Wyangala Dam
Wyangala Dam is a major gated rock fill with clay core embankment and gravity dam with eight radial gates and a concrete chute spillway across the Lachlan River, located in the south-western slopes region of New South Wales, Australia. The dam's purpose includes flood mitigation, hydro-power, irrigation, water supply and conservation. The impounded reservoir is called Lake Wyangala.
| Wyangala Dam | |
|---|---|
 Wyangala Dam, near full capacity, 2012 | |
  Location of the Wyangala Dam in New South Wales | |
| Location | New South Wales, Australia |
| Coordinates | 33°57′S 148°59′E |
| Status | Operational |
| Construction began | 1928 |
| Opening date | 1935 |
| Construction cost | A£1.352 million |
| Owner(s) | State Water Corporation |
| Dam and spillways | |
| Type of dam | Embankment dam |
| Impounds | Lachlan River |
| Height | 85 m (279 ft) |
| Length | 1,370 m (4,490 ft) |
| Dam volume | 3,580 m3 (126,000 cu ft) |
| Spillways | 9 |
| Spillway type | Radial gates and concrete chute |
| Spillway capacity | 14,700 m3/s (520,000 cu ft/s) |
| Reservoir | |
| Creates | Lake Wyangala |
| Total capacity | 1,220,000 ML (43,000×106 cu ft) |
| Catchment area | 8,300 km2 (3,200 sq mi) |
| Surface area | 5,390 ha (13,300 acres) |
| Maximum water depth | 79 m (259 ft) |
| Normal elevation | 379 m (1,243 ft) AHD |
| Power Station | |
| Type | Conventional |
| Installed capacity | 18 MW (24,000 hp) |
| Annual generation | 42.9 GWh (154 TJ) |
| Website Wyangala Dam at www.statewater.com.au | |
Location and features
Commenced in 1928, completed in 1935, and upgraded in 1971, Wyangala Dam is a major reservoir situated below the confluence of the Lachlan and Abercrombie rivers, located approximately 38 km (24 mi) upstream, east of Cowra. The dam was built by the New South Wales Water Conservation & Irrigation Commission to supply water for irrigation, flood mitigation and potable water for the towns of Cowra, Forbes, Parkes, Condobolin, Lake Cargelligo, Euabalong and Euabalong West.[1][2][3] The dam also provides water for a far larger area and operates in conjunction with Lake Brewster and Lake Cargelligo, to supply water to the lower Lachlan valley customers.[1]
The dam wall constructed with 3,580 m3 (126,000 cu ft) of rockfill and a clay core is 85 m (279 ft) high and 1,370 m (4,490 ft) long. The maximum water depth is 79 m (259 ft) and at 100% capacity the dam wall holds back 1,220,000 ML (43,000×106 cu ft) of water at 379 m (1,243 ft) AHD. The surface area of Lake Wyangala is 5,390 ha (13,300 acres) and the catchment area is 8,300 km2 (3,200 sq mi). The eight radial gates and concrete chute of the spillway are capable of discharging 14,700 m3/s (520,000 cu ft/s).[1][2][3] A A$43 million upgrade of facilities commenced in 2009 and, when completed by 2016, is expected to result in the raising and locking of the spillway radial gates; raising of the spillway chute wall; and raising of the parapet wall crest.[4][5]
The Wyangala Dam is the second oldest dam built for irrigation in New South Wales and was one of the last dams in the state where a railway or tramway system for construction purposes was utilised.[6] It is the only dam on the Lachlan River system,[1] which feeds the Murrumbidgee River, and in turn feeds the Murray River.
Power generation
A hydro-electric power station generates up to 22.5 MW (30,200 hp) of electricity from the flow of the water leaving Wyangala Dam with an average output of 42.9 GWh (154 TJ) per annum.[2] A 7.5 MW (10,100 hp) station was initially constructed below the dam wall and opened in 1947,[7][8] and the new facility, managed by Hydro Power Pty Ltd,[1] completed in 1992.[7]
History
The name Wyangala is said to originate from an indigenous Wiradjuri word of unknown meaning and is the name of Wyangala Station, one of the properties flooded by Lake Wyangala waters when construction of the dam was completed in 1935.[9] The Wyangala Station homestead site, which was originally settled by the Newham family, is under the water level and can only be seen when the dam is close to being dry. The small settlement of Wyangala, located downstream of the dam wall, was established to house workers during the dam construction.
The current earth and rock wall was constructed between 1961 and 1971 due to fears that the original dam wall was beginning to lift away from its base, and as a result, would not be able to withstand a major flood. The original dam wall can be seen when the water level is around 30 per cent of the reservoir's catchment capacity.
In 2008, water entitlements were down to just 10 per cent of normal availability. Some inflows to the reservoir later in the year allowed restrictions for high security licence holders to be relaxed.[10] In late 2009, drought had reduced the water storage level to 4.5 per cent of the reservoir's capacity.[11]
The 2022 south eastern Australia floods in late October and early November 2022 resulted in the dam releasing a record 230,000,000,000 litres (230,000,000 m3)/day.[12] The previous record release rate was 205,000,000,000 litres (205,000,000 m3)/day set in 1990.[12]
See also
- Irrigation in Australia - review of irrigation practices used in Australia.
- Lake Cowal - the largest inland lake in New South Wales.
- Dams and Reservoirs - list of dams and reservoirs in NSW.
- Lowbidgee Floodplain - floodplain of the lower Murrumbidgee River.
References
- "Wyangala Dam" (PDF brochure). State Water Corporation. 2009. Retrieved 21 April 2013.
- "Register of Large Dams in Australia". Dams information. The Australian National Committee on Large Dams Incorporated. 2010. Archived from the original (Excel (requires download)) on 12 December 2013. Retrieved 21 April 2013.
- "Wyangala Dam". Water delivery: dams. State Water Corporation. Retrieved 21 April 2013.
- "Wyangala upgrade". Projects: Dam safety upgrades. State Water Corporation. 2012. Retrieved 21 April 2013.
- "Councils get Wyangala Dam report". ABC News. Australia. 11 March 2010. Retrieved 12 June 2011.
- Newland, John R. (1989). "The Construction Railways of Wyangala Dam". Australian Railway Historical Society Bulletin. Australian Railway Historical Society (September–October): 199–211, 228–236.
- "Wyangala Dam". Basin Kids: Electricity Generation. Murray-Darling Basin Commission. Retrieved 21 April 2013.
- "Wyangala Power Station Opened". The Canberra Times. National Library of Australia. 28 April 1947. Retrieved 21 April 2013.
- "Wyangala Dam". Geographical Names Register (GNR) of NSW. Geographical Names Board of New South Wales. Retrieved 21 April 2013.
- "Boost for Lachlan Valley water allocations". ABC News. Australia. 4 November 2008. Retrieved 12 June 2011.
- Kelly, Joe (15 December 2009). "Premier Kristina Keneally waives fees for water". The Australian. Retrieved 12 June 2011.
- Sato, Kenji; Pezet, Lauren. "Thousands stranded in homes as flash flooding batters Central West NSW, Wyangala Dam spills at record rate". ABC News. Australian Broadcasting Corporation. Retrieved 18 November 2022.