Water resource issues in Melbourne, Australia

Transcription

1 A climate for change Water resource issues in Melbourne, Australia A case study prepared by Tony Weatherley Dept. Agriculture and Food Systems, The University of Melbourne Introduction As world population continues to climb many dilemmas for human kind begin to unfold. Larger populations command a greater ecological footprint as our requirements for the fundamentals of food, fibre and shelter increase. A safe water supply is of course central to this. The UNDP (2000) defines safe water in terms of: access to water; adequate amounts of water; quality; affordability and; reliability of supply. The Camdessus report (Winpenny, 2003) stated that the achievement of water security would do more for poverty, development and the other Millennium Development Goals than almost any other conceivable actions and that globally spending will need to increase from 80 to 180 billion a year to achieve this 1. So the world needs water security for an ever increasing population in a time of accelerated climate change 2. Lets look at how population and climate combine to affect water security in a first world country, in particular the city of Melbourne, Victoria, Australia. The Climate I love a sunburnt country, a land of sweeping plains. Of ragged mountain ranges, of droughts and flooding plains, I love her far horizons, I love her jewel- sea, Her beauty and her terror - The wide brown land for me! So goes the second stanza of a 1904 poem by Dorothea Mackellar the lines of this poem are etched in the memory of most Australians. In 2009, Victoria (south- eastern Australia) experienced devastating wildfire (fuelled by some 12 years of drought) and last year (2011) near record flooding occurred Mackellar s words have never been so true. Yet is the climate of 1904 alike that in 2012 or have things changed? Melbourne, the capital of Victoria experiences a temperate climate (the Köppen climate classification is Cfb). Historical annual rainfall data for the state of Victoria shows several periods of extended drought (Figure 1), although recent annual maximum temperatures have never been as consistently above the long term average (Figure 2) saw a number of records broken, with the hottest day in Melbourne (46.7 C) since records began, and the driest start to a year (at total of 3.3 mm of rainfall for January and February, compared to the long- term average of 95.2 mm). It is clear that Melbourne s weather is being affected by climate change (Australian Bureau of Meteorology 2009). So perhaps we should stop pretending and admit that this is not just an extended drought but in fact the new climate reality for Melbourne. 1 However the source of funds, privatisation and user pays, has been hotly contested by social and environmental groups. See 2 Climate change may however increase rainfall in some parts of the world. For an Australian example see: bin/climate/change/trendmaps.cgi?map=rain&area=aus&season=0112&period=1970

2 Figure 1. Average annual rainfall for Victoria since The 11 year running average which smooths out short term temporal variation is in indicated by the black line. Source: bin/climate/change/timeseries.cgi?graph=rain&area=vic&season=0112&ave_yr=11 Figure 2. Average annual maximum temperature anomaly (relative to baseline) for Victoria. The 11 year running average which smooths out short term temporal variation is in indicated by the black line. Source: bin/climate/change/timeseries.cgi?graph=tmax&area=vic&season=0112&ave_yr=11 2

