Transcript

Northern Gold Coast Catchment Story

This map journal is part of a series prepared for the catchments of South East Queensland.

Understanding how water flows in the catchment

To effectively manage a catchment it is important to have a collective understanding by all stakeholders of how the catchment works. This Map Journal gathers together information from expert input and data sources to provide that understanding.

The information was gathered using the ‘walking the landscape’ process, where experts systematically worked through a catchment landscape in a facilitated workshop, to incorporate diverse knowledge on the landscape components and processes, both natural and human. It is focussed on water flows and the key factors that affect water movement.

The Map Journal was prepared by the Queensland Wetlands Program in the Queensland Department of Environment and Science in collaboration with local partners.

Main image : Coomera and Yarrabilgong Falls, Lamington National Park, provided by Darren Jew.

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Map Journal for the northern Gold Coast– water movement

This Map Journal describes the location, extent and values of catchments within the northern Gold Coast region (Pimpama and Coomera Catchments). It demonstrates the key features which influence water flow, including geology, topography, rainfall and runoff, natural features and human modifications and land uses.

Knowing how water moves in the landscape is fundamental to sustainably manage the catchment and the values it provides.

Please note that the terms 'Catchment' and 'Basin' are sometimes used interchangeably. In this Map Journal the term 'Catchment' has been used.

In addition the term, ‘Northern Gold Coast Catchments’ relates to the geographic location of the catchments included in this Map Journal product and do not refer to any particular catchment terminology.

Northern Gold Coast Catchment Story

The Northern Gold Coast catchments area, for this story, is located south of Brisbane and within the Pimpama and Coomera River catchments.

The Pimpama River Catchment is located just south of the Logan River Catchment, bordering the Albert River Catchment to the west, and southern Moreton Bay Marine Park to the east and covers a catchment area 13,070 hectares.

The Coomera River catchment is located south of the Pimpama River catchment, bordered by the Albert River Catchment to the west and Nerang River Catchment to the south. The Coomera River catchment is large and covers an area of 48,900 hectares. Its headwaters begin in Lamington National Park. (click to play animation).

The catchment areas of the Pimpama and Coomera rivers primarily fall within the City of Gold Coast area, with the upper parts of the Coomera River catchment falling in Scenic Rim Regional Council area.

Values of the catchments – environmental and social

The northern catchments of the Gold Coast contain many environmental, economic and social values. The wider City of Gold Coast area has a population of more than 500,000 people. About 200,000 people live in the Pimpama and Coomera catchments, which include many urban centres. The upper parts of the Coomera catchment lies within protected areas, with the headwaters of the Coomera River remaining in almost pristine condition.

The catchment provides habitat for a range of threatened species including plants, crayfish, frogs, quolls, and invertebrates - the Richmond birdwing butterfly and pink underwing Moth*.

The catchment areas provide for many social and recreational activities such as camping, canoeing, boating, fishing, bush walking, mountain biking, horse riding and holidaymaking. These activities not only provide substantial social and health benefits but they are also very important for tourism.

Information about the different types of wetlands shown in this mapping is provided here†.

*For more information on species in the Gold Coast region see links at the end of this map journal.

† For more information see links at the end of this map journal

Values of the catchment area – land use

Land use in the catchment area varies significantly between conservation areas, cropping such as sugar cane, and large areas of rural and urban living. The coastal parts include large areas of mangrove and saltmarsh. There has been substantial development over time, particularly across coastal areas (click to see interactive swipe map showing changes in development over time - zoom to an area of interest).*

Sugar cane farm on Stewart Road, Pimpama. Photo by City of Gold Coast

The Coomera River Catchment features highly diverse land uses ranging from its undisturbed headwaters in Lamington National Park, to rural living,cropping and grazing, to high density residential and riverside/estuary development for canal estates, marinas and golf courses. There is also mining and quarrying.

The Pimpama River Catchment is largely rural in its upper areas, with increasing rural and urban residential development in the mid to lower reaches. There are also areas of hardrock extraction. There is a major highwayrunning straight through the middle of the catchment (The Pacific Motorway) as well as a commuter train line. In the alluvial plains and unconsolidated sediment, there is sugar cane farming with some artificial channels and tidal floodgates. The lower reaches are also popular for fishing, boating and recreation. There is also mining and quarrying.

