Lake Eyre Basin Catchment Story – Cooper catchment

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Transcript

Understanding how water flows in the Cooper Creek catchment

This Map Journal is part of a series prepared for the catchments of Queensland.

We acknowledge the Aboriginal peoples and Torres Strait Islander peoples as the Traditional Owners and Custodians of this Country. We recognise and honour their ancient cultures, and their connection to land, sea and community. We pay our respect to them, their cultures, and to their Elders, past, present and emerging.

Main image - View of Cooper Creek, Windorah, South West Queensland, provided by Gary Cranitch, © Qld.Museum.

Cooper Creek Catchment Story

This map journal demonstrates the key features which influence water flow, including geology, topography, rainfall and runoff, vegetation, human modifications and land uses. Knowing how water moves in the landscape is fundamental to sustainably managing the catchment and the services it provides.

It is to be used in conjunction with the Queensland Reconstruction Authority's Central West Resilience Strategy. The strategy is provided in the first tab of this map series, and includes details on the following components of the Cooper Creek catchment:

• Environmental values
• Social values
• Economic values

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 the Queensland Reconstruction Authority and local partners.

Main image - View of Cooper Creek, Windorah, South West Queensland, provided by Gary Cranitch, © Qld.Museum.

*Walking the Landscape—A Whole-of-system Framework for Understanding and Mapping Environmental Processes and Values (Department of Environment and Heritage Protection 2012) - see links at the end of this map journal for further information.

Table of contents

1. How to view this map journal
2. Subcatchments
3. Geology and topography
4. Rainfall
5. Vegetation
6. Infrastructure
7. Water flow
8. Upper Thomson
9. Lower Thomson
10. Barcoo River
11. Cooper Creek
12. Conclusion

How to view this map journal

This map journal is best viewed in Chrome or Firefox, not Explorer.

Main image - Kyabra Waterhole at dusk, photo by Water Planning Ecology, QLD Government

Subcatchments

The Lake Eyre Basin is the largest drainage division in Australia, and includes large parts of Queensland, New South Wales, South Australia and the Northern Territory.

The Lake Eyre Basin has one of the most variable flow regimes in the world, and is one of the largest unregulated arid zone basins in the world.

Natural areas such as wetlands, channels and waterholes become vital areas of the landscapes for flora and fauna to persist, in both wet and dry periods. Despite long hot and dry conditions, the channels and waterholes in the Lake Eyre Basin provide habitat for a diverse array of flora and fauna.

The Cooper Creek catchment contains wetlands recognised as having national importance (Directory of Important Wetlands). These wetlands are of high ecological significance and contain unique values. 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.*

The Cooper Creek catchment drains an area of approximately 237,000 square kilometres and is bordered by the Diamantina, Flinders, Suttor, Nogoa, Warrego and Bulloo River basins.

The Thomson and Barcoo rivers merge into Cooper Creek (click for animation), where the channel country starts, and crosses the border into South Australia to flow into Kati Thanda-Lake Eyre.

The Cooper Creek catchment consists of several distinct areas which have similar characteristics:

1. Upper Thomson (Torrens, Towerhill creeks with many other waterways)
2. Lower Thomson (with other waterways)
3. Barcoo River (with other waterways)
4. Cooper Creek (with other waterways)

*Definition sourced from the City of Gold Coast website - see links at the end of this map journal.

Main image - Channel millet swamp in Cooper Creek, provided by R. Jaensch, Wetlands International

Geology and topography

Above the town of Windorah, the Thomson and Barcoo rivers have typically well-defined creeks and channels. Below the town, true channel country develops, with wide channels and expansive floodplains.

Different rock types combine to make up the geology of the Cooper Creek catchment.

Generally, water flow is fast off hard geologies such as granitoids, sedimentaries (arenites), volcanics (mafites and felsites), particularly when the topography is steep. More porous geologies, such as alluvium and colluvium allow some surface water to infiltrate and recharge groundwater systems. Metamorphic geologies can allow for some local recharge of groundwater systems through fracturing.

