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

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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.