Transcript Fluxes of water, sediment, and elements class 1. Introduce instrumentation and approach for surveying and flow gauging 2.

Fluxes of water, sediment,
and elements class
1. Introduce instrumentation and approach for
surveying and flow gauging
2. Introduce and understand Manning’s
equation
3. Consider the meaning of Floods and Bankful
Discharge
4. Getting and understanding watershed flux
data
5. Logisitcs
1
FLOW GAUGING
• QUANTIFY VOLUME OF WATER
MOVING THROUGH CHANNEL
• NEED CHANNEL GEOMETRY
• NEED VELOCITY
1
Survey Across
Stream
Distance
Velocity
Water Depth
1
The auto level
Your view
1
:(
(:
Level the instrument
1
TOP = DISTANCE
BOTTOM = DISTANCE
CENTER LINE - ELEVATION D
1
Good Data Table is key
Point Hi
cent
D elev top
bott
D T-b
dist
1
1.31m 1.31m 0.0m 1.40m 1.20m 0.1m
20m
2
1.31m 1.41m -0.1m 1.50m 1.10m 0.40m
40 m
3
1.31m 1.21m +0.1m 1.70m 0.91m 0.79m
79 m
4
Flow meter for measuring water speed
1
Divide and Conquer
1
Add up the pieces
1
1
From counts to speed
Stage and Discharge related through
rating curve
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
1
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Water Resources of North Dakota
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The top of a U.S. Geological Survey staff gage (a
graduated rod against which water levels can be
read) is barely visible above the water.The top of
the gage represents a water level or river stage of
54.50 feet, 2 feet above the 1997 East Grand Forks
city levee.During the 1997 flood, the Red River
crested at 54.35 feet; the National Weather Service
flood stage at Grand Forks is 28.00 feet.
1
WEIR is the permanent solution
1
water
heigh
v notch weir
6
5
4
3
2
1
0
0
50
100
discharge (cfs)
Q = 2.47h2.5
150
2
Manning