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City of Central outlines data-driven flood program, real-time forecasting and grants strategy
Summary
Mayor Wade Evans and consultant Stoker Brown described Central's living hydraulic model, a real-time EarlyFlows forecasting tool, lidar updates and an aggressive grant strategy that the city says reduced flood risk and lowered residents' FEMA Community Rating System discounts.
Mayor Wade Evans, mayor of the City of Central, told the Amite River Basin Drainage and Water Conservation District that his city has rebuilt its flood program around a living hydraulic model, new lidar, local maintenance and a public-facing forecast tool that shows projected water depths in real time.
The presentation, delivered to commissioners by Evans and CSRS consultant Stoker Brown, summarized technical work Central says it has financed and deployed since the 2016 floods: a high-resolution lidar flight completed in January, upgrades to the city’s hydraulic model, a program of proactive roadside-ditch excavation and culvert replacement, and a web-based forecast and gauge network the city calls EarlyFlows.
The model and data infrastructure are intended to do two things, Evans said: better evaluate proposed development’s off-site drainage effects and give residents timely information to reduce anxiety. “We were able to get our FEMA community rating system down to a 5,” Mayor Wade Evans said. “With the implementation of the flood forecasting system … we’re going to be reapplying to try to get down to a 4.” He added that the change from class 5 to class 4 would increase the community’s overall flood-insurance savings from about 25% to about 30% for participating policyholders.
Why it matters: Central says the package — modeling plus maintenance plus public outreach — not only improves local flood protection but also makes projects more competitive for grants. “If you go after everything and ask for it, the worst thing they can tell you is no,” Evans said, describing a strategy of submitting multiple funding applications for the same projects. The mayor said Central has secured “over $60,000,000 in grants funding to implement those critical infrastructure improvements.”
Details and methods: Brown said Central used new 1-foot-resolution lidar flown this winter, then incorporated maintenance and construction changes into an updated hydraulic model. The city has standardized off-site drainage assessments for all proposed development and said it has downscaled its engineering models so they run in about 15 minutes for near-real-time forecasting rather than hours. Brown described an automated workflow that runs multiple hourly rainfall forecasts, hindcasts of recently observed rain, and measured gauge data to produce a range of projected flood depths — “similar to the spaghetti model that you see with the hurricanes,” he said.
Evans listed several specific costs Central has incurred to build capacity: roughly $42,000 for the lidar flight, about $85,000 on survey equipment and ongoing contract crews for ditch and culvert work. The city used American Rescue Plan Act funds to buy hydrology equipment for local watershed crossings and to install gauges that feed the EarlyFlows system.
Questions and scalability: Commissioners asked how the model handles forecast uncertainty and whether it “learns” from errors. Brown and Evans described a process that compares hindcasts to measured gauge readings after events and refines model inputs; they stressed that forecasting and real-time measurements are both used to inform response decisions. On scalability, Brown said the approach is scalable by nesting models at different scales (city-scale downscaled models running quickly, larger HUC-scale models for basin-wide forecasting), but cautioned that no single model will provide the same level of detail across an entire multi-parish basin.
Other points: Evans said Central is exploring groundwater recharge and local wetland mitigation banks so mitigation actions benefit the local watershed. He also noted a local ordinance change to increase on-site green infrastructure and said Central contracted day-to-day operations to a general services firm (IBTS) and uses consultants for specialized technical work.
Ending: Central’s leadership urged basin partners to consider adopting similar approaches at appropriate scales. “Anybody who wants to reinvent the wheel is a fool,” Evans said; he offered to share Central’s model and approach with other local governments.
