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Differences between GDE mapping rule-sets in South East Queensland

There are a number of very similar mapping rule-sets in South East Queensland (SEQ). These rules are generally based on a broad geology type (e.g. basalts, alluvia). However, in many cases these have been further divided depending on:

key mapping attributes (based on the National GDE Atlas) such as aquifer porosity, aquifer salinity and groundwater connectivity time
modifications such as impacts from large water storage dams, presence of small in-stream dams and presence of sewerage treatment plants.

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Tertiary volcanic rocks

There are five volcanic/basalt related rule-sets in SEQ divided by groundwater connectivity time, aquifer porosity and other characteristics.

Table: Core differences between the basalt rule-sets

Rule-set	Groundwater connectivity time (Qld)	Aquifer porosity	Other characteristics	Example catchments
High rainfall permeable rocks (basalts) with near-permanent flow	Near permanent	Primary and secondary		Many catchments
High rainfall permeable rocks (basalts) with permanent flow	Permanent	Primary and secondary		Albert
Low rainfall and/or low capacity permeable rocks (basalts)	Intermittent	Primary and secondary	generally found at lower elevations often associated with rolling hills rather than steep slopes generally receives lower rainfall (i.e. less than 800mm/yr) and/or the basalt occurs in small isolated patches outcropping in the catchment (i.e. have low groundwater discharge capacity)	Many catchments
Petrie Formation along the shoreline of Moreton Bay (Redland basalt)	Near-permanent	Primary	relates to a specific type of basalt (Petrie Basalt) associated with land zone 5 (Old loam and sandy plains), not land zone 3 (Basalt plains and hills) generally found near the coast	Redland, Islands of Moreton Bay
Deeply weathered rises and crests	Near-permanent	Primary	relates to a specific type of basalt (Petrie Basalt)	A few catchments (e.g. Logan)

Sedimentary rocks

There are ten sedimentary rock rule-sets in SEQ, divided by groundwater salinity, groundwater connectivity time, aquifer porosity and other characteristics.

Table: Core differences between the sedimentary rock rule-sets

Rule-set	Groundwater salinity	Groundwater connectivity time	Aquifer porosity	Other characteristics	Example catchments
Sedimentary rocks with saline flow	Saline	Intermittent	Secondary	Drainage lines greater than first order	Mid-Brisbane
Low porosity fractured sedimentary rocks	Saline	Intermittent	Secondary	Drainage lines greater than third order	Upper Brisbane
Sedimentary rocks with near-permanent flow	Fresh	Near-permanent	Primary and secondary	Drainage lines greater than first order	Most catchments
Edge of Clarence-Moreton Basin sedimentary rocks	Fresh	Near-permanent	Primary and secondary	All drainage lines	Many catchments
Sedimentary rocks associated with Leslie Harrison Dam	Fresh	Near-permanent	Primary and secondary	All drainage lines associated with specific water body	Redland
Fassifern scrub	Fresh	Near-permanent	Secondary	Specific regional ecosystems	Bremer, Logan
Medium porosity sedimentary rocks with intermittent flow	Fresh	Intermittent	Primary and secondary	All drainage lines	Many catchments
Sandstone overlying impervious rock	Fresh	Intermittent	Primary	Underlying rocks are impervious	Maroochy
Silkstone Formation	Fresh	Intermittent	Primary and secondary	Sedimentary rocks are high in calcium carbonate	Bremer, Lower Brisbane
Low porosity sedimentary rocks with intermittent flow	Fresh	Intermittent	Primary and secondary	Drainage lines greater than first order	Many catchments

Alluvia

There are 16 alluvia related rule-sets in SEQ, divided by natural/modified, groundwater salinity, groundwater connectivity time and other characteristics.

