無論是自然災害或人為造成的缺水，是當今世界一個最具挑戰性的課題。在台灣，尤其是在颱風侵襲期間，飆高的原水濁度往往超過自來水淨水場的處理能力，以致可能造成為期數日的停水。本研究之目的是引進雨水做為在短期緊急缺水期間的另一種可靠次要水源，評估雙效性雨水貯集系統(Dual-mode Rainwater Harvesting System, DM-RWHS)提供日常及緊急缺水期間次級用水之功效與主要水源的可節省水量。案例研究部分，同時對台灣北部及南部的小學和不同數量成員之家庭進行利用成效分析。

在既有供水系統提供衛生設備(WC)的非飲用情況下，本研究設計具雙重水源及利用功效的DM-RWHS 做為原供水系統的輔助部分，以利用雨水做為補充水源。由於必須在DM-RWHS中保持一定的蓄水，同時估算所利用的雨水量，本研究修正通用的「溢流後出水(YAS)」模式，並據以發展優化方法設計最經濟的DM-RWHS。本研究對DM-RWHS系統設計兩個新的水量控制指標，在適當設定後有助於使DM-RWHS不致發生任缺水。其中之一是最低安全蓄水量(minimum safe storage volume, MSSV)，在台灣一般相當於 3天的需求水量，另一個控制指標是適應性蓄水量(ASV)。 此ASV的體積將隨用水需求、降雨量及其時間與季節分佈、緊急缺水期間之日數、集雨器面積、雨水貯集桶之容量等而異。如果一段時間沒有降雨，雨水貯集桶內之水量達到或低於MSSV時，該系統將自動注入主要水源以使筒內蓄水量達到 ASV的水準。本研究在假設可能造成緊急缺水情況的某一定雨量下，另發展一模式以模擬不同容量的雨水貯集桶在長期使用過程中可穩定供水的最少天數。

對台北地區一座小型小學的案例研究結果顯示，減少缺水發生的同時，節省的自來水水量及效益極為顯著。對台南地區相同案例的研究結果顯示，為了減少緊急期間的缺水，節省的自來水水量及效益比起台北地區較不顯著。本研究另外對台北、台南地區有二、四、六個成員的家庭進行案例研究，結果發現所有類型的家庭，DM-RWHS系統均可有效地消除緊急時期的缺水。

本研究結果證明一最適容量的雨水貯集桶可以適切解決緊急時期的缺水。將DM-RWHS系統應用在台北地區會比在台南地區利用更多雨量，本研究還發現台灣政府可以提供適當補助以推動 RWHS之利用。

The water shortage of today’s world is one of the most challenging problems which is caused by human or natural calamities. In Taiwan, especially during typhoon, the turbidity of raw water increases beyond the treatment level and the plant cannot supply required amount of water for a couple of days. The purpose of this study is to introduce rainwater as an alternative and reliable water source during short term emergency period, and assess the efficacy and mains water saving of the dual-mode Rainwater Harvesting System (RWHS) for supplying emergency and ordinary water demands in case of primary school and household having different numbers of family members for both northern and southern Taiwan as case study.

A dual-mode RWHS was designed for this study as supplement of the existing supply system to support the selected non-potable toilet and urinal flushing (WC) component. An optimal design algorithm was developed using a newly developed modified YAS (yield after spillage) model for this study which originated from YAS release rule. Two new important parameters were also introduced for the system which would help to use the dual-mode system without any shortage. One of the two is minimum safe storage volume (mssv), which is equivalent to three days demand. Another parameter is adapted storage volume (asv). This asv volume level will be guided according to the users requirements. If there is no rainfall and the water level reaches mssv level, the system will collect and store mains supply up to asv level. Another model was developed to simulate the water release system and to find the minimum number of days the system can support using rainwater with different tank volumes when the rainfall is more than 250 mm/day.

