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Water flows
The wetlands, rivers and wet places of our region have developed over a long period, responding to the natural weather patterns, water flows and sequences of climatic changes. The species that live and rely on these wet habitats have also developed and adapted to the natural sequences of flooding and extended dry periods, that are experienced over much of our semi-arid region. These places generally rely on water flows from nearby creeks, upstream rivers or widespread flooding to function as a natural system with the capacity to sustain themselves in a healthy condition over time.
Source: Daryl Albertson/OEH
However when the regime of natural water flows in our rivers is altered by upstream activities, the water flows that reach our wet areas are also altered. This new state in water availability puts pressure on the habitats and species to quickly adapt and many native plants and animals have difficulty in responding to these new conditions. Exotic species in particular, have the capacity to optimise altered conditions and can quickly dominate previously healthy wetland communities. An example of these changes is the widespread invasion of exotic plant species, such Lippia, which is a vigorous ground cover originating in the Americas. This exotic plant thrives in those wetland areas that no longer receive natural flows, for they prefer the smaller and less frequent watering that results from upstream river regulation and reduced water flows and flooding.
Source: Daryl Albertson/OEH
The damming and regulation of our major rivers has supported the development of irrigation and agriculture on the western floodplains of our region which has also had a major impact and the natural functioning of our rivers, wetlands and wet places. In turn, the habitats that rely on natural water flows are also impacted by these rapid changes in the volume, timing and duration of flows. These impacts can result in a decline in condition and extent of wetlands communities, habitat changes as a result of exotic or feral species invasions to the complete removal of our native wetlands.
However a number of our major regional dams currently have environmental water allocations that are solely for the benefit downstream environments. In this way the impacts of dams and river regulation can be reduced and our wet places can receive the water they need to function naturally. Working to reverse these impacts are a diverse group of committed people, who work together to deliver flows to the environment, in a way that supports both river and wetlands communities. They include local landowners, scientists, bird watchers and volunteers, the local Environmental Water Advisory Groups, staff from NSW Office of Environment & Heritage, WaterNSW, NSW Department of Primary Industries (Water) and the Commonwealth Environmental Water Office.
To find out more go to: http://www.environment.nsw.gov.au/topics/water/water-for-the-environment
Copeton Dam
Copeton Dam is a major dam across the Gwydir River, between Bingara and Bundarra in the New England region of New South Wales, Australia. The dam's purpose is for irrigation and downstream water supply with benefits of flood mitigation, which means that downstream impacts from large floods, can be reduced through the capture of a portion of the floodwaters in the dam. Releases from the dam also generates hydro-electric power for use in the operation at the dam facility. One other use of the dam is to delivery environmental flows from water accounts, held in the dam for the environment.
Source: WaterNSW
The large water body created by the dam is called Lake Copeton. Commenced in March 1968, commissioned in 1973, and completed in 1976, The maximum water depth is 104 metres and at 100% capacity the dam wall holds back 1,364,000 megalitres. The surface area of Lake Copeton is 4,620 hectares and the catchment area is 2,360 square kilometres. Together with a series of diversionary weirs and regulatory works downstream from the dam, Copeton is able to provide a reliable flow of water to 30,000 hectares of land mostly for irrigation purposes.
Burrendong Dam
Burrendong Dam is a major gated dam across the Macquarie River upstream of Wellington in the central west region of New South Wales, Australia. The dam's purpose includes flood mitigation, irrigation, water supply and hydro-electric power generation. The dam impounds Lake Burrendong and is filled by the waters from the Macquarie, and Cudgegong rivers as well as Meroo Creek.
Source: WaterNSW
Commenced in 1958 and completed in 1967, the Burrendong Dam is a major dam on the Macquarie River within the Macquarie Valley, approximately 30 kilometres (19 mi) southeast of Wellington. The dam was built by the New South Wales Water Conservation & Irrigation Commission for the purposes of providing flood mitigation, irrigation, and water supply. The dams water depth is 57 metres and at 100% capacity has a capacity of 1,188 gigalitres. The surface area of the dam is 7,200 hectares and the catchment area of the dam is 13,900 square kilometres. The spillway on the dam is a gated concrete chute with a release capacity of 13,720 cubic metres per second. Burrendong Dam has twice been recorded at a critically low level of 1.5% in drought. Contrastingly, however, Burrendong has mitigated potentially devastating floods downstream by using its flood capacity and releasing water in accordance with downstream tributary flows, safely reaching 160% of capacity in 1990 and 152.8% in 2010.
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