Conceptual models for several of the catchment's geology types and flow characteristics are provided at the end of this slide.

The Cooper Creek catchment, including the sub basins of the Thomson and Barcoo Rivers, has very low relief with little slope. There are few obvious catchment divides with the exception of the existence of 'jump-ups' or Cainozoic duricrusts - which are formed on a variety of rock types, usually forming mesas or scarps. East of Aramac and Muttaburra, the desert uplands lead to an area of higher elevation.

In the eastern headwaters of the catchment, including catchment areas for Torrens, Bullock and Prairie Creek, Cornish Creek and Alice River (and all associated tributaries) there are large areas of colluvium, a friable and porous geology and areas of alluvium associated with channel areas. Sandstone ridges are also present at the top of the floodplain here.

Further south and west, harder geologies create areas of fast runoff with little to no infiltration on mudstones and arenite. The floodplain is narrow with smaller areas of alluvium.

The Thomson and Barcoo River converge to form a series of braided channels. Here Cooper Creek consists of large areas of alluvium and sand, mostly to the west. The floodplain and channels become very wide and extend over large areas until close to the border with South Australia, where Cooper Creek flows through a narrow constriction of sedimentary rock.

Exclusion zones - conceptual diagram by Queensland Government

Permeable rocks - conceptual diagram by Queensland Government

Fractured rock - conceptual diagram by Queensland Government

Alluvia - conceptual diagram by Queensland Government

Alluvial aquifers - conceptual diagram by Queensland Government

Channel shape - conceptual model by Queensland Government

*Land zone 3 (Alluvial river and creek flats). Defined as 'Recent Quaternary alluvial systems, including closed depressions, paleo-estuarine deposits currently under freshwater influence, inland lakes and associated wave built lunettes. Excludes colluvial deposits such as talus slopes and pediments. Includes a diverse range of soils, predominantly Vertosols and Sodosols; also with Dermosols, Kurosols, Chromosols, Kandosols, Tenosols, Rudosols and Hydrosols; and Organosols in high rainfall areas.' (Wilson et al. 2012) - see links at the end of this map journal for further information. Land zone mapping is available within the preclear vegetation mapping by clicking on the relevant polygon.

**Mostly land zone 5 (old loamy and sandy plains). Defined as 'Tertiary-early Quaternary extensive, uniform near level or gently undulating plains with sandy or loamy soils. Includes dissected remnants of these surfaces. Also includes plains with sandy or loamy soils of uncertain origin, and plateau remnants with moderate to deep soils usually overlying duricrust. Excludes recent Quaternary alluvial systems (land zone 3), exposed duricrust (land zone 7), and soils derived from underlying bedrock (land zones 8 to 12). Soils are usually Tenosols and Kandosols, also minor deep sandy surfaced Sodosols and Chromosols. There may be a duricrust at depth.' (Wilson et al. 2012) - see links at the end of this map journal for further information. Land zone mapping is available within the preclear vegetation mapping by clicking on the relevant polygon.

***Most sedimentary rock types have low permeability. The Elliot Formation sedimentary rock consists of sandstone, siltstone with minor mudstone, conglomerate and shale, and have experienced periods of deep weathering. This has caused sediments to become mottled, iron-rich or bleached and developed a distinct duricrust appearance, and increased permeability (Marshall et al. 2015; Wilson et al. 1999) - see links at the end of this map journal for further information.

Main image - Black Gin Creek, provided by QLD Government

Rainfall

The Cooper Creek catchment experiences highly variable rainfall totals in any given year, and experiences low to very low average rainfall. This highly variable rainfall has resulted in sparse vegetation cover and intermittent river systems.

Generally, the northern area of the catchment is influenced by monsoonal events, and most of the rainfall occurs during summer and into autumn. Southern areas experience far less rainfall.

