City West Water (CWW) is one of the three water retail authorities in the Melbourne metropolitan area in Australia and is wholly owned by the Victorian State Government. The core business of CWW is the delivery of drinking water and recycled water, and the collection of sewage and trade waste from customers in Melbourne’s Central Business District and inner and western suburbs. CWW’s servicing area includes nine (9) different city councils with different socio-economic status. CWW works closely with local government councils to develop alternative servicing strategies for their open spaces.
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To demonstrate the effectiveness of the GIS based screening tool methodology, the current study considers the application of the GIS screening tool on a highly urbanised area and on a semi urbanised area. For this purpose, two city councils within the CWW servicing area were selected respectively: City of Melbourne (CoM) and City of Brimbank (CoB).
The CoM is a highly urbanised council comprising of mainly commercial and park landuse, while the CoB is developing semi urbanised council compromising of mainly residential and open spaces land use. The details of study area (CoM and CoB) are described in Section 3.3.1 and 3.3.2 respectively.
3.3.1 City of Melbourne (CoM)
The study area for CoM within the CWW servicing region is shown in Figure 3.3. The CoM is the local government municipality covering Melbourne’s Central Business District and surrounding inner suburbs.
Geographically, the CoM covers an area of 36.5 Km2 situated at the downstream end of the following three catchments: the Yarra River catchment, the Maribyrnong River catchment, and the Moonee Ponds creek catchment. The Maribyrnong River and Moonee Ponds creek flow into the Yarra River, which enters Port Phillip Bay. The soils in this area are categorised as heavy clay formed on Basalt Rocks. The topography of the CoM is mostly flat with 70% of its land having slopes less than 5%. The CoM also covers the Central Business District (CBD) of Melbourne with a residential population of 96,552, and approximately 788,000 people use city per day for various purposes (ABS, 2009; CoM, 2010).
Greater Melbourne has a temperate climate which is influenced by topography and seasonal weather patterns. Surface water is the main source of water in Melbourne which comes from mountain ash forest catchments in the Yarra Ranges to the east of the city. The mean maximum temperature of Melbourne is 19.8°C and the mean minimum temperature is 10.2°C.
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Figure 3.3: City of Melbourne - Case Study
The average annual rainfall of Melbourne is 650 mm
(http://www.bom.gov.au/climate/averages/tables/cw_086071_All.shtml) The maximum rainfall occurs during late winter (June, July, August) and early spring (September, October, November), while the minimum occurs during summer (December, January, February) and early autumn (March, April, May).
Melbourne’s climate is affected by El Niño wind patterns which caused a severe drought from 1997 until late 2010. Although the Australian Government officially declared cessation of the drought in 2011 (DPI, 2011), the climate change prediction study conducted by Howe et al. (2005) has forecasted higher average temperatures, less rainfall, more frequent hot and dry days, and intense storms in future for Melbourne. Therefore, the City of Melbourne (CoM) is currently taking an active role in saving water, improving water quality and identifying new water sources with an overall target to reduce the per capita potable water consumption by 40 per cent by 2020 (CoM, 2011).
The GIS screening methodology was applied to a portion of the CoM, an area of 26 Km2 within CWW’s service area of 640 Km2 (Figure 3.3). The rest of the CoM area is separated by the Yarra River and serviced by South East Water (another water retail
Melbourne City Council ( in CWW Region) Australia Victoria Victoria
City West Water
City West Water Australia
Melbourne City Council ( in CWW Region)
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authority in Melbourne). The study area comprises predominantly commercial land use; other land uses include public parks, reserves, residential and industrial. The total non- residential water demand for the study area in the year 2010 was estimated as 11 GL, where as the total demand including residential demand constituted as 15 GL. This non- residential demand is mainly commercial water use which constitutes 82% (of the total non-residential demand of 11 GL). The next highest non-residential demand results from the irrigation of parks and open spaces accounting for 6%. This high irrigation demand is currently supplied by potable water which is subjected to water supply restrictions.
3.3.2 City of Brimbank (CoB)
The City of Brimbank (CoB) is the second largest municipality in Melbourne with 123 Km2 of land area. Moreover, CoB boasts its cultural diversity by embracing more than 156 nationalities from around the globe, making it Victoria State’s most culturally diverse municipality (City of Brimbank, 2013). Geographically, CoB is located across western and north-western suburbs of Melbourne. The population in CoB is around 191,084 with population density of 13.3 per ha as of year 2011 estimate (City of Brimbank, 2013). The study area for CoB is shown in Figure 3.4.
The CoB is situated in the Victorian Volcanic Plain, formed from volcanic eruptions and lava flows. The council has many natural features which comprise of grasslands, grassy wetlands, escarpments and riparian sites. Prominent waterways in CoB feature Maribyrnong River, Kororoit Creek, Taylors Creek, Jones Creek, Steele Creek and Stony Creek. The landuse mostly comprised growing residential area (46%) followed by the parklands (20 %) and other areas including industrial and commercial areas. Residential growth is expected to continue in various suburbs in the council (City of Brimbank, 2013)
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Figure 3.4: City of Brimbank – Case Study
The Brimbank region averages 400-500 mm rainfall a year, which is amongst the lowest in the greater Melbourne area. Having majority of landuse as residential area, CoB had a total water demand (including residential demand) of 12.8 GL in year 2010. The non- residential water demand for same year constituted as 2.8 GL. This non-residential demand was dominated by industries which constituting 82% of total demand, followed by the commercial use (7%) and park irrigation demand (5%) which is subjected to potable water restrictions.