快速工業化以及人口成長已經加速各種有限自然資源的耗竭如淡水、森林以及石油，天然淡水資源耗竭更是近幾年備受關注的重要議題。因為無論對於人類的福祉或者生態環境而言，淡水都是十分重要的資源。
建立水資源的盤查方法也是最近幾年許多學者與團體所關注的議題，譬如國際標準化組織（International Organization for Standardization，ISO）已經著手建立評估產品水足跡的標準。然而，與其他環境衝擊相比，例如溫室氣體排放，水資源消耗是一個新興的環境衝擊評估項目。目前，由於沒有完整與一致的評估標準，對企業而言，十分困難自行著手評估其企業或產品水足跡。
本研究建立了一個可供企業應用的水足跡評估方法。運用本研究建立的水足跡評估方法，企業可以自行結合國家經濟投入產出表(national economic input-output table)、其企業財務資料與直接用水量以建構環境延伸的投入產出表，而後評估該企業的水足跡。本研究中以一間台灣矽晶太陽能電池廠商作為檢驗此水足跡評估方法的個案，評估結果顯示該太陽能電池廠商在2006年的矽晶太陽能電池生產活動所造成的企業水足跡（business water footprint）為2百64億公升水，其中，大多數企業水足跡來自生產活動中使用的矽原料如：晶塊、晶碇。
台灣經濟投入產出表每五年編制一次，例如最新的編制年度為2006年，因此在非投入產出表編制年度如2008年，台灣並沒有經濟投入產出表可供使用，應用本研究建立的水足跡評估方法，企業依然可以計算該企業每年度由生產活動所造成的水足跡。此外，本研究建立的水足跡評估方法可以讓企業以該企業的水足跡評估他們產品的水足跡。在現今相關各企業或產品水足跡資料不完整的情況下，本研究已經建立一個可以讓企業進行相關水足跡評估的方法。

Rapid industrialization and population growth have increased the rate of depletion of various scarce natural resources, such as freshwater, forest, and oil. The depletion of natural freshwater is an issue of particular importance because freshwater is indispensable both for human well-being and for ecological systems.
The development of water use (WU) inventories for many human activities has thus received increasing attention. For example, the International Organization for Standardization (ISO) is working on the establishment of a standard for the assessment of a water footprint of a product. And, compared to other environmental impact categories such as greenhouse gas emissions, freshwater consumption is relatively new and no consistent standard. Therefore, it is difficult for industries to conduct a water footprint study on their products in a consistent and comprehensive manner.
In this study, a comprehensive business water footprint (BWF) framework for companies is developed. Using this framework, companies can combine their financial data and direct water used with the national economic input-output (IO) table to construct environmentally extended IO table to evaluate their BWF. A Taiwanese crystalline silicon solar cells company is taken as a case study to verify this framework. The results show that the company had a BWF of 26.4 billion L for its production of crystalline silicon solar cells in 2006. The indirect (upstream supply chain) BWF associated with the silicon materials, such as ingots and wafers, had the largest contribution.
The IO table is compiled every five years (ex. the most recent update is made for 2006); therefore, there is no input-output table available in other years (such as 2008). Using the methodology described in the framework, the BWFs for companies were calculated. Under the proposed framework, product water footprints (PWFs) can also be estimated from the BWF for company. The framework provides a simple yet comprehensive means of calculating BWFs in a company, especially where related data are not widely available or accessible for a process-based product-specific water footprint.

1. Cominelli, E., et al., Water: the invisible problem. EMBO reports, 10(7): p. 671-676. 2009.
2. 經濟部水利署. 台灣水資源特性. 台灣地區水資源調配及開發策略 2004/8/22 [cited 2010 December 9]; Available from: http://www.wra.gov.tw/ct.asp?xItem=11733&ctNode=2314&comefrom=lp.
3. Geography Statistics, Precipitation (most recent) by country. [cited 2010 12/9]; Available from: http://www.nationmaster.com/graph/geo_pre-geography-precipitation.
