How the City of Miami is Using Technology to Help Plan for Management of Urban Flooding in the Face of Sea Level Rise

The City of Miami faces unique climate change-related challenges. With a sea level that is projected to rise significantly over the next 40 years, the City needed a plan to protect public safety and vulnerable assets and provide a strategy to combat the ever-increasing impacts of climate change. The City of Miami developed an innovative SWMP and climate change strategy that included an extensive Geographic Information System (GIS) data development, dynamic stormwater models, and innovative engineering solutions. The City of Miami's Stormwater Master Plan was developed as a holistic effort to digitize and model existing infrastructure with anticipated development and climate data to allow the City to identify cost-effective existing and future stormwater capital investments. From a technology perspective, the City's SWMP and climate change strategy involved: -Implementation of an extensive stormwater GIS environment that provided the foundation for the modeling process. This process involved digitization of more than 30,000 pages of existing as-builts drawings, extensive Global Positioning Satellite (GPS) data location and subsurface mapping, and development of GIS and integrated asset management databases. -Acquisition of LiDAR topographic data using digital sensors and completion of high-accuracy topographic field survey of critical assets including more than 90 miles of coastal perimeter for seawalls and the primary stormwater management system (PSMS) which consists of pipes and channels greater than 24 inches in size or equivalent. -Implementation of web, mobile, and dashboard solutions to support the data collection process, visualization of data, and sharing of information between the City and the project team. -Development of a city-wide United States Environmental Protection Agency (USEPA) Storm Water Management Model (SWMM) for hydrology and hydraulics that takes into consideration pervious and impervious areas of the urban landscape. This model was used to plan and prioritize future stormwater infrastructure investments in response to chronic flooding and an ever-changing climate. -Application of the Federal Emergency Management Agency (FEMA) Hazards United States (HAZUS) tool for benefit-cost analyses using GIS data to enumerate flood damages and flood damage reduction and confirm cost-effectiveness Once the data collected was validated, models were developed for the City's eight major stormwater basins. These models incorporated data from the City's PSMS and account for tidal and groundwater influence and two future seal level rise scenarios. Modeling inputs and parameters required extensive manipulation and analyses using GIS tools such as the Geographic Watershed Information System schema (GWIS) and ArcHydro. When completed, by blending several technology environments the models and resultant data provided a comprehensive basin-by-basin analysis of the level of service (LOS) for both existing and proposed stormwater systems, with consideration of the effects of future projected climatological conditions. The City's project team then evaluated alternative conceptual solutions for individual neighborhood capital improvement projects, specifically in areas found to be most susceptible to flooding. The plan provides the City: -A new detailed, dynamic, and comprehensive city-wide stormwater model to simulate predicted rainfall flooding and the effects of sea level rise and storm surge on the existing and proposed stormwater management system. The model can be modified and enhanced in the future as new projects come online or system conditions change. -A city-wide CIP to cost-effectively mitigate flooding issues for two alternative levels of service and a prioritized list of project areas and improvements with planning-level budgets at the neighborhood scale. -Increased aquifer recharge to reduce saltwater intrusion for future potable water supply and water quality treatment improvements to protect Biscayne Bay. -A benefit-cost analysis for the proposed improvement alternatives. -A modern GIS database with digital mapping and metadata to archive and access the City's vast stormwater assets and record document plans linked to the stormwater model. -A foundation and roadmap plan for stormwater and coastal resiliency in the future. -A series of comprehensive stormwater management strategies which are permittable and can be implemented in a prioritized, phased program. These strategies help address the City's chronic flooding, improve stormwater and coastal resiliency, and provide strategies for sea level rise. During this presentation the process for how the City used modeling, GIS, dashboard, mobile, and web technologies to develop an evolving strategy that will help the City combat flooding and the effects of sea level rise will be presented and evaluated.