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Ross River Dam

The Ross River Dam is an earth- and rock-filled embankment dam across the Ross River, located between Kelso and Mount Stuart in the City of Townsville in northern Queensland, Australia. Built initially for flood control, Lake Ross, the impoundment created by the dam, serves as one of the major water supplies for the region, and provides approximately 85 percent of the city's potable water.

The reservoir reached 250% capacity in February 2019 as a result of mass rainfall and flooding in the area.

Location and features

The dam was constructed by Leighton Contractors between 1971 and 1974 for the purposes of flood mitigation and water storage. The dam was an attempt to address Townsville's dual water concerns, abundance and scarcity. The initial capacity of the reservoir was .

In the 1980s, the second stage of the dam necessitated a deviation of the Flinders Highway and Mount Isa railway line (which previously ran straight north-south) to be further east. This was completed by 1986 and resulted in the closure of Toonpan and Barringha railway stations on the removed route; they were not re-established on new route. The resultant capacity of the reservoir increased to .

Following a 2007 upgrade of facilities, the dam an earth and rock embankment that is high and long that was, , the longest embankment dam in the southern hemisphere. The dam wall can hold back , or 514 percent of full supply capacity. However, full supply, or active capacity, is , that covers , and draws from a catchment area of . The controlled and gated spillway comprises three hydraulically-operated steel radial gates on concrete piers with a concrete service bridge, and can discharge .

In 2019 there was major floods and the dam reached the highest capacity it ever has at 232.79% which caused the 2019 Townsville flood.

Upgrade of the dam wall

Since completion of stage I construction in 1974 and stage II extension in 1986, upgrades of the dam include:

  • 1976the embankment was raised to
  • 1977a steel radial gate was installed that increased storage capacity to
  • 1987the radial gate was removed and the concrete spillway raised to , that increased storage capacity to
  • 2001a panel of experts in dam safety and construction undertook an investigation of the dam. Over two years, the panel conducted studies of the dam's compliance with world standards.
  • 2003The report confirmed that upgrades were required and by late 2003 because the dam moved a year. At that rate, the dam would have burst in a 10-year period, causing the whole suburb of Kelso to be inundated. The spillway was lowered by to , that reduced storage capacity to . The reduction had the impact of significantly reducing water supply available to the community and addressing the risk of flooding events damaging downstream settlements.
  • 2004A combined GHD-MWH team was appointed to design the remaining work and manage the project; and the following year, John Holland Group and Macmahon were contracted.
  • 2007Construction was completed with sand filters and supporting earthfill, extra rockwork to the dam embankment, and the contraction of the gates. The embankment was raised to , the three radial gates were added to the spillway, and storage capacity increased to

The spillway gates increased the reservoir's capacity by approximately nine percent, which is about or four months extra supply of water. Three spillway gates span the spillway. The upgrade was planned for completion in mid-2008, subject to rainfall delays, however it was completed in late 2007, ahead of time, at a cost of approximately .

See also

References

External links