4. 莊順興, et al., 我國水回收及再生利用法規評析與推動建議. 工業污染防治, (112): p. 107-121. 2009.
5. Schnoor, J.L., Three Myths about Water. Environmental science & technology, 44(5): p. 1516-1517. 2010.
6. WHO/UNICEF, Water for life: making it happen. WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation. 2005.
7. CMO. 奇美電子取得面板業第一張產品供應鏈「水足跡」查證聲明. 最新消息 [cited 2010 Octorber 4]; Available from: http://www.chimei-innolux.com/opencms/cmo/media_center/News/index.html?news_no=9&__locale=zh_TW.
8. UMC. 聯華電子領先業界完成積體電路晶圓產品水足跡查證. [cited 2010 Auguest 18]; Available from: http://www.umc.com/chinese/news/2010/20100818.asp.
9. Hoekstra, A., et al., Water footprint manual: State of the art 2009: Water Footprint Network. 2009.
10. Intel, 2007 Annual Report. Intel Corporation. 2007.
11. Cooper, T. and J. Pafumi. Performing a water footprint assessment for a semiconductor industry. 2010: IEEE.
12. Allan, J.A., Virtual water: A strategic resource global solutions to regional deficits. Ground Water, 36(4): p. 545-546. 1998.
13. Hoekstra, A. and P. Hung. Virtual water trade: a quantification of virtual water flows between nations in relation to international crop trade. 2002: IHE.
14. Finkbeiner, M., Carbon footprinting─opportunities and threats. The International Journal of Life Cycle Assessment, 14(2): p. 91-94. 2009.
15. Cooney, C., LCA finally takes water into account. Environmental science & technology, 43(11): p. 3986-3986. 2009.
16. Lifset, R., Industrial Ecology in the Age of Input-Output Analysis. Handbook of Input-Output Economics in Industrial Ecology: p. 3-21. 2009.
17. Ridoutt, B.G., et al., The water footprint of food waste: case study of fresh mango in Australia. Journal of Cleaner Production, 18(16-17): p. 1714-1721. 2010.
18. Cumberland, J., A regional interindustry model for analysis of development objectives. Papers in Regional Science, 17(1): p. 65-94. 1966.
19. Stoevener, H. and E. Castle, Input-Output Models and Benefit-Cost Analysis in Water Resources Research. Journal of Farm Economics, 47(5): p. 1572-1579. 1965.
20. Leontief, W., Environmental repercussions and the economic structure: an input-output approach. The review of economics and statistics, 52(3): p. 262-271. 1970.
21. Joshi, S., Product environmental life-cycle assessment using input-output techniques. Journal of Industrial Ecology, 3(2-3): p. 95-120. 1999.
22. Suh, S., et al., System boundary selection in life-cycle inventories using hybrid approaches. Environ. Sci. Technol, 38(3): p. 657-664. 2004.
23. 陳梅英, PIDA︰我去年光電產業總產值破2兆, in 自由時報(電子報): 台北市. 2011.
24. Fthenakis, V. and H.C. Kim, Life-cycle uses of water in U.S. electricity generation. Renewable and Sustainable Energy Reviews, 14(7): p. 2039-2048. 2010.
25. 李展能, Study of the degradation mechanism of TFT-LCD organic wastewater under aerobic, anoxic and anaerobic conditions, in 環境工程學系碩博士班. 國立成功大學. p. 62. 2008.
26. Park, S.-J., et al., Biological treatment of wastewater containing dimethyl sulphoxide from the semi-conductor industry. Process Biochemistry, 36(6): p. 579-589. 2001.
27. Gleick, P., Water resources. Encyclopedia of climate and weather, 2: p. 817-823. 1996.
28. Postel, S., Entering an era of water scarcity: the challenges ahead. Ecological Applications, 10(4): p. 941-948. 2000.
29. Postel, S., G. Daily, and P. Ehrlich, Human appropriation of renewable fresh water. Science, 271(5250): p. 785. 1996.
