Lake Eyre Basin Catchment Story – Georgina catchment

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Transcript

Understanding how water flows in the Georgina 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 - Georgina River at Roxborough Downs, South West Queensland, provided by Gary Cranitch, © Qld.Museum.

Georgina 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 Georgina 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 - Georgina River at Roxborough Downs, 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. Georgina River
9. Burke and Hamilton
10. Eyre Creek

Main image - Zygochloa (cane grass) on Upper-Lower Titheropatchie connection, provided by R. Jaensch, Wetlands International.

How to view this map journal

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

Main image - Munga-Thirri National Park, Simpson Desert Wildflowers © Tourism and Events Qld

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. 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 Georgina catchment contains wetlands recognised as having national significance (Directory of Important Wetlands). These wetlands are of high ecological significance, contain unique values and support high numbers of migratory shorebirds.

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 Georgina catchment is listed as a single catchment (or sub-basin*) but consists of several distinct areas referred to as subcatchments.

The Georgina catchment (click for animation) includes the Georgina River and Eyre Creek sub-basins, (including the Burke and Hamilton Rivers) and eventually flows to Kati-Thanda Lake-Eyre via Eyre Creek which joins the Diamantina River over the border in South Australia. The Diamantina catchment lies to the east and the Hay River catchment to the west.

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

Main image - King Creek in the lower Georgina, photo provided by Water Planning Ecology, QLD Government

Geology and topography

The geology of the Georgina catchment is the most complex and varied of the catchments in the Lake Eyre Basin drainage division and there are many different rock types.

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 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 headwaters of the Georgina River, and associated waterways are underlain by complex geology. Many of the headwater streams of the Georgina originate in the Northern Territory and the Georgina River winds in and out of Queensland through Camooweal Dolomite (limestone or dolomite) and colluvium (clay and black soil dominated). In this North West Highlands bioregion there are limestone caves.

Near the state border, the Georgina River flows over a large area of alluvium. Watercourses further east are underlain by complex geologies. Water flow in flood events is fast over the harder geologies of ferricrete and sandstones. There are areas of mixed siliclastic rocks and carbonate-based rocks (limestone, shale) which absorb more water than the harder geologies.

Water flow is typically faster over harder geologies but slows once in the floodplain. As the waterways flow further west, there are large areas of alluvium, colluvium, and carbonates.

Channelisation of the waterways begins much higher in the Georgina catchment compared to the Diamantina and Cooper Creek catchments. Gravel can extend beyond the channels.

To the south, mudrock surrounds large areas of alluvium, with large areas of sand to the west.

Similar to the upper Georgina, there are no defined banks and the water flow will easily turn to sheet flow in flood events, despite the existence of deep channels in some areas.

The lower areas of the catchment, where the Georgina River joins Eyre Creek there are a number of separate waterholes, lakes, and palustrine wetlands which hold water between floods. High value lakes and waterholes remain wet between floods. There is some interconnection between waterholes, especially in flooding events.

The confluence of long sand dunes and floodplains is a key influence on occurrence of lakes and swamps in the Lower Georgina, until the channels eventually run into the Simpson Desert.

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 - overlooking the Diamantina from a jump up near Winton, provided by QLD Government

Rainfall

The Georgina Catchment experiences highly variable rainfall totals in any given year, with low to very low average rainfall. 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 less rainfall.

Rainfall, although variable, can supply large amounts of water which may flood larger areas downstream.

This means that rivers and creeks in the Georgina catchment experience highly variable and unpredictable flows, with high transmission losses in drier periods, and over low gradients (flat landscapes).

Areas in the lower Georgina experience what is sometimes termed 'dry floods'. The local area experiences a flood with no local rain, as large volumes of floodwater move down the catchment from rainfall events upstream.

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

Urandangi mean annual rainfall (mm) for years 1891 to 2012.

