AOP Pilot Project Field Measurement Descriptions
Study Sites in order of priority
1. Sullivan Gulch
2. Soldier Ck at Evans Bar Rd
3. Cedar Creek
4. Lindsay Creek
First Site Visit Measurements
The first site visit measurements are focused on surveying the longitudinal profile and
characterizing the design channel. The design channel includes all of the following
components:
 The in-structure channel
 The transition from the natural channel to and from the structure
 Any reconstructed channel elements adjacent to the structure
Data Collection and Measurements:
1. Define the structure type and collect basic measurements – develop data
collection form (get from existing templates such as culvert inventory data form)
2. Create detailed field sketches of the structure, the channel and bed within the
design channel.
3. Survey the longitudinal profile w/water depths
The longitudinal profile length should be 20-30 channel widths US and DS of the
design channel unless the culvert is 10 times longer than the channel width. For
long culverts, extend the longitudinal profile length to five times the culvert
length.
Clearly identify the points on longitudinal profile listed in Table 5.1 of the Stream
Simulation design manual by PCode in the survey and field notes, on the site
sketches and in the longitudinal profile plot. The stability of grade controls will
be qualitatively assessed using Table 5.3 in the Stream Simulation design manual.
Channel unit boundaries should be identified in notes, survey points and labeled
on all plots
4. Bed material and roughness characterization – pebble counts and particle size
measurements. Measurement method varies by channel unit type.
Pool/riffle channels and plain bed channels
Pebble counts are measured starting at the upper portion of a riffle or plain bed
with transects moving downstream to span the entire riffle or plain bed length.
Transverse measurement interval is the largest observed particle size. The
longitudinal measurement interval is selected to collect 100 - 200 pebble
measurements over the full length of the riffle or plain bed. The minimum
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AOP Pilot Project Field Measurement Descriptions
longitudinal interval distance is also the largest particle size.
For the particle size measurements, measure all axes of the10-20 largest particles,
wherever they exist on the riffle. If the particle can not be moved or will
“dismantle” the channel estimate its measurements in place and note that the
measurements are an estimate. Measurements should be limited to particles
greater than 64mm (cobble size) if they are present. The shape (platy, bladed,
elongate, and compact), roundness, and embedment of the particles measured will
be qualitatively assessed/described.
Steps, Cascades, Chutes, etc.
Visually assess the flow through or over steps and the material size upstream of
step including the size and packing of particles that fill in the voids between key
step rocks. Photographs and the channel bed sketch should show flow channels
and direction over the steps. Site sketch should include a plan pattern of grade
control. Percentage of fines in representative reach versus design channel should
be described qualitatively and include particle embedment. Description should
include upstream and the face of the step.
Collect particle size measurement (all axes) of actual step elements. If the particle
cannot be moved or will “dismantle” the channel, estimate its measurements in
place and note that the measurements are an estimate. The shape (platy, bladed,
elongate, and compact), roundness, and embedment of the particles measured will
be qualitatively assessed/described. Measure at least one step, if more than one
step, measure all steps in the design channel then measure the same number of
steps in the representative reach. Multiple step measurements will grouped
separately to assess particle size variation between steps and then composited for
an overall distribution.
Cascades and chutes – measure using similar method to riffles for both pebble
count and particle sizes
For channel units with characteristics of both riffle and step-pool channels (e.g. no
well-defined pools but identifiable key pieces steps), use the riffle pebble count
protocol through the entire channel unit but identify the key pieces (microsteps) in
sketches, notes and the largest particle size measurements.
Pools (for all types of systems)
For pools in all types of channels, qualitatively assess and provide photographs to
show, whether pool bed sediment characteristics are similar to, finer than or
coarser than the step bed materials or riffle bed materials. Photographs taken at
the channel margins during low flows may show this the most clearly.
If the pool has a significant tailout (> ½ the channel width), the tailout should be
treated as a separate channel unit and a pebble count conducted on the tailout.
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AOP Pilot Project Field Measurement Descriptions
Wood
If wood is a significant control for the channel bed, note the presence of key
pieces and debris jams on the longitudinal profile and sketches. Use the Table 5.6
to describe the key features, size and role of the wood. Summarize the size
(length, diameter and embedment) of key wood pieces forming debris jams and
bed features, such as steps.
5. Cross Sections
Measure XSs in the design channel at the inlet and outlet grade controls, and
through each type of channel unit in design channel. For riffles, the XS should be
measured through the upper portion but DS of the riffle crest. In pools the XS
should be measured at the maximum width. For steps, the XS should be measured
just upstream of the step crest. For pools associated with steps, the XS should be
measured at the maximum width of the pool.
If a single channel unit extends beyond the structure, measure additional XSs –
one in the structure channel and one in the same channel unit outside of the
structure. Criteria used to determine: if 70% of channel unit is within the structure
than measure XS in the culvert, if less than 70% is within the structure, then
measure XS in culvert and outside of culvert. This may be captured by or the
same as the transition XS.
XSs at the transition between the design and natural channel will be measured at
the maximum width of the transition zone.
More XSs may be needed in the design channel if analysis of the longitudinal
profile shows distinct slope changes within a single channel unit. Add one XS for
each distinct slope segment.
