Resilience and risk management in urban water supply: assessing the potential contribution of alternative systems

背景***全球城市供水部门在满足枯竭资源日益增长的需求方面面临巨大挑战。在气候变化和城市化逐渐加剧这些挑战的同时，自然灾害和人为灾害等破坏性事件的频率也在上升。加拿大城市迫切需要投资来升级老化的供水基础设施，而最近在南魁北克发生的事件凸显了缺乏灵活性的供水系统在冲击下的脆弱性。多样化的水源和基础设施是提高城市供水系统弹性的一项策略，即通过基于废水或雨水/雨水的分散式替代供水系统。由于集中式基础设施的遗留问题，aws的集成导致集中式和分散式系统共存。这种混合系统创造了更多的互连，但人们对互连知之甚少：需要模型来检查aws对集中式系统和uws弹性的影响。***目标和方法***该项目将产生尖端的科学和分析方法，结合最先进的定量风险评估方法和建模，以支持在自然和人为压力和冲击下改善城市供水的风险管理和恢复能力。通过HQP培训（3名博士和4名硕士），将开发模型来模拟混合系统，并比较UWS在不同风险情景下从源头到源头的弹性。大蒙特利尔地区（GMA）被用作研究区域，其中包括几个与供水弹性有关的城市；然而，本研究在全球范围内探讨了这些模型和发现的理论含义。考虑了供水风险的两个方面：（一）水量，即缺水的风险（WS）；（二）水质，即暴露于不合格的水质所造成的公共健康风险（PH）。定量微生物风险评估将用于评估饮用水或替代水中参考病原体/指标引起的感染概率。蒙特卡罗模拟将用于计算集中式和混合式uws在不同压力情景下的WS和PH风险。***影响***通过专家合作，该项目在城市规模的跨学科工作方面是统一的。它提供了(i)一个非常需要的混合模型，对于理解不同风险情景下AWSs对供水弹性的影响至关重要；（ii）主动适应、短期/中期和长期冲击反应以及向决策者提供沟通支持的工具和指导。模型和结果是根据GMA的需求量身定制的，但可以适用于其他城市，并有助于更广泛的气候和灾害恢复领域，并可在涉及关键基础设施的其他部门中应用。

Background***The global urban water sector faces colossal challenges in meeting growing demands from depleted resources. While climate change and urbanization gradually exacerbate these challenges, the frequency of disruptive events such as natural and man-made disasters also rises. Investment is urgently required in Canadian cities to upgrade aging water infrastructure, while recent events in Southern Quebec highlighted the vulnerability of inflexible water systems to shocks. Diversifying sources and infrastructure is put forth as a strategy to increase resilience of urban water systems (UWSs), namely through decentralized alternative water systems (AWSs) based on wastewater or rain/stormwater. With a legacy of centralized infrastructure, integration of AWSs results in the co-existence of centralized and decentralized systems. Such hybrid systems create increased interconnections, which are poorly understood: models are needed to examine the impact of AWSs on centralized systems and on UWSs' resilience. ***Objective and approach***This program will generate cutting-edge science and analytical approaches incorporating state-of-the-art quantitative risk assessment methods and modeling in support of improved risk management and resilience in urban water supply under natural and anthropogenic pressures and shocks. Through HQP training (3 PhDs and 4 MScAs), models will be developed to simulate hybrid systems and compare the resilience of the UWS from source to tap under different risk scenarios. The Greater Montreal Area (GMA) is used as a study region harboring several municipalities concerned with water supply resiliency; yet this study explores the theoretical implications of the models and findings at a global scale. Two dimensions of the water supply risk are considered: (i) water quantity, the risk of a water shortage (WS) and (ii) water quality, the public health risk (PH) from exposure to inadequate water quality. Quantitative Microbial Risk Assessment will be used to evaluate the probability of infection derived from reference pathogens/indicators in drinking or alternative water. Monte Carlo simulations will be used to calculate WS and PH risks under different pressure scenarios on centralized vs. hybrid UWSs. ***Impact***This program is unifying in terms of working across disciplines at the city scale through expert collaborations. It provides (i) a much needed hybrid model, critical to understanding the impact of AWSs on water supply resilience under different risk scenarios, (ii) tools and guidance on proactive adaptation, short/medium and long-term shock responses and communication support to decision makers. Models and results are tailored to the needs of the GMA but can be adapted to other cities and contribute to the broader fields of climate and disaster resilience with foreseen applications in other sectors involving critical infrastructure.