Table: Core differences between the alluvia rule-sets

Rule-set	Natural or modified	Salinity	Groundwater connectivity time	Other	Example catchments
Tertiary-Quaternary high-level alluvium	Natural	Fresh	Intermittent	Land zone 5	Lower Brisbane
Alluvial aquifers with permanent natural flow	Natural	Fresh	Permanent		Albert, Pine
Alluvial aquifers with near-permanent flow	Natural	Fresh	Near-permanent		Most catchments
Alluvial aquifers with intermittent flow	Natural	Fresh	Intermittent		Most catchments
Alluvial aquifers with saline, near-permanent flow	Natural	Saline	Near-permanent		Lockyer, Upper Brisbane
Alluvial aquifers with saline, intermittent groundwater discharge	Natural	Saline	Intermittent		Lockyer, Mid-Brisbane
Alluvial aquifers with brackish, intermittent flow	Natural	Brackish	Intermittent		Mid-Brisbane
Alluvial aquifers with intermittent flow and fluctuating salinity	Natural	Fluctuating	Intermittent		Lockyer, Mid-Brisbane, Upper Brisbane
Modified alluvial aquifers with near-permanent flow	Modified	Fresh	Near-permanent		Lower Brisbane
Alluvial aquifers with permanent regulated flow from dams	Modified	Fresh	Permanent	Single, large, dam	Nerang, Pine, Bremer
Alluvial aquifers with sustained flow from many in-stream dams	Modified	Fresh	Permanent	Many, small dams	Redland
Alluvial aquifers with sustained flow from in-stream dams	Modified	Fresh	Near-permanent		Redland
Alluvial aquifers with regulated, intermittent flow from dams	Modified	Fresh	Intermittent		Lower Brisbane, Mid-Brisbane, Upper Brisbane
Alluvial aquifers supplemented with effluent	Modified	Fresh	Permanent		Upper Brisbane, Mid-Brisbane
Saline alluvial aquifers supplemented with effluent	Modified	Saline	Permanent		Mid-Brisbane
Alluvial aquifers with permanent regulated flow and fluctuating salinity	Modified	Fluctuating	Permanent		Mid-Brisbane

Fractured rocks

There are three fractured rock related rule-sets in SEQ divided by groundwater connectivity time and the type of rock.

Table: Core differences between the fractured rock rule-sets

Rule-set	Groundwater connectivity time	Rock type	Example catchments
Fractured metamorphic rocks	Intermittent	Metamorphic rocks	Many catchments
Fractured igneous rocks with intermittent flow	Intermittent	Mesozoic igneous rocks	Stanley
Fractured igneous rocks with near-permanent flow	Near-permanent	Mesozoic igneous rocks	Stanley

Coastal sand masses

There are five coastal sand masses rule-sets in SEQ, divided by ridge/dunes, type of lake and groundwater connectivity time.

Table: Core differences between the coastal sand masses rule-sets

Rule-set	Beach ridge or dunes	Lake type	Groundwater connectivity time	Example catchments
Coastal sand masses (beach ridges)	Beach ridge	na	Near-permanent	Many catchments
Coastal sand masses (high dunes)	Dunes	na	Near-permanent	Islands of Moreton Bay
Permanent perched lakes on coastal sand masses	Dunes	Perched	Permanent	Islands of Moreton Bay
Near-permanent perched lakes on coastal sand masses	Dunes	Perched	Near-permanent	Islands of Moreton Bay
Permanent window lakes on coastal sand masses	Dunes	Window	Permanent	Islands of Moreton Bay

Catchment constrictions

There are two constriction rule-sets in SEQ, divided by salinity:

Catchment constriction
Saline catchment constriction.

The first rule-set is applied to the Caboolture, Bremer, Logan and Upper Brisbane catchments. The second rule-set is applied in the Lockyer and Mid-Brisbane catchments.

Low-lying coastal swamps

There are two low-lying coastal swamp rule-sets in SEQ, divided by groundwater connectivity time:

Near-permanent low-lying coastal swamp
Permanent low-lying coastal swamp.

The first rule-set is found in all catchments in SEQ that have a coastal association. The second rule-set is found only in the Maroochy catchment.

Canal estates

There are two rule-sets associated with canal-estates in SEQ, divided by salinity level:

Estuarine canal estates
Brackish canal estates.

Both rule-sets are applied to several catchments in SEQ that have a coastal association.

Colluvium

There is only one rule that addresses large patches of colluvium. Many of the volcanic rock rule-sets will have small patches of colluvium included. The rule-set is applied to one area in SEQ, associated with Mt French (Logan and Bremer catchments).

Last updated: 12 May 2015

This page should be cited as:

Queensland Government, Queensland (2015) Differences between GDE mapping rule-sets in South East Queensland, WetlandInfo website, accessed 20 December 2024. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/facts-maps/gde-background/gde-faq/gde-map-rules/gde-map-rules-seq.html