The case study results of primary school for Taipei revealed that the mains supply savings and benefit would be significant to reduce the water shortage. The case study results for Tainan explored that the mains supply savings and benefit would be less significant than that of Taipei to reduce emergency water shortage. The case study of the families having two, four and six members’ for both Taipei and Tainan was performed. The study results found that for all kinds of family members’, the system would satisfy the emergency water shortage effectively for both places.

The study result proved that an optimum volume of tank can solve the emergency water shortage properly. The system was found to be more reliable in Taipei area than that of Tainan area. The study also discovered that government may provide subsidy to promote the RWHS in Taiwan.

Aberhart,G., 2004. Massive flooding spurs calls for land protection. Taiwan Panorama,
<http://www.sinorama.com.tw/en/show_issue.php?id=200489308162e.txt&table=2&h1=Ecology%20and%20Environment&h2=Environmental%20Protection> (last accessed 20 April 2010).
ABRI (Architecture and Building Research Institute), 2000a. Evaluation Manual for Green Buildings in Taiwan. Ministry of Interior, Taipei, Taiwan, R.O.C.
ABRI (Architecture and Building Research Institute), 2000b. The Research on the Water Consumption Management of Residences and Office Buildings. Ministry of Interior, Taipei, Taiwan, R.O.C.
ABS, 1994. Environmental issues - people's views and practices. Australian Bureau of Statistics, catalogue number 4602.0.
Agarwal, A. and Narain, S., 1997. Dying wisdom: the rise, fall and potential of India’s traditional water harvesting systems. State of India’s Environment 4, A Citizen’s Report, CSE, New Delhi, p404.
Alegre, N., Jeffrey, P., McIntosh, B., Thomas, J.S., Hardwick, I. and Riley, S., 2004. Strategic options for sustainable water management at new developments: the application of a simulation model to explore potential water savings. Water, Science & Technology, 50 (2), pp9-15.
Appan, A., 1989. Proposal for a dual-mode rain watr cistern system in industrial areas of two hectares lots. Proc. of the 4th International Conference on Rain Water Cistern Systems, Manila, Philippines, August 1989.
Appan, A., Leong, L.K., and Kit, L.S., 1987. The Utilization of High-Rise Building Rooftops for Development of a Dual-Mode of A Water Supply In Singapore. Proc. of 3rd International Rainwater Catchment Systems Association, Khon Kaen, Thailand, 14-16 January, 1987, pp C10-1 to 14.
Birks R., 2002. Personal communication, Thames Water, UK. Rebecca. Birks@thameswater.co.uk.
Branvall G., Eriksson M., Johansson U. and Svensson P., 1999. Physical and monetary data connected to abstraction, use and discharge of water in the Swedish NAMEA. Statistika centralbyran (Statistics Sweden).
Butler, D., 1991. A small-scale study of wastewater discharges from domestic appliances. J.IWEM 5, 178-185.
Butler, D. and Davies, J.W., 2004. Urban Drainage. 2nd edition, Spon Press, London.
Butler, D. and Memon, F.A., 2006. Water consumption trends and demand forecasting techniques. In: Butler, D. and Memon, F.A. (Eds), Water Demand Management, IWA Publishing. London. pp1-26.
Centre for the Analysis and Dissemination of Demonstrated Energy Technologies (CADDET), (1999). Combined and stepped use of energy in Sumida City Office. http://www.etis.net (Last accessed on 20th February, 2010)
Chambers, V.K., Creasey, J.D., Glennie, E.B., Kowalski, M. and Marshallsay, D., 2005. Increasing the value of domestic water use data for demand management - summary report. WRC collaborative project CP187, report no. P6805, March 2005.
Chang, Y.M., 2007. Questions of water conservation. Taipei Times.
<http://www.taipeitimes.com/News/editorials/archives/2007/07/31/2003372121> (Last accessed on 31st March, 2010).
Chen, H. and Petley, D.N., 2005. The impact of landslides and debris flows triggered by Typhoon Mindulle in Taiwan. Quarterly Journal of Engineering Geology and Hydrogeology, 38(3), 301-304.