30. Hanjra, M.A. and M.E. Qureshi, Global water crisis and future food security in an era of climate change. Food Policy, 35(5): p. 365-377. 2010.
31. USGS. Earth's water distribution. [cited 2011 February 26]; Available from: http://ga.water.usgs.gov/edu/waterdistribution.html.
32. Ridoutt, B.G., et al., Water footprinting at the product brand level: case study and future challenges. Journal of Cleaner Production, 17(13): p. 1228-1235. 2009.
33. Falkenmark, M., Land-water linkages: a synopsis. Land and Water integration and river basin management. FAO Land and Water Bulletin, 1: p. 15¡V17. 1995.
34. Rockström, J., On-farm green water estimates as a tool for increased food production in water scarce regions. Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 24(4): p. 375-383. 1999.
35. Falkenmark, M., Freshwater as shared between society and ecosystems: from divided approaches to integrated challenges. Philosophical Transactions of the Royal Society B: Biological Sciences, 358(1440): p. 2037. 2003.
36. Rockstrom, J., Green water security for the food makers of tomorrow: windows of opportunity in drought-prone savannahs. Water Science and Technology: p. 71-78. 2001.
37. Surface Water Classification and Water Quality Standards, E.P. Administration, Editor: R.O.C. (Taiwan) Environmental Law Library. 1998.
38. Ridoutt, B.G. and S. Pfister, A revised approach to water footprinting to make transparent the impacts of consumption and production on global freshwater scarcity. Global Environmental Change, 20(1): p. 113-120. 2010.
39. 丁澈士 and 周柏儀, 區域性虛擬水資源交易之初步探討--以屏東平原為例. 臺灣水利, 53卷(1期總號209): p. 頁46-53. 2005.
40. Chapagain, A. and A. Hoekstra, The water footprint of coffee and tea consumption in the Netherlands. Ecological economics, 64(1): p. 109-118. 2007.
41. Adeoti, O., Water use impact of ethanol at a gasoline substitution ratio of 5% from cassava in Nigeria. Biomass and Bioenergy, 34(7): p. 985-992. 2010.
42. Dominguez-Faus, R., et al., The water footprint of biofuels: a drink or drive issue? Environmental science & technology, 43(9): p. 3005-3010. 2009.
43. Gerbens-Leenes, P., A. Hoekstra, and T. Meer, Water footprint of bio-energy and other primary energy carriers. 2008.
44. Gerbens-Leenes, P., A. Hoekstra, and T. Van der Meer, The water footprint of energy from biomass: A quantitative assessment and consequences of an increasing share of bio-energy in energy supply. Ecological economics, 68(4): p. 1052-1060. 2009.
45. Gerbens-Leenes, W., A. Hoekstra, and T. Van der Meer, The water footprint of bioenergy. Proceedings of the National Academy of Sciences, 106(25): p. 10219. 2009.
46. Jongschaap, R., et al., The water footprint of bioenergy from Jatropha curcas L. Proceedings of the National Academy of Sciences, 106(35): p. E92. 2009.
47. Tan, R.R., et al., The use of graphical pinch analysis for visualizing water footprint constraints in biofuel production. Applied Energy, 86(5): p. 605-609. 2009.
48. Yang, H., Y. Zhou, and J. Liu, Land and water requirements of biofuel and implications for food supply and the environment in China. Energy Policy, 37(5): p. 1876-1885. 2009.
49. Katsoufis, S., Cradle-to-Gate Water Footprint Analysis of Borealis Group Polyolefin Value Chain. Master of Science Thesis. Royal Institute of Technology. Stockholm. 2009.
50. Ecoinvent Centre Homepage. [cited 2010 December 23]; Available from: http://www.ecoinvent.org/.
51. GaBi Software Homepage. [cited 2010 December 23]; Available from: http://www.gabi-software.com/.
52. JEMAI-LCA Pro. Available from: http://www.jemai.or.jp/CACHE/lca_details_lcaobj198.cfm.
53. DoITPro. [cited 2010 December 23]; Available from: http://www.itri.org.tw/chi/tech-transfer/04.asp?RootNodeId=040&NodeId=041&id=2023.
