West Virginia Flood Hazard Determination Tool

Tucker Clevenger, PE, CFM AMEC Environment and Infrastructure

Kevin Sneed West Virginia NFIP Coordinator

Brought to you by: WV Division of Homeland Security WVU GIS Technical Center FEMA Region III AMEC

Start with the Web site

WWW.MAPWV.GOV/FLOOD

Click Overview

Next is FEATURES

Important Contact Information

Data Layers

Resources and Glossary

Lets get started by clicking the LAUNCH TOOL button

Read the DISCLAIMER and then click I AGREE

ZOOM TO box

Navigation

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Zoom by drawing box

In the ZOOM TO box you can navigate 1) by full address

2) by LAT LONG

Type in the ADDRESS if you know it

You can change it to EXPERT or RISK MAP view

Choose a BASE-MAP

For best view, choose BING or WV Best Leaf Off

Adjust transparency of flood layer

Reference will let you add more detail to your map

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What you will see

TOPO Lines Studied Area

Unstudied Ares (Approximate A Zone)

If you click the PRINT Icon, the PRINT MAP as PDF box will appear.

Add your notes to the map

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

WV Flood Hazard Development Goals

• Improve upon effective approximate floodplains – Provide more accurate approximate floodplain boundaries – Resolve legacy “DFIRM Conversion” issues

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

• Expand coverage of approximate floodplain boundaries – All streams down to 2 Square Miles – 4600 miles of approximate floodplains

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

• Expand coverage of approximate floodplain boundaries – All streams down to 2 Square Miles – 4600 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

WV Terrain Data – DEMs

WV Terrain Data - LiDAR

7 ft 0.4 ft

0.9 ft

Comparison of Methods

Benefits/Future Enhancements

Alignment with FEMA Risk MAP Program West Virginia executing Risk MAP Program ahead of FEMA rollout Better Communicate Flood Risk Promote sound Floodplain Management All Approximate Floodplains now model backed

Now accepted by FEMA for LOMA Determinations/Elevation Certificates Growing importance with changing regulations/Biggert-Waters Future Enhancements

Data/Model Download Mobile Application

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

Questions?

http://MapWV.gov/flood