2.7.3.1.1 Overview
The ‘Springs’ landscape group contains a single landscape class (‘Springs’; see Section 2.3.3 in companion product 2.3 for the Galilee subregion (Evans et al., 2018b)). Within the zone of potential hydrological change, the springs that comprise this landscape group occur mainly in the central and western parts of the zone (Figure 6). There are two main types of springs defined within this landscape group: recharge (also referred to as ‘outcrop’) springs and discharge springs (Figure 7). Section 2.3.2.2.2.3 in companion product 2.3 for the Galilee subregion (Evans et al., 2018b) provides a detailed conceptualisation of the groundwater flow systems that contribute to both spring types.
In the Galilee subregion, recharge springs are typically associated with topographically elevated areas, such as along the eastern margin of the Eromanga Basin where major aquifers of the Great Artesian Basin (GAB) outcrop. For this spring type, the aquifer is largely unconfined, and groundwater flow occurs away from topographically high areas, discharging near to where the ground surface intersects with a saturated aquifer. As a consequence, recharge springs may be strongly influenced by rainfall events and can exhibit dynamism in flow in response to recent rainfall (Fensham et al., 2016). Groundwater flow paths for recharge springs are thought to be relatively short and associated with shallow, local-scale groundwater systems (Figure 7).
In contrast to recharge springs, the source aquifers for discharge springs tend to be regional-scale confined aquifer systems with longer groundwater flow paths (Figure 7). Discharge springs originate from aquifers that are largely confined and under pressure, and form in areas where the confining bed or aquitard is weakened or thin, or where groundwater flow is disrupted by faults, folds or some other flow barrier such as a change in rock type (e.g. associated with geological basement rocks). In these aquifers groundwater typically has a longer residence time compared to groundwater that occurs in source aquifers for recharge springs. Unlike recharge springs, discharge springs are generally located remote from their recharge zones.
At the surface, discharge springs are commonly mounded with moisture accumulation around the vent. In contrast to recharge springs, the water flow of discharge springs is disconnected from the local rainfall regime. However, the size of the wetland area surrounding a spring is influenced by seasonal conditions and may fluctuate, for example, between the dry and wet seasons. Another feature of some discharge springs is the presence of salt scalds (Fensham et al., 2016). These form in areas surrounding spring wetlands due to the precipitation of salts (including carbonates) when the discharged groundwater evaporates. In arid regions, salt scalds are accentuated because of the absence of flushing by overland flow.
The three geographic clusters of springs that occur within the zone of potential hydrological change of the Galilee subregion were all previously recognised and described as part of the work presented in the Lake Eyre Basin Springs Assessment (Fensham et al., 2016). This is one of a series of research projects funded by the Department of the Environment and Energy as part of the broader Bioregional Assessment Programme. From north to south these spring clusters are: (i) the Doongmabulla Springs complex, (ii) a series of springs that overlie either the Colinlea Sandstone or the Joe Joe Group, which are geological units of Permian age (hereafter referred to as the ‘Permian springs cluster’), and (iii) a series of springs associated with Triassic geological units (hereafter referred to as the ‘Triassic springs cluster’). The assessment that follows in this section covers each of the three geographic clusters separately as there are important differences between them. The Barcaldine Springs supergroup in the Lake Eyre Basin Springs Assessment Project (Fensham et al., 2016) includes springs associated with GAB recharge beds around the margin of the Eromanga Basin and the Doongmabulla Springs complex. The Permian and Triassic springs clusters are separate entities and are not recognised as part of the Barcaldine Springs supergroup (Figure 8).
Data: Bioregional Assessment Programme (Dataset 1); Queensland Herbarium, Department of Science, Information Technology, Innovation and the Arts (Dataset 2)
Discharge springs occur in areas where the hydrostatic pressure in a confined aquifer is artesian, and where the overlying aquitard is compromised, for example, by thinning of the aquitard or due to the influence of geological structures, or the presence of a barrier that disrupts regional groundwater flow. Discharge springs are typically remote from the recharge areas for their source aquifers.
Recharge (or outcrop) springs, are associated with unconfined aquifers that occur either at or near to aquifer outcrop areas. In contrast to discharge springs, groundwater flow systems tend to be more localised, with recharge springs commonly occurring around outcrop margins or near the break of a valley slope.
