Lindhe Andreas, Rosén Lars, Norberg Tommy, Bergstedt Olof
Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Water Res. 2009 Apr;43(6):1641-53. doi: 10.1016/j.watres.2008.12.034. Epub 2009 Jan 3.
Drinking water systems are vulnerable and subject to a wide range of risks. To avoid sub-optimisation of risk-reduction options, risk analyses need to include the entire drinking water system, from source to tap. Such an integrated approach demands tools that are able to model interactions between different events. Fault tree analysis is a risk estimation tool with the ability to model interactions between events. Using fault tree analysis on an integrated level, a probabilistic risk analysis of a large drinking water system in Sweden was carried out. The primary aims of the study were: (1) to develop a method for integrated and probabilistic risk analysis of entire drinking water systems; and (2) to evaluate the applicability of Customer Minutes Lost (CML) as a measure of risk. The analysis included situations where no water is delivered to the consumer (quantity failure) and situations where water is delivered but does not comply with water quality standards (quality failure). Hard data as well as expert judgements were used to estimate probabilities of events and uncertainties in the estimates. The calculations were performed using Monte Carlo simulations. CML is shown to be a useful measure of risks associated with drinking water systems. The method presented provides information on risk levels, probabilities of failure, failure rates and downtimes of the system. This information is available for the entire system as well as its different sub-systems. Furthermore, the method enables comparison of the results with performance targets and acceptable levels of risk. The method thus facilitates integrated risk analysis and consequently helps decision-makers to minimise sub-optimisation of risk-reduction options.
饮用水系统较为脆弱，面临着各种各样的风险。为避免降低风险方案未达到最佳效果，风险分析需要涵盖整个饮用水系统，从水源到水龙头。这种综合方法需要能够对不同事件之间的相互作用进行建模的工具。故障树分析是一种能够对事件之间的相互作用进行建模的风险评估工具。在综合层面上使用故障树分析，对瑞典一个大型饮用水系统进行了概率风险分析。该研究的主要目的是：（1）开发一种对整个饮用水系统进行综合概率风险分析的方法；（2）评估客户分钟损失（CML）作为风险衡量指标的适用性。分析包括未向消费者供水的情况（水量故障）以及供水但不符合水质标准的情况（水质故障）。硬数据以及专家判断被用于估计事件的概率和估计中的不确定性。计算使用蒙特卡罗模拟进行。结果表明，CML是衡量与饮用水系统相关风险的一种有用指标。所提出的方法提供了有关系统风险水平、故障概率、故障率和停机时间的信息。这些信息适用于整个系统及其不同的子系统。此外，该方法能够将结果与性能目标和可接受的风险水平进行比较。因此，该方法有助于进行综合风险分析，从而帮助决策者尽量减少降低风险方案的次优情况。