54. WBCSD Global Water Tool. [cited 2010 December 23]; Available from: http://www.wbcsd.org/web/watertool.htm.
55. CROPWAT software. [cited 2010 December 23]; Available from: http://www.fao.org/nr/water/infores_databases_cropwat.html.
56. Bayart, J.-B., et al., A framework for assessing off-stream freshwater use in LCA. The International Journal of Life Cycle Assessment, 15(5): p. 439-453. 2010.
57. Berger, M. and M. Finkbeiner, Water Footprinting: How to Address Water Use in Life Cycle Assessment? Sustainability, 2(4): p. 919-944. 2010.
58. Van Oel, P., M. Mekonnen, and A. Hoekstra, The external water footprint of the Netherlands: Geographically-explicit quantification and impact assessment. Ecological economics, 69(1): p. 82-92. 2009.
59. Guan, D. and K. Hubacek, Assessment of regional trade and virtual water flows in China. Ecological economics, 61(1): p. 159-170. 2007.
60. Hubacek, K. and L. Sun, A scenario analysis of China's land use and land cover change: incorporating biophysical information into input-output modeling. Structural Change and Economic Dynamics, 12(4): p. 367-397. 2001.
61. Hubacek, K. and S. Giljum, Applying physical input-output analysis to estimate land appropriation (ecological footprints) of international trade activities. Ecological economics, 44(1): p. 137-151. 2003.
62. Velazquez, E., Water trade in Andalusia. Virtual water: An alternative way to manage water use. Ecological economics, 63(1): p. 201-208. 2007.
63. Wiedmann, T., et al., Examining the global environmental impact of regional consumption activities--Part 2: Review of input-output models for the assessment of environmental impacts embodied in trade. Ecological economics, 61(1): p. 15-26. 2007.
64. 周嫦娥 and 李繼宇, 虛擬水資源與糧食安全. 水資源管理會刊, 10卷(1期): p. 頁15-22. 2008.
65. Pfister, S., A. Koehler, and S. Hellweg, Assessing the environmental impacts of freshwater consumption in LCA. Environmental science & technology, 43(11): p. 4098-4104. 2009.
66. Mila i Canals, L., et al., Assessing freshwater use impacts in LCA: Part I--inventory modelling and characterisation factors for the main impact pathways. The International Journal of Life Cycle Assessment, 14(1): p. 28-42. 2009.
67. Mila i Canals, L., et al., Assessing freshwater use impacts in LCA, part 2: case study of broccoli production in the UK and Spain. The International Journal of Life Cycle Assessment, 15(6): p. 598-607. 2010.
68. Suh, S., Functions, commodities and environmental impacts in an ecological-economic model. Ecological economics, 48(4): p. 451-467. 2004.
69. Wiedmann, T., A review of recent multi-region input-output models used for consumption-based emission and resource accounting. Ecological economics, 69(2): p. 211-222. 2009.
70. Dixon, R., Inter-industry transactions and input-output analysis. Australian Economic Review, 29(3): p. 327-336. 1996.
71. Lenzen, M., Errors in Conventional and Input-Output-based Life-Cycle Inventories. Journal of Industrial Ecology, 4(4): p. 127-148. 2000.
72. Bullard Peter, S. and W. Clark, Net energy analysis* 1:: Handbook for combining process and input-output analysis. Resources and Energy, 1(3): p. 267-313. 1978.
73. Lenzen, M., A guide for compiling inventories in hybrid life-cycle assessments: some Australian results. Journal of Cleaner Production, 10(6): p. 545-572. 2002.
74. Stromman, A. and C. Solli, Applying Leontief's price model to estimate missing elements in hybrid life cycle inventories. Journal of Industrial Ecology, 12(1): p. 26-33. 2008.