These different land use types combine to make up the land use of the Pimpama and Coomera catchments.

*This application may take time to load. Please note mapping is currently only available for the coastal areas.

Values of the catchment – overland flow, retention areas

There are many areas in the Pimpama and Coomera Catchments that retain water in times of high flow, known as detention or retention areas. Retention and detention areas are used to manage stormwater runoff to prevent flooding and downstream erosion. Retention or detention zones can form naturally in lower parts of the catchment (such as wetland areas), and can be left relatively undeveloped or artificially constructed or modified. Detention areas are developed to be left dry between high flow events. Retention areas retain some level of permanent water.

In the Coomera catchment, sports fields double as detention areas in times of higher flows and serve a flood mitigation purpose. In addition, lower parts of the Coomera catchment, such as wetland areas and even some golf courses serve this detention/retention function.

In the Pimpama catchment, where new developments are occurring, detention and retention areas are being constructed to help manage stormwater runoff from these developments. In the lower parts of the Pimpama catchment, these areas serve a flood mitigation purpose.

The Pimpama catchment overall has a low gradient, with high potential for overland flow. There are many natural overland flow paths and paleochannels present.

Natural landscape features - geology and topography

Various geology types make up the Pimpama and Coomera catchment areas.

The Pimpama catchment consists of large areas of fractured metamorphic andsedimentary rocks, with little to no infiltration in the upper parts. In times of high flows, these areas would experience high runoff.

There are large areas of alluvium in the lower parts of the catchment, as well asunconsolidated sediments and marine muds – all of which absorb and hold water, and recharge groundwater systems.

The Coomera catchment contains highly permeable basalts in the steep, upper regions. Basalts usually enable high amounts of water infiltration and recharge the groundwater system with good quality water. Combined with steeper slopes in these areas, there is also fast run-off in high flow events.

The mid to lower reaches of the catchment have undulating terrain and contain large areas of fine grained sedimentary rocks and fractured metamorphic rocks, much like the Pimpama, where there is little infiltration and high runoff.

In the flatter, floodplain areas of the catchment there are large areas ofalluvium, unconsolidated sediments, artificial fill and marine muds, areas of high water infiltration and groundwater recharge. There are many wetland areas, including the Coombabah Lakes wetland area.

Natural features – rainfall

The Pimpama and Coomera Catchments receive very high to high rainfall, with the highest falls occurring in the upper areas of the catchment, with the upper Coomera areas receiving over 2000mm/year. These areas are one of the highest yielding catchments in South East Queensland for rainfall.

Natural features – vegetation in the Pimpama Catchment

Vegetation affects how water flows through the catchment, and this process is affected by land use and management practices.

Historically, the vegetation in the Pimpama Catchment consisted of patches ofrainforests and scrubs in the upper regions, with mostly eucalypt woodlands to open forests dominating most of the catchment, as well as small pockets ofwet eucalypt open forest.

Along the waterways, the vegetation consisted of woodlands and open woodlands dominated by blue gum (Eucalyptus tereticornis).

In the mid to lower reaches of the catchment, there were also large pockets of open forests and woodland dominated by swamp paperbark (Melaleuca quinquenervia).

The lower Pimpama area also had pockets of open to closed shrubland, grassland, low woodland and open forests on strand and foredunes, with coastal sheoak (Casuarina equisetifolia). There were also areas of open heathsand dwarf open heaths and mangroves and saltmarshes. Saltmarsh (vulnerable) and lowland tropical rainforest (critically endangered) are listed in the Environment Protection and Biodiversity Conservation Act 1999 (EPBC).

This is how the preclear vegetation communities combine in the Pimpama Catchment.

This vegetation slowed water, retaining it longer in the landscape and recharging groundwater aquifers, and reducing the erosion potential and the loss of soil from the catchment.

*Please also note that the regional ecosystems have been grouped into major vegetation types to suit the level of detail for this catchment story. Further detail about regional ecosystems and their structure can be found here:https://www.qld.gov.au/environment/plants-animals/plants/ecosystems/descriptions/

Natural features – vegetation in the Coomera Catchment

Vegetation affects how water flows through the catchment, and this process is affected by land use and management practices.

Historically, the vegetation of the Coomera Catchment contained large areas ofrainforests, vine forests and scrubs, mostly in the upper sections but also around the mid catchment areas. Throughout the catchment there was also patches of wet eucalypt forest dominated by species such as flooded gum, red mahogany, brush box and stringybark.