Although rainfall can be variable, it can supply large amounts of water which flood larger areas downstream.

This means that rivers and creeks in the Cooper Creek catchment experience high variability and largely unpredictable flows, with high transmission losses in drier periods, and low gradients (flat landscapes).

The mean rainfall graphs below are an indication of local rainfall only. There can be significant differences in topography and rainfall within a region. Locations were chosen from available sites that record rainfall data and from each end of the catchment where possible.

Mean annual rainfall (mm) for years 1886 - 2019 for Barcaldine - Provided by the Bureau of Meteorology

Mean monthly rainfall (mm) for years 1886 - 2019 for Barcaldine - Provided by the Bureau of Meteorology

Mean annual rainfall (mm) for years 1887 - 2019 for Windorah - Provided by the Bureau of Meteorology

Mean monthly rainfall (mm) for years 1887-2019 for Windorah - Provided by the Bureau of Meteorology

Mean annual rainfall (mm) for years 1877 to 2019 for Tambo - Provided by the Bureau of Meteorology

Mean monthly rainfall (mm) for years 1877 to 2019 Tambo - Provided by the Bureau of Meteorology

Main image - Dry gutters in the Cooper Creek catchment, provided by R. Jaensch, Wetlands International

Vegetation

Water that falls as rain, or moves over the land as runoff or floodwater, is slowed by vegetation, which then allows it to filter down into the soil and sub-soil and recharge aquifers.

The Channel Country bioregion contains vast braided floodplains, surrounded by gravel or gibber plains, dunefields, low ranges and jump-ups. Vegetation types vary from eucalypt woodlands with a spinifex understorey, acacia woodlands in the desert uplands, to largely treeless plains with some occasional ridges, rivers and gorges. Vegetation is predominantly mitchell grass, gidgee and spinifex.

Vegetation cover and water flow - conceptual model by Queensland Government

Water moving slowly across the surface of the land reduces the potential for erosion to occur and the associated issues with water quality and sedimentation further downstream. Reducing the speed of runoff also plays a role in protecting banks and parts of the landscape prone to gully and rill erosion.

The grazing industry makes up the majority land use of the Cooper Creek Catchment. Grazing is mostly for cattle, however there is some sheep grazing in the upper sections. Tourism also makes up some of the land use in the Cooper Creek catchment.

There are some areas of mining (oil and gas) in the lower sections.

Large areas of the original native (preclear) vegetation* remain with some areas cleared or partially cleared**.

Explore the swipe map showing vegetation mapping over time (preclearing and remnant), using either of the options below.^

• Interactive Swipe App where you can zoom into cleared 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)

Vegetation clearing and associated activities change the shape of the landscape and can modify surface and groundwater flow patterns. Vegetation type can also modify flood patterns. Dense grasses can capture silt, and gidgee has potential to create excess run-off.

*Broad Vegetation Groups (BVGs) are mapped for original native (preclear) vegetation and remnant vegetation. The BVGs are derived from Regional Ecosystems (REs), which are vegetation communities in a bioregion that are consistently associated with a particular combination of geology, landform and soil.

*The 2011 remnant vegetation mapping was undertaken at a map scale of 1:100,000 and 1:50,000 in part (including the Wet Tropics and South-eastern Queensland) and based on the Landsat imagery for 2011. It does not show all clearing, particularly relatively thin linear infrastructure.

***This dataset take time to load. Smaller areas of regrowth are not shown in this mapping. This dataset was prepared to support certain category C additions to the Regulated Vegetation Management Map under the Vegetation Management (Reinstatement) and Other Legislation Amendment Bill 2016. This dataset is described as: The 2013 areas of non-remnant native woody vegetation that have not been cleared between 1988 and 2014 that are homogenous for at least 0.5 hectare and occur in clumps of at least 2 hectares in coastal regions and 5 hectares elsewhere.