Cheng, C.L. and Hong, Y.T., 2004. Evaluating water utilization in primary schools. Building and Environment, 39, pp 837-845.
Cheng, C.L., Liu, Y.C. and Ting, C.W., 2009. An urban drought-prevention model using raft foundation and urban reservoir. Building Services Engineering Research and Technology, 30 (4) 343-355.
Chu, S.C., Liaw, C.H., Tsai, Y.L., Chen, J.C., Chen, J.T. and Lee, S.C., 1997. Planning strategy study for roof rainwater catchment systems. Proc. of 8th International Conference on Rainwater Catchment Systems, Tehran, Iran, April 1997.
Council for Economic Planning and Development (CEPD), 2008. (http://www.tcoc.org.tw/IS/Dotnet/ShowArticle.aspx?ID=42877 last accessed on 31st March, 2010), in Chinese.
Chilton JC., Midment GG., Marriott D., Francis A. and Tobias G., 1999. Case study of a rainwater recovery system in a commercial building with a large roof. Urban Water, 1(4), 345–54.
Chou, N.-F., and Wu, C.W., 2007. A network Flow Model for Evaluating Water Supply Strategies in Taiwan. Proc. of the 2nd IASTED International Conference on Water Resources Management, August 20-22, 2007, Homolulu, Hawai’i, USA.
Coombes, P.J., 2002. Rainwater tanks revisited: new opportunities for urban water cycle management. PhD thesis. Newcastle University, New South Wales, Australia.
Coombes, P.J., Kuczera, G. and Kalma, J.D., 2000c. Rainwater quality from roofs, tanks and hot water systems at Figtree Place. 3rd International Hydrology and Water Resources Symposium, Perth, Australia, pp1042-1047.
Cooper, P., 2001. Clag Hall community centre, Derby, Rainwater utilisation system. Proc. of 1st Nat. Conf. on Sustainable Drainage, 18th -19th June 2001, Coventry University, UK, pp250-254.
Crasta, F., Fasso, C., Patta, F. and Putzu, G., 1982. Carthaginian – Roman cisterns in Sardinia. Proc. of International Conference on Rainwater Cistern Systems, University of Hawaii, Honolulu, pp37-45.
Cummings, S., 2001. Future directions for water closet and sanitation systems. National Water Conservation Group Meeting on 14-9-2001, London.
CWB http://cwb.hinet.net/V6e/education/encyclopedia/ty015.html (Last accessed on March 30, 2010)
DCLG, 2007. Code for sustainable homes: technical guide. Department for Communities and Local Government, Communities and Local Government Publications, UK.
Dixon, A., 1999. Simulation of domestic water re-use systems: greywater and rainwater in
combination. PhD Thesis, Environmental and Water Resources Engineering, Department of Civil and Environmental Engineering, Imperial College of Science, Technology and Medicine, London.
Dominguez, M.A., Schiller, E. and Serpokylov, S., 2001. Sizing of rainwater storage tanks in urban zones. Proc. of 10th International Rainwater Catchment Systems Conference, Mannheim, Germany, September 2001.
Environment Agency, 2001a. A scenario approach to water demand forecasting. National
Water Demand Management Centre, Environment Agency, West Sussex, UK.
Environment Agency, 2003b. Harvesting rainwater for domestic uses: an information guide. July 2003.
Evenari, M., 1961. Ancient agriculture in the Negev. Science, volume 133, pp976-986.
Fewkes, A., 1997. The instrumentation and field testing of a rainwater collector. Proc. of 8th International Conference on Rainwater Catchment Systems, Tehran, Iran, April 1997.
Fewkes, A., 1999a. The use of rainwater for WC flushing: the field testing of a collection system. Building and Environment, volume 34, pp765-772.
Fewkes, A., 2006. The technology, design and utility of rainwater catchment systems. In: Butler, D. and Memon, F.A. (Eds), Water Demand Management, IWA Publishing. London, pp27-61.
Fewkes, A. and Butler, D., 1999. The sizing of rainwater stores using behavioural models. Proc. of 9th International Rainwater Catchment Systems Conference, Petrolina, Brazil, July 1999.
