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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.

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:

Differences between GDE mapping rule-sets in South East Queensland, WetlandInfo 2014, Queensland Government, Queensland, viewed 12 September 2017, <https://wetlandinfo.ehp.qld.gov.au/wetlands/facts-maps/gde-background/gde-faq/gde-map-rules/gde-map-rules-seq.html>.

Queensland Government
WetlandInfo   —   Department of Environment and Heritage Protection