1.1.6 Surface water – groundwater interactions


Unconfined aquifers, such as alluvial aquifer systems, are typically in direct connection with surface water features such as streams and wetlands. There are also likely to be hydraulic connections where bedrock aquifers directly underlie streams — especially where these streams are deeply incised into the bedrock. Surface water – groundwater interactions are an important part of the hydrological cycle for the Clarence-Moreton Basin. In some instances, streams can provide recharge to the shallow aquifers (losing streams) and elsewhere, baseflow from aquifers can sustain streamflow (gaining streams). In addition, the extraction of groundwater for irrigation or other purposes can also affect stream hydrology. The nature of this interaction is likely to be different, both spatially and temporally, and controlled by many factors such as climate variability, topographic gradients and the lithological and hydraulic properties of the underlying aquifer.

Acid sulfate soils are associated with coastal sediments along the eastern coastline in the Clarence and Richmond river basins. They can discharge significant concentrations of weathering products – including metals and acids – to streams or wetlands. The abundance of coastal acid sulfate soils in the Tweed, Clarence and Richmond river basins makes understanding the interaction between these sediments, shallow groundwater and surface water bodies very important.

In this section, an overview is given for each river basin on the interaction between surface water bodies and groundwater within different river basins and from different hydrostratigraphic units.

Mapped wetlands and groundwater-dependent ecosystems (GDE), which are the surface expression of groundwater discharge, can be viewed for the different river basins within the Clarence-Moreton bioregion in Queensland on the Department of Environment and Heritage Protection Interactive WetlandInfo website (Department of Environment and Heritage Protection, 2013). In addition to the information on the Interactive WetlandInfo site, a mapping program is currently underway that will delineate the wetlands and GDEs for these river basins in more detail (M Ronan, 2013, pers. comm.). In NSW, recent mapping of groundwater-dependant ecosystems in coastal river basins including the Clarence river basin and Richmond river basin is available from NSW Office of Water (2013).

Last updated:
8 January 2018
Thumbnail images of the Clarence-Moreton bioregion

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