Oregon Statewide Flood Hazard Framework Geodatabase and Web Library, version 1.0 Seamless statewide...

Oregon Statewide Flood Hazard Framework Geodatabase and Web

Library, version 1.0

Seamless statewide GIS floodplain element that conforms to standards

adopted by the Hazard-FIT.

A concurrent effort - “Flood Hazard Data Standard and Stewardship Plan, Version 2.0”, was endorsed

by OGIC in 2014

Three overarching thematic datasets linking to static information hosted at the Web Library:

•FEMA Flood Insurance Studies and associated data

•Non-FEMA Flood Studies

•Observed Flood Inundation

What is the problem we are trying to solve?Reconciling inconsistent FEMA data in various formats to a single usable database that is accessible, and incorporate related floodplain information.

Theme 1 - FEMA Flood Insurance Studies

• The Federal Emergency Management Agency (FEMA) administers the National Flood Insurance Program (NFIP) which provides flood insurance to homeowners, renters, and business owners in communities that participate in the program.

• For insurance rating purposes FEMA develops Flood Insurance Studies (FIS) and Flood Insurance Rate Maps (FIRM) that depict various flood hazard zones. High hazard zones -- also called Special Flood Hazard Areas (SFHA) -- are defined by areas that would become inundated by a statistical 1%-annual-chance flood event (e.g. 100-year flood).

GIS representations of FIRM flood hazard zones and supporting layers are not consistent or easily accessible. Currently FIRM flood hazard zones are available in GIS format from four different sources:

• FEMA DFIRM data, effective -- a digital FIRM geodatabase released with all FIS developed after 2000 that includes complete suite of supplemental layers

• FEMA DFIRM data, preliminary -- a digital FIRM geodatabase released with all FIS developed after 2000 that includes complete suite of supplemental layers

• FEMA Q3 data -- developed from scanned and (sometimes poorly) rectified paper FIRMs

• DAS GEO digitized data -- developed from scanned and rectified paper FIRMs in areas of the state where Q3 and DFIRM data are unavailable

The only element common across these sources is the SFHA (Special Flood Hazard Area, or “100-year” flood)

-0.2%-annual-chance flood hazard zones and other essential layers are not consistently available.

Map of FIRMs

FEMA Regulatory Products

Several supplemental layers are very important for determining flood elevations at specific locations, the quality of the FIS, and where revisions to the FIS have

occurred.

• BFE and Cross-section compilation. • DFIRM areas already compiled by DLCD;

“paper” FIRM BFE/XS digitized• All Cross-sections will be linked to scanned

Flood Insurance Study profiles-Output: BFE and XS Arcs

Base Flood Elevations (BFE)

Additional data supporting the FEMA/NFIP process:

Incorporating published Letters of Map Change (LOMC) into State Floodplain dataset and webservice

LOMR (Letter of Map Revision)

Theme 2 – Non-FEMA Flood Studies

While FIRM flood hazard zones are most widely and consistently available throughout Oregon, many additional flood studies have been developed outside of the FEMA FIS process that provide valuable information about flood hazards.

• Common sources include U.S. Army Corps of Engineers (USACE) flood studies, community-sponsored flood studies, and FEMA-funded flood studies that have not been incorporated into a FIS.

Theme 3 - Observed Flood Inundation

• Post-event flood inundation data has been collected on an ad hoc basis by various entities, including USACE and the U.S. Geological Survey (USGS).

• Post-event data collection focuses on the capture of high water marks, which are point locations where the highest elevation of flood inundation are determined.

High Water Marks (2011) and Observed Flood Inundation (1948)

DraftFIRM

FEMA Map Service Center https://msc.fema.gov/portal