Areas in the lower Diamantina experience what sometimes called a ‘dry flood’. The local area experiences a flood with no local rain, as large volumes of floodwater move down the catchment from rainfall events upstream. Flooding is vital for the economy in these areas.

Often described as a 'boom and bust' system, flora and fauna have adapted to long periods of drying and times of intensive flooding. Refuge areas, such as waterholes are vital to the survival of species over time. The response of pasture to floods sustains a large grazing economy.

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.

Urandangi mean annual rainfall (mm) for years 1891 to 2012.

Urandangi mean monthly rainfall (mm) for years 1891 to 2012 - Provided by the Bureau of Meteorology

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

Boulia airport - mean monthly rainfall (mm) for years 1886 to 2019 - Provided by the Bureau of Meteorology

Bedourie - mean annual rainfall (mm) for years 1932 to 2019 - Provided by the Bureau of Meteorology

Bedourie - mean monthly rainfall (mm) for years 1932 to 2019 - Provided by the Bureau of Meteorology

Main image - Georgina River at Roxborough Downs, provided by Gary Cranitch, © Qld.Museum

Vegetation

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

The Northwest Highlands bioregion, in the north of the Georgina catchment, is characterised by rugged hills, mountain ranges and undulating valleys. The vegetation is dominated by low open woodland over spinifex hummock grasslands.

The Mitchell Grass Downs bioregion is largely treeless plains, with occasional ridges and vast areas of Mitchell grasslands.

The Channel Country bioregion contains vast braided floodplains, surrounded by gravel or gibber plains, dunefields, low ranges and jump-ups.

Vegetation cover and water flow - conceptual model by Queensland Government

Water moving slowly across the surface of the land also reduces the potential for erosion to occur and reduces 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 wetlands, waterholes and creeks of the catchment also provide habitat and refuge for many important aquatic species, including plants, fish, birds and macro invertebrates. There are groundwater dependent ecosystems (GDEs) in parts of the catchment.

Wetland types - conceptual model by Queensland Government

There is a small range of different land uses in the Georgina Catchment.

Cattle on a dry shore in the upper Georgina, provided by R. Jaensch, Wetlands International

Large areas of the original native (preclear) vegetation* remain and only small areas have been cleared or partially cleared**. The dominant land use is grazing on native pastures. The catchment has a low population with large stations for predominantly grazing cattle.

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 Southeastern 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 - Bluebush in the upper Georgina, provided by R. Jaensch, Wetlands International

Infrastructure

Important infrastructure such as roads, 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.

The catchment contains almost no significant modifications to flow with no major dams or weirs. The Georgina Catchment is a free-flowing catchment.

Roads and water flow - conceptual model by Queensland Government

The catchment has no major infrastructure aside from roads and some rural water storages.

Town water supply comes from bores*, some of which are artesian.

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

**Referred to as Kanakas at the time, which literally means 'A native or inhabitant of Hawaii', but is historically defined as 'A Pacific Islander employed as an indentured labourer in Australia, especially in the sugar and cotton plantations of Queensland' (Oxford Dictionary).

Main image - grassy shallows in the upper Georgina, provided by R. Jaensch, Wetlands International

Water Flow

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

The remaining water either sinks into the ground, is retained in waterholes or evaporates - where it supports a variety of terrestrial and groundwater dependent ecosystems 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 - Lower Titheropatchie - R. Jaensch, Wetlands International

Georgina River

In the upper part of the catchment, the Georgina River flows over complex volcanic geologies which have been pushed up through sedimentary rocks.

Many of the headwater streams of the Georgina River originate in the Northern Territory and the Georgina River winds in and out of Queensland through Camooweal Dolomite (limestone or dolomite) and colluvium (clay and black soil dominated). In this North West Highlands bioregion there are limestone caves.

Water flow in events is fast over the harder geologies of ferricrete, mudrock and arenite in the upper catchment.

There are areas of mixed siliclastic rocks and carbonate-based rocks (limestone, shale) which can absorb more water than the harder geologies.