Source: DEHP (2013)
Spring complexes showing 100% active springs (solid), partially (1% to 99%) active (grey) and 100% inactive (open symbols). Recharge springs (triangles) are distinguished from discharge springs (circles).
Fensham et al. (2016) included the Doongmabulla Springs complex as part of the Barcaldine Springs supergroup.
The Barcaldine Springs supergroup (springs enclosed by black line) includes two north-trending lines of springs to the north of Blackall, as well as the Doongmabulla Springs complex.
Source: Fensham et al. (2016)
Doongmabulla Springs complex
The Doongmabulla Springs complex is located on Doongmabulla and Labona pastoral stations near the confluence of Dyllingo Creek and Cattle Creek. The springs form an isolated cluster of wetlands associated with the Carmichael River and its tributaries (Figure 9). The springs complex consists of 187 individual spring vents forming 160 separate wetlands (Fensham et al., 2016).
Springs situated in areas underlain by Triassic rocks of the Moolayember Formation are classed as discharge springs (Figure 9). This categorisation is based on the relatively flat topography, mounded vents and the absence of source aquifer outcrop (Fensham et al., 2016). Discharge springs in the Doongmabulla Springs complex include: the House Springs, Joshua Spring, the Mouldy Crumpet Springs, the Stepping Stone Springs, the Moses Springs (comprising 65 separate vents), the Keelback Springs, Geschlichen Spring, Camp Springs (Figure 10), Bush Pig Trap Springs, Camaldulensis Spring, the Wobbly Springs and the Bonanza Springs. One of the largest of these individual spring groups, the Moses Springs, includes spring-fed wetlands with a combined area of approximately 3.25 ha (about 0.03 km2) (GHD, 2012a, 2013a).
The more easterly springs in the Doongmabulla Springs complex are interpreted (based on morphology) as being recharge springs as they occur in areas where either the Clematis Group aquifer or the Dunda beds aquifer (the upper part of the generally low permeability Rewan Group) subcrops beneath the Carmichael River. These springs have vents on the edge of wetlands at the base of gentle slopes which suggests lateral discharge (Fensham et al., 2016) and include Little Moses Springs and Yukunna Kumoo Springs (Figure 9). Little Moses Springs (Figure 11) supports a wetland of 200 m by 50 m (GHD, 2013a).
Dusk Springs and Surprise Spring are the most easterly springs in the Doongmabulla Springs complex. The source aquifer for these recharge springs is likely to be the Dunda beds aquifer, as they are both situated in areas dominated by Dunda beds outcrop. For most hydrogeological interpretation purposes of the bioregional assessment (BA) for the Galilee subregion, the Dunda beds were grouped with the thicker and more extensive (underlying) Rewan Group aquitard. This is due to a lack of data specifically defining the lateral and vertical extents of the Dunda beds at an appropriate regional scale (companion product 2.1-2.2 for the Galilee subregion (Evans et al., 2018a)).
Data: Queensland Herbarium, Department of Science, Information Technology, Innovation and the Arts (Dataset 2); Bioregional Assessment Programme (Dataset 3, Dataset 4, Dataset 5); Queensland Department of State Development, Infrastructure and Planning (Dataset 6)
Figure 10 Main discharge vent at Camp Spring in the Doongmabulla Springs complex
Source: Fensham et al. (2016)
Figure 11 Aerial view of the Little Moses Spring at the Doongmabulla Springs complex
Source: Fensham et al. (2016)
Permian springs cluster
The Permian springs cluster consists of springs that are interpreted as being sourced from aquifers of Permian age within the Galilee Basin, particularly the Colinlea Sandstone or Joe Joe Group (Land Court of Queensland, 2015a). The Permian springs cluster includes: Lignum Spring, the Mellaluka Springs complex and the Albro Springs. The Mellaluka Springs complex consists of three vents and the Albro Springs group has two vents (Fensham et al., 2016). Of these three spring groups, the Albro Springs group are considered to be recharge springs and Lignum and Mellaluka springs are considered to be discharge springs by Fensham et al. (2016). In contrast to Fensham et al. (2016), work undertaken to support the environmental impact statement for the proposed Carmichael Coal Mine defined the Mellaluka Springs complex to include the Mellaluka Springs, Stories Spring and Lignum Spring (GHD, 2013a).
