1.1.5 Surface water hydrology and water quality

Summary

The Galilee subregion of the Lake Eyre Basin bioregion is located in the state of Queensland and it intersects several river basins including the Cooper-Bulloo and Diamantina in the west, the Flinders in the north, the Burdekin and Fitzroy in the east and the Warrego in the south. The area of the Galilee subregion is about 247,000 km² of which 46% is included in the Cooper creek-Bulloo river basin followed by 17% in Diamantina, 14% in Flinders, 12% in Warrego, 8% in Burdekin and 3% in Fitzroy river basins.

Much of the Galilee subregion is part of the Cooper creek-Bulloo river basin. Cooper Creek and the Thomson, Barcoo and Bulloo rivers are the major waterways in this basin. The Thomson and Barcoo rivers originate in the Galilee subregion and join each other at Currareva. The stream below the junction of Thomson and Barcoo rivers is known as Cooper Creek and is characterised by complex anastomosing channels and numerous wetlands and waterholes. Floods occur infrequently on the floodplain of Cooper Creek but can be much more damaging and disruptive due to the flat topography and the large number of braided channels in the floodplain. Water quality information such as total phosphorus (TP), total nitrogen (TN), electrical conductivity (EC) and turbidity is scarce for this basin. Salinity is normally low and stable. Turbidity is high and subject to varying trends as a result of local influences.

The north-western part of the Galilee subregion is part of the Diamantina river basin. The Diamantina River originates in the Galilee subregion and flows through a series of wetlands, lakes and waterholes along its 1000 km length. The Diamantina River is one of the major contributors of surface water to Kati Thanda – Lake Eyre. The flow regimes of the basin are dominated by late summer flow events resulting from highly variable monsoonal rainfall in the upper catchments. The rivers have greatly varying widths of active channel and floodplain. Floods are infrequent but during large events, floodwaters inundate thousands of square kilometres. There are no permanent water quality monitoring sites in the basin. However, data from occasional in situ measurements indicate low salinity and high turbidity in this basin.

The northern part of the Galilee subregion is included in the Flinders river basin. The Flinders River and two of its tributaries originate in the Galilee subregion. The flow regimes of the Flinders river basin are characterised as dry seasonal. The Flinders River carries large volumes of water during wet months. Floods are infrequent and can occur both upstream and downstream of the Flinders River. Water quality in the Flinders region appears to be reasonably good. There is spatial variability in the magnitude and ranges of both salinity and turbidity, and although there are some broad regional trends in salinity, turbidity appears to be dominated by local influences.

A small proportion of the Galilee subregion in the east is part of the Burdekin river basin. The Cape and Belyando rivers are the two major waterways of the Burdekin river basin that originate in the Galilee subregion. These two rivers carry upper catchments runoff to the Burdekin River above the Burdekin Falls Dam. The flow regime of the basin varies between locations, ranging from perennial to dry seasonal. Floods occur along the major rivers both upstream and downstream of the Burdekin Falls Dam. Although floods in the lower part of the basin can occur from local rainfall, inflows from upstream rivers contribute significantly to flood volume and duration. Availability of water quality data for the areas included in the Galilee subregion is very poor. Overall, salinity is low all across the basin but TN, TP and turbidity concentrations are high at many locations.

Only a small proportion of the Galilee subregion is part of the Fitzroy river basin. The Nogoa and Claude rivers originate in the Galilee subregion and carry catchment runoff to the Fitzroy River. The Fitzroy Basin comprises both perennial and seasonal streams. Inflows from headwater streams including Nogoa contribute greatly to flood volume on floodplain of the Fitzroy River and due to its immense size and fan-like shape the Fitzroy River has produced several large floods in the past. Water quality indicators such as TP, TN and turbidity show higher concentration in all major rivers although salinity is generally low.

The south-eastern part of the Galilee subregion is part of the Warrego river basin. The Warrego River and its three upstream tributaries originate in the Galilee subregion. The river flows through a series of reservoirs including swamps, billabongs, waterholes and dams. The flow regime of the Warrego River is characterised as perennial. Although floods are infrequent several large floods occurred in the past. Water quality indicators are generally good in this basin.