75. 盧怡靜, 台灣公路運輸部門能源耗用與CO2排放趨勢變動因素探討, in 環境工程學系碩博士班. 國立成功大學. p. 136. 2007.
76. Harto, C., R. Meyers, and E. Williams, Life cycle water use of low-carbon transport fuels. Energy Policy, 38(9): p. 4933-4944. 2010.
77. Owens, J., Water Resources in Life Cycle Impact Assessment: Considerations in Choosing Category Indicators. Journal of Industrial Ecology, 5(2): p. 37-54. 2001.
78. Hoekstra, A., A. Chapagain, and MyiLibrary, Globalization of water: sharing the planet's freshwater resources: Blackwell Pub. 2008.
79. OECD. Glossary of statistical terms. Available from: http://stats.oecd.org/glossary/.
80. Product gallery. [cited 2010 December 28]; Available from: http://www.waterfootprint.org/?page=files/productgallery.
81. Nakamura, S. and Y. Kondo, Waste input-output analysis: concepts and application to industrial ecology: Springer Verlag. 2009.
82. Hubacek, K. and L. Sun, Economic and Societal Changes in China and their Effects on Water Use A Scenario Analysis. Journal of Industrial Ecology, 9(1 2): p. 187-200. 2005.
83. Fischer, G. and L. Sun, Model based analysis of future land-use development in China. Agriculture, Ecosystems & Environment, 85(1-3): p. 163-176. 2001.
84. Zhao, X., et al., Applying the Input-Output Method to Account for Water Footprint and Virtual Water Trade in the Haihe River Basin in China. Environmental science & technology: p. null-null. 2010.
85. 經濟部水利署, 水資源供需情勢統計調查方式改善與彙編94-96年各項用水統計報告總報告. [臺北市]: 經濟部水利署. 2008.
86. King, C. and M. Webber, Water intensity of transportation. Environmental science & technology, 42(21): p. 7866-7872. 2008.
87. Solley, W., et al., Estimated use of water in the United States in 1995: US Dept. of the Interior, US Geological Survey. 1998.
88. Webber, M., The water intensity of the transitional hydrogen economy. Environmental Research Letters, 2: p. 034007. 2007.
89. Inhaber, H., Water use in renewable and conventional electricity production. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 26(3): p. 309-322. 2004.
90. (2010) Taiwan Power Company Sustainability Report 2010 (台灣電力公司永續報告書 2010).
91. 行政院主計處, 中華民國九十五年產業關聯表編制報告(The Report on 2006 Input-Output Tables): Taipei. 2010.
92. 行政院主計處, 中華民國九十五年台灣地區產業關聯表部門分類. 2010.
93. de Wild-Scholten, M. and E. Alsema, Environmental Life Cycle Inventory of Crystalline Silicon Photovoltaic System Production-Status 2005/2006 (Excel file). ECN-E--07-026 Energy research Centre of the Netherlands, Petten, the Netherlands. 2007.
94. Gleick, P., Environmental consequences of hydroelectric development: The role of facility size and type. Energy, 17(8): p. 735-747. 1992.
95. Torcellini, P., et al., Consumptive water use for US power production. National Renewable Energy Laboratory. 2003.
96. King, C.W. and M.E. Webber, The Water Intensity of the Plugged-In Automotive Economy. Environmental science & technology, 42(12): p. 4305-4311. 2008.
97. Fthenakis, V. and H. Kim. Energy use and greenhouse gas emissions in the life cycle of CdTe photovoltaics. 2006: Warrendale, Pa.; Materials Research Society; 1999.
98. Tsujimura, K. and M. Mizoshita, Compilation and Application of Asset-Liability Matrices: A Flow-of-Funds Analysis of the Japanese Economy 1954-1999. 2004.
99. Cullen, J. and J. Allwood, The role of washing machines in life cycle assessment studies. Journal of Industrial Ecology, 13(1): p. 27-37. 2009.
100. 盧文俊 and 林志鴻, 用水計畫書查核服務系統作業(含工業用水量統計推估模式研究): 經濟部水利署. 2006.