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

Main image - Subsiding floodwaters, Noccundra, South Western Queensland, Gary Cranitch, © Qld.Museum

Infrastructure

Important infrastructure such as roads, 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. Channelling, and modifications to natural channels such as straightening and diversions, can increase flow rates and erosion.

Roads and water flow - conceptual model by Queensland Government

The catchment contains limited modifications to flow with no major dams or weirs, aside from small weirs on the Thomson at Stonehenge and Alice River at Barcaldine. The Cooper Creek catchment is a free-flowing catchment.

There are also some groundwater bores*, which extract water for residential, stock and domestic use.

Infrastructure can also affect fish passage through the catchment, although during periods of flood many of the smaller barriers are “drowned out” by water flowing over the top of them.

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

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 retained in waterholes, evaporates or is used for other purposes.

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

*Please note this application takes time to load.

Main image - View over the Barcoo River, provided by Gary Cranitch, © Qld.Museum.

Upper Thomson

The geology of the upper Thomson River region contains large areas of colluvium in the east (Torrens Creek and surrounds) and mudstone/arenite (fine grained sedimentary rocks) to the west. Channel areas contain alluvium and colluvium. Black soils are present which pose issues for access when wet, until saturated and they seal. Red soils swell when wet and become difficult to traverse.

Towerhill Creek and Aramac Creek have relatively fast flows over the mudstone/arenite, with the potential for flash flooding due to smaller floodplains and narrow channels. There are no records of the Landsborough River, Towerhill Creek or Cornish Creek (which all converge into the Thomson River) flowing at the same time. Speed of flow is variable across these areas which can limit the potential for all three rivers to reach the same place at the same time.

Towerhill Creek, provided by Water Planning Ecology, QLD Government

The Torrens Creek and Perry Creek areas contain many waterholes. These waterholes have the potential to fill with silt and which is becoming an emerging issue.

Land use is predominantly grazing on native pasture.

Significant wetland areas in this region include:

• Lake Buchanan: a brackish palustrine and lacustrine intermittent wetland with large numbers of non-breeding waterbirds, including migratory shorebirds. It is a periodically important habitat and refuge for waterbirds and Buchanan’s fairy shrimp (Branchinella buchananensis).
• Lake Galilee: this internally draining, intermittent terminal lake hosts colonial nesting waterbird species, up to 10,000 pelicans and totals for all species that nest estimated at 80,000. At non-nesting times it still supports large populations of non-breeding birds.

Both Lake Buchanan and Galilee do not connect to the Cooper Creek catchment and have their own, individual, catchment areas.

Vegetation types in this area can impact on flow. Introduced buffel grass can hold silt. Prickly acacia is also dominant in some areas, particularly in the Mitchell grass downs where it can form dense infestations.

There are also ecologically important springs* in this area including the Barcaldine Supergroup and Edgbaston Springs. These springs contain a diverse array of species, some protected and endemic to the area such as red-finned blue eye (Scaturiginichthys vermeilipinnis) and Edgbaston Goby (Chlamydogobius squamigenus). Other species in the area include Squatter Pidgeon (Geophaps scripta), Brolga (Grus rubicunda), Australian Bustard (Ardeotis australis), and black headed python (Aspidites melanocephalus) among many others.

Fairmount Weir supplies the town of Longreach with water. Water supply in the upper catchments, such as around Aramac Creek and Pelican Creek is from bores.

Main image - Lake Galilee, provided by Gary Cranitch, © Qld.Museum.

*Springs include artesian and non-artesian springs

Lower Thomson

The geology downstream of Longreach has areas of fine grained sedimentary rocks that surround the floodplain.

There is potential for fast flows and water can rise quickly due to mostly impervious geology, little groundwater infiltration and the very flat landscape. Alluvial areas associated with channels have higher infiltration of water. In smaller events, water is absorbed into the alluvium.

Scours in the floodplain retain water over longer periods, potentially becoming refuges for species during dry times.

