A Stepwise Approach to Developing a Flood Emergency Planning and Climate Adaptation Program with Case Studies from Clayton County, GA and Boston, MA

Many communities perceive climate adaptation efforts as being prohibitively expensive, resource intensive, and complex. This presentation introduces a step-by-step approach that communities can follow to overcome these barriers by examining climate adaptation efforts undertaken by two unique communities. The approach illustrates how lower cost efforts that utilize publicly available data can help communities begin adapting to climate change threats such as intense rainfall, rising sea levels, and coastal or fluvial flooding while also laying the groundwork for future, more intensive efforts. One example is the Flood Warning and Response Plan (FWRP) project for the Clayton County Water Authority (CCWA), which demonstrates how publicly available datasets can be used to inform emergency planning and flood preparedness. Another case study highlights inundation modeling and coastal stormwater conceptual design efforts that were recently completed in Boston. Topics covered include the following:

*Strategies for identifying, obtaining, and analyzing publicly available datasets for resilience planning and vulnerability assessment

*Leveraging climate change projections to update and establish appropriate design storms and future levels of service

*Development and application of two-dimensional (2D) hydraulic/inundation models to develop flood management solutions and characterize flooding for various adaptation scenarios (using PCSWMM and parallel computing)

*Tools for public communication including static mapping, interactive mapping, emergency planning dashboards, and 360-degree photos and flood renderings The FWRP project for CCWA will be used as a case study for communities interested in beginning the process of identifying and adapting to climate threats, that do not currently have the ability, or are not ready, to engage in more intensive efforts involving the development of custom hydrologic and hydraulic models. Clayton County, Georgia and its incorporated municipalities are partially located in the floodplains of the Flint and Ocmulgee Rivers, which pose a risk of flooding to the community. A countywide FWRP was developed as a tool to coordinate and guide effective response to flood events with the goals of promoting public safety and mitigating damage to critical infrastructure. The flood analysis used GIS, HEC-RAS, and publicly available data to identify the highest risk critical facilities and road crossings for flooding in Clayton County. The resulting flood maps highlight the facilities and roadways most vulnerable to impacts by the FEMA 100-year floodplain allowing CCWA to better understand where to focus emergency response and future climate adaptation efforts. The FWRP was developed in collaboration with CCWA, emergency responders, and other public agencies. It outlines strategies for flood preparedness, flood forecasting and monitoring methods, communication and response procedures, and post-flood recovery actions. The plan was adopted by CCWA and distributed to stakeholders in 2023. Future considerations for plan development include inundation modeling in high-risk areas for a range of design storms based on climate change projections and the development of more robust flood monitoring and simulation tools. The case study/work in Boston, however, demonstrates the implementation of these future steps. Figures 1 and 2 depict mapping and a response plan developed during the project. In 2017, Hurricane Harvey highlighted the severe impacts that extreme storm events can have on coastal urban areas. In the wake of this disaster, BWSC initiated the Inundation Model project to evaluate Boston's vulnerability to similar extreme storm events and develop a tool for emergency planners, City agencies, and residents to use ahead of extreme storm events. This resulted in Boston's first, citywide, 2D flood model and groundbreaking visualization and analysis tools. During the project, emergency planning tools and model predictions were developed to help increase Boston's preparedness for climate change and extreme storms. The Inundation Model project culminated in the development of a suite of tools including an innovative, custom-coded dashboard and online interface called the Inundation Model Viewer, that combines high-resolution, 360-degree images; ESRI ArcGIS story maps and a custom map viewer; and Microsoft PowerBI and SQL Server to visualize results, as shown in Figure 3, 4, and 5. Combining these technologies presented complexities but produced an elegant and simple means for users to interact with and 'see' model predicted flooding at well-known locations throughout Boston for various extreme storm events. The publicly accessible web-based Inundation Model Viewer maximizes accessibility of study results to the public, and aids in comprehension through non-technical visualizations such as maps and interactive streetview renderings of flood predictions. The work represents a benchmark for future practitioners publicly communicating flood study findings and helps facilitate awareness of flood risks among residents and other public officials. Using each of these projects as case studies, this paper and presentation will summarize key data needs, level of effort, challenges, and expected outcomes at each step (starting with static mapping and concluding with fully interactive mapping and tools) in the development of a flood emergency planning and climate adaptat