Climate Change Impacts and Risks in the Anthropocene (C-CIA), Institute for Environmental Sciences, University of Geneva, Switzerland.
European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, United Kingdom.
Environ Int. 2019 Jun;127:291-304. doi: 10.1016/j.envint.2019.02.072. Epub 2019 Apr 2.
Extreme precipitation events with high local precipitation intensities, heavy snowfall or extensive freezing rain can have devastating impacts on society and economy. Not only is the quantitative forecast of such events sometimes difficult and associated with large uncertainties, also are the potential consequences highly complex and challenging to predict. It is thus a demanding task to anticipate or nowcast the impacts of extreme precipitation, even more so in situations where human lives or critical infrastructure might be at risk. In recent years, the term "cascading effects" has been increasingly used to describe events in which an initial trigger leads to a sequence of consequences with significant magnitude. We here analyze three examples for different precipitation types where the initial triggering event generated a cascade of events and impacts, namely a convective precipitation event in the Swiss Prealps, a freezing rain in Slovenia, and a heavy snowfall episode in Catalonia. With the aim to improve process understanding of complex precipitation-triggered events, we assess the prediction of the selected events and analyze the cascading effects that caused diverse impacts. To this end, we use a framework of cascading effects which should ultimately allow the development of a better design risk assessment and management strategies. Our findings confirm that damage of extreme precipitation events is clearly related to the knowledge of potential cascading effects. Major challenges of predicting cascading effects are the high complexity, the interdependencies and the increasing uncertainty along the cascade. We propose a framework for cascading effects including two approaches: (i) one to analyze cascading effects during past extreme precipitation events, which then serves as a basis for a (ii) more generalized approach to increase the preparedness level of operational services before and during future extreme precipitation events and to anticipate potential cascading effects of extreme precipitation. Both approaches are based on pathway schemes that can be used in addition to numerical models or hazard maps to analyze and predict potential cascading effects, but also as training tools.
极端降水事件具有局地降水强度高、降雪量大或大范围冻雨等特点，会对社会和经济造成毁灭性影响。此类事件的定量预测有时较为困难且存在较大不确定性，潜在后果也非常复杂，难以预测。因此，即使在人类生命或关键基础设施可能面临风险的情况下，预测或临近预报极端降水的影响也是一项艰巨的任务。近年来，“级联效应”一词越来越多地被用来描述初始触发事件导致具有显著规模的一系列后果的事件。我们在这里分析了三种不同降水类型的例子，即瑞士阿尔卑斯山前地区的对流降水事件、斯洛文尼亚的冻雨事件和加泰罗尼亚的大雪事件，其中初始触发事件引发了一系列事件和影响。为了提高对复杂降水触发事件的过程理解，我们评估了所选事件的预测，并分析了造成各种影响的级联效应。为此，我们使用了级联效应框架，最终应能够制定更好的设计风险评估和管理策略。我们的研究结果证实，极端降水事件的破坏显然与潜在级联效应的知识有关。预测级联效应的主要挑战是其高度复杂性、相互依赖性和沿级联不断增加的不确定性。我们提出了一个级联效应框架，包括两种方法：(i)一种方法用于分析过去极端降水事件中的级联效应，然后作为一种基础，用于（ii）更广义的方法，以提高业务服务在未来极端降水事件之前和期间的准备水平，并预测极端降水的潜在级联效应。这两种方法都基于路径方案，可以在数值模型或灾害图之外用于分析和预测潜在的级联效应，也可用作培训工具。