Water flow is typically faster over harder geologies and slows once it hits the alluvial floodplain. Vast areas of alluvium, colluvium and carbonates dominate the waterways as they flow west.

Further along the Georgina river, there are no defined banks and the water flow will easily turn to sheet flow in flood events, despite the existence of deep channels. There are black soils in these areas.

Where the Georgina River joins Eyre Creek there are a number of waterholes and lakes, and palustrine wetlands which hold water between floods.

Main image - Georgina River at Urandangi, photo provided by Water Planning Ecology, QLD Government

Burke and Hamilton

The headwaters of Burke River and Hamilton River, and associated waterways flow through alluvium and the headwaters flow through complex, harder geologies. The Hamilton River flows out of more unconsolidated sediments and alluvium than its northern catchment neighbours. Mudrock surrounds large areas of alluvium, with large areas of sand to the west.

The land use is predominantly grazing on native vegetation, with some townships such as Duchess, Dajarra, and Selwyn.

Main photo - Burke River at Boulia, photo provided by Water Planning Ecology, QLD Government

Eyre Creek

Where the Georgina River becomes Eyre Creek there are a number of separate waterholes and lakes, and palustrine wetlands which hold water between floods. This landscape is flat with high connectivity. Channels along the lower Georgina and Eyre Creek do not hold water as long as channels in the Cooper. After dry periods, there is a spike in salinity in most waterholes.

The floodplains are characterised by anastomosing channels and waterholes lined with open Coolibah woodland and surrounded by grasslands, forblands, samphire and lignum on the floodplains.

Old ibis nests in lignum - provided by R. Jaensch, Wetlands International

High value lakes and waterholes remain wet between floods. There is some interconnection between waterholes, especially in flooding events. Eyre Creek feeds many lakes as the water moves downstream, and combined with lignum-belalie dominated vegetation, it can form important waterbird habitat.

Lake Machattie is an important bird breeding area for thousands of birds after inundation and is fed by distributary channels off Eyre Creek. The Australian Pelican breeding colony that often forms at Lake Machattie (after floods) is one of the largest in Australia (with over 20,000 nests). This makes it a major recruitment area for the Australian Pelican, and many other waterbirds such as the Black-tailed native hen.

Lake Torquinie is fed partly by the Mulligan River and is a well known duck and shorebird habitat. Water in these lakes becomes trapped and remains until evaporated and can become quite saline. There are several areas around the Mulligan River before the confluence with Eyre Creek that can also be saline.

Other nationally important wetlands include:

• Muncoonie Lakes area
• Lake Mipia Area
• Georgina River – King Creek Floodout
• Lake Phillipi
• Lake Torquinie Area.

The main land use is grazing on native vegetation. Munga-Thirri National Park lies to the west of Eyre Creek, in the Hay catchment, and is Queensland's largest protected area.

Beyond Muncoonie Lakes, Eyre Creek flows through the parallel dunefields of the eastern Simpson Desert, spreading at times through 5-10 parallel swales - a unique characteristic to this river.

The park adjoins South Australia's Simpson Desert Conservation Park and the Northern Territory's Simpson Desert Regional Reserve. The entire Simpson Desert covers more than 17 million hectares of Central Australia.

Vegetation in the Simpson desert area, such as spinifex and cane grass, holds substrate to create slopes and crests. Flat plains between dunes can contain wind-polished gibber pebbles, mineral encrusted claypans, and many areas that support open shrublands of acacias, hakeas and grevilleas.

The combination of vegetation types and the wide, vast areas that become inundated in large floods (including a variety of wetland types) make the areas of the lower Georgina vital for breeding and feeding of waterbirds in the Lake Eyre Basin.

Main image - Nesting cormorants in Eyre Creek, R. Jaensch, Wetlands International

Conclusion

The Georgina catchment shows how 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 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 supply, agricultural 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.

Main image - Muncoonie Lakes, provided by R. Jaensch, Wetlands International

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Last updated: 24 September 2020