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

背景*全球城市水务部门在满足日益增长的枯竭资源需求方面面临巨大挑战。虽然气候变化和城市化逐渐加剧了这些挑战，但自然灾害和人为灾难等破坏性事件的频率也在上升。加拿大各城市迫切需要投资，以升级老化的供水基础设施，而魁北克南部最近发生的事件突出表明，僵化的供水系统容易受到冲击。水源和基础设施多样化的提出是为了提高城市供水系统(UWS)的复原力，即通过以废水或雨水/雨水为基础的分散式替代供水系统(AWSS)。由于有集中式基础设施的遗产，AWSS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，但人们对此知之甚少：需要建立模型来检查AWSS对中央系统的影响以及对UWS的弹性的影响。*目标和方法*该计划将产生尖端科学和分析方法，结合最先进的定量风险评估方法和建模，以支持改善城市供水在自然和人为压力和冲击下的风险管理和弹性。通过HQP培训(3名博士和4名MSCA)，将开发模型来模拟混合系统，并比较UWS从来源到TAP在不同风险情景下的弹性。大蒙特利尔地区(GMA)被用作一个研究区域，其中包括几个关注供水弹性的市政当局；然而，这项研究探索了这些模型和发现在全球范围内的理论意义。供水风险的两个维度被考虑：(I)水量，缺水风险(WS)和(Ii)水质，暴露在水质不足的情况下的公共健康风险(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/指示物产生感染的可能性。蒙特卡罗模拟将被用来计算集中式与混合式UWS在不同压力情景下的WS和PH风险。*影响*该计划通过专家协作，在城市范围内实现跨学科合作的统一。它提供了(1)一个急需的混合模式，对于了解不同风险情景下自动供水系统对供水复原力的影响至关重要；(2)为决策者提供了关于主动适应、短期/中期和长期应对冲击和沟通支持的工具和指导。模型和成果是根据全球气候变化评估的需要量身定做的，但可以适应其他城市，并有助于气候和抗灾能力等更广泛的领域，并在涉及关键基础设施的其他部门得到预见的应用。

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.