Presented by Troy Brandt of River Design Group.

1. Willamette River Basin
Inundation Mapping
Troy Brandt, Principal Biologist
December 11, 2012
Courtesy Eagle Digital Imaging, Inc.

3. • What is inundation mapping?
A cost-effective analysis for predicting floodplain
inundation associated with a given flood event.
• Who will use the information?
Fish and wildlife agencies, conservation/restoration
organizations, planners, emergency responders(?).
• How will the information be used?
To assess how regulated flows influence the floodplain
• Ecological
• Social
• Economic

4. • Willamette River –
Eugene to Oregon City
• Middle Fork and Coast
Fork Willamette River
• McKenzie River

5. • Use available gage data • Overlay on topographic
• Determine 2-year surface model
discharge and stage • “Bathtub” model –
• Create 2-year discharge based on elevations, not
profile and layer a hydraulic model

6. • Based on elevation differences
• Does not account for obstructions (e.g. roads)
• Mainstem depth relates to elevation above water
surface at time of LiDAR acquisition
• Not for regulatory use

12. • USACE revetment analysis
• Floodplain habitat fish use
• Conservation easement prioritization
• Historical wetlands analysis
• Emergency responder access

14. • Maps and GIS data offer a tool for restoration
planning and other efforts
• Products are useful for assessing historical
conditions and predicting possible ecological
outcomes associated with river management
• Help direct restoration prioritization and spending

15. • Currently available
- Mainstem Willamette River
 Regulated 2-year water surface GIS layer
 Regulated 2-year inundation maps in pdf format
 2012 Flood air photos
 2012 Flood air photo maps in pdf format
• To come
- MF-CF Willamette River GIS, maps and documentation
- McKenzie River maps GIS, maps and documentation
www.riverdesigngroup.com info@riverdesigngroup.com