The mid to lower reaches supported areas of eucalypt open forests on floodplains dominated by species such as blue gum (Eucalyptus tereticornis). These areas also contained open forests and woodlands dominated byMelaleuca quinquenervia (swamp paperbark).

The majority of the catchment besides these areas contained large areas of eucalypt woodlands to open woodlands dominated by various different species including spotted gum (Corymbia citriodora subsp. variegata), blue gum(Eucalyptus tereticornis)  and stringybarks (Eucalyptus spp.).

The lower reaches of the catchment contained mangroves and saltmarshes, as well as other other coastal communities including heath. Saltmarsh (vulnerable) and lowland tropcial rainforst (critically endangered) are listed in the Environment Protection and Biodiversity Conservation Act 1999 (EPBC).

This is how the preclear vegetation communities combine in the Coomera Catchment.

This vegetation slowed water, retaining it longer in the landscape and recharging groundwater aquifers, and reduced the erosion potential and the loss of soil from the catchment.

*Please also note that the regional ecosystems have been grouped into major vegetation types to suit the level of detail for this catchment story. Further detail about regional ecosystems and their structure can be found here:https://www.qld.gov.au/environment/plants-animals/plants/ecosystems/descriptions/

Modified features – vegetation clearing

Much of both the Pimpama and Coomera catchments were historically cleared for settlement and various land uses.

There are some vegetated areas in the upper Pimpama catchment, with the mid to lower reaches being mostly cleared of remnant vegetation. At the mouth, there are still substantial areas of mangroves and saltmarshes.

There are substantial amounts of remnant vegetation remaining in the upper and mid reaches of the Coomera catchment, especially within protected areas, such as Lamington National Park. There are cleared areas for grazing in the upstream areas and heavy urban development in the lower catchment areas.

Large areas of vegetation have regrown since initial clearing, and there are relatively large areas of remnant and regrowth vegetation across the catchment.

Explore the Swipe Map using either of the options below.

• Interactive Swipe App where you can zoom into areas and use the swipe bar (ESRI version).

• Interactive Swipe App where you can use the swipe bar. Use the white slide bar at the bottom of the map for a comparison (HTML version).

These developments and activities change the shape of the landscape and can modify water flow patterns.

*Depending on your internet browser, you may experience issues with one or the other. Please note this application takes time to load.

Modified features – channels and infrastructure

The Pimpama River catchment contains many artificial channels, re-profiled channels and shallow drains, primarily in the lower catchment. There are also large areas of artificial canals in the catchment.

The waters in these drains is mainly brackish and has a high detention time with the exception of flow events when water is usually drained in four days (this requirement is only for certain events i.e. 1/10). The detention is extended in low and base flows due to current floodgate management practices.

Sugar cane farm in Pimpama catchment. Photo by City of Gold Coast

There are also tidal gates at present at Behm Creek and Kerkins Road, which close at high tide, and open (drain) at low tide.

Kerkin Road floodgates, Pimpama. Photo by City of Gold Coast

Infrastructure, such as roads, railways and creek crossings, can createimpermeable surfaces and barriers that redirect water through single points or culverts, leading to channelling of water and increasing water flow rates.

The Coomera River catchment contains many canal areas, roads and causeways, railway and creek crossings. The whole of the Gold Coast area contains more than 400 kilometres of constructed canals. Canal areas range from a mix of fresh and estuarine water, to fully estuarine systems. Canals usually have locks and tidal gates operating and directing freshwater and tidal flows. Each individual canal system operates in slightly different ways and is further explained in the subcatchment slides.

Modified features – dams and weirs

Although there are no major impoundments in the Pimpama and Coomera River catchments, there are weirs on both catchments. The catchments also have numerous rural water storages, which also modify water flows.

Water quality

Water quality is influenced by runoff and point source inputs.

Runoff in these catchments is from a variety of land uses including rural, industrial, commercial and residential areas.

Point source inputs include sewage treatment plants (STPs), septic tank seepage, stormwater discharge and industrial discharge. There are sewage treatment plants (STPs) at Pimpama and Coombabah. There are also rural areas that use septic tanks, as discussed in the subcatchment slides.

