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Canal estates (brackish)

Direction of marine water movement Groundwater and marine water interface Negligible groundwater movement Infiltration and percolation Infiltration and percolation Infiltration and percolation Direction of groundwater movement Direction of groundwater movement Direction of groundwater movement Direction of groundwater movement Direction of groundwater movement Low permeability rock Sand Sand Corymbia spp Corymbia spp Corymbia spp Corymbia spp Melaleuca spp Corymbia spp Corymbia spp Melaleuca spp Melaleuca spp Melaleuca spp Pumping station Canal lock Subterranean GDEs Surface expression GDEs Subterranean GDEs Surface expression GDEs Surface expression GDEs Subterranean GDEs Weir Sand Sand Sand (saturated with marine water) Sand (saturated with groundwater) Basement of the model Low-lying coastal swamps Direction of groundwater movement Infiltration and percolation Coastal sand masses – beach ridges

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Brackish canal estates are man-made canals with locks or weirs that restrict connection to estuaries and therefore have limited tidal influence. The canals are usually dug into unconsolidated sedimentary aquifers including coastal sand masses (see coastal sand masses – beach ridges) or alluvia deposited during periods of higher sea level by fluvial processes in current river channels, floodplains, estuaries, deltas and other near-shore environments (see low-lying coastal swamps). These unconsolidated sedimentary aquifers store and transmit groundwater through inter-granular voids between gravel and sand particles. Groundwater within the unconsolidated sedimentary aquifers is predominantly fresh and may discharge into the canal. To prevent stagnation of water within the canal, marine water may be allowed to leak through the locks or in some cases is actively pumped into the canal resulting in brackish waters. These areas may support flora and fauna communities, ecological processes and delivery of ecosystem services.

  • Brackish canal estates may depend on the surface expression of groundwater from the underlying unconsolidated sedimentary aquifers.
  • Unconsolidated sedimentary aquifers associated with brackish canal estates may also support aquifer ecosystems which can be indicated by the presence of stygofauna.

Pictorial conceptual model PDF


Last updated: 18 December 2015

This page should be cited as:

Canal estates (brackish), WetlandInfo 2015, Queensland Government, Queensland, viewed 12 September 2017, <https://wetlandinfo.ehp.qld.gov.au/wetlands/ecology/aquatic-ecosystems-natural/groundwater-dependent/canal-estates-brackish/>.

Queensland Government
WetlandInfo   —   Department of Environment and Heritage Protection