An integrated top-down and bottom-up approach to assess and mitigate river flood risks under climate and land-use change

洪水作为一种世界性的重大自然灾害，每年威胁着人类的生命，造成数十亿美元的损失。与气候和土地利用变化相关的极端降水强度和频率、融雪时间、雨雪事件以及渗透率的降低都会加剧灾难性的洪水事件。因此，通过适当描述洪水风险、脆弱性和暴露程度，准确评估洪水风险，对于社会和基础设施的设计、规划和管理至关重要。该项目将开发一个综合建模框架，以分析河流洪水风险，并为关键基础设施制定有效的复原力计划。它将把二维(2D)洪水淹没模型与风险评估平台结合起来，作为一种新的自上而下和自下而上的气候和土地利用变化影响评估方法的基础。我们将根据一套全球气候模型以及市政当局、保护当局和其他利益攸关方的知识和愿景，生成和整合未来情景，以分析历史和未来的洪水风险。我们将分析气候模型、降尺度方法、水文和水动力模型和参数化以及排放情景和当地定义情景中的不确定性。将开发多模型集合平均方法来估计高概率和高风险情景，并驱动风险评估平台。该项目将研究一种新的极值分布，该分布不需要为洪水建模选择阈值，并将提出一种用于模型优化的多目标性能衡量标准。通过该项目制定的综合框架将系统地评估关键基础设施在洪灾中的脆弱性，同时考虑到气候和土地利用变化的影响，并提出复原力计划。基于拟议框架制定的洪灾缓解战略将为加拿大和全球的市政当局和其他利益攸关方提供显著的社会、经济和环境效益。

Flooding, as a major natural disaster worldwide, threatens human lives and causes billions of dollars in damage each year. Increases in the intensity and frequency of extreme precipitation, timing of snowmelt, rain-on-snow events as well as reduced infiltration rates associated with climate and land-use change can exacerbate catastrophic flood events. Therefore, accurate flood risk assessment, through proper characterization of flood hazard, vulnerability and exposure is critical for the design, planning and management of societies and infrastructure. This project will develop an integrated modelling framework to analyze river flood risks and develop effective resilience plans for critical infrastructure. It will combine two-dimensional (2D) flood inundation models with a risk assessment platform as the basis of a novel top-down and bottom-up approach for climate and land-use change impact assessment. We will generate and combine ensembles of future scenarios based on a suite of global climate models and the knowledge and vision of municipalities, conservation authorities, and other stakeholders to analyze historical and future flood risks. We will analyze uncertainties in climate models, downscaling methods, hydrologic and hydrodynamic models and parameterization as well as emission scenarios and locally defined scenarios. Multi-model ensemble averaging methods will be developed to estimate high probable and high-risk scenarios and drive the risk assessment platform. The project will investigate a novel extreme value distribution that does not require threshold selection for flood modelling and will propose a multi-objective performance measure for model optimization. The integrated framework developed through this project will systematically assess the vulnerability of critical infrastructure to flooding considering climate and land-use change effects and propose resilience plans. The development of flood mitigation strategies based on the proposed framework will provide significant social, economic, and environmental benefits for municipalities and other stakeholders in Canada and around the globe.