During 2016, Healthy Land and Water graded the overall Environmental Condition Grade of the Pimpama and Coomera catchments as B.* The overall environmental condition of the Pimpama an Coomera remains good. Estuarine water quality remains very good .** The water quality above the floodgates in the lower Pimpama is affected by metals leaching from the soils.

Excerpt from Healthy Waterways report card (larger segment of pie chart indicates better score - see links at end of map journal for more information).

*2016 was an unusually dry year. The Environmental Condition Grade improved for many catchments in South East Queensland during 2016 as there was less rainfall and associated run-off carrying sediment and potential contaminants to waterways (rather than an improvement in condition).

**Healthy Waterways Lower Brisbane Catchment Report Card (for current report see links at end of map journal).

Water Flow

Water flows across the landscape into streams and eventually into the main watercourses of the Pimpama River and Coomera River.

Click to see 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 upper reaches of the catchment have relatively steep slopes which create the potential for increased runoff which may lead to flooding in areas where the floodplain has restricted channels and gullies.

The restricted channels and gullies eventually flatten out to form waterways that meander across the floodplain. They pass through alluvial areas which store and release water, prolonging the time streams flow.

The subcatchments

A catchment is an area with a natural boundary (for example ridges, hills or mountains) where all surface water drains to a common channel to form rivers or creeks.*

Larger catchments are made up of smaller areas, sometimes called subcatchments.

The Pimpama and Coomera catchments consist of large and small subcatchments.

For the purposes of this map journal, the Pimpama catchment is divided into:

• Upper Pimpama River
• Hotham Creek
• Yawalpah Road and McCoys Creek
• Lower Pimpama River
• Kerkins Drain, Jacobs Well, Southern Moreton Bay and Behm Creek

The Coomera catchment is divided into:

• Upper Coomera and Back Creek
• Middle Coomera and Mount Nathan
• Guanaba Creek
• Wongawallan Creek
• Maudsland
• Saltwater Creek
• Coombabah Creek
• Lower Coomera
• Broadwater (Paradise Point, Runaway Bay, Arundel, Parkwood, Loders Creek and Southport)

The characteristics of each subcatchment are different, and therefore water will flow differently in each one.

City of Gold Coast (2021) About water catchments. [webpage] Accessed 25 August 2021

Upper Pimpama River

The Upper Pimpama River experiences very high rainfall in the upper catchment, and high rainfall in the rest of the catchment. The rock types in the area, especially in the upper to mid reaches of the catchment, promote fast run-off. The channel is confined in the upper parts of the catchment. Further downstream, there are increasing amounts of shallow alluvium and unconsolidated sediment and shallow channels.

There are also some constructed detention areas associated with increasing development further downstream, as well as potential detention / retention zones which serve a flood mitigation purpose. In times of high flow, the train line may affect hydrology as it restricts water flow. The Pimpama River is over a low gradient and so there is more potential for overland flow.

There is some fine sediment in the system, and some acid sulphate presence in the lower sections.

There is greenstone extraction to the north, and many semi-rural areas with private reserves. There is also some grazing in the area and sugarcane farmingfurther downstream.

Photo: Upper Pimpama River. Credit: City of Gold Coast

Hotham Creek

Hotham Creek is situated south of the Pimpama River and joins it further east in the lower areas of Pimpama River. The Hotham Creek subcatchment receives high rainfall. The headwaters and upper sections of the catchment have constricted flows and semi-confined and bedrock controlled channels. The geology is mostly fractured rock. There is some alluvial and unconsolidated sediment development along the watercourses.

The lower parts of the sub-catchment have had feeder streams filled in, is highly modified, and has little riparian vegetation. There is still some ponding in the lower areas. Near the confluence with the Pimpama River there arewetland areas with the potential for rehabilitation for this area to serve as a detention and/or retention zone.

Cattle in Hotham Creek, Pimpama. Photo by City of Gold Coast

Yawalpah Road and McCoys Creek

Yawalpah Road and McCoys Creek are connected to the lower parts of the Pimpama River. These areas experience high rainfall and are situated onfractured rock in the upper areas, with alluvium and unconsolidated sediments downstream.

The Yawalpah Road sub-catchment is well vegetated, however also subject tourban development occurring in the area. The railway runs through this catchment as does the major road corridor of the Pacific Motorway. Buildings and important infrastructure such as roads, railways and creek crossings create impermeable surfaces and barriers that redirect water through single points or culverts, leading to channelling of water. This increases the rate of flow and the potential for erosion.

