National Wetlands Update 2012
Issue No. 20, February 2012
Adelaide's Botanic Wetlands
Botanic Gardens of Adelaide, South Australian Department of Environment and Natural Resources
Adelaide Botanic Garden Sunken Garden, adjacent to the First Creek Wetlands (Board of the Botanic Gardens and State Herbarium South Australia)
Located in Adelaide's inner city parklands, the unique Adelaide Botanic Garden Wetland will address the impact of drought and climate change through the development of a self-sustaining natural environment combined with an aquifer recharge and reuse facility.
Jointly funded by the South Australian and Australian Governments as part of the National Urban Water and Desalination Plan, the urban-constructed wetland will divert stormwater as it enters the Botanic Garden. The wetland will combine natural and mechanical filtering before storing water, and subsequently recovering it from, an aquifer forty metres below ground.
Highlighting the Gardens' preparedness to significantly scale back its reliance on the River Murray as its main source of water, the aquifer recharge and reuse program will replace current potable water usage of 100 megalitres a year. In securing water self-sufficiency, the recharge and recovery cycle in the aquifer will be carefully controlled over the establishment phase to meet the anticipated sustainable levels of recoverable water within a five year period. If, as modelled, the predicted water levels of 130-135 megalitres per annum are secured, nearby Botanic Park will also utilise the surplus water as a replacement for the average 40 megalitres per annum it currently sources from the River Torrens and potable water supply.
In cooperation with the Adelaide and Mount Lofty Ranges Natural Resources Management Board, pollutant traps will improve the health of the source watercourse and clean associated water catchments by capturing hundreds of tonnes of organic and man-made litter and debris.
A supplementary benefit of the project is the identification, treatment and removal of contaminated soil from the site's historical use as a tram and bus depot. The removal of the 25 000 tonnes of contaminated soil ensures improved ground and aquifer water quality and a richer habitat for the diversity of native animals and plants.
Adelaide Botanic Garden view looking south-east over the First Creek Wetlands showing First Creek visible behind ponds (Board of the Botanic Gardens and State Herbarium South Australia)
A total of 280 000kwh of energy is used to supply current water needs which results in 235 tonnes of carbon emissions. This benchmark will be used to calculate an expected significant reduction in carbon emissions to contribute to South Australia's strategic greenhouse reduction targets.
Adelaide Botanic Garden attracts 1.5 million visitors each year. Visitors include approximately 50 000 school children using the Gardens' resources as part of their curriculum. In this setting visitors enjoy the beauty and tranquillity of the Gardens as well as engaging with the Gardens' messages about our relationship with plants.
The First Creek Wetland Project will provide a unique opportunity to connect visitors with the critical role that plants play in the water cycle, provide an accessible example of the ecosystem services provided by plants, and illustrate both the challenges of water scarcity and the nature of innovative approaches to addressing water scarcity.
The project is achieving an effective integration between botanists, horticulturists, ecologists, educationalists and interpretive and landscape designers to complement the Gardens' cultural landscapes. The result will provide an innovative, engaging and relevant learning experience for all involved. It will resolve an area of the Adelaide Botanic Garden that was identified in the Gardens' master plan for this purpose in 2006 through preliminary studies dating back to 2004.
First Creek Wetland will be an invaluable resource for the Adelaide Botanic Garden, residents of and visitors to South Australia, particularly because of its accessible location in the heart of Adelaide. It will open to the public in 2013.