1. John M. Buffington Research Geomorphologist US Forest Service Rocky Mountain Research Station Boise, Idaho, USA PNAMP Protocol Comparison Meeting February 1, 2006, Portland, OR

2. The truth …

3. Overview of study design & “truth” protocol Treatments: 3 channel types Plane-bed (Tinker, Bridge, Camas, Potamus) Pool-riffle (WF Lick, Crane, Trail, Big) Step-pool (Whiskey, Myrtle, Indian, Crawfish) plane-bedpool-rifflestep-pool

4. Protocol overview Treatments: 4 reaches of each channel type, representing a range of topographic complexity e.g., simple, self-formed pool-riffle (WF Lick Ck) vs. complex, wood-forced pool-riffle (Big Ck) WF Lick, simple pool-riffleBig, complex pool-riffle

5. Protocol overview Treatments: Reach length 3 long reaches (80 bankfull channel widths): Bridge (plane-bed), Crane (pool-riffle), Myrtle (step-pool) 9 short reaches (40 bankfull channel widths) bankfull width initially estimated by making measurements every 20 m over first 200 m of reach

6. Protocol overview Measurements: Cross sections (surveyed with total station): 1 every 0.5 bankfull widths for first 40 channel widths, and every 1 bankfull width for second 40 channel widths (long reaches only) 5 PNAMP cross sections (starting point, and every 10 channel widths) cross sections extend out onto floodplain, or confining hillslopes; i.e., well beyond top of bank Longitudinal profile of bed along center-line of bankfull width (total station) Pebble counts: 10 grains per cross section, evenly spaced across bed Pools: residual depth type of pool: self-formed vs. forced (wood, bedrock, etc.) surface area

7. Protocol overview Measurements: Wood: count of all pieces > 1 m in length & > 10 cm in diameter geomorphic function: forming a pool assisting in pool scour, but not dominant cause not causing scour location: within bankfull channel, suspended above, or both inventory divided into 4 subsections between each PNAMP cross section no length or volume measurements Undercut banks: depth of undercut if > 10 cm left & right banks at each cross section not done at all sites

8. Crane Ck (reach length = 80 channel widths) survey points pool bar contour interval = 10 cm riffle

9. Protocol overview Derived data: channel dimensions: width and depth for: bankfull flow any given stage (for protocols that measure wetted values) reach slope number and size of channel units: pools vs. shallows shallows could be divided into different types (glide, riffle, rapid, etc.) based on slope and flow depth grain size: reach-average, by cross section, or by channel unit wood: number, geomorphic function, spatial distribution undercut banks: spatial distribution and depth of undercut

10. The “truth” There are many shades of the “truth”, depending on 1.Flow stage (bankfull vs. wetted measurements on a given day) Working on bankfull analysis. Should we also examine solutions for other stages for protocols that use wetted parameters? 2.Method of analysis 3.Spatial scale of analysis Results of each protocol are likely sensitive to sample domain (spatial extent) and sampling density within that domain, both of which vary between protocols. Correct that we will compare protocols “as is” (i.e., mixed- scale analysis)? Will reach length and sample size be factors of analysis? Could attempt to match scales (i.e., clip protocols with long reaches to extent of “truth” data, and clip “truth” data to extent of protocols with short reaches).

11. “truth” is sensitive to methodology Example: average bankfull width at Trail Ck, derived from “truth” data set Method 1: average of 5 PNAMP cross sections (8.48 m) Method 2: average of all 75 cross sections (8.79 m) Method 3: total bankfull volume of the channel divided by total bankfull surface area, both determined from topographic map constructed from all total station data (7.81 m)

12. Longitudinal profile of bankfull elevation Noise implies high potential error for small sample size (e.g., 5 PNAMP cross sections) Crane Ck

13. Partial truth Were not able to survey all sites Plane-bed: Bridge (long reach), Tinker, Camas, Potamus Pool-riffle: Crane (long reach), WF Lick, Trail, Big Step-pool: Myrtle (long reach), Whiskey, Crawfish, Indian Black = completed Blue = 14 cross sections + 5 PNAMP cross sections Red = only 5 PNAMP cross sections, with 10 grain-size measurements each