McCoys Creek joins the Pimpama River near its mouth, with intact wetlandsand healthy riparian vegetation, including black mangroves. Despite this, there is a lack of fish diversity due to a lack of connections from the headwaters to the lower sections of the catchments. There are indications that fish diversity in McCoys creek has been impacted by a range of factors. These include activation of acid sulfate soils, poor sediment and erosion controls on development sites and altered hydrology associated with rapid urbanisation.

Photo credit: City of Gold Coast

Lower Pimpama River

The Lower Pimpama River sub-catchment is a flat area, with many overland flow paths and paleochannels. The geology is some fractured rock, with larger areas of alluvium and unconsolidated sediments. The flow in this area is slow and runs into wetlands, especially when over the alluvial plains andunconsolidated sediments. The presence of the shallow drains in the catchment can impact on the amount of water that can reach the wetlandareas.

The area has minimal riparian vegetation, with large areas of sugarcane farming. Kerkin Road floodgates is located on Kerkins Road. The Pimpama Sewage Treatment Plant is located in the centre of the subcatchment.

Water Treatment Plant, Pimpama. Photo by City of Gold Coast

Near the mouth of the Pimpama River, the Pimpama River Conservation Reserve supports a variety of coastal vegetation communities includingmangroves, shrubland, sedges, swamp oak and paperbark open forest and eucalypt coastal woodland. It also provides habitat for many species of terrestrial and estuarine wildlife including the vulnerable water mouse (Xeromys myoides). It borders the Southern Moreton Bay Marine Park andRamsar wetland site, with the endangered eastern curlew (Numenius madagascariensis) been recorded in the area.

Kerkins Drain, Jacobs Well, Southern Moreton Bay and Behm Creek

Kerkins Drain is located just east of the Jacobs Well catchment. It is a highly modified, flat area, over mostly unconsolidated sediments. There are manydrains in the area, artificial canals, and sugarcane farming. The Jacobs Well Environmental Education Centre is located in this area also, and offers camping or day visits. Water equipment for high quality environmental education programs are available through the Centre.

Jacobs Well contains the urban areas of Jacobs Well and Calypso Bay (marina and canal estate). There is a small amount of cane farming and large areas ofreserve, including the Jacobs Well Reserve situated over a coastal wetland.

The Southern Moreton Bay area is almost entirely comprised of estuarine and palustrine wetlands and contains the Pimpama River Conservation Reserve.

Upper Coomera and Back Creek

The headwaters of the Coomera Catchment contain basalts which usually enable good water infiltration and recharge the groundwater system, resulting in good quality water. Due to steeper slopes in these areas, there is also fast run-off in high flow events. The Upper Coomera sub-catchment is densely vegetated, within Lamington National Park, and has many bedrock controlled channels. There are also large areas of grazing, where riparian vegetation has been reduced. The channel is semi-confined further down the catchment.

There are some slips associated with the layering of geologies (colluvium, over rhyolite). The colluvium absorbs water and slips over the rhyolite—a geology that does not allow infiltration. Waterfalls are also common in these areas.

Back Creek and Armitage Creek are also situated in the highly permeablebasalts, however there is some development of sedimentary rocks with low permeability (Naranleigh Fernvale beds) and rhyolite (Chillingham volcanics). This sub-catchment contains grazing and some rural living. The upper sections of Back Creek have been cleared, however there are some dense areas of vegetation further downstream. There are some defence-managed lands with dense vegetation preventing sediment moving downstream.

Image: Waterfalls in Lamington National Park. Credit: Darren Jew.

Middle Coomera and Mount Nathan

Moving further down the Coomera River, the Middle Coomera and Mount Nathan sub-catchment areas have a major shift in their main geology type tofractured metamorphic rocks which allow for some infiltration. The catchment is still very steep at this point, with good vegetation cover. The areas contain mostly rural residential/rural living with some cropping / horticulture. There are some septic and onsite sewage treatment systems associated with rural living/rural residential. Due to the geology in this area, there is limited natural riparian vegetation.

The area typically experiences fast runoff, with some areas of discontinuous floodplain with frequent flooding. There is some water extraction on the floodplains for horticulture development.

Guanaba Creek

The Guanaba Creek sub-catchment is located north of the Coomera River and joins it near Maudsland sub-catchment. Guanaba Creek lies mostly onfractured metamorphic rocks, apart from some small areas of basalt. The channel is dominated by bedrock in the upper reaches however, loses its definition further downstream.

Crossings in the catchment such as causeways can cause sand and sediment to build up above them, and there are several pinch points in the catchment. There is also a constriction near the confluence with the Coomera River.

There are many rural water storages in this catchment, as well as onsite sewage treatment and septic systems.

The Tamborine township is located over a large recharge area (due to basalt geology). There are also areas of Tamborine National Park within the catchment which protect areas of wet eucalypt forest dominated by tall flooded gums, open forest with bracken fern understorey and woodland.

Wongawallan Creek

The Wongawallen Creek sub-catchment sits north of the Guanaba Creek sub-catchment, also joining the Coomera River in the Maudsland sub-catchment.

Wongawallen Creek is mostly underlain by fractured metamorphic rocks, much like Guanaba Creek, with a small area of basalt to the west. It is another area of high runoff and little infiltration, and joins the Coomera River from the north.

The channel is bedrock controlled, with some instream boulder bars. The catchment is well vegetated with some semi-rural/rural living. It contains the township of Eagle Heights.

Sediment transfer, mostly sand, from the surrounding alluvium, occurs in this catchment.

Maudsland

The Coomera River continues from the Mount Nathan/Clagiraba sub-catchment into the Maudsland sub-catchment. The catchment is dominated byfractured metamorphic rocks, and there is alluvium present. The channel flattens out in this area.

There has been some modification to the channel with levees constructed to protect a local ski park. There is a large amount of hydraulic energy above this work, and the lower Coomera River is vulnerable to large flows as it is sitting lower in the catchment.

There is a pony club in this area as well as acreage, semi-rural and urban areas.

Coomera River Weir is located in this catchment. This marks the point at which the Coomera River becomes estuarine. Sand is deposited into the weir pool. Parts of this sub-catchment have high ecological values. 

Saltwater Creek

To the east of Maudsland, Saltwater Creek runs almost parallel to the Coomera River and joins Coombabah Creek just prior to the Broadwater. The upper sections are well vegetated and a part of Nerang National Park. Downstream in the mid to lower sections, it is highly urbanised, including canal estates, golf clubs and theme parks. Saltwater Creek is an open channel until the Monterey Keys lock diverts water into Coombabah Lake. There is also an anabranchconnecting Saltwater Creek with the Coomera River.

It is a fast flowing catchment due to its geology (fractured metamorphic rocks which allow for some infiltration) with alluvium increasing further downstream.

There are many channelised tributaries with little storage capacity which can lead to high and fast flows in the area. As well as channelised smaller tributaries, the sub-catchment also hosts retention areas in the form ofwetlands and sports fields. There are some stored nutrients in the catchment.

Coombabah Creek

Coombabah Creek begins in the well vegetated Nerang National Park before flowing into the lower parts of the sub-catchment – Coombabah Lakes. This area is a flat, broad wetland area with a combination of freshwater and saltwater wetlands and includes the Coombabah Lakelands Conservation Area and Coombabah Fish Habitat area. Coombabah Lakelands Conservation Area protects more than 1200 hectares of wetland, eucalypt forest, salt marsh and mangrove habitat. Coombabah Lakes contains critically important habitat for rare migratory seabirds.

Coombabah Lakelands Conservation Area

Lake Coombabah and its estuarine system are important coastal wetlands and migratory water bird habitat. The Conservation Area is home to 274 species of animals, with seven species listed as 'vulnerable' or 'near threatened', including the koala, powerful owl and grey-headed flying fox, along with 24 internationally protected migratory bird species.

The subcatchment has fractured rock geology in the upper reaches, whilst the wetlands are over alluvium and colluvium, which allows for some infiltration.

There is an sewage treatment plant (STP) in the middle of Coombabah Lakelands Conservation Area, at sea level.

This area is a hotspot for future development, which has the potential to place pressure on the wetland values in the sub-catchment. Despite this, buffer zones are a part of the planning for future development, including areas for rehabilitation.