Fewkes, A. and Warm, P., 2000. A method of modelling the performance of rainwater collection systems in the United Kingdom. Building Services Engineering Research and Technology, volume 21, pp257-265.
Ghisi, E., Bressan, D.L. and Martini, M., 2007. Rainwater tank capacity and potential for potable water savings by using rainwater in the residential sector of south-eastern Brazil. Building and Environment, volume 42, pp1654-1666.
Gould, J. and Nissen-Petersen E., 1999. Rainwater catchment systems for domestic supply, design, construction, and implementation. London: Intermediate Technology Publication.
Hasse, R., 1989. Rainwater reservoirs above ground structures for roof catchment. Gate, Vieweg, Braunschweig/Wiesbaden, Germany, p102.
Hassell, C., 2005. Rainwater harvesting in the UK – a solution to increasing water shortages?. Proc. of 12th International Conference on Rainwater Catchment Systems, New Delhi, India.
Heggen, R.J., 1993. Value of daily data for rainwater catchment. Proc. of 6th International Conference on Rainwater Catchment Systems, Nairobi, Kenya, August 1993.
Heggen, R.J., 2000. Rainwater catchment and the challenges of sustainable development. Water, Science and Technology, 42 (1-2), pp141-145.
Hills S., Birks R. and McKenzie B., 2001. The Millenium Dome ‘Watercycle’ Experiment: to evaluate water efficiency and customer perception at a recycling scheme for 6 million visitors. Proc. of the IWA 2nd World Water Congress, Berlin 15–19, October, 2001.
Ho, J., 2004. 10,000 homes lack power. Taipei Times,
<http://www.taipeitimes.com/News/taiwan/archives/2004/07/06/2003177875> (Last accessed on 31st March, 2010).
Hwang, J.S., 1985. The study and planning of reservoir desilting in Taiwan. Water International, 10, 7-13.
Ikebuchi, S. and Furukawa, S. 1982. Feasibility of Rain Water Cistern Systems as an Urban Water Supply source. Proc. 1st International Conference on Rain Water Cistern Systems, Honolulu, Hawaii, USA, June 1982, pp 118-127.
Islam, M. M., 2001. Study on Rainwater Harvesting Techniques. MSc thesis, Department of Water Resources Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.
Jan, C.D., 2004. Debris flow hazards mitigation in Taiwan.
<http://www.saboint.org/projects/taiwan.html> (Last accessed on 31st March, 2010).
Jenkins. D., Pearson, F., Moore, E., Sun, J.K. and Valentine, R., 1978. Feasibility of rainwater collection systems in California. Contribution No.173 (California Water Resources Centre), University of California.
Kim, R., Lee, S., Jeong, J., Lee, J. and Kim, Y., 2007. Reuse of greywater and rainwater using fibre filter media and metal membrane. Desalination, volume 202, pp326-332.
Konig, K.W., 2001. The rainwater technology handbook: rain harvesting in building. Wilo-Brain, Dortmund, Germany.
Kovacs, G., 1979. Traditions of rainwater harvesting in Europe. Report to UNEP Rain and Stormwater Harvesting Project, Nairobi, p30.
Latham, B.G., 1983. Rainwater collection systems: the design of single purpose reservoirs.
MSc thesis, University of Ottawa, Canada.
Lee, K.C., 2005. Water woes demand creative fixes. Taipei Times,
<http://www.taipeitimes.com/News/editorials/archives/2005/08/13/2003267580> (Last accessed on 31st March, 2010).
Lee, S.-C., Lin, M.-C., Chou, W.-H. and Chen, J.-C., 2001. Rainwater Utilization of Quake Disaster Area Rebuilding Programs in Taiwan. Proc. of the 10th International Rainwater Catchment Systems Conference, Mannheim, Germany.
Leggett, D.J., Brown, R., Stanfield, G., Brewer, D. and Holliday, E., 2001a. Rainwater and greywater use in buildings: decision-making for water conservation. CIRIA report PR80, London.
