wv flood tool update
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Update on West Virginia Disaster Recovery Floodplain Mapping and the
West Virginia Flood Hazard Determination Tool
Tucker Clevenger, PE, CFM
AMEC Environment and Infrastructure
Eric Hopkins
West Virginia University
May 14, 2012
Agenda
►Goals of WV Flood Hazard Development
► Statewide Update Status
►AFHs – How are they developed?
►Quality and Accuracy of Models
►AFHs – What is their value?
►AFH Limitations
►WV Flood Tool Update
► Future Potential Tool Enhancements
►User Feedback
WV Flood Hazard Development Goals
► Improve upon effective approximate floodplains Provide more accurate approximate floodplain boundaries
Resolve legacy “DFIRM Conversion” issues
2150 revised effective Zone A miles to date
WSEL=1170ft WSEL=1145ft WSEL=1170ft WSEL=1145ft
AFH=1143ft
WV Flood Hazard Development Goals
► Improve upon effective approximate floodplains Provide more accurate approximate floodplain boundaries
Resolve legacy “DFIRM Conversion” issues
2150 revised effective Zone A miles to date
► Expand coverage of approximate floodplain boundaries All streams down to 2 Square Miles
1340 additional miles of approximate floodplains
WV Flood Hazard Development Goals
WV Flood Hazard Development Goals
WV Flood Hazard Development Goals
► Improve upon effective approximate floodplains Provide more accurate approximate floodplain boundaries
Resolve legacy “DFIRM Conversion” issues
2150 revised effective Zone A miles to date
► Expand coverage of approximate floodplain boundaries All streams down to 2 Square Miles
1340 additional miles of approximate floodplains
► Provide enhanced data utility -> leverage technology Model backed floodplains with AFH elevations
Accessible via the WV Flood Determination Tool Website
Improve floodplain management and permitting decisions
Support LOMA determinations
WV Flood Hazard Refinement Goals
Statewide Status Update
Statewide Status Update
AFH Floodplain Modeling
► 2003 WV SAMB 3M DEM topographic data
► USGS Regression Equation Hydrology
► HEC-RAS Hydraulic Modeling
► No hydraulic structures included
► No channel survey
► Depth and water-surface elevation grids developed
► No BFEs on the FIRM
FEMA BFE Development Priority
► Full Detailed FIS Flood Studies – BENCHMARK
► Limited Detailed FIS Flood Studies
► Enhanced Approximates (Model Backed)
► Quick-2
► Single Cross Section Normal Depth
► Contour Interpolation (Point on Boundary)
FEMA Detailed Studies
► LiDAR or Aerial Topo Terrain Data (4-foot contours or better)
► Regression/Gage/HEC-HMS Hydrologic Analyses
► Steady or Unsteady HEC-RAS modeling
► Stream channel data incorporated in model
Typically field surveyed at 500’ or less interval
► Structures modeled in detail based on field survey
► Detailed floodway modeling included
► Multiple Frequency Analyses
► Supports BFEs and floodways on FIRM
WV Terrain Data – DEMs
WV Terrain Data - LiDAR
7 ft 0.4 ft
0.9 ft
Comparison of Methods
Limitations of Enhanced Approximate Studies
► Not accurate immediately upstream of hydraulic structures (bridges/culverts)
► No channel survey data included in HEC-RAS models
► Cannot support BFE inclusion on FIRMs
► Terrain Data Predominantly based on SAMB 3M DEMs
LiDAR/Aerial topo only selectively available
► Field survey data is always paramount
Limitations of Enhanced Approximate Studies
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
► Used as best available data for floodplain management and permitting
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
► Used as best available data for floodplain management and permitting
► AFHs can support LOMA determinations BFEs are higher level of quality than FEMA LOMA WSEL
determination approaches
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
► Used as best available data for floodplain management and permitting
► AFHs can support LOMA determinations BFEs are higher level of quality than FEMA LOMA WSEL
determination approaches
► Cost effective technology to develop high volume of improved floodplains
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
► Used as best available data for floodplain management and permitting
► AFHs can support LOMA determinations BFEs are higher level of quality than FEMA LOMA WSEL
determination approaches
► Cost effective technology to develop high volume of improved floodplains
► Can be updated/enhanced to limited detailed or detailed studies
Value of Enhanced Approximate Studies
► Replace outdated effective Zone A boundaries
► Used as best available data for floodplain management and permitting
► AFHs can support LOMA determinations BFEs are higher level of quality than FEMA LOMA WSEL
determination approaches
► Cost effective technology to develop high volume of improved floodplains
► Can be updated/enhanced to limited detailed or detailed studies
► Accessible via the WV Flood Determination Tool – unique to West Virginia
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Future Potential Enhancements
► Expand towards statewide coverage
Improve level of detail of H&H studies
► Utilize more detailed topo data where available to support flood hazard studies
LiDAR or Aerial Topo Data (utilized in Wyoming and McDowell)
► Flood Profile linkage to detailed study streams
► Automated LOMA functionality
► GIS data and HEC-RAS model downloads
► Flood Data Web Services (Streaming download of data)
► Enhanced datset availability within tool
Hosting more detailed topo data on website
Demographic/Population Data
Parcel geometry/PID
► Mobile Application
► Additional feedback and ideas?
FIS Flood Profile Viewer
Flood Profile Viewer
FIS Flood Profile Viewer
FIS Flood Profile Viewer
Data Download Tool
Data Download Tool
Data Download Tool
Disaster Mileage Summary
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