Summary and conclu China possesses a per capita water resource less than 1/3 of the world average, and due to an uneven distribution of annual rainfall. most of the water resources are concentrated in the south and southeast river basins, resulting in a large water deficient area in north China. The four north river basins, namely the Heilongjiang River, Liao River, Hai River, Yellow River and Huai River, are suffering from chronic water shortages charac terised by:(1)low rainfall and high potential evaporation;(2)extremely low per capita water resource; and (3)high percentages or over-withdrawal of water resources. Agricul ture uses approximately 80% of the water and is the main reason of over-withdrawal water resources. As a result, the water environment has severely deteriorated and many rivers water quality have become unsuitable for any purpose. ×Q≤9g卫天 Analysis results show that the potential of treated wastewater is extremely large to be used as an additional water resource in the whole country, especially north China Should the goal of 45% domestic wastewater treatment be attained, and 1/3 to 1/2 of the treated wastewater be re-used, the problem of water shortage in most of the cities could be greatly relieved With low rainfall and high potential evaporation, gardening and afforestation in the north cities need large quantities of water and, therefore, is considered to be the main se tor for treated wastewater re-use. The construction of a large-scale centralised wastewater system often requires high costs for long distance transfer of collected wastewater from the city area to the sewage treatment plant, and for the treated wastewater to be returned back to the city area for re-use. This becomes the main difficulty for the popularisation of wastewater re-use in less developed areas. In this regard, decentralised systems should be put into consideration in formulating wastewater treatment and re-use strategie References Asano, T. and Levine, A D.(1996). Wastewater reclamation, recycling and reuse: past, present, and future. ech,33(l01), Beijing Municipality (2004). Master Plan of Beijing Municipality (2004-2020). Abstract available on-line at: http://www.people.comcn/gb/jinGji/ Engelman, R. and Leroy, P. ( 1993). Sustaining Water: Population and the Future of Renewable Water Supplies, Population Action Intemational, Washington, DC. Falkenmark, M. and widstrand, C(1992). Population and Water Resources: A Delicate Balance. Population Bulletin, Population Reference Bureau, Washington, DC Institute of Geographic Science and Resources (2004). Scientific database. Institute of Geographic Science andResourcesChineseAcademyofScienceAvailableOn-lineat:http://www.data.ac.cn/index.asp International Hydrological Programme (1999). Inter Basin Water Transfer. International Workshop on Interbasin Water Transfer, UNESCO, Paris, 25-27 April 1999 Liu, C.M. and Chen, Z.K.(2001). Assessment of the Present Condition of Water Resources in China and Analysis of the Trend of Demand and Supply(in Chinese), China Water Power Press, Beijing Pan, J.Z. and Zhang. ZZ(2001). Rational Water Allocation in North China and South-North Water Transfer(in Chinese), China WaterPower Press, Beijing Meteorological Bureau of Shaanxi Province(2002). Daily Rainfall Recording of Xi'an Station Unpublished data Ministry of Water Resources(2002). Report of Water Resources in 2002 (in Chinese), Ministry of Water Minton, J, Luster, T, Silva, P, Spath, D. and Sugar. J. (2003). Desalination Task Force Report(Draft). Desalination Task Force, Department of Water Resources, California. Qian, Y and Tang, H.X. (2004). Study on the Measures of Water Pollution Control in Northwest China (in Chinese). Science Press, Beijing. State Environmental Protection Administration of China(2002). Environmental Quality Standards for Surface Water(GB 3838-2002), State Environmental Protection Administration of China. Beijing United Nation Population Division(2003). World Population Prospects: The 2002 Revision. ESA/P/WP. 180Summary and conclusion China possesses a per capita water resource less than 1/3 of the world average, and due to an uneven distribution of annual rainfall, most of the water resources are concentrated in the south and southeast river basins, resulting in a large water deficient area in north China. The four north river basins, namely the Heilongjiang River, Liao River, Hai River, Yellow River and Huai River, are suffering from chronic water shortages charac￾terised by: (1) low rainfall and high potential evaporation; (2) extremely low per capita water resource; and (3) high percentages or over-withdrawal of water resources. Agricul￾ture uses approximately 80% of the water and is the main reason of over-withdrawal of water resources. As a result, the water environment has severely deteriorated and many rivers’ water quality have become unsuitable for any purpose. Analysis results show that the potential of treated wastewater is extremely large to be used as an additional water resource in the whole country, especially north China. Should the goal of 45% domestic wastewater treatment be attained, and 1/3 to 1/2 of the treated wastewater be re-used, the problem of water shortage in most of the cities could be greatly relieved. With low rainfall and high potential evaporation, gardening and afforestation in the north cities need large quantities of water and, therefore, is considered to be the main sec￾tor for treated wastewater re-use. The construction of a large-scale centralised wastewater system often requires high costs for long distance transfer of collected wastewater from the city area to the sewage treatment plant, and for the treated wastewater to be returned back to the city area for re-use. This becomes the main difficulty for the popularisation of wastewater re-use in less developed areas. In this regard, decentralised systems should be put into consideration in formulating wastewater treatment and re-use strategies. References Asano, T. and Levine, A.D. (1996). Wastewater reclamation, recycling and reuse: past, present, and future. Wat. Sci. Tech., 33(10/11), 1–14. Beijing Municipality (2004). Master Plan of Beijing Municipality (2004–2020). Abstract available on-line at: http://www.people.com.cn/GB/jingji/. Engelman, R. and Leroy, P. (1993). Sustaining Water: Population and the Future of Renewable Water Supplies, Population Action International, Washington, DC. Falkenmark, M. and Widstrand, C. (1992). Population and Water Resources: A Delicate Balance. Population Bulletin, Population Reference Bureau, Washington, DC. Institute of Geographic Science and Resources (2004). Scientific database. Institute of Geographic Science and Resources, Chinese Academy of Science. Available On-line at: http://www.data.ac.cn/index.asp. International Hydrological Programme (1999). Inter Basin Water Transfer. International Workshop on Interbasin Water Transfer, UNESCO, Paris, 25–27 April 1999. Liu, C.M. and Chen, Z.K. (2001). Assessment of the Present Condition of Water Resources in China and Analysis of the Trend of Demand and Supply (in Chinese), China WaterPower Press, Beijing. Pan, J.Z. and Zhang, Z.Z. (2001). Rational Water Allocation in North China and South –North Water Transfer (in Chinese), China WaterPower Press, Beijing. Meteorological Bureau of Shaanxi Province (2002). Daily Rainfall Recording of Xi’an Station, Unpublished data. Ministry of Water Resources (2002). Report of Water Resources in 2002 (in Chinese), Ministry of Water Resources, P.R.C.. Minton, J., Luster, T., Silva, P., Spath, D. and Sugar, J. (2003). Desalination Task Force Report (Draft), Desalination Task Force, Department of Water Resources, California. Qian, Y. and Tang, H.X. (2004). Study on the Measures of Water Pollution Control in Northwest China (in Chinese), Science Press, Beijing. State Environmental Protection Administration of China (2002). Environmental Quality Standards for Surface Water (GB 3838–2002), State Environmental Protection Administration of China, Beijing. United Nation Population Division (2003). World Population Prospects: The 2002 Revision. ESA/P/WP. 180. X.C. Wang and P.K. Jin 43