3 Population 7:23 am, Melbourne Airport. Singapore airlines code share 3 has just landed. Aboard are just a few of the estimated 43,000 people that will immigrate to Melbourne this year and every year for the foreseeable future. In fact immigration will be the major contributor to Melbourne s population growth with population expected to increase by 1.8 million in the next 30 years to 5.6 million (although natural population growth, birth less deaths, will also contribute positively). The largest proportion of immigrants is from the UK, followed by India and China. Skilled workers represent the largest proportion of visas granted (Department of Immigration and Citizenship 2008). A smaller proportion of visas (< 10% of those allocated to the migration program) are granted as part of Australia s humanitarian program. The Ecological Footprint of the average Victorian is 6.8 global ha and if everyone lived like us the global population would require at least another three Earths to support it (Environmental Protection Agency, Victoria 2009). The Victorian government has a strategy in place to accommodate an extra one million people by 2030 ( tory/melbourne2030), although this estimate has been subsequently revised upwards 4. Drought As stated previously, Melbourne has recently experienced thirteen consecutive years of drought. The city was 'drought proofed' through the installation of several large dams in the 1960's and '70's, with the catchments of these dams remaining forested to ensure the quality of the drinking water. Melbourne is one of the few cities in the world to have forested catchments for water harvesting. The drought reduced water storage in these dams to less than 30 % of capacity and restrictions on water use were enshrined into law. The recent wildfires have also threatened the water catchments 5, with the potential for increased ash and soil runoff into dams and also fire retardants. Water storage and supply is managed by Victorian government agencies 6. Water Security Using the conservative estimate of Melbourne s population growth (1 million extra people by 2030) and the average water demand experienced during the 1990 s around 660 GL of water are required per annum for water security. The problem is that the current reliable water yield from Melbourne s catchments is around 560 GL/yr. Further, the average inflow into Melbourne s main storage reservoirs over the period was 385 GL/year compared to the long term average flow of 615 GL/yr. Climate modeling by CSIRO (Howe et al. 2005) suggests a mid range predicted reduction in water inflows to Melbourne s catchment of 8% in 2020 and rising to 20% by Faced with the dilemma of providing a secure water supply to its citizens, the Victorian government embarked on a multi- pronged strategy to secure Melbourne s water future in These have been documented in the government 3 Shared with Lufthansa, Virgin Atlantic and Air- India. 4 Victoria is the second largest state in Australia. There is no official population policy for Australia and estimates of an optimal population range from million people. An intergenerational report recently predicted population will grow from the present 22 million to 36 million by This is the worst natural disaster in the 200 year history of European settlement in Australia with over 200 people killed, thousands of homes destroyed and countless livestock and native animals killed. 6 Water storage is managed by Melbourne Water. Water supply is managed by region by three separate companies. 3

4 White Paper 7 imaginatively titled The next stage of the Governments water plan (Victorian government 2007). In brief the plan involves: a desalination plant; irrigation channel upgrade and a statewide water grid; water conservation programs and; recycling. Desalinisation A desalinisation plant is under construction to provide up to 150 GL of drinking water by The desalinisation plant uses seawater reverse osmosis and will be the largest such plant in Australia 8. The plant is sited on the south- eastern coast and when complete, water will be piped around 90 km to an existing storage dam. Reverse osmosis requires large inputs of energy to drive the process and the Victorian government has pledged to completely offset the energy requirement through the purchase of additional renewable energy (the government has not said the plant will be carbon neutral both the Western Australian and Queensland governments have made this commitment with the WA plant powered by wind turbines). There is considerable local opposition to the siting of the plant and concern over the environmental impact of the hyper- saline water returned to Bass Strait (see Food bowl modernization The food bowl modernisation project is an attempt to save water (Perry, 2007). Like many arid regions, inland Victoria is highly dependant on irrigation water for food production (and supply of this produce to local and export markets). The Goulburn- Broken catchment, immediately to the North of Melbourne s water catchment, and separated by the Great Dividing Range, is regarded as the food- bowl of Victoria with high levels of food production per unit area, revenue and employment (Goulburn- Broken Catchment Management Authority, 2003). The infrastructure for water supply is however failing, flawed and inefficient. The Victorian government considers that 225 GL of water can be saved by the modernisation of the system and the savings shared equally by the irrigators, the environment 9 and Melburnians. An 85 km North- south pipeline has been constructed to divert 75 GL of water annually from the Goulburn river to water storages in Melbourne s water catchment. The problem was however that inland Victoria was subject to the same extended period of drought with the major water storage in the Goulburn- Broken catchment (Lake Eildon) at just 20% of capacity 10 with irrigators receiving less than a third of their annual entitlements. Estimates of potential reductions in water available for diversion to irrigation range from 50% under median climate change scenarios to 90% in extreme scenarios (CSIRO, 2008). Not surprisingly there is considerable opposition to this project from many country Victorians ( Water conservation and recycling One toilet flush in the developed world uses as much water as the average person in the developing world uses for a whole day s washing, cleaning, cooking and drinking. (UNDPI, 2002) The average Melburnian uses far less water now than 30 years ago. Household water saving devices (reduced flow shower rose, tap aerators, front loading washing machines, dual and reduced flush toilets), water restrictions and education campaigns have reduced average daily per capita consumption from 500 L in 1982 to 350 L in The last water conservation 7 A white paper contains the official policy of the government of the day. 8 Western Australia and Queensland each have a 45 GL operational plant; South Australia and New South Wales have 50 and 90 GL plants under construction. 9 Stored in Eildon reservoir and released where appropriate as environmental flows 10 Capacity is six times that of Sydney harbour or 3,300 GL! 4

