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Channel Cross Section. Shifts are applied by developing “V-diagrams”. Recent Measurements. Measurements plotted on axes of V-diagram. Channel Cross Section. Here is what a v-diagram and its shift curve generally look like. Shift curve. Variable shift diagram. Shifts vary by STAGE and TIME. - PowerPoint PPT Presentation
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Channel Cross Section
Recent Measurements
2.0
2.2
2.4
2.6
2.8
3.0
3.2
-0.40 -0.35 -0.30 -0.25 -0.20
Site Number: 00000000 - Site Name: Rating Curve Exercise 5 - DD: 6 - Rating Number: 0000Shift: 06/16/1974 12:43
Sta
ge
Shift
Measurements plotted on axes of V-diagram
Shifts are applied by developing “V-diagrams”
Channel Cross Section
Variable shift diagram
Shift curve
Here is what a v-diagram and its shift curve generally look like
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000Discharge, in cfs
Gag
e H
eigh
t - o
ffset
Variable shift diagram
0
1
2
3
4
5
6
7
-0.3 -0.1
Shift, in feet
Gag
e H
eigh
t
July 1Sept. 1
Shifts vary by STAGE and TIME
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000
Discharge, in cfs
Gag
e H
eigh
t - o
ffset
Variable shift diagram
0
1
2
3
4
5
6
7
-0.3 -0.1
Shift, in feet
Gag
e H
eigh
t
July 1Sept. 1
Meas. made 7/20and 8/15
Shifts should be faithful to the base rating
GH Q Shift0.38 0.29 -0.24
0.4 0.39 -0.241.95 110 -0.15
6.5 3000 0.973.94 805 02.66 299 0
Recent Measurements Concrete
Control
Let’s follow an application of shifts at a site
San Francisquito Creek
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000Discharge, in cfs
Gag
e H
eigh
t - o
ffset
0
1
2
3
4
5
6
7
-1 -0.5 0 0.5 1
Shift, in feet
Gag
e H
eigh
t
1 2
3
46
2
3
4
6
5
1
5
It would be easy (but WRONG) to lump all measurements into one shift----
0
1
2
3
4
5
6
7
-1 -0.5 0 0.5 1
Shift, in feet
Gag
e H
eigh
t
San Francisquito Creek
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000
Discharge, in cfs
Gag
e H
eigh
t - o
ffset
Section Control
Channel Control
One shift doesn’t always work
Date GH Q Shift09/20 0.38 0.29 -0.2411/15 0.4 0.39 -0.2402/10 1.95 110 -0.1502/20 6.5 3000 0.9703/05 3.94 805 003/10 2.66 299 0
You need to consider the hydrograph when applying shifts
San Francisquito Creek
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000
Discharge, in cfs
Gag
e H
eigh
t - o
ffset Section
Control
Channel Control
Algae growth?
Let’s see how all the available information
should be put together
Channel Control
Upstream view of control at GH of 5.40 feet
Downstream view of control at GH of 6.25 feet
San Francisquito Creek
1
10
100
100 1000 10000
Discharge, in cfs
Gag
e H
eigh
t - o
ffset
Changes in the channel control caused the rating to shift
San Francisquito Creek
0.01
0.1
1
10
100
0.1 1 10 100 1000 10000Discharge, in cfs
Gag
e H
eigh
t - o
ffset
0
2
4
6
8
10
12
-1 -0.5 0 0.5 1
Shift, in feet
Gag
e H
eigh
t
3
4
6
1
5
2
V-diagram representing channel
control
V-diagram representing section control
Measurements were used to define two shift curves
0
2
4
6
8
10
12
-1 -0.5 0 0.5 1
Shift, in feet
Gag
e H
eigh
t
Effective from ???
Effective from ????
Shift application took the hydrograph into account
X
X
X=Discharge Measurement
Prorate
Hold ScourFill
X
#1
#2 #3
Here is a generalized example of how shifts can be timed