Triassic springs cluster
Relatively little information is known about the Triassic springs cluster, which encompasses the southernmost springs within the zone of potential hydrological change. Fensham et al. (2016) included three groups in the Triassic springs cluster: Hunter, Greentree and Hector. Hunter Springs consists of two vents, whereas Hector Springs has three main vents and several smaller ones (Fensham et al., 2016). Greentree Springs is inactive, and has not flown since the 19th century (Fensham et al., 2016). All springs in the Triassic springs cluster are interpreted as being recharge springs by Fensham et al. (2016). As Hunter and Greentree springs are situated on Dunda beds outcrop (i.e. the upper and more permeable part of the Rewan Group), the Dunda beds is considered the likely source aquifer. However, outcrop at Hector Springs is obscured by an extensive cover of Cenozoic sediments. It is possible though that the primary groundwater source is the Dunda beds, as the Hector Springs group is located several kilometres east of Dunda beds outcrop (Fensham et al., 2016), but west of known occurrences of sedimentary rocks that comprise the upper Permian coal measures.
2.7.3.1.2 Hydrological regimes and connectivity
Doongmabulla Springs complex
Both recharge and discharge springs occur within the Doongmabulla Springs complex (refer to Section 2.7.3.1.1 and companion product 3-4 (Lewis et al., 2018) for the Galilee subregion). Fensham (as cited in GHD, 2012a) estimated the daily flow rate of all the springs in this complex (combined) to be about 1.35 ML/day , which equates to some 493 ML/year (companion product 2.5 for the Galilee subregion (Karim et al., 2018a)). The daily flow rate of Joshua Spring is estimated to be 432 to 864 KL/day (GHD, 2013b). There was no information provided in either GHD (2012a) or GHD (2013b) to indicate how these various spring flow rate estimates were derived.
Discharge from some springs of the Doongmabulla Springs complex contributes flow to tributaries of the Carmichael River (Figure 9). The outflow from Joshua Spring and the House Springs group converge to provide the main discharge feeding the Carmichael River for a distance of up to 20 km downstream (Fensham et al., 2016). These springs also provide surface water to adjacent wetlands. As noted previously, the Doongmabulla Springs complex has 187 vents that feed 160 separate wetlands, of which 149 wetlands are fed by discharge springs (Fensham et al., 2016). The largest spring wetland in the complex is about 8.7 hectares (Fensham et al., 2016, p. 189). The surface water in the springs is perennial. The larger wetlands, such as those fed by Moses Springs and Keelback Springs, flow into permanent open pools and channels in the bed of Cattle Creek. In turn, these flow into the Carmichael River. However, during periods of low flow due to lower rainfall or drought conditions, the channels do not discharge into the Carmichael River (Fensham et al., 2016). Further information and analysis of hydrological dynamics and temporal variability of the different spring vents that comprise the Doongmabulla Springs complex is in companion product 3-4 for the Galilee subregion (Lewis et al., 2018). This includes preliminary analysis of remotely sensed data sourced from the available 30-year Landsat archive provided by Digital Earth Australia (see Section 3.2 in companion product 3-4 for the Galilee subregion (Lewis et al., 2018) for further details).
The source of groundwater that supplies the Doongmabulla Springs complex has been a contentious issue, and the cause of considerable debate. Further detail on the available evidence and the various interpretations that have been made about the spring’s source aquifer is in Section 3.4.3.1.1 of companion product 3-4 for the Galilee subregion (Lewis et al., 2018). In the context of the BA for the Galilee subregion, the primary source aquifer of the Doongmabulla Springs complex is considered to be the Clematis Group aquifer. The multiple lines of evidence and reasoning supporting this interpretation is outlined in Section 3.4.3.1.1 of companion product 3-4 for the Galilee subregion (Lewis et al., 2018), as well as Section 2.3.2 of companion product 2.3 for the Galilee subregion (Evans et al., 2018b).
