MEASURING WATER USE IN A GREEN ECONOMY - UNEP

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espective ecosystems; this is often used synonymously with double decoupling which captures the notion of decoupling resource use from both economic activity and environmental impacts. • Absolute decoupling in contrast occurs when resource use declines irrespective of the growth rate of the economic driver. Absolute reduction in resource use only occurs when the growth rate of resource productivity exceeds the growth rate of the economy (<strong>UNEP</strong>, 2011a). However, depending on the nature of the environmental impact, this can, but does not necessarily, also lead to impact decoupling. Coupling or decoupling can be described, as in Figure 2.6, by a decoupling index, which Figure 2.4 Figure 2.4 Stylised Stylised representation reprentation of of resource resource decoupling decoupling and and impact impact decoupling decoupling Human well-being Economic activity (GDP) Resource decoupling Resource use Impact decoupling Time Environmental impact Sorce: (<strong>UNEP</strong>, 2011a) Box 2.2 The case of Singapore – an example of significant relative decoupling of economic growth from freshwater abstraction and use Singapore’s 4.4 million people live within a city-state that has an area of about 700 km 2 . The main source of freshwater has been imported water from Johor, Malaysia via three large pipelines across the 2 km causeway that separates the two countries. This was necessary because, despite an annual rainfall of 2 400 mm/year, Singapore has no large water catchments external to the city or groundwater aquifers from which to draw water to meet its needs and is considered a water-scarce country. These factors have focused attention at Singapore’s water utility, the Public Utilities Board (PUB) to reducing the demand for water by improving efficiency, cutting waste and expanding alternative sources of supply, resulting in the achievement of significant levels of relative decoupling (PUB, 2009). Over the last 40 years, Singapore’s economy has grown by a factor of 25. It has had one of the fastest transitions from a ‘developing’ to a ‘leading first-world’ country in history, with the highest per capita incomes in Asia. The population has grown by a factor of 2.5 in the period, from 1.7 million to 4.4 million today, yet water use has only increased five-fold. In terms of water consumption in absolute terms this represents a five-fold relative decoupling for the whole Singapore economy (Figure 2.5). This has been achieved through effective, purposeful and long-term demand management, water efficiency and water-leakage prevention programmes. Per capita residential water use has fallen 24
Measuring water use in a green economy Figure 2.5 Singapore GDP, population and total water consumption, 1965–2007 (index, 1965 =1) 30 25 GDP grow 26 times Total Consumption (mgdy) Population (’000) 20 15 10 5 Consumption grew 5 times GDP (S$ millions) 0 Population grew 2.5 times GDP Index Consumption Index Population Index Source: Khoo (2008) consistently for the last 15 years providing an exception to an otherwise worldwide increase. This result is no accident. The Singapore government is one of the few with a publically stated target for residential sector per capita water use of 140 litres per capita per day by 2030. Singapore and its Public Utilities Board have also reduced growth in water consumption by minimising water leakage throughout the city’s water infrastructure which is tracked by measuring the level of ‘unaccounted for water (UFW)’ (Tortajada, 2006b). This has been reduced from 9.5 per cent of total water production in 1990 (Khoo, 2005) to 5 per cent by 2002. This is a level that no other country can match at present and contrasts with the fact that unaccounted for water in most Asian urban centres now ranges between 40 and 60 per cent. Singapore has also reduced absolute freshwater consumption by 60 per cent through the development of alternative sources such as extensive stormwater harvesting, treatment and reuse, treated and recycled municipal water, and desalination. Today, 35 per cent of Singapore’s water comes from rainfall captured on its own limited territory, about 15 per cent is high-quality recycled water produced from wastewater by its ‘NEWater’ treatment plants, 10 per cent comes from desalinated water, and around 40 per cent is imported from Malaysia (ADB, 2005). In 2010, the Singapore government and its Public Utilities Board announced that it has now committed to replacing the final 40 per cent of imported freshwater usage with further waterefficiency improvements as well as the development of greater levels of water recycling and desalination so as to eliminate the need for imports from Malaysia by 2060. This remarkably integrated and holistic approach to sustainable urban water management has been institutionally possible because Singapore’s Public Utilities Board currently manages the entire water cycle of Singapore, as well as electricity and gas. This includes sewerage, protection and expansion of water sources, stormwater management, desalination, demand management, pricing, community-driven programmes, catchment management, and public education and awareness programmes, leading to wastewater treatment and reuse on an unprecedented scale. 25
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Water is an essential resource for
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