| St. Louis River - River
Watch Discharge Calculations Fall 2003 |
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Name _____________________________________ |
Site Name ________________________________
Date ___________________ |
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Where |
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DISCHARGE = |
A L C |
A = Avg. cross sectional area of
stream |
C =
Coefficient or correction factor |
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T |
L = Length of stream reach measured_ |
T =
Time for float to travel length L |
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"A" AVERAGE
CROSS-SECTIONAL AREA |
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Transect #1 (upstream) |
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Transect #2 (downstream) |
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Stream
width (ft): |
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Stream
width (ft): |
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Interval |
Depth (inches) |
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Interval |
Depth (inches) |
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A to B |
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(at B) |
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A to B |
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(at B) |
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B to C |
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(at C) |
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B to C |
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(at C) |
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C to D |
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(at D) |
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C to D |
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(at D) |
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D to E |
0 |
(at shoreline) |
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D to E |
0 |
(at shoreline) |
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Total |
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¸ 4 = |
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¸ 12
= |
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Total |
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¸ 4
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¸ 12
= |
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Convert to ft. |
Average |
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Convert to ft. |
Average |
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depth (ft) |
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depth
(ft) |
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Cross-sectional area of
Transect #1: |
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Cross-sectional area of
Transect #2: |
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x |
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= |
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ft2 |
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x |
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ft2 |
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Width (ft) |
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Avg. depth (ft) |
(a) |
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Width (ft) |
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Avg. depth (ft) |
(b) |
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Average Cross-sectional Area: |
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+ |
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= |
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¸ 2
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ft2 |
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(a) |
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(b) |
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(A) |
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"L" LENGTH OF STREAM REACH (usually 20 ft.) |
"T" TRAVEL TIME FROM TRANSECT #1 TO #2 |
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travel time of float |
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ft |
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Trial #1 |
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sec. |
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(L) |
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Trial #2 |
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sec. |
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Trial #3 |
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sec. |
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"C" COEFFICIENT |
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0.8 for rocky-bottom streams |
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Total |
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¸ 3
= |
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0.9 for soft-bottom streams |
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Avg. time (sec.) |
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(C) |
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(T) |
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x |
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x |
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| Discharge = |
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A |
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L |
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C |
= |
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ft3/sec |
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Volunteer Stream Monitoring: A Methods Manual,
USEPA |
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T |
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source: |
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