Water Quantity and Quality Risk Assessment of Urban Water Supply Systems with Consideration of Uncertainties

Document Type : Research Paper



Sufficient drinking water supply with acceptable quality has been one of the important challenges that decision makers in urban water systems have always faced. Different natural, non-natural and operational hazards, may threaten different components of urban water systems and they may lead to irreversible consequences.  In this research, Fuzzy Hierarchical Risk Assessment model has been presented which is capable of considering the complexities and uncertainties in urban water systems. Different stages of the proposed modeling process include systems components and threatening hazards identification, analyzing the information (i.e. probability of hazard, consequences of hazard and components vulnerabilities) in a fuzzy environment and finally aggregation of estimated risks in different parts of water supply systems and ranking them. Another risk analysis method has been introduced which is based on Monte Carlo simulation using crisp numbers and then results  of these models have been compared together for an example of urban water supply system. Presented approaches in this paper, can be very useful for real world risk-based decision making in urban water supply management with respect to the probable hazards.


1- Aven, T. (2011). “On some recent definitions and analysis frameworks for risk, vulnerability and resilience.” J. of Risk Analysis, 31, 515-522.
2- Torres, J., Brumbelow, K., and Guikema, S. (2009). “Risk classification and uncertainty propagation for virtual water distribution systems.” J. of Reliability Engineering and System Safety, 94, 1259-1273.
3- ASME. (2006). RAMCAP: Risk analysis and management for critical asset protection-version 2.0, Innovative Technologies Institute, LLC, Washington DC.
4- Federal Emergency Management America (FEMA). (2003). Primer for design of commercial buildings to mitigate terrorist attacks, Risk Management Series.
5- Li, H. (2007). “Hierarchical risk assessment of water supply systems.” Ph.D. Thesis, Loughborough University.
6- Fares, H., and Zayed, T. (2010). “Hierarchical fuzzy expert system for risk of failure of water mains.” J. of Pipeline Systems Engineering and Practice, 1(1), 53-62.
7- Sadiq, R., Kleiner, Y., and Rajani, B. (2004). “Aggregative risk analysis for water quality failure in distribution networks.” J. of Water Supply Research and Technology, 53(4), 241-261.
8- Vairavamoorthy, K., Yan, J., Gagale, H.M., and Gorantiwar, S.D. (2007). “IRA-WDS: A GIS-based risk analysis tool for water distribution systems.” J. of Environmental Modeling and software, 22, 951-965.
9- Lee, M., McBean, E., Ghazali, M., Schuster, C., and Huang, J. (2009). “Fuzzy-logic modeling of risk assessment for a small drinking-water supply system.” J. of Water Resources Planning and Management, 135(6), 547-552.
10- Tabesh, M., Jafari, H., and Delavar, M. R. (2009). “A water distribution network accident management model using GIS.” J. of Water and Wastewater, 70, 2-15. (In Persian)
11- Tchorzewska, B. (2011). “Fuzzy failure risk analysis in drinking water technical system.” RT&A, 1(20), 138-148.
12- Haestad, M., Walski, T. M., Chase, D. V., Savic, D. A., Grayman, W., Backwith, S., and Koelle, E. (2003). Advanced water distribution modeling and management, Haestad Press, Waterbury, CT USA.
13- Sadiq, R., Rodríguez, M., and Tesfamariam, S. (2010). “Integrating indicators for performance assessment of small water utilities using ordered weighted averaging (OWA) operators.” J. of Expert Systems with Application, 37, 4881-4891.
14- Lee, H. M. (1996). “Applying fuzzy set theory to evaluate the rate of aggregative risk in software development.” J. of Fuzzy Sets and Systems, 79, 323-336.
15- Rausand, M., and Høyland, A. (2004). System reliability theory: Models, statistical methods, and applications, Wiley-Interscience, Hoboken, N.J.