5 campaign targeted 155 L per person per day and this target is generally met when moderate daily temperatures prevail. High daily air temperatures tend to increase water use and this is probably due to increased water use for gardens. Water pricing is also used to discourage wasteful consumption with a three tiered tariff system. Water restrictions are enforced through community pressure and financial penalties (fines) for using water in the garden on specific days of the week. Government rebates may be obtained for expenditure on water saving devices and the installation of rainwater tanks. Many new residential developments are required to have rainwater tanks and often reuse and recycle water (after local treatment) through a third pipe in the dwelling. Water from the third pipe can be used for toilet flushing and watering of gardens. Industry has also been encouraged to use recycled water, for example in cooling systems, provided from tertiary treated sewage (although this water is pure enough to drink). Other possibilities Clearly, there are other possibilities for water security for Melburnians and new dams have been considered. However these are costly and very few new possibilities exist, most of the major rivers are dammed. A dam on the Mitchell river (280 km east of Melbourne) has been suggested but this would potentially impact on RAMSAR listed wetlands, involve around 120 km of pumping, piping and tunnelling and would impact on the local farming community (SKM, 2005). Conclusion Climate change and population growth appears to have placed the future of Melburnians water security in doubt. New water is however coming to Melbourne at the expense of rural Victoria 11 and the environment. At face value the plan appears sensible, saving, creating and sharing and similar ideas have been put forward by others (Rogers, 2008). However recent rains and the break of the drought cast doubt on these strategies and undermine government commitment to greenhouse gas reductions to address climate change. As the Minister for Water what would you do and why? What lessons can be learnt in your region from Melbourne s experience? There are a number of questions in water security lesson plan to help you decide. Postscript In 2010, the drought broke and Victoria experienced its 5 th wettest year on record. The North- South pipeline is complete but not currently in use, the complaints of the Northern Irrigators now heard after a change of government. Lake Eildon is full and Melbourne s dams are 66 % full, the all- important Thompson River dam, which buffers Melbourne from drought years, is at 50% of capacity. Construction of the desalinisation plant continues. Last week 12, Melbournians used on average 177 L of water a day. Melbourne is now on stage one water restrictions. 11 Water flowed from through the North- South pipeline on 10 February The pipeline was closed after a change in government. In response to increase inflows to dams over the last two years the government has relaxed water restrictions to Melburnians January

6 References Australian Bureau of Meteorology (2012). Climate Change. Accessed 9 January Department of Immigration and Citizenship (2011). Population Flows: Immigration Aspects. flows- chapter1.pdf Accessed 9 January Environmental Protection Agency, Victoria (2009). Accessed 9 January 2012 CSIRO (2008). Water Availability in the Murray- Darling Basin. A report to the Australian Government from the CSIRO. Murray- Darling Basin Sustainable Yields Project. 67 pp. Goulburn- Broken Catchment Management Authority, (2003). Regional Catchment Strategy. Goulburn- Broken Catchment Management Authority. Howe, C., Jones, R.N., Maheepala, S. and Rhodes, B. (2005). Melbourne water climate change study: Implications of Potential Climate Change for Melbourne s Water Resources. CSIRO, Australia. Perry, C. (2007). Efficient irrigation; inefficient communication; Flawed recommendations. Irrigation and Drainage. 56: Rogers, P. (2008). Facing the Freshwater Crisis. Scientific American. 229: Sinclair Knight Mertz (2005). Eastern Water Recycling Proposal. data/assets/pdf_file/0008/32687/skm_dams_24aug- 05.pdf Accessed 9 January 2012 UNDP (2000). Charting the progress of populations. Chapt 10. Access to Safe Water. Accessed 9 January UNDPI (2002). Freshwater: Action on the ground. Accessed 9 January Victorian Government (2007). Then next stage of the governments water plan. stage Accessed 5 March Winpenny J. (2003). Financing Water For All. Report of the World Panel on Financing Water Infrastructure. s/camdessussummary.pdf Accessed 9 January

7 Some online video resources: About the Murray River (in the northern part of the state) Plug the pipe campaign Fires in Victoria Victorian drought Saving water saving- video Desalination 7