Canning Reservoir
| Canning Reservoir | |||||||||
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| Coordinates | 32 ° 10 '12 " S , 116 ° 8' 34" O | ||||||||
| Data on the structure | |||||||||
| Construction time: | 1933-1940 | ||||||||
| Height of the structure crown: | 66 m | ||||||||
| Crown length: | 466 m | ||||||||
| Data on the reservoir | |||||||||
| Altitude (at congestion destination ) | 279 m | ||||||||
| Water surface | 5.01 km² | ||||||||
| Reservoir length | 11.5 km | ||||||||
| Reservoir width | 1.2 km | ||||||||
| Storage space | 90.352 million m³ | ||||||||
| Catchment area | 804 km² | ||||||||
The Canning Reservoir is a reservoir in the southwest of the Australian state of Western Australia . It is an important reservoir of drinking water for the city of Perth and is located in the Darling Range along the Canning River . At the time of its construction, the concrete gravity dam had a particularly modern construction and hydraulic design. Until the 1960s, the Canning Reservoir was the main source of fresh water for Perth; only then were further reservoirs built. Today the reservoir provides about 20% of the fresh water for the city. The inflow to the Canning Reservoir is estimated at 22 million m³ / year and the storage capacity at 90.352 million m³.
Since its completion in 1940, the Canning Reservoir has caused a variety of ecological problems, including increased algal bloom , habitat loss, and sedimentation . Nevertheless, the Canning Reservoir and its surroundings are popular as a recreational area.
history
The expansion of the Canning River as a source of fresh water for Perth was first proposed in 1896 by the first Metropolitan Water Works Board of Perth . The site investigations began in 1897 when the civil engineer Thomas Hodgeson measured the location of the current dam and suggested it as a possible location. Despite demands for further investigations and an extreme water shortage in a few years, it was not possible to raise any money for the construction of the dam until the Great Depression in the 1930s.
In 1924 a small weir was built 6 km below the current Canning dam. It was only intended as a quick fix to Perth's water supply problems, and it soon became apparent that a larger reservoir was needed. Nevertheless, it took nine years for the construction of today's dam to start. In 1940 the reservoir was completed at a cost of AU $ 1.1 million. Civil engineer Russell Dumas designed the dam and supervised most of the construction.
In 1951 a concrete-paved canal was built as an improvement to divert the water flow from the catchment area of the nearby Kangaroo Gully . The Canning Reservoir was the city's main source of freshwater until Perth's boom in the 1960s and the Serpentine Reservoir was built in 1961. 1975, the reservoir was by Canning tunnel to the Integrated Water Supply Scheme Perth connected. Before it opened, the water had flowed through the Canning Contour Channel to Gosnells .
Today, the Canning Reservoir still provides about 20% of Perth's drinking water and plays an important role in the city's development.
The Canning Reservoir also serves as storage for the recently completed Kwinana Desalienation Plant ( reverse osmosis plant). The desalinated water from the plant can be pumped into the lake from the Forrestdale Pumping Station .
Hydrology
The catchment area of the reservoir is in the Darling Range, which is part of the shield , which consists mainly of granite with some linear deposits of modified sedimentary rock and volcanic rock .
The dam is located in a narrow valley that runs in an east-west direction, with rockfalls towards the river bed. Behind the dam, the Canning River South flows into the main river. The water formed a reservoir that has three main branches to the east, south-east and south.
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The catchment area is 804 km². The reservoir is at a height of 200 m and the highest point in the catchment area, Mount Cooke, is 582 m high.
The annual rainfall is around 900 mm; most of the rain falls from May to September. The distribution of rainfall in the catchment area varies greatly between 700 mm and 1300 mm per year.
Since 1975 the long-term average rainfall at the reservoir has decreased by 20% and the water flow into the catchment area by approx. 60% - the annual water flow from 1948 to 1974 was 52 million m³, while from 1975 to 2004 it was only 22 million m³ amounted to.
construction
The construction of the Canning Reservoir put an end to a long period of inadequate water supply for Perth. During this time there were both quality defects (salt content or bacterial contamination or both) and quantity defects. The project, the largest public works program of the decade, resulted in noticeable growth in the local economy and created around 500 much-needed jobs.