For the purposes of the BA of the Galilee subregion, the main features of the hydrogeological conceptualisation of the Doongmabulla Springs complex includes:
- The discharge springs (mound springs) in the western part of the Doongmabulla Springs complex (Figure 9) are most likely fed by groundwater leakage from the confined Clematis Group aquifer through the Moolayember Formation aquitard. This occurs in areas where the integrity of the aquitard is compromised, which may be due thinning or weathering of the aquitard near its contact with the Clematis Group aquifer, or the influence of geological structures (or possibly a combination of these factors). At the surface, the discharge springs are formed on alluvium that overlies the Moolayember Formation aquitard. The discharge springs source water from regional-scale groundwater flow that occurs in confined parts of the Clematis Group aquifer. Groundwater flow within this aquifer occurs from the west and south, and focuses towards the discharge springs.
- The recharge (outcrop) springs immediately east of the discharge springs are sourced from the unconfined parts of the Clematis Group aquifer. These include the Little Moses (Figure 11) and Yukunna Kumoo springs (Figure 9), which are located on or near outcrop of the Clematis Group. These springs are fed by more local-scale groundwater systems with recharge to the aquifer occurring in nearby hills to the east and north of the springs.
- The source for the easternmost recharge springs in the Doongmabulla springs complex (Figure 9, Surprise and Dusk) is likely to be the Dunda beds aquifer. This aquifer outcrops in nearby hills, as well as underlying the alluvium where these springs occur in the valley of the Carmichael River.
- Groundwater discharge at the surface across the Doongmabulla Springs complex contributes directly to baseflow in the Carmichael River and helps to maintain permanent pools in nearby drainage channels (discussed in Section 3.5 of companion product 3-4 for the Galilee subregion (Lewis et al., 2018)). There is also potential for groundwater from the Clematis Group and Dunda beds aquifers to discharge directly into the alluvium, where these units subcrop beneath alluvium (Figure 9).
Permian springs cluster
The Permian springs cluster occurs to the west of the Belyando River. The likely groundwater sources for these springs are either the Colinlea Sandstone (part of the upper Permian coal measures) or the stratigraphically lower Joe Joe Group (the basal sequence of the Galilee Basin’s Carboniferous to Permian stratigraphy).
The Permian springs cluster has four wetlands fed by the springs. The flow is predominantly south to north in this region. Albro Springs has moderate flows (combined flow of the two vents is about 40 L/min) and Lignum Spring has low flows (about 0.5 L/min). The highest flows are in the three vents of the Mellaluka Springs complex (~1200 L/min, combined).
Triassic springs cluster
The springs in the Triassic springs cluster are all recharge springs. All three of these springs groups are likely to source groundwater from the Dunda beds aquifer. The Greentree and Hunter springs are surrounded by outcrop of the Dunda beds. Hector Springs are about 2 km east of the currently mapped extent of the Dunda beds but also appear to have a gravity-fed source.
2.7.3.1.3 Vegetation
The three geographic clusters of springs vary in vegetation composition. There is also considerable variation within the clusters.
Doongmabulla Springs complex
Within the Doongmabulla Springs complex some springs and spring groups are substantially disturbed, either by human activity or by the actions of livestock. An example of this is Joshua Spring (Figure 12), which has been heavily modified to provide drinking water for the Doongmabulla Station homestead and for livestock water supplies. It is now enclosed by a turkey’s nest dam (GHD, 2012a).
Other springs and spring groups are relatively intact. Dominant vegetation surrounding the various springs includes: (i) bare, scalded plains supporting very sparse grass and herb cover; (ii) grassland generally dominated by Sporobolus pamelae; (iii) mixed sedgeland dominated by sedges in the genus Cyperus; (iv) coolibah (Eucalyptus coolabah) or river red gum (E. camaldulensis var. obtusa) woodland and open woodland; (v) weeping paperbark (Melaleuca leucadendra) forest; (vi) peppermint box (E. persistens) low open woodland with a grassy ground layer dominated by spinifex (Triodia); and (vii) Reid River box (E. brownii) woodland.
The first three vegetation assemblages and the weeping paperbark forest are contained within regional ecosystem (RE) 10.3.31 under the Queensland Government’s remnant vegetation mapping (GHD, 2013a). This RE is described as ‘Artesian springs emerging on alluvial plains’. It has the conservation status ‘Of concern’. Three of the four vegetation assemblages within RE 10.3.31 (the exception is bare, scalded plains) are considered to be obligate groundwater-dependent systems.
