. Many ecosystems rely on groundwater to stay healthy and survive including streams, rivers, wetlands, plants and cave ecosystems as well as the animals that feed on vegetation sustained by groundwater. These are known as Groundwater Dependent Ecosystems (GDEs).Where groundwater resources and surface ecosystems interact strongly, it may be beneficial to co-manage them.

Interaction between groundwater and surface water

Water can flow in both directions between unconfined aquifer and surface water bodies such as streams, rivers, lakes and wetlands. The level and nature of the interaction can change over distance and time. 

While the interaction between groundwater and surface water bodies cannot be directly measured, the effect can be seen in ecosystems that continue to thrive during dry seasons. Several estimation methods exist but the results can differ significantly.

Example of a gaining stream

Diagram that shows that during dry periods when stream flows are low and the groundwater level is higher than the stream water level, groundwater can discharge into the stream.

This diagram shows that during dry periods when stream flows are low and the groundwater level is higher than the stream water level, groundwater can discharge into the stream. Where this occurs to a surface water environment such as a wetland or lake, it is known as a gaining water body. Diagram: ©Spatial Vision Innovations Pty Ltd (2015)

Example of a losing stream

Diagram showing that when the water level in a stream, lake or wetland is higher than the groundwater level, it can lose water to the aquifer.

This diagram shows that when the water level in a stream, lake or wetland is higher than the groundwater level, it can lose water to the aquifer. Diagram: ©Spatial Vision Innovations Pty Ltd (2015)

Dependence of GDEs on groundwater

GDEs have varying levels of dependence on groundwater, however it is difficult to quantify. Completely dependent systems may not survive if there is even a slight change in the groundwater source they rely on, whereas periodically dependent systems may rely on groundwater during dry periods only.

Since the mid-2000s our ability to identify and map potential GDEs has improved greatly. The National Water Commission has produced a GDE Atlas that identifies potential GDEs using satellite imagery, depth to groundwater maps, vegetation mapping and field surveys. However unless testing is conducted at the site this information is likely to include many sites that are not GDEs. Research currently under way into underground ecosystems in the Port Phillip and Western Port Region shows that microscopic animals called stygofauna can be found in shallow aquifers along current and prior streams.

Evapotranspiration

This occurs when plants and trees use groundwater from shallow water tables. While the volume used varies depending on the plant type and climatic conditions it cannot be directly measured.

Management

Site-specific studies are currently being conducted across Southern Victoria to help us increase our understanding of groundwater and improve management of this important resource. Where groundwater interacts strongly with surface ecosystems it may be beneficial to co-manage them.

Southern Rural Water takes the needs of the environment into account in all licensing decisions through our referral processes.  When developing local management rules we invite representatives for the environment to participate in stakeholder engagement activities.

 

 

Page last updated28th April 2015
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