Many innovative design principles and methods that were new to Australia were used in this project. Proven methods used in the construction of the nearby Wellington Reservoir have been improved.
With the Canning dam, as with all dams, care had to be taken to avoid leaks between the rock bed and the dam. At the Canning Dam, in addition to the removal of the rock beds down to the solid stone without breaks, a trench was planned on the water side of the dam wall, which was combined with a rock-filled drainage with open, connected pipes to avoid any leakage between the rock beds and the concrete to meet the dam. The installation of an internal drainage system was considered new at the time. Almost vertical, 200 mm thick drainage pipes were installed at a distance of 1.52 m along the dam to drain internal leaks through the concrete.
In addition to working methods that were state-of-the-art at the time, labor-saving machines were also used in some cases to improve work performance. Auxiliary staff was mainly used for suburban construction, road construction, earthworks for the foundation of the dam, the clearing of the areas of the later lake basin and for some concrete work. Skilled workers were required to build the formwork into which the concrete was poured on the dam . These workers were presumably employed at normal daily rates, as was the norm with this project. The storage of cement in silos was also used here for the first time on an Australian construction site, which resulted in significant time savings compared to the usual handling of cement sacks.
In general, work progressed as planned and there were few setbacks from an engineering perspective. However, a major problem arose soon after construction began: in March 1934 a bad storm brought 130 mm of rain in less than two days. As a result, the river rose rapidly and flooded the construction site of the dam foundation. Pumps had to be installed and work continued three days later.
In September 1940 the dam was completed. It was the longest concrete gravity dam in Australia at the time, and also the second tallest after the Burrinjuck Dam in New South Wales . In 1997, the Canning Dam was still the fifth tallest and sixth longest among 90 large concrete and masonry gravity dams in Australia. It is the largest concrete dam in Western Australia in terms of crown length and wall volume.
The construction costs were well below the planned amount and the work was completed on time. The construction time was 7 years.
Repair work
In the upper part and on the crown there were clear cracks on the dam. Studies have shown that these are due to alkaline reactions in concrete. These reactions cause the concrete to swell, which can lead to an increase in secondary compressive stresses and local cracks. Ultimately, this leads to cracks in the structure of the concrete wall. In addition, the tensile strength and elasticity of the concrete decrease significantly. Many old concrete dams suffer from these alkaline reactions, u. a. also the Fontana Dam in Tennessee and the Pian Telessio in Italy .
In the years 1999 to 2001 extensive repair work was carried out to strengthen the dam. The upper 3.8 m of the existing dam wall was removed and drill holes and blast holes were made in the dam wall and up to 70 m in the rock foundation below. The upper part of the dam was then rebuilt from reinforced concrete. Finally, permanent, retensionable ground anchors were inserted through the drilled and blasted holes into the rock foundation. At the time this work was completed, these were the longest and strongest permanent ground anchors ever installed.
A new drilling and blasting technique called Penetrating Cone Fracture (PCF) was used in this repair work. PCF was preferred to conventional drilling and blasting techniques because of the lower risk of damage to the existing structure from vibrations and the lower occurrence of harmful gases and dust.
environmental issues
As with similar drinking water reservoirs, the construction of the Canning Reservoir lowered the water level in the Canning River by up to 96%. Some freshwater fish species endemic to the waters of southwestern Western Australia are found in the Canning River, but studies of fish and their habitats in the area showed that fish numbers increased due to habitat loss and connection with the Spawning grounds are small because of the low water level. The migration of the fish upstream to the spawning grounds is severely impeded. Standing water, which occurs when the water level is too low, has created a habitat and spawning space for an introduced fish species, the goblin fish ( Gambusia affinis ).
The damming of the Canning River caused a dramatic lowering of the water level, which significantly changed the population of microorganisms below the dam. The lack of water has also led to a reduced flushing effect below the dam. A huge amount of nutrients from fertilizers and animal excrement has caused algal bloom and eutrophication .
Many pools in the river, which were important retreats for aquatic and terrestrial flora and fauna, were lost to sedimentation and changes in water flow caused by the damming of the Canning River.
