Plane Catchment Story - Physical features

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• Overview
• Physical features
• Natural values
• Subcatchment key messages
• Sandy subcatchment
• Sandringham Lagoon subcatchment
• Rocky Dam Creek subcatchment
• Acknowledgements

View the Plane catchment story

Transcript

Physical features

The Plane catchment features a complex range of geology and topography. The hills, floodplains and depressions in the landscape contribute to the diversity of plants and animals that live within the catchment. The rocks and soils help to shape the land and there are strong connections with how water flows across the landscape and into creeks and groundwater.

Main image. Waterfall on a tributary to lower Rocky Dam Creek - provided by Matthew Moore.

Table of contents

1. Geology and topography
2. Rainfall
3. Modified features—infrastructure, dams, weirs and bores
4. Modified features—sediment
5. Water quality
6. Water flow

Geology and topography

Several different rock types combine to make up the geology of the Plane catchment.

The headwaters of the catchment are dominated by hard geologies such as mixed volcanics, granitoids, gabbroids and mafites and felsites in the north, and granitoids and mafites and felsites in the south. Some of the hard geologies are fractured and allow for some local groundwater infiltration.

Most of the lower elevations are dominated by alluvium and other unconsolidated sediments. These unconsolidated geologies allow water infiltration, where not developed. Much of the lower catchment is flat and prone to flooding. 

Conceptual models for several of the catchment's geology types are provided below.

Fractured rocks - conceptual diagram by Queensland Government.

Exclusion zones - conceptual diagram by Queensland Government.

Alluvia - conceptual diagram by Queensland Government.

Alluvia - lower catchment - conceptual diagram by Queensland Government.

Groundwater-dependent ecosystems (GDE) types - conceptual model provided by Queensland Government.

Main image. Geological feature, Running Creek - provided by Reef Catchments.

Rainfall

The Mackay Whitsunday region usually experiences annual wet and dry seasons, with most of the rainfall typically between November and March.

The hydrological seasonality associated with these wet and dry season flow conditions are critical to the ecological character, function and associated values of aquatic ecosystems. The dry season is also an essential part of the functioning of the system with these semi-permanent waterholes just as vital to the ecosystems as the wet season flows.

Average annual rainfall* ranges from 1,001 to 2,000 millimetres per year with higher rainfall over most of the north and foothills of the range.

Main image. Carmilla Creek - provided by Reef Catchments.

*This dataset depicts the 50-year mean annual rainfall isoheyts (contours) over Queensland for the period 1920 to 1969. The dataset was produced from the mean annual rainfall of as many locations as possible including private collections. Incomplete datasets were `made whole` by calculating values for missing periods through correlation with adjacent rainfall stations.

Modified features—infrastructure, dams, weirs and bores

Buildings and important infrastructure such as roads and tracks, railways and creek crossings can create barriers and impermeable surfaces that redirect water through single points or culverts, leading to channelling of water in some parts of the catchment. This increases the rate of flow and the potential for erosion. Modifications to channels, such as straightening and diversions, can also increase flow rates.

Roads and levees - conceptual diagram by Queensland Government

Low permeability surfaces - conceptual diagram by Queensland Government

Infrastructure, Oaky Creek - provided by Reef Catchments.

Dams and weirs also modify natural water flow patterns, by holding water that would otherwise flow straight into the stream network. There are rural water storages (farm dams), weirs and bunds in parts of the catchment.

Lake Kinchant is located on a tributary of upper Sandy Creek (North Arm) and has full supply volume of more than 62,000 megalitres. Water is diverted from Mirani Weir in the Pioneer catchment through an open channel into Kinchant Dam. The dam releases water for irrigation purposes via the Oakenden Main Channel, and flood releases may be made from the dam into Sandy Creek during high rainfall events. There are a series of channels* and pipelines* in association with Sandy Creek (Eton Water Supply Scheme) and near Carmila.

Eton scheme - provided by Sunwater.

There are also many bores**, particularly in the north of the catchment. The bores extract water for mostly irrigation and can influence groundwater systems. 

Infrastructure, dams and weirs can affect fish passage through the catchment. Several fish ways have been installed across the catchment, particularly in the Rocky Dam subcatchment.

Fish way construction on Boundary Creek - provided by Matthew Moore.

Main image. Bridge crossings, Bakers Creek - provided by Reef Catchments.

*Showing canals and pipelines in the Sandy and Pioneer catchments only.

**Taken from database storing registered water bore data from private water bores and Queensland Government groundwater investigation and monitoring bores. 

Modified features—sediment

Increases in the volume and speed of runoff, and disturbed vegetation through activities such as construction or grazing, can increase erosion in the landscape and the stream channels. This can result in sediment being carried downstream and reduced water quality. The construction stage of a development typically generates more sediment in runoff than more mature stages of a development.

The suspended sediment of most risk to the Great Barrier Reef (GBR) is the fine fraction. Fine sediment:

• contains most of the nitrogen and phosphorus content (and other potential contaminants such as metals),
• travels widely in flood plumes rather than all depositing near the river mouth, and
• substantially reduces light when in suspension.

Furthermore, the impacts of suspended sediment contributes to the cumulative impacts of other stressors (e.g. freshwater flood plumes, elevated nutrients, impacts from cyclones, increasing sea surface temperatures) to increase the overall impact on organisms of the GBR.

Main image. West Hill Creek - provided by Reef Catchments.

Water quality

Water quality is influenced by diffuse runoff and point source inputs. Runoff is from a variety of land uses, including rural, residential, industrial and commercial areas.

Diffuse runoff includes on-site sewage facilities (e.g. septic tanks) and runoff from farming areas and low permeability surfaces common in urban areas. The concentration of potential contaminants in the stormwater discharge depends on the land use of the area. 

Point source inputs include the Mirani, Mackay South and Sarina sewage treatment plants in the north. Many of the southern parts use septic tanks.

Cattle, pigs and other animals can also directly influence water quality by disturbing the substrate and/or trampling vegetation.

Information regarding monitoring sites (gauging stations*) and catchment load monitoring** can be found in the reference section at the end of this map journal.

Catchment conceptual model - provided by Queensland Government.***Main image. Increased turbidity associated with land use - provided by Reef Catchments.

See links at the end of this map journal for further information on the following references.

*Water Monitoring Information Portal (Queensland Government 2017)

**Great Barrier Reef Catchment Loads Modelling Program (Queensland Government, 2017)

***Reef 2050 Water Quality Improvement Plan (Queensland Government (2018) 

Related literature:

Reef 2050 Water Quality Improvement Plan - Report cards (Queensland Government (2017) 

Water flow

Water flows across the landscape into the waterways of the catchment (click for animation)*.

The remaining water either sinks into the ground where it supports a variety of terrestrial and groundwater dependent ecosystems or is used for other purposes.

The smaller channels and gullies eventually flatten out to form larger waterways that flow through lower lying land. They pass through unconsolidated areas which store and release water, prolonging the time streams flow.

Main image. Flow in Rocky Dam Creek - provided by Matthew Moore.

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Last updated: 18 November 2025