Stieglitz, 2005:

"Along the tropical coastline of the Great Barrier Reef (GBR) region, little is known to date about submarine groundwater discharge (SGD) into the near-shore ocean. In an oceanographic sense, SGD consists of freshwater flow from land as well as seawater circulated through sediments. Recent radiochemical and geophysical studies, using the tracer 222Rn and apparent ground conductivity respectively, provide evidence for SGD to occur in a variety of hydrogeological settings. In this paper, a non-quantitative overview of different settings of SGD in the region is presented: (1) recirculation of seawater through animal burrows in mangrove forests, (2) freshwater SGD from unconfined aquifers as a narrow coastal fringe of freshwater along Wet Tropics beaches, (3) SGD from coastal dune systems in form of localised freshwater springs in the intertidal zone, (4) inner-shelf SGD from confined submarine aquifer systems comprised of riverine paleochannels incised into the shelf."

Fig. 3. Conceptual hydrogeological models for SGD in the GBR region; (a) Seawater recirculation through crustacean burrows, (b) Discharge from unconfined coastal aquifers, (c) Discharge from confined or semi-confined coastal aquifers in form of discrete springs, (d) Discharge from confined submarine aquifers through 'Wonky Holes'. The spatial scale of each groundwater system is indicated (cf. Table 1).

Fig. 2. Apparent ground conductivity transects (a) at Ella Bay in May 2003, (b) at Elim Beach in April 2002 and (c) through a 'Wonky Hole' in Halifax Bay in January 2000, together with photographs of discharge sites at (a) and (b) and acoustic multibeam image of the investigated 'Wonky Hole' at (c) respectively. Note the different scales on the axes. The same conductivity colour scheme applies. The cross in (a) marks the highest location of visible seeps, and the grid in the multibeam image in (c) has 10m spacings in both directions.

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Citation and/or URL

Stieglitz, T., 2005, Submarine groundwater discharge into the near-shore zone of the Great Barrier Reef, Australia, Marine Pollution Bulletin 51: 51-59.

Spatial Coverage

Coastal central GBR 

Temporal Coverage

2002-2003

Update Frequency

Not applicable 

Other Information

None