Post on 25-Aug-2020
Reading RiverscapesMapping Valley Bottoms
LTPBR WORKSHOP
Purpose
•Get your eye trained for reading riverscapes
•Build your intuition about processes• Specifically, Wood
Accumulation & Beaver Dam Activity broken into component pieces:
• Hydrologic• Hydraulic• Geomorphic• Ecologic
i.e. Crash course in fluvial geomorphology
Recommend Fryirs & Brierley (2013)DOI: 10.1002/9781118305454
PHASE 1 with Low-Tech
Figure 3.3 (p. 91) from Bennett et al. (2019) – Chapter 3 LTPBR Manual
DOI: 10.13140/RG.2.2.15815.75680
PHASE 1 with Low-Tech
Figure 3.3 (p. 91) from Bennett et al. (2019) – Chapter 3 LTPBR Manual
DOI: 10.13140/RG.2.2.15815.75680
RECALL, Streams need space (i.e. their valley bottoms)
From Figure 2.1 (p. 60) Wheaton et al. (2019) Chapter 2 of LTPBR Manual
DOI: 10.13140/RG.2.2.19590.63049/1
What part of valley bottom is available for low-tech restoration?
Where are we talking about?
How much of valley bottom?
Figure 3.7 from Bennett et al. (2019) – Chapter 3 LTPBR Manual
DOI: 10.13140/RG.2.2.15815.75680
We care about Mesic Habitat – i.e. RiparianCross Sectional Valley View
• Riparian vegetation associations with different surfaces
• Floodplain = Valley Bottom = MAXIMUM Probable Riparian Extent
• Terraces = Former Floodplains
• Uplands = NON-Riparian
The lateral and vertical dimensions…
From: USFS (2004) Riparian Restoration(SDTDC 04231 1201)
Riparian Dimensions & Connectivity
• Vertical cross section determines water availability
• Longitudinal patterns control fluxes of water, sediment, nutrients and seeds (sources, transfer vs. sinks) From: USFS (2004) Riparian Restoration
(SDTDC 04231 1201)
• Lateral extent determines potential width of riparian area
What is a Valley?
From Glossary in Wheton et al. (2019, p 20) – LTPBR Manual. DOI: 10.13140/RG.2.2.19590.63049/2
Valley Bottom vs. Valley?
What are the building blocks of: • A Valley?
vs.• A Valley Bottom?
From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010
Valley Margins In Different Settings
• Interesting thing is identifying where different margins overlap
• Fundamental control on channel’s capacity to adjust
• Differentiates reach types
• Sets up planform steering of flows
From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010
From: Fryirs et al. (2015) – ESPL;DOI: 10.1002/esp.3893
Reading your riverscape… to look for opportunities
From page 9 of Pocket Guide; Wheaton et al. (2019) DOI: 10.13140/RG.2.2.28222.13123/1
Where are their mesic/riparian restoration opportunities?
From page 10 of Pocket Guide; Wheaton et al. (2019) DOI: 10.13140/RG.2.2.28222.13123/1
Contrasting Valley Settings Define Reach Breaks
From pages 9-10 of Pocket Guide; Wheaton et al. (2019) DOI: 10.13140/RG.2.2.28222.13123/1
← Which way is river flowing? →
Exercise – Reading Valley SettingSouth Fork Asotin CreekRiver Mile 1.5 to 2.2
0 750 1000 ft250 500
1. Map Channel(s)2. Map Fan(s) and/or Terrace(s)3. Map Active Confining
Margin(s)4. Estimate % Confinement
ContextSouth Fork Asotin CreekRiver Mile 1.5 to 2.2
0 750 1000 ft250 500
NHD Stream Network –Perennial Line (1:24,000)
Trace the Actual ChannelSouth Fork Asotin CreekRiver Mile 1.5 to 2.2
0 750 1000 ft250 500
Map the Fans
Anthropogenically Disconnected river left Fans
Coupled river left fans
South Fork Asotin CreekRiver Mile 1.5 to 2.2
0 750 1000 ft250 500
Map the Confining Margins
Hillslope/Bedrock(HS/BR) Fan
Fan
FanFan
Anthropogenic - Road
South Fork Asotin CreekRiver Mile 1.5 to 2.2
0 750 1000 ft250 500
Natural Capacity For Adjustment
• Plausible limits on what adjustments are possible
• Geomorphic context matters• Confinement• Sediment Supply• Flow Regime• Vegetation• Land use• History
From Brierley & Fryirs (2005)
Valley Bottom (Riparian) Delineation
Sets maximum lateral extent for potential riparian & flooding
From http://rcat.riverscapes.xyz
Key Question(s):• What is in play for
freedom space?• What is the maximum
probable extent of riparian vegetation?
From: Gilbert et al. (2016) DOI: 10.1016/j.cageo.2016.07.014
V-BET: Valley Bottom Extraction Tool• From topography (e.g. USGS 10
m NED or LiDAR) & V-BET
From: Gilbert et al. (2016) – Computers & Geosciences ; DOI: 10.1016/j.cageo.2016.07.014http://rcat.riverscapes.xyz
VBET with Higher Resolution Data?
• More precise answer (better resolved)
• Coarser data may be accurate enough in many cases
From: Gilbert et al. (2016) DOI: 10.1016/j.cageo.2016.07.014
Province-wide or Watershed Wide: VALLEY BOTTOMS
• Tool can run @ broad spatial scales from DEM (e.g. here for Utah over 25,000 km of riverscape in a region ~ 220,000 km2 ; by comparison Upper yellow River is about 140,00 to 178,000 km2)
Making Investment
https://restoration-usu.github.io/Ecohydraulics/Modules/NetworkTools.html#network-scale-assessments
Want to learn more?
Map Confinement – Understand Valley Setting
From: Fryirs et al. (2015) – ESPL;DOI: 10.1002/esp.3893
From: O’Brien et al. (2019) – ESPL;DOI: 10.1002/esp.4615
Check out: Confinement Tool in GNAT: http://gnat.riverscapes.xyz/
Inputs: VB + Channel(s) Position
Mapping margin types helps identify connectivity to local sediment supplies
From: O’Brien et al. (2019) : DOI: 10.13140/RG.2.2.28838.57924/1
Stacked Profile Plots
Network models of Geomorphic Attributes
Give us reach types (River Styles) and condition
Check out: Confinement Tool in GNAT: http://gnat.riverscapes.xyz/ &Network Profiler Tool: https://riverscapes.github.io/NetworkProfiler/
From: O’Brien et al. (2019) : DOI: 10.13140/RG.2.2.28838.57924/1
Reading Riverscapes – On your own time…
http://lowtechpbr.restoration.usu.edu/resources/Topics/03_Planning/sturcturalForcing
To help you experience a little of what you would with an in-person workshop• We take you out in the field
virtually with the help of UAVs, GoPro, some maps, and some narration by Joe
• Includes: