Burdekin River

The Burdekin River is a river in North and Far North Queensland, Australia. The river rises on the northern slopes of Boulder Mountain at Valley of Lagoons, part of the western slope of the Seaview Range, and flows into the Coral Sea at Upstart Bay over 200 kilometres (124 mi) to the southeast of the source, with a catchment area of approximately 130,000 square kilometres (50,000 sq mi). The Burdekin River is Australia's largest river by (peak) discharge volume.

The river was first encountered by Europeans during the expedition led by Ludwig Leichhardt in 1845 and named in honour of Thomas Burdekin, one of the sponsors of the expedition.

The Burdekin River rises on the western slopes of the Seaview Range, part of the Great Dividing Range, west of Ingham. In the river's upper catchment, from its source the river generally flows west and then south out of the Girringun National Park, part of the UNESCO Wet Tropics World Heritage Area. This area, now part of Basalt was the location of one of the earliest inland settlements in northern Australia and was known as Dalrymple. The river is joined by Lucy Creek, the Running River, Star River and Keelbottom Creek, above Charters Towers. From the west in the Dry Tropics to the west of the river, the river is joined by the Clarke, Basalt and Dry rivers. South of Charters Towers, the upper catchment of the Burdekin River is joined by the Fanning River, and then continues to flow south through wetlands before entering Lake Dalrymple, the reservoir created by the Burdekin Falls Dam.

Within Lake Dalrymple, the Burdekin River is joined by the Cape, Suttor/Belyando rivers. The source of the Belyando River in central western Queensland is almost 500 kilometres (311 mi) from the mouth of the Burdekin River, and extends into the typical black-soil grassland of Central Queensland, with the Belyando draining the Drummond and Galilee Basins and flowing north for over 1,000 kilometres (620 mi).

Below the dam wall, in the river's lower catchment, is northern Australia's largest irrigation area with approximately 80,000 hectares (200,000 acres) under irrigation, predominantly for growing sugarcane. It consists of two broad regions, the earlier established delta region located on the coarse sedimentary deposits of the Burdekin River Delta, a groundwater dominated scheme, and the Burdekin Haughton Water Supply Scheme (BHWSS) – a more recently developed surface water dominated scheme on alluvial floodplains of the Burdekin River. Here the Burdekin is joined by the Bowen and Bogie rivers.

The Burdekin River descends 620 metres (2,030 ft) over its 886-kilometre (551 mi) course.

Four DIWA wetlands can be found along the course of the river. The first is at the Valley of Lagoons in the upper region of the catchment, the next is a Lake Dalrymple, then at the junction of the Burdekin and Bowen rivers known as the Burdekin-Bowen Junction and Blue Valley Weir Aggregation and the last is at the river delta which forms a 342.5 square kilometres (132 sq mi) wetland.

The Burdekin River is one of the most economically important rivers in Australia, and has the fourth-largest watershed of any exorheic drainage system in Australia. It is also the fourth-largest river in Australia by volume of flow, but is so erratic that its discharge can reach the mean discharge of the Yangtze River (after two severe cyclones in 1958) or have as many as seven months with no flow whatsoever (as in 1923). This exceedingly erratic flow is due to the extreme variability of precipitation throughout the entire basin. Annual rainfall at most gauges within the basin can range from 200 to 1,600 millimetres (7.9 to 63.0 in) depending on the monsoon and the number of cyclones that cross the coast. On the coast itself, the variability is even higher: at Bowen not far from the river's mouth, the annual rainfall has ranged from 216 millimetres (9 in) in 1915 to over 2,200 millimetres (87 in) in 1950. It has the highest mean annual flow for any river adjacent to the Great Barrier Reef.