Measure XSs in the same locations (channel units and positions within the
channel units) in reconstructed adjacent channels as the in-structure channel
XS measurement point spacing will be no greater than 1 ft measurements should
be made at this set interval across the entire cross sections. However, additional,
finer-scale measurements should be added as needed to capture bed structure such
as slope breaks, bed forming large particles, etc. All XSs at a site (design channel
and representative reach) should be measured using the same set interval but
finer-scale measurements will vary between XSs. A minimum of 20
measurements will be collected per XS. Top elevation of XS should be at least
two times where practical the maximum bankfull depth so that the adjacent
floodplains, terraces, or side slopes are included in the XS. Measurement spacing
can increase above bankfull to capture slope breaks and general shape of the
floodplain and terrace.
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AOP Pilot Project Field Measurement Descriptions
Cross section comparisons and hydraulic geometry analyses can be made using
just the set interval measurements or the full XS measurement data as needed.
Second Site Visit Measurements
Using the first site visit data, identify and determine the possible representative reaches
before the second site visit. One representative reach is sufficient but if two are present,
use two to assess differences between measurements in two “natural channel” reaches.
1. Design channel and representative reach characteristics:
Select the representative reach length so that the representative reach is within
25% of culvert length.
Representative reach slopes should also match the design channel slope within
25%.
Boundaries of the representative reach are grade controls, and channel unit types
and their sequence should match those of the design channel as closely as
possible.
2. Width and bank diversity measurements:
Bank width measurements will be made at three elevations: 1) the water surface at
the time of the site visit, 2) ½ bankfull depth, and 3) bankfull depth. The elevation
difference from the current water surface to the bankfull depth will be estimated
in the representative reach and this vertical distance will be used throughout the
design channel to determine the elevation of the ½-bankfull and bankfull depth
measurements. If this distance is above the banks in the culvert, the width
measurement will extend from the centerline to the culvert wall.
The channel width measurements are made by measuring the distance to the left
and right bank from the channel centerline to the channel edge at the three
elevations described above. In the design channel, these measurements are made
from the US extent of transition to the inlet through design channel to DS extent
of transition zone at the outlet. The measurements within the representative reach
are made from the US grade control to the DS grade control that defines the
representative reach boundaries.
The longitudinal distance between width measurements is selected to get 20
measurements through the shorter of the culvert or the representative reach. The
same longitudinal spacing should be used in both reaches. The maximum
longitudinal interval distance should be limited to 20-25% of the bankfull width.
A minimum of 20 widths should be collected through a design channel or
representative reach, and the tape should be as close to horizontal as possible
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AOP Pilot Project Field Measurement Descriptions
when collecting the width measurements.
3. XSs in representative reach:
XSs measured in the representative reach should be one per channel unit type
similar to the XSs collected in the design channel. Measurement guidelines for
XS, outlined above for the design channel, will be followed with regard to
spacing and extent of XSs.
4. Bed material and roughness characterization – pebble counts and particle size
measurements.
The bed measurement methods described above for the design channel will also
be used in the representative reach. The sampling interval may be modified if bed
material sizes in the representative reach dictate it, but the procedure is the same.
Third and Fourth Site Visit Measurements
The focus of the third visit is collecting velocity and depth measurements throughout
both the design and representative channels. This data will be collected following a
protocol established by M. Weinhold.
1. Measure on a uniform grid with approximately 200 measurement points. Grid
width is the larger of the structure width and bankfull width. Clearly distinguish
points with no velocity but depth from those on exposed surfaces (no depth and
no velocity).
2. These measurements should be collected at two flows a low fish passage flow and
a moderate flow. If the two site measurements show inconsistent comparisons
between the design channel and representative reach, then measurements at a third
flow rate may be needed.
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AOP Pilot Project Field Measurement Descriptions
Measurement
Analysis
Slope segments – gradient control to gradient control – for culvert inlet to outlet. Use this info to
inform selection of representative reach
Channel unit boundaries and lengths delineated along long profile – clearly delineate spacing of
grade controls, pool depths, step height
Longitudinal Profile
Look at vertical variability (Bartley & Rutherford, 2005) – this may need a limit on maximum
spacing between long profile points (proposed conference call to discuss actual analysis method
which will influence long profile point frequency)
Planform analysis – compare angle of variance between points on the long profile through the
representative reach and the design channel (Bartley & Rutherford, 2005)
Hydraulic geometry – perform some type statistical analysis of stage-width data
XS
Width/Bank Margin
diversity
Vertical variability (Bartley & Rutherford, 2005)
Average and variance for widths collected at the different elevations (low water, toe of bank and top
of bank)
May also evaluate the distribution with K-S (or similar analysis of the distribution)
Compare sizes of D50 and D84 in design channel and representative reach
Pebble Count
Compare particle size distributions in design channel and representative reach
Mean, std. dev. of particle axes and compare in culvert and representative reach
Particle size measurements
Keep analysis of each step separate but composite within culvert and representative reach if it seems
reasonable.
Bartley, R. and I. Rutherford. 2005. Measuring the reach-scale geomorphic diversity of streams: Application to a stream disturbed by a sediment slug. River
Research and Applications. V 21, No. 1. p. 39-59.
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