Wivenhoe Dam
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| Wivenhoe Dam | |
|---|---|
| Location | Queensland |
| Coordinates | |
| Lake type | reservoir |
| Primary inflows | Brisbane River |
| Primary outflows | Brisbane River |
| Catchment area | 5554 km² |
| Basin countries | Australia |
| Surface area | 109.4 km² |
| Max. depth | 67 m |
| Water volume | 1,160,000 ML |
| Shore length1 | 462 km |
| Surface elevation | 67.00 m |
| 1 Shore length is not a well-defined measure. | |
Wivenhoe Dam is a dam built across the Brisbane River that creates the artificial Lake Wivenhoe. The dam is located about 80 kilometres by road from the centre of Brisbane, Queensland, Australia.
The dam holds a volume of water two and a half times the water in Sydney Harbour. The primary purpose of the dam is to provide a water storage for south-eastern Queensland as well as extra storage for mitigation of periodic flooding of the Brisbane River. The lake also forms part of the water storages for the Wivenhoe Power Station.
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[edit] Purpose
The dam was designed as a multifunctional facility and built in the late 1970s - early 1980s by a consortium of construction companies including Thiess.
Its primary function is to provide a safe water supply to the people of Brisbane and adjacent regions. Additionally, Wivenhoe Dam serves as;
- the lower storage in a pumped-storage, hydro-electric generating facility, the Wivenhoe Power Station.
- the upper reservoir is formed by Splityard Creek Dam, of earth and rock construction, with a capacity of 28 700 megalitres.
- Under normal conditions the dam supplies water via pipeline to both Tarong Power Station and Tarong North Power Station, but due to drought conditions only supplies water to Tarong North.
- during a flood the dam is designed to hold back 1.45 million megalitres of additional water for flood mitigation.
- Lake Wivenhoe is also a camping and outdoor recreation destination. The managed camping facilities at Captain Logan Camp include hot showers, barbecues and toilets, and are adjacent to playgrounds, kiosk, boat hire and boat ramps at Logan Inlet.
[edit] Fishing
A Stocked Impoundment Permit is required to fish in the dam[1].
[edit] Key facts
Wivenhoe Dam consists of an earth and rock embankment 2.3 kilometres long and 50 metres high. It has a concrete spillway section on which five steel crest gates are installed. The gates, at 12 metres wide and 16.6 metres high, are amongst the largest of their type in the world.
The dam has a total storage capacity of 2.61 km³, of which 1.16 km³ is used for urban water storage. 200 properties were acquired to provide the 337.50 square kilometres of land required for the dam. The catchment area is 5,554 square kilometres.
The dam holds twice as much water as Sydney Harbour and is about seven times bigger than Hinze Dam at the Gold Coast. Wivenhoe Dam does contribute to the Gold Coast's water supply.
[edit] Drought
As of 2007, the reservoir has diminished in the midst of Queensland's severe drought, and the original path of the Brisbane River has become increasingly visible. Pockets of isolated water have begun to form and an island has revealed itself towards the lake's centre.
A previously unseen sandbar emerged from the waters of the lake towards the end of 2006. It presented a high risk that the power stations' water supply could prematuraly cease the supply of water from the Caboonbah pumping station.[citation needed] Enough water now has to be released from Somerset Dam to ensure that the pumping station can draw water for Tarong North Power Station. Tarong North will be unable to take any water from the dam if storage levels drop below 14.2%.[citation needed]
As of June 4, 2008, the combined storage levels in Wivenhoe, Somerset and North Pine Dams have risen pretty well after early winter rain sitting at a promising 39.06%, still short of the 40 per cent level needed to relax water restrictions.[2]
[edit] Statistics
- Average annual rainfall: 940 mm
- Capacity – water supply: 1 165 000 ML
- Capacity – flood storage: 1 450 000 ML
- Submerged area at full supply level: 109.4 km²
- Stream Bed Level at Structure (AHD): 23 m
- Embankment or Crest Level (AHD): 79 m
- Type of Structure: Embankment (4 000 000 m³) and Concrete (140 000 m³)
- Year of Completion: 1985
- Length of Wall: 2 300 m
- Spillway Gates: 5 x 12.0 m x 16.6 m
- Regulator Valves: 2 x 1.5 m diameter
- Average Evaporation (mm/year): 1 872
- Hydro Electric Station/dam structure: 4.5 megawatts
- Design: Queensland Water Resources Commission
[edit] Construction
Wivenhoe was initially investigated for a dam site in the 1890s and again in 1933[3]. Further investigations into a dam began in the mid 1960s. In November 1971, Government approval was given to proceed with construction. Acquisition of lands of the submerged portion of the dam began in March 1973. In 1976 the Government gave approval to proceed with construction of the pumped storage hydro-electric scheme. Total cost for the hydro-electric project was $450 million.
[edit] See also
[edit] References
- ^ Fishing in Queensland dams? You may need a permit.
- ^ Robinson, Georgina. Dam levels still too low to relax Level 6 (Web article). Brisbane Times. Retrieved on 2008-02-13.
- ^ Queensland Environmental Protection Agency, Heritage Trails of the Great South East, State of Queensland, 2000 ISBN 0-7345-1008-X
[edit] External links