The vegetation assemblage containing coolibah and/or river red gum woodland is contained within RE 10.3.14 ‘Eucalyptus camaldulensis and/or E. coolabah woodland to open woodland along channels and on floodplains’. It is considered to be a facultative groundwater-dependent ecosystem although in some areas around the springs access to groundwater will be permanent. This RE is listed as ‘Least concern’. The Reid River box woodland occurs within RE 10.3.6, whereas the peppermint box low open woodland is within RE 10.7.2 (GHD, 2013a). These vegetation assemblages are not considered to be groundwater-dependent and both are listed as ‘Least concern’.
Source: Fensham et al. (2016)
Permian springs cluster
The wetland vegetation in the Mellaluka Springs group is mostly a tall sedgeland dominated by the sedge Baumea rubiginosa, the fern Cyclosorus interruptus and the grass Phragmites australis. Drier areas adjacent to the springs support grassland of Sporobolus mitchellii with a variety of chenopod shrubs and sub-shrubs. The vegetation in the vicinity of the springs group is mostly ‘non-remnant’; however, the springs supports up to 0.04 km2 of RE 11.3.22 that is classified as ‘Of concern’. RE 11.3.22 is described as ‘Springs associated with recent alluvia, but also including those on fine-grained sedimentary rocks, basalt, ancient alluvia and metamorphic rocks’.
The wetlands at Lignum Spring and Stories Spring almost exclusively contain cumbungi (Typha domingensis) (GHD, 2013a). The springs are surrounded by grassy woodland that is either silver-leaved ironbark (E. melanophloia) woodland (RE 10.3.28) or Reid River box woodland (RE 10.3.6). Both REs are classified as ‘Least concern’.
Triassic springs cluster
The springs in the Triassic springs cluster have all been heavily modified (Fensham et al., 2016). Specifically, two of the three Hector Springs have been excavated to provide access for cattle.
2.7.3.1.4 Flora and fauna
Springs in the GAB are known to be sites of high endemicity. Within the ‘Springs’ landscape group of the zone of potential hydrological change, the spring wetlands support endemic plants as do the salt scalds surrounding discharge springs.
Doongmabulla Springs complex
The discharge springs in the Doongmabulla Springs complex are part of a nationally threatened ecological community listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), ‘The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin’ (Fensham et al., 2010). The community occurs in parts of NSW, within the Galilee assessment extent (and elsewhere in Queensland), and also in parts of SA (Fensham et al., 2010). The Doongmabulla Springs complex differs from other GAB spring complexes in being adjacent to an easterly flowing, outward-draining river system. Specifically, it occurs in the vicinity of the Carmichael River which flows into the Burdekin River and then to the sea along the east coast of Queensland between Ayr and Home Hill. By comparison, the other major GAB spring complexes are in the internally draining Lake Eyre Basin, and occur in more arid environments.
The wetlands associated with discharge springs in the Doongmabulla Springs complex support a number of spring-endemic plants. These include two nationally threatened herbs, salt pipewort (Eriocaulon carsonii) and blue devil (Eryngium fontanum) (Fensham et al., 2010). Other spring-endemic plants include Hydrocotyle dipleura, Myriophyllum artesium, Sporobolus pamelae and Utricularia fenshamii.
Salt pipewort is a small aquatic herb that grows in shallow water (including water depths as shallow as 10 cm) where it forms dense floating mats. It is listed as ‘Endangered’ nationally under the EPBC Act and as ‘Endangered’ under Queensland’s Nature Conservation Act 1992 (Nature Conservation Act). The species occurs in 20 spring complexes within the GAB in Queensland, NSW and SA. It also occurs at two non-GAB springs in Queensland (Fensham et al., 2010).
Blue devil is an erect perennial herb that can reach a height of up to 80 cm. The entire distribution of this species occurs in only two spring complexes, one of which is the Moses Springs group in the Doongmabulla Springs complex, within the zone of potential hydrological change (Fensham et al., 2010). It is listed as ‘Endangered’ both nationally (EPBC Act) and in Queensland (Nature Conservation Act). The species occupies two spring wetlands at Moses Springs. One wetland has an area of 2.4 ha, and the other, 0.02 ha. The approximate population size of the species at Moses Springs is estimated at 10,000 plants (Fensham et al., 2010).