Leggett, D.J., Brown, R., Brewer, D., Stanfield, G. and Holliday, E., 2001b. Rainwater and greywater use in buildings: best practice guidance. CIRIA report C539, London.
Liaw, C.H. and Tsai, Y., 2004. Optimum storage volume of rooftop rain water harvesting systems for domestic use. Journal of the American Water Resources Association, 40 (4), pp901-912.
Lo, A., 2005. Rainwater Harvesting – An Alternate Water Resources in Taiwan. Proc. of the 12th International Rainwater Catchment Systems Conference, New Delhi, India.
McMahon, T.A., Pegram, G.G.S., Vogel, R.M. and Peel, M.C., 2007. Revisiting reservoir
storage-yield relationships using a global streamflow database. Advances in Water Resources, volume 30, pp1858-1872.
Mitchell, V.G., 2007. How important is the selection of computational analysis method to the accuracy of rainwater tank behaviour modelling?. Journal of Hydrological Processes, 21, 2850–2861.
Murase M., 2002. Promoting a rainwater utilization based society for sustainable development in urban areas. Available at www.ircsa.org.
Ofwat, 2006a. Security of supply, leakage and water efficiency. 2005-2006 report, Office of Water Services, UK, Birmingham, November 2006.
Perrens, S., 1982. Design strategy for domestic rainwater systems in Australia. Proc. of 1st International Conference on Rainwater Cistern Systems, Hawaii, Honolulu.
Pinfold, J.V., Horan, N.J., Wirojanagud, W. and Mara, D., 1993. The bacteriological quality of rainjar water in rural Northeast Thailand. Water Res. 27 (2), 297–302.
POST, 2000. Water efficiency in the home. Parliamentary Office of Science and Technology Note, 135, London.
Rahman, M.M. and Yusaf, F.M.S., 2000. Rainwater harvesting and the reliability concept. Proc. of 8th ASCE Speciality Conference on Probabilistic Mechanics and Structural Reliability, University of Notre Dame, Paris, France, July 24th -26th.
Ratcliffe, J., 2002. Telford rainwater harvesting project. Proc. of 22nd meeting of the Standing Conference on Stormwater Source Control: Quantity and Quality, Coventry University, 13th February 2002.
Roaf, S., 2006. Drivers and barriers for water conservation and reuse in the UK. In: Butler, D. and Memon, F.A. (Eds), Water Demand Management, IWA Publishing. London. pp215-235.
Roebuck, R., 2007. A Whole Life Costing Approach for Rainwater Harvesting Systems. Ph.D. thesis, Bradford University, UK.
Sakellari, I., Makropoulos, C., Butler, D. and Memon, F.A., 2005. Modelling sustainable urban water management options. Proc. of the Institution of Civil Engineers. Engineering Sustainability 158, September 2005, Issue ES3, pp143-153.
Schiller, E. and Latham, B., 1982. Rainwater roof catchment systems. Information and Training for Low-Cost Water Supply and Sanitation, Ch4.1, Trattles D., World Bank, p198.
Shaffer, P., Elliott, C., Reed, J., Holmes, J. and Ward, M., 2004. Model agreements for sustainable water management systems: model agreements for rainwater and greywater use systems. CIRIA report C626, London.
Shil, N.C. and Parvez, M., 2007. Life cycle costing: an alternative selection tool. Department of Business Administration, Daffodil International University, Bangladesh. (http://mpra.ub.uni-muenchen.de/7709/, last accessed April 06, 2010).
Sim, P., McDonald, A., Parsons, J. and Rees, P., 2005. The options for UK domestic water reduction: a review. Version 1.0, August 2005, University of Leeds, UK.
Simmons, G., Hope, V., Lewis, G., Whitmore, J. and Wanzhen, G., 2001. Contamination of potable roof-collected rainwater in Auckland, New Zealand. Water Res. 35 (6), 1518–1524.
SODCON, 1994. Survey of domestic consumption. Anglian Water.
