Hydrology and Earth System Sciences Discussions www.hydrol-earth-syst-sci-discuss.net 1812-2108 1812-2116 5 3 2008 10.5194/hessd-5-1479-2008 http://www.hydrol-earth-syst-sci-discuss.net/5/1479/2008/ http://www.hydrol-earth-syst-sci-discuss.net/5/1479/2008/hessd-5-1479-2008.html http://www.hydrol-earth-syst-sci-discuss.net/5/1479/2008/hessd-5-1479-2008.pdf 1479 1509 2008-06-17 Staged cost optimization of urban storm drainage systems based on hydraulic performance in a changing environment M. Maharjan A. Pathirana a.pathirana@unesco-ihe.org B. Gersonius K. Vairavamoorthy UNESCO-IHE Institute for Water Education, P.O. Box 3015, 2601 DA Delft, The Netherlands Urban flooding causes large economic losses, property damage and loss of lives. The impact of environmental changes mainly, the urbanization and the climatic change leads to increased runoff and increased peak flows which the drainage system must be able to cope with to overcome possible damage and inconveniences caused by the induced flooding. Allowing for detention storage to compliment the capacity of the drainage system network is one of the approaches to reduce urban floods. The traditional practice was to design systems against stationary environmental forcings – including design rainfall, landuse, etc. Due to the rapid change in climate-environment, this approach is no longer economically viable and safe, and explicit consideration of changes that gradually take place during the life-time of the drainage system is warranted. In this paper, a staged cost optimization tool based on the hydraulic performance of the drainage system is presented. A one dimensional hydraulic model is used for hydraulic evaluation of the network together with a genetic algorithm based optimization tool to determine optimal intervention timings and amounts throughout the lifespan of the drainage network. The model was applied in a case study area in the city of Porto Alegre, Brazil. It was concluded that considerable financial savings and/or additional level of flood-safety can be achieved by approaching the design problem as a staged plan rather than one-off scheme. Bemfica, D. C.: Análise da aplicabilidade de padrões de chuva de projeto a Porto Alegre, Porto Alegre Universidade Federal do Rio Grande do Sul (UFRGS), Curso de Pós-Graduação em Recursos Hídricos e Saneamento Ambiental, 1999. Campana, N. A. and Tucci, C.: Estimativa de área impermeável de macrobacias urbanas. Revista Brasileria de Engenharia, 12(N2), 79–94, 1994. Dutta, D., Herath, S., and Musiake, K.: A mathematical model for flood loss estimation, J. Hydrol., 277(1–2), 24–49, 2003. EPA, US: Storm Water Management Model (SWMM), online: http://www.epa.gov/ednnrmrl/models/swmm/index.htm (access date: December 2007), 2008. Fraser, A. S.: Simulation of Genetic Systems by Automatic Digital Computers. I. Introduction, Australian Journal of Biological Sciences, 10, 484–491, 1957. Goldberg, D. E.: Genetic Algorithms in Search, Optimization and Machine Learning, Kluwer Academic Publishers, Boston, MA, 1989. Gruntfest, E. and Ripps, A.: Flash floods – warning and mitigation efforts and prospects, edited by: Parker, D., Routledge, 2000. Gupta, R. S.: Hydrology and Hydraulic Systems, Waveland Press Inc., Long Grove, IL, 2nd Ed., 2001. Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K., and Johnson, C. A.: Climate change 2001: The scientific basis, Cambridge University Press, Cambridge, 2001. Mitchell, T.: Machine Learning, McGraw Hill, 1997. Rossman, L. A.: Storm Water Management Model User's Mannual, US Environmental Protection Agency, Cincinnati, 2004. Sapir, D. G.: Disaster Data: A Balanced Perspective: Natural disasters in 2007, CRED CRUNCH, Brussels, Belgium, 2008. Shepherd, W., Cashman, A., Djordjevic, S., Dorini, G, Saul, A., Savic, D., Lewis, L., Walters, G., and Ashley, R.: Whole life costing of sewer systems, in: Proceedings of WaPUG Autumn Meeting, http://www.wapug.org.uk/past_papers/Autumn_2004/shepherd.pdf, Blackpool, England, 10–12 November 2004. Woods-Ballard, B., Kellagher, R., Martin, P., Jefferies, C., Bray, R., and Shaffer, P.: Sustainable Urban drainage systems, design mannual, CIRIA, CIRIA Classic House 174–180 Old Street London EC1V 9BP UK, C697, 2007.