Lower Coomera

The areas around Yaun Creek and Brygon Creek are highly developed, and are situated over sedimentary rocks with low permeability with some alluvium. The combination of urban residential hard surfaces and the existing geology results in high runoff and fast flows with little to no infiltration. There is good riparianvegetation around these creeks.

Regatta Lake is designed for capturing flood flows.

Oakey Creek is a small stream that runs into the Coomera River. It has good riparian condition, however freshwater fish and macroinvertebrate diversity is low. Dense development in the upper catchment has impacted on the creek health.

Downstream of the Pacific Motorway, the surface geology is mostly artificial fill and alluvium, resulting in a flat landscape and broad channels. There is much urban and residential canal development. The Gold Coast City Marina and Shipyard is located on the lower Coomera River. The river is dredged to allow large boats to reach the marina. There is also some sugar cane farming.

Further down the Coomera River, there are large areas of residential canal estate and a series of canal locks. There is some bank slumping and instability in the main channel. Spoil is used on the edges of canals to stabilise them.

The area around Coomera Island has some good salt marsh habitat and is undeveloped.

Broadwater (Paradise Point, Runaway Bay, Arundel, Parkwood, Loders Creek and Southport)

The creeks in the area around the Broadwater flow into the the Broadwater itself, but not the Coomera River. The area is highly modified with mostly urban residential and some manufacturing, golf courses and the Gold Coast Hospital.

The underlying geology is mostly fractured metamorphic rocks in the upper areas (limited infiltration) and alluvium in lower areas (high infiltration). However, in developed areas, hard surface areas allow little to no infiltration.

Some riparian corridors are present in Arundel, such as those in Biggera Creek. The rest of the areas have little to no riparian areas. The wallum froglet and green-thighed frog were recorded in Loders Creek, near the Smith Street and Wardoo street intersection. A Nature Trail from Baratta Street to Beale Street, Southport has been constructed.

Photo credit: City of Gold Coast

Conclusion

The Pimpama and Coomera Catchments cover the catchment areas of the Northern Gold Coast.

There are a number of significant values in these catchments including natural, social and economical. The Gold Coast is a haven for lovers of nature and the water. They are productive catchments in many ways. The various land uses, ranging from National Park to sugar cane cropping, to urban residential – all playing a significant part in how the catchments function.

These catchments show how natural and modified features within the landscape impact on how water flows. These issues need to be managed to ensure that the significant natural and social values of the catchment are protected, while providing for residential, tourism, farming and other important land uses of the catchment.

Knowing how the catchment functions is also important for future planning, including climate resilience. With this knowledge, we can make better decisions about how we manage this vital area.

Acknowledgements

Developed by the Queensland Wetlands Program in the Department of Environment and Science in partnership with:

City of Gold Coast

Scenic Rim Regional Council

Council of Mayors South East Queensland

Healthy Land and Water

Gold Coast Waterways Authority

This resource should be cited as: Walking the Landscape – Northern Gold Coast Catchments Map Journal v1.0 (2017), presentation, Department of Environment and Science, Queensland.

Images provided by City of Gold Coast Council.

The Queensland Wetlands Program supports projects and activities that result in long-term benefits to the sustainable management, wise use and protection of wetlands in Queensland. The tools developed by the Program help wetlands landholders, managers and decision makers in government and industry.

Contact wetlands♲des.qld.gov.au or visit wetlandinfo.des.qld.gov.au

Disclaimer

This map journal has been prepared with all due diligence and care, based on the best available information at the time of publication. The department holds no responsibility for any errors or omissions within the document. Any decisions made by other parties based on this document are solely the responsibility of those parties. Information contained in this education module is from a number of sources and, as such, does not necessarily represent government or departmental policy.

Data source, links and information

Software Used

ArcGIS for Desktop | ArcGIS Online | Story Map Journal 

Some of the information used to put together this Map Journal can be viewed on the QLD Globe. Queensland Globe allows you to view and explore Queensland spatial data and imagery. You can also download a cadastral SmartMap or purchase and download a current titles search.

More information about the layers used can be found here:

Source Data Table

Flooding Information

Scenic Rim Regional Council

City of Gold Coast

City of Gold Coast's flora and fauna website

Wetland (aquatic ecosystem) types

Healthy Waterways (2017), Pimpama / Coomera Catchment 2016 Report Card.[webpage] Accessed 17 August 2017.

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Last updated: 25 August 2021