Sydney Water, 2003. Plumbing requirements information for rainwater tank suppliers and plumbers. Sydney Water, Australian Government, Australia.
Taiwan Statistical Data Book, 2000. (http://www.gio.gov.tw/info/taiwan-story/economy/edown/table/table-12.htm, last accessed on 19th Feb, 2010).
Thackray, J.E., Crocker, V. and Archibald, G., 1978. The Malvern and Mansfield studies of domestic water usage. Proc. of the Institute of Civil Engineers, 64 (1), pp37-61.
Thomas, T., 2002a. RWH performance predictor for use with coarse (i.e. monthly) rainfall data. Domestic Roofwater Harvesting Research Programme Report RN-RWH04, Development Technology Unit, University of Warwick.
Thornton, J., 2005. The water book. Antony Rowe Limited, UK.
United Nations Environmental Program-DTIE-EITC, 2002. Sumida City Government/People for Promoting Rainwater Utilization. Rainwater harvesting and utilization. An environmentally sound approach for sustainable urban water management. An introductory guide for decision-makers.
Villarreal, E.L. and Dixon, A., 2005. Analysis of a rainwater collection system for domestic water supply in Ringdansen, Norrköping, Sweden. Building and Environment 40, 1174–1184.
Vivian, W.Y.T., Leona, T. and Zeng, S.X., 2010. Cost effectiveness and tradeoff on the use of rainwater tank: An empirical study in Australian residential decision-making. Resources, Conservation and Recycling, 54, pp 178–186.
Vörösmarty, C. J., Green, P., Salisbury, J. and Lammers, R. B., 2000. Global Water Resources: Vulnerability from Climate change and population growth. Science 289 (7), 284-288.
Water Resources Agency, 1996. The Strategic Planning for the development of multi water resources. Technical Report.
Water Resources Agency, 2001. The 1998 Statistical Report of Residential Water Use in Taiwan Region. Ministry of Economic Affairs, Taipei, Taiwan, R.O.C.
Water Resources Agency (WRA), 2005. Kaoping weir.
<http://www.wrasb.gov.tw/sw94/english/sw/sw_01_3_1.htm> (Last accessed on 31st March, 2010)
Water Resources Agency (WRA), Southern Region Water Resources Office, 2006.
Water resources management.
<http://www.wrasb.gov.tw/sw94/english/Busines/Busines_02.htm> (Last accessed on 31st March, 2010)
Water Resources Agency (WRA), 2008. Pipe-connection project between Nanhwa
Reservoir and Kao-ping Diversion Weir.
<http://eng.wra.gov.tw/ct.asp?xItem=12692&ctNode=5182&comefrom=lp> (Last accessed on 31st March, 2010)
Wehrle, K., 2001. Securing Domestic Water Supplies for Rural Bangladesh Through Combined Systems. Proc. of the 10th International Rainwater Catchment Systems Association, Mannheim, Germany, September 2001.
Weiner, J., 2003. Incorporating rain water harvesting in the suburban landscape. Proc. of 11th International Conference on Rainwater Catchment Systems, Texcoco, Mexico.
Wilson, E.M., 1990. Engineering hydrology. Macmillan Press Ltd, London. 4th edition.
Wung, T. C., Lin, S. H. and Huang, S. M., 2006. Rainwater reuse supply and demand response in urban elementary school of different districts in Taipei. Resources, Conservation and Recycling, 46, 149–167.
Yaziz, M.I., Gunting, N., Sapari, N. and Ghazali, A., 1989. Variations in rainwater quality from roof catchments. Water Research, 23(6), pp761-765.
Yu, P.S., Yang, T.C., and Kuo, C.C., 2006. Evaluating Long-Term Trends in Annual and Seasonal Precipitation in Taiwan. Water Resources Management, 20: 1007–1023
Zaizen M., Urakawa T., Matsumoto Y. and Takai H., 1999. The collection of rainwater from dome stadiums in Japan. Urban Water 1(4), 335–59.