Many frogs, fairy shrimp, and clams aestivate (summer hibernation) during hot and dry periods until there is water flow or flooding. Waterholes become important refuges and competition for space can occur, especially with turtles.

Land use, aside from town centres such as Longreach, Ilfracombe and Stonehenge, is predominately grazing on native pastures.

Main image - Thomson River channel country after good rains, Gary Cranitch, © Qld.Museum.

Barcoo River

In its upper reaches the Barcoo River has a similar geology to that of the upper Thomson. It is located in the desert uplands bioregion and contains sandstone ridges. There are large areas of permeable colluvium derived from fine grained sedimentary rocks (Winton Formation). This area is also a key groundwater recharge area for the Great Artesian Basin.

There is minimal floodplain area higher in the catchment, with the main watercourses containing many feeder creeks. The town of Blackall contains a natural choke point, and water can back up from fast flows.

Powell Creek - photo by Water Planning Ecology, QLD Government

Flowing in a south westerly direction, the Barcoo River and the Alice River join with the Thomson River just north of Windorah to form Cooper Creek. The floodplain here is wide with good vegetation. Jump-ups confine and direct water flow.

Grazing on native vegetation is the main land use. Roads are often cut off when there are floods.

Main image - Barcoo River, Welford National Park, provided by Gary Cranitch, © Qld.Museum.

Cooper Creek

The river system changes dramatically after the convergence of the Thomson River and Barcoo River past the town of Windorah. There is an increase of alluvium and channels become sandy. The floodplain becomes broad where water can spread over 30 kilometres across.

The channels split, to the point that there is no clearly defined main channel, and cover much wider areas downstream from Windorah to Nappa Merrie where they rejoin.

Water flow is variable from sheet flow during times of good floods, to the water splitting into braided streams across the floodplains at other times.

For the most part, it is a network of ephemeral wetlands, waterholes and floodouts, some that retain water due to underlying heavy clay soils which seal once saturated and prevent leakage, and small variations in the slope.

Small changes to the slope can alter sheet flow, and land uses which alter the landscape, or infrastructure such as roads, can contribute to changes in flow regime in this part of the catchment. Slight changes to the floodplain can redirect flow, or stop it completely from filling waterholes and wetland areas. This can also impact pasture growth.

Some waterholes retain water for extended periods, despite the area receiving on average, less than 250mm of rainfall per year. Waterhole water quality can change during dry periods to have high turbidity. These areas support areas of dense lignum and belalie (Acacia stenophylla) that are key wildlife habitats.

Lake Yamma Yamma, is Queensland's largest fresh, terminal water body which fills to capacity about once every 25 to 30 years. It supports internationally recognised populations of plumed whistling-ducks, sharp-tailed sandpipers, and Australian pelicans. The lake fills from overflows from Cooper Creek. Naturally turbid, its waters often appear milky.

Cooper Creek then narrows to a single channel prior to flowing over the South Australian border where it drains to Kati Thanda-Lake Eyre.

Main image - View of Cooper Creek, Windorah, South West Queensland, Gary Cranitch, © Qld.Museum.

Conclusion

The Cooper Creek catchment shows how natural and modified features within the landscape impact on how water flows. It demonstrates that even in highly variable climate and rainfall, environmental processes continue and flora and fauna adapt to their environment.

This variability, and the processes that stem from it, need to be managed to ensure that the significant natural, cultural and social values of the catchment are protected. It is vital to minimise impacts on the multitude of values within the catchment and the significant ecological refuges it provides, while supporting residential water supplies, grazing, tourism and other important land uses of the catchment.

Knowing how the catchment functions is also important for future planning, including climate resilience, traditional and non-traditional industries, the control of invasive species and future developments in the resources industries. With this knowledge, we can make better decisions about how we manage this vital area.

Main image - Cooper Creek floodplains, image provided by Gary Cranitch, © Qld.Museum.

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Last updated: 24 September 2020