Periodic flooding of the Canning River from the reservoir is necessary to distribute seeds, stimulate germination, ensure that the seedlings survive, replenish low water levels - which is particularly important during periods of drought - and contain weed growth. In times of low rainfall, however, the flooding is reduced.
free time activities
There are various recreational opportunities at the reservoir and in the vicinity. There are a number of picnic areas (with gas grills), lookout points, and hiking trails - many with wheelchair access. You can hike in the entire catchment area, especially along the Bibbulum Track , which leads about 10 km upstream of the dam through the catchment area. Various mountain bike trails traverse the Monadnocks Conservation Reserve on the Canning River and adjacent state forests.
In Canning Dam, in the Canning River and its tributaries is illegal under Marron - crayfish (Cherax tenuimanus or Cherax cainii) fished, especially in summer. Boating, fishing and swimming are prohibited in the reservoir for reasons of hygiene. Wild camping (including overnight stays outside of designated areas) and the unauthorized creation of hiking trails are becoming increasingly common in the reservoir's catchment area. Many people also drive into the area by car, fish and hunt wild boar .
Web links and sources
- Website Canning reservoir (English)
- Canning Reservoir - WA . ExplorOz.com
- Map of Canning Reservoir, WA . Bonzle.com
- Steve Parish: Australian Touring Atlas. Steve Parish Publishing Pty., Acherfield QLD 2007, ISBN 978-1-74193-232-4 , p. 78.
Individual evidence
- ↑ a b c d e f g h i j k Canning Dam and Reservoir, McNess Drive, Roleystone, Western Australia. Australian Heritage Database. Government of Australia.
- ↑ a b c d Cathy Day: Register of Heritage Places - Canning Contour Channel . ( Memento of the original from July 22, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Heritage Council of Western Australia. (February 2003)
- ↑ a b The Canning Dam. ( Memento of the original from September 7, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Water Corporation
- ↑ WA Dam levels up . ABC News (March 3, 2008).
- ↑ a b c d e f g h Canning River Catchment Area Drinking Water Source Protection Plan . Water Resource Protection Series. Department of Water ( Memento of the original from July 25, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (June 2007). ISSN 1326-7442
- ^ Statewide Dam Storage - Canning Dam . ( Memento of the original from October 2, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Water Corporation
- ↑ Bruce Bulley, Bob Wark, Michael Somerford: Dams in the Darling Range. ( Memento of the original of July 14, 2005 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Australian Geomechanics Symposium (2003).
- ↑ V. Saouma, L. Perotti, T. Shimpo: Stress Analysis of Concrete Structures Subjected to Alkali-Aggregate Reactions. In: ACI Structural Journal. September / October 2007.
- ↑ Tony Molds: Canning Dam Remedial Works 1999-2001. In: 11th National Conference on Engineering Heritage: Federation Engineering a Nation; Proceedings. Institution of Engineers. Barton ACT (2001), ISBN 1-74092-215-5 .
- ^ Canning Dam Ground Anchors . ( Memento of the original from July 21, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Structural Systems.
- ↑ Penetrating Cone Fracture (PCF) - Frequently Asked Questions . Rockbreaking Solutions. Alterrain (2002) ( Memento of the original from July 18, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 203 kB).
- ^ Workplace Giving Towards a Healthier Canning River . ( Memento of the original from May 31, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Landcare.
- ↑ Canning River Flows ( Memento of the original from July 25, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF). Department of Environment. Government of Western Australia.
- ↑ a b c Caring for the Canning ( Memento of the original from September 1, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF). Swan River Trust. Government of Western Australia.
- ↑ DL Saunders, JJ Meeuwig, ACJ Vincent: Freshwater Protected Areas: Strategies for Conservation. Conservation Biology. Volume 16. Issue 1. Wiley Interscience (2002). doi : 10.1046 / j.1523-1739.2002.99562.x pp. 30-41.
- ↑ Algal Blooms. ( Memento of the original from July 20, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Water Facts 6. Water and Rivers Commission. Government of Western Australia.
- ↑ Canning Dam Facilities Brochure ( Memento of the original from September 26, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.3 MB). Water Corporation.
- ↑ Parks and Picnic Spots. ( Memento of the original from December 28, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Experience Perth. Perth Region Tourism Organization Inc. Perth 2007.
