Description

1) Evaluating Canada-wide Flood Hazard Model Performance: Supporting Flood Insurance Options Analysis
Robin Bourke, P. Eng, Public Safety Canada, robin.bourke@ps-sp.gc.ca
Co-presenters: None

Abstract: In 2020, Public Safety Canada launched a Canada-wide assessment of financial flood risk to residential properties to support the Flood Insurance and Relocation Project, an investigation into the viability of different flood insurance options for Canada. The Data Science and Engineering Team at the Emergency Management and Programs Branch of Public Safety Canada led this technical investigation, which involved evaluating and using three different Canada-wide flood hazard models, developing a high-quality residential address exposure data set from multiple sources, and four different damage estimation methodologies to generate event set losses and annual average losses for the whole country. The results were then provided to teams of actuaries and consultants to evaluate different flood insurance options for Canada, culminating in the publication of Public Safety Canada’s “Adapting to Rising Flood Risk: A Report by Canada's Task Force on Flood Insurance and Relocation” report, released in August 2022. This presentation will cover the evaluation of three Canada-wide flood hazard models which are currently in use by the insurance industry, the financial sector, governments, and others requiring complete coverage of flood hazard at multiple return periods and flood generating mechanisms. In Canada, local flood hazard mapping (e.g. regulatory, or engineering-level mapping) is not universally available, can sometimes be outdated, and often lacks the suite of annual exceedance probabilities required to complete comprehensive financial analysis. The results of the analysis, including performance metrics such as agreement, over-prediction, under-prediction, and a combined performance score, will be discussed and presented. This presentation has relevance to anybody using large flood hazard models, professionals conducting financial or insurance analyses for large portfolios, and practitioners responsible for assessing flood hazard and flood risk beyond areas covered by local flood hazard mapping.

2) The Intersection of Green Energy and Flood Risk
Byron Hinchey, PE, CFM, EVS, Inc., bhinchey@evs-eng.com
Co-presenters: None

Abstract: Green energy, particularly solar energy, projects in the United States have been growing rapidly in recent years. In the last decade alone, solar has experienced an average annual growth rate of 33%, and the fastest growth sector has been utility-scale solar. Utility-scale solar describes large solar power plants that produce electricity for the utility grid. As of 2021, the largest utility-scale solar project in the United States spans more than 3,200 acres. With the continual growth of green energy, several larger projects are under development. As with any large site development, utility-scale solar can require massive land areas. As with any large development, these power plants are generally sited where land is cheaply available. Consequently, these large developments are very often located in rural areas that have few stormwater regulations and lack FEMA flood hazard information. To evaluate flood risk for utility-scale solar projects, hydrologic and/or hydraulic models are developed at two critical phases: the due diligence phase for owners/developers during project development and the design phase for design-build contractors. The standard industry approach to determine flood risk for these projects involves watershed-scale two-dimensional (2D) hydraulic models that employ the rain-on-grid approach. Model scale can involve dozens, if not hundreds, of square miles. Flood risk products include inundation maps, water depth maps, velocity maps, and scour maps. This presentation will discuss the hydrologic and hydraulic modeling approach normally performed to define flood risk for large utility-scale green energy (solar) projects, the FEMA compliance for those projects, the opportunities for Floodplain Administrators to leverage model results, and regulatory policies that local officials should consider when one of these projects is proposed in the local Community.

3) Out with the Old River: A New Approach to Statewide Modeling in Louisiana
Jim Keith, Freese and Nichols, Inc., jim.keith@freese.com
Co-presenters: Billy Williamson, LA Department of Transportation and Development, PE, billy.williamson@la.gov

Abstract: Freese and Nichols, Inc. (FNI) is working with the Louisiana Department of Transportation and Development (DOTD) for the Louisiana Watershed Initiative (LWI) Modeling Contract encompassing Region 2. The five-year, $18 million contract involves the development of calibrated 1-D/2-D HEC-RAS models for use in consequence and risk assessment, ultimately informing the implementation of flood risk reduction projects via watershed coalitions in coordination with parish, state and federal entities. Region 2 is made up of nine Hydrologic Unit Code-8 (HUC-8) watersheds covering approximately 9,500 square miles in the north central part of the state. Each HUC8 region is being developed using a tiered approach in terms of the spatial extent of the model (catchment size and channel network extent), the hydraulic modeling technique (1-D, 2-D, and/or hybrid 1-D/2-D), and spatial resolution (i.e., level of detail). The spatial resolution or level of modeling detail largely depends on extents of existing flooding and the potential consequences, with flood risk factors include population density, presence of infrastructure, and previously recorded flood losses in an area. Unique to Region 2 is the modeling of the Old River Control Complex (ORCC), a system of structures that control the diversion of flow from the Mississippi River to the Atchafalaya River, while also providing navigation between the Mississippi, Atchafalaya, and Red Rivers. The ORCC represents the most downstream end of our region and determines the downstream boundary conditions and backwater for the Lower Red and Black Rivers upstream. FNI staff received a guided tour of the ORCC from USACE staff to gain a better understanding of the operation and inform the modeling approach. This presentation will discuss the challenges of managing and executing a project of this magnitude, including the development of tools and processes that allowed for project teams distributed across multiple offices to consistently develop the H&H models. Additionally, the operation and modeling of the ORCC will be discussed.