Flood Mapping Across the Pond: A Comparison of Programs and Technical Requirements The US, the UK, and the Republic of Ireland Michele Seib, PE, CFM Neil Breton, Chartered Hydrologist
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Introduction US Longest River 4,543 miles UK Longest River 220 miles Ireland Longest River 240 miles
Introduction US UK Ireland NFIP EU Directive 2007/60/EU
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Gathering & Analyzing Flood Data Determining Drainage Areas US UKIreland Delineated for EACH study Use best available topography Drainage Areas pre-defined by catchment descriptors Standard Approach Datasets
Gathering & Analyzing Flood Data Hydrology US UKIreland Regression Gages Rainfall Runoff Other FEMA approved models FEH rainfall-runoff FEH Hydrographs IOH124 for urban locations Rational/Wallingford FSR FSU
Gathering & Analyzing Flood Data Hydraulics US UKIreland HEC-RAS 2-D Models Other FEMA approved models 1-D 2-D 1-D 2-D
Gathering & Analyzing Flood Data Structures
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Mapping Flood Risk FIRM & FISSFRM & SFRACFRAM
Mapping Flood Risk FIRM & FIS
Mapping Flood Risk SFRM & SFRA
Mapping Flood Risk CFRAM
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Using the Flood Data Mitigation Insurance Land Use Planning Development Flood Defense Structures
Overview Introduction Gathering & Analyzing Flood Data Mapping Flood Risk Using the Flood Data Conclusions
Combining different sources of risk assessment (such as in the UK) provides a holistic overview of all flood sources Revising entire maps/products (as in the US) provides a singular, definitive flood outline incorporating all changes and modifications Uncertainty maps highlight areas where flooding is still a risk for a particular event
Michele Seib Neil Breton