Hydrocotyle dipleura, Myriophyllum artesium and Sporobolus pamelae are listed as threatened in Queensland under the Nature Conservation Act, but not nationally. Hydrocotyle dipleura is a perennial prostrate herb that occurs in saline sands and clay soils beyond the saturated zone of discharge spring wetlands. It has been recorded in low woodland of Melaleuca bracteata. The distribution of this species is confined to seven springs complexes in the GAB of Queensland including the Moses Springs group at the Doongmabulla Springs complex (Fensham et al., 2010). It is listed as ‘Vulnerable’ in Queensland (Nature Conservation Act).
Myriophyllum artesium is an aquatic, mat-forming herb that grows to 15 cm. It has a distribution that is confined to wetland habitat in arid Queensland and is listed as ‘Endangered’ in Queensland (Nature Conservation Act). This species generally grows in shallow pools of spring wetlands and is also found in bore drains (Fensham et al., 2010).
Sporobolus pamelae is a tussock grass that grows to a height of 80 to 120 cm along the margins of springs and spring wetlands. It has a geographic range that is confined to six spring complexes in the GAB of Queensland (Fensham et al., 2010). It is listed as ‘Endangered’ in Queensland (Nature Conservation Act). The species is found at 15 spring wetlands within the Doongmabulla Springs complex (Fensham et al., 2016).
The salt scalds around spring wetlands at Moses and Mouldy Crumpet springs support endemic plants – so called ‘scald endemics’ (Fensham et al., 2016). These species include Sporobolus partimpatens, Sclerolaena “dioceia” and Trianthema sp. (Coorabulka RW Purdie 1404). None of these scald endemics is currently listed as threatened.
In addition to spring wetland and scald endemics, another threatened plant occurs at Doongmabulla Springs complex. Waxy cabbage palm (Livistona lanuginosa), a species that occurs mainly in the ‘Streams’ landscape group, has been recorded at Moses Springs (GHD, 2013c). It is endemic to the Burdekin river basin and is listed as ‘Vulnerable’ both nationally (EPBC Act) and in Queensland (Nature Conservation Act) (Department of the Environment, 2015). The population at Moses Springs is the only one known to occur at a GAB spring and is estimated to be about 20 individuals (GHD, 2013c).
The Doongmabulla Springs complex supports a diversity of fish species though, based on current knowledge, none are known to be endemic. Up to 18 fish species are expected to occur in the area (GHD, 2012b). Eleven fish species were recorded during recent surveys in the vicinity of the Doongmabulla Springs complex (GHD, 2012b): Agassiz's glassfish (Ambassis agassizii), Midgley's carp gudgeon (Hypseleotris species 1), purple-spotted gudgeon (Mogurnda adspersa), sleepy cod (Oxyeleotris lineolata), eastern rainbowfish (Melanotaenia splendida splendida), Hyrtl's tandan (Neosilurus hyrtlii), spangled perch (Leiopotherapon unicolor), barred grunter (Amniataba percoides), flyspecked hardyhead (Craterocephalus stercusmuscarum), western carp gudgeon (Hypseleotris klunzingeri) and bony bream (Nematalosa erebi). Most of these species are likely to periodically occupy the spring wetlands.
The aquatic invertebrates of the Doongmabulla Springs complex are poorly known. Two spring-endemic invertebrate species have been recorded from the area. These are the mollusc Gabbia rotunda, which is endemic to the Doongmabulla Springs complex, and the water mite Mammersela sp. AMS KS85341, which is endemic to GAB spring wetlands (GHD, 2012b). It is highly likely that further sampling will detect new (previously unknown) species of molluscs and other aquatic invertebrates.
Permian springs cluster
The Permian springs cluster does not support any spring endemics (Fensham et al., 2016). The plants present are common and widespread species of no conservation significance. The fish fauna is limited, with only the spangled perch and eastern rainbowfish positively identified (GHD, 2013a).
Triassic springs cluster
The plants and invertebrates identified from the springs of the Triassic springs cluster are all common and widespread wetland species (Fensham et al., 2016). None are of specific conservation significance.
