MEASURING WATER USE IN A GREEN ECONOMY - UNEP

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Figure 4.2 Per capita water footprint Figure (CWRF) 4.2 for food consumption Per capita water footprint (CWRF) in China for from food 1961 consumption to 2003 in China from 1961 to 2003 900 800 700 CWRF (m 3 cap -1 y -1 ) 600 500 400 300 200 100 0 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Cereals & Roots Vegetables & Fruits Sugar & Sweeteners Alcoholic beverages Oil crops & Vegetable oils Animal products Basic level Low subsistance level High subsistance level The spatial distribution of water resources in China is highly uneven. The North China Plain constitutes roughly the three river basins, Huanghe, Huaihe and Haihe (the HHH region). Its water resource availability is extremely low. Yet the region is the major bread basket of the country, especially for wheat and corn. Various measures have been implemented to deal with the water scarcity problem. One of them is to transfer water from the Yangtze River to the north, the so-called South-North Water Transfer (SNWT) project. On the other hand, the north region is currently a net exporter of virtual water through food trade to the south. Each year, a huge amount of virtual water (52 billion m 3 /yr) flows from northern to southern China in the form of agricultural commodities (Ma et al., 2006). This volume of virtual water is 20 per cent more than the total volume of water from the SNWT project, or 43 billion m 3 /yr. A question that has been debated in the political arena and scientific community is the rationale of the transfers of real water and virtual water between the south and the north. Such transfers have often been criticised for not following the virtual water strategy. The far-reaching impact of the current patterns of real water and virtual water transfers on China’s ecosystems has also been a major concern. In reality, however, water is only one of the factors among many that influence decisions on trade. In Southern China, arable land is a scarce resource relative to the north, and the rapid development in urban sectors has led to an increase in the opportunity costs of inputs, particularly land and labour. Meanwhile, the dominant sub-tropical climate in the south is not favourable for wheat and corn. Hence, water endowments alone cannot be the sole criterion to judge the rationale of the transfer patterns. A more comprehensive analysis is needed to take natural conditions and socio-economic factors into account. Nevertheless, a quantification of virtual water embedded in the food transfers from north to south provides useful information for a comprehensive assessment of trade-offs of the real and virtual water transfers. 60
Measuring water use in a green economy of the blue water footprint, the environmental flows can be subtracted from natural runoff to get blue water availability. The blue water footprint can then be compared to the blue water availability. The analysis should be done monthly to accurately address intra-annual variability of river flows and water consumption. If the blue water footprint exceeds water availability at any time in the catchment, the water footprint is not sustainable at that time. In this case, action would need to be taken to reduce the blue water footprint to bring it within sustainability boundaries. The green water footprint can also be compared to green water availability, as outlined in the WFA handbook (Hoekstra et al., 2011), although this analysis has yet to be done in case studies. The total grey water footprint for a specific pollutant in a catchment can be compared to the total runoff to determine whether the full assimilation capacity of the river has been used or exceeded. If the total grey water footprint is less than the total runoff, the footprint is sustainable. If environmental flows or water quality standards are violated, it would be expected that the secondary impacts on ecosystem services, biodiversity, human health and other uses of water would begin to occur. Analysis of water scarcity and water pollution levels addresses the environmental aspects of sustainability. However additional criteria must be developed to assess economic and social sustainability. Integration of these three aspects of sustainability will need to be considered to ensure that the trade-offs are accurately understood and perverse outcomes are avoided. 4.4.4 Life Cycle Assessment and Weighted Water Footprint Life Cycle Assessment is an ISO-standardised (ISO 14040/14044) tool that evaluates the environmental performance of products and services along their life cycle (ISO, 2006). It assesses the various environmental impacts by quantifying all inputs (e.g. extraction and consumption of resources) and outputs (e.g. waste and emissions), and then evaluates the contribution of these inputs and outputs to the impact categories, e.g. climate change, ecotoxicity and ozone depletion. As shown in Figure 4.3, the full ‘cradle-to-grave’ life cycle of a product or service comprises numerous stages: extracting materials from Figure 4.3 Figure 4.3 Life cycle of an aluminium product, e.g. can for soft drinks Life Cycle Assessment - Life cycle of an aluminium product, e.g. can for soft drinks Disposal ? Production Resources Use Recycling Reuse ? Resource Extraction ? Emission Source: <strong>UNEP</strong> (2002) 61
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MEASURING WATER USE IN A GREEN ECONOMY - UNEP

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