VBET - from LiDAR

[joewheaton]

NOTES From Discussion

@joewheaton capturing notes from 3/25 discussion. @sshahverdian, @coloradomurph, @nbouwes, and @nick4rivers present. Please add comments and thoughts

Relative Elevation Model

Hitting an "active floodplain" with high resolution topography

• Flood prone width
• Amount of valley bottom available at different elevations

@nbouwes was saying we just need RBT (River Bathymetry Toolkit) - This has now been refactored to open source in River Tools. This means

@nick4rivers - there is already GGL and REM

Brian Murphy Shared:

Resolution really matters:

Getting cross sections

Played with REM from LiDAR over 15 miles and

6 feet above channel

Active floodplain width as proportion of valley bottom (type of metric):

VBET based on slope falling short at both 10 m an 1m 👍

Scott's thoughts:

• Initial DEM matters and only current conditions
• We want something that feels more "transparent"
• Don't use REM's to "define" use to "inform" how we define it this way. Still based on judgement
• What would the field assessment aligned with on the 1m vs. 10 m. Don't want to get anywhere near idea that LiDAR gets us away from walking streams. We will always being walking... the utility of this is a prettier map for client.

Brian's Reaction:

• One observation: Whether its 1 mile, 15 miles or 20 miles, we have to walk this stuff - totally agree. Its still conditioned on understanding what's on the ground
• One counterpoint: when we're trying to get to scales of 15, 20, or 50 miles we "need" these tools to filter those field observations, prioritize and more efficiently assess where opportunities. We're trying to work at larger scales....

Nick Bouwes

• What is the plan for incorporating high resolution data set for low-tech?
• What's available now?
  REM, GGL, HAND.
• What's coming?
  A professional-grade plug-in to QGIS that is next gen RBT.

1. Upload a reference coarse valley bottom and channel polyline/polygon.
2. Upload your HRT DEM
3. After producing REM output, there will be a multi-pick slider tool (picker for channel, picker for active flooplain, picker for valley bottom)
4. Then option to edit vertices of those draft polygons
5. Then segment your polygons of valley bottom to get your VB sausages (Reaches)
6. Cut profiles and cross sections
7. Pull off metrics (e.g. table above) - integrated widths of each, graphs

[joewheaton]

@philipbaileynar and @nick4rivers, can you guys post any updates here and/or links to issues in appropriate places if conversation moves there? Thanks.

[joewheaton]

Just closing out this discussion. Since this discussion started, we do NOW have a working HAND model that runs off LiDAR. This proves to us we can also run VBET following same logic (but we've yet to do it). We have the request and authorization to do so on three projects. @philipbaileynar as you and I work with @KellyMWhitehead to ramp up getting VBET done in production mode, this should be running in parallel.

• @philipbaileynar & @joewheaton need to transfer the actionable enhancements in this discussion into individual tickets and issues to get done. Can you queue some of that up in my absence Mon- Wed morning this week please?