The Galilee subregion contributes surface water to six river basins (Cooper-Bulloo, Diamantina, Flinders, Burdekin, Fitzroy and Warrego) by its numerous headwater streams. Each of these river basins are characterised by large variations in discharge and flow duration. Streamflow monitoring sites are relatively sparse in the Galilee subregion. A list of available stream gauges within and adjacent to the Galilee subregion along with their length of record is given in Table 7. Detail of streamflow characteristics of the six river basins that are included in the Galilee subregion are described in the subsequent sections.
Table 7 List of stream gauges in the Galilee subregion and surrounding areas located in six river basins that are part of Galilee hydrological study
1.1.5.3.1 Cooper creek-Bulloo river basin
Water in the Cooper creek basin is predominantly derived from runoff from headwater catchments. The Thomson and Barcoo rivers that originate in the Galilee subregion play an important role in flow into Cooper Creek. Transmission losses are generally very high. The long term (1901–2003) average modelled runoff coefficient in the Cooper creek basin varies from a low of 1.2% for the Alice River at Barcaldine to a high 6.6% for the Thomson River at Stonehenge. The runoff coefficients are 5.8% at Currareva and 1.6% at Nappa Merrie (McMahon et al., 2005).
Streamflow in Cooper Creek and its tributaries varies greatly between years from almost no flow to significant flooding, and between months with no flow for some months. Figure 44 shows an example of yearly and monthly flow distribution based on observed data (1967–2011) at Stonehenge. Streams are ephemeral and carry water mostly between December and May. The maximum monthly flow varies depending on the location of the gauging site and contributing catchment area, with some sites having very high flows (up to 15,900 GL/month, on the Cooper Creek at Currareva). Both annual and monthly flows generally increase down the basin, although there are exceptions to this trend. On average there is flow in Cooper Creek at Nappa Merrie about 60% of the time. The flow duration curves are steep for all gauging sites in the Cooper creek basin, confirming the observation that streamflow is highly variable and that there is little groundwater contribution to the overall flow (McMahon et al., 2005).
Due to its low gradient, water propagates very slowly on the floodplain and for a big flood it takes around 16 days for the water to pass through the floodplain with a wave speed of 0.3 m/s, while for a small flood the speed can be as low as 0.1 m/s (Costelloe et al., 2003). The long travel time allows the air and earth to absorb much of the water on the flat floodplain. On average the water of the Cooper Creek reaches Kati Thanda – Lake Eyre only once in every six years (Kingsford et al., 1999). For the biggest flood in the recorded history of Cooper Creek in 1974, around 25,000 GL of water inundated the creek and 40% of the water was lost by the time the flood peak arrived in Callamurra near the Queensland–South Australia border. For flow events below 5,000 GL the transmission loss is often above 80% (McMahon et al., 2005).
1.1.5.3.2 Diamantina river basin
The flow regimes of the Diamantina River are dominated by late summer flow events resulting from highly variable monsoonal rainfall in the upper catchments. Due to the location of the basin, which includes semi-arid and arid regions, the streams are ephemeral (Knighton and Nanson, 2001). Like many arid zone rivers, the Diamantina river basin has few gauging sites to record streamflow, with two stations currently operating, one at Oondooroo on the Mills Creek and the other at Diamantina Lakes on the Diamantina River (Figure 39). These two stream gauges are within the Galilee subregion. Streamflow varies greatly between years from almost no flow to significant flooding (Figure 45a) and between months with almost no flow in August, September and October (Figure 45b). The maximum monthly flow varies depending on the location and contributing catchment area, with some gauges having high maximum mean monthly flows of up to 574 GL at Diamantina Lakes and 926 GL at Birdsville. On average, this basin contributes some inflow to Lake Eyre North every two years (Kotwicki, 2005). At Diamantina Lakes, cease-to-flow conditions occur approximately 53% of the time.
1.1.5.3.3 Flinders river basin
The flow regimes of the Flinders river basin are characterised as dry seasonal (i.e. high annual variability and dry for more than half of the year). The Flinders River has five stream gauges with four gauges currently operating at Glendower, Richmond, Etta Plains and Walkers Bend, and one station currently closed at Hughenden (Figure 39). Three upstream gauges (Glendower, Hughenden and Richmond) are located within the Galilee subregion. Streamflow in the Flinders River varies greatly between years ranging from no flow to big flood (Figure 46a) and between months with no flow for some months (Figure 46b). The Flinders River and its tributaries are ephemeral and carry water mostly between December and April. At Richmond, mean monthly and maximum flow are 52 and 340 GL respectively. The average surface water availability in the Flinders river basin is 2023 GL/year and on average about 107 GL/year (or 5%) of this water is used for consumptive purposes (CSIRO, 2009).
1.1.5.3.4 Burdekin river basin
The flow regime of the basin varies between locations ranging from perennial to dry seasonal. Streamflow is well monitored in the lower part of the basin while only a few gauges are available in the upper part of the basin (Figure 41). Stream gauges at Pentland on Cape River and Violet Grove on Native Companion Creek are located in the Galilee subregion but they capture only a fraction of flow draining from the Galilee subregion. The next available stream gauges that capture much of the flow draining from Galilee are located at Taemas on the Cape River and Gregory Development Road on the Belyando River. An example of annual flow at Taemas shows high annual variability although there are at least some flows in each year (Figure 47a). Monthly flows also vary largely between months with almost no flow from July to October (Figure 47b). More than 80% of flows occur between January and March. The mean annual flow at the basin outlet is 9300 GL with an inter-annual range (400–53,000 GL) which covers two orders of magnitude (Post, 2009).
1.1.5.3.5 Fitzroy river basin
The Fitzroy river basin comprises both perennial and seasonal streams. There are a large number of stream gauges across the basin including two gauges within Galilee subregion, one at Clare Lagoon on the Claude River (a tributary of Nogoa River) and the other at Raymond on the Nogoa River (Figure 42). An example of annual flow at Duck Ponds shows a prolonged low flow period followed by wet years (Figure 48a). The majority of flows occur during high flow events between December and March (Figure 48b). The Nogoa River is a relatively small tributary of the Fitzroy River and it produces a mean annual flow of 212 GL at Fairbairn Dam. The mean annual flow at the downstream end of the Fitzroy River is 4316 GL, which is about 20 times more than Nogoa River flow.
1.1.5.3.6 Warrego river basin
The flow regime of the Warrego basin is characterised as perennial. There are seven stream gauges on the Warrego River including two gauges within Galilee subregion at Augathella and Charleville. Streamflow in the Warrego River is highly variable between years having minimum of 31 GL and maximum of 3042 GL between 1967 to 2011 (Figure 49a). Mean monthly flow varies between months with the majority of flows occurring between December and April (Figure 49b). Transmission losses are generally high in the basin and it produces a basin mean runoff of about 1.7%. The stream gauge at Charleville captures streamflow that originates in the Galilee subregion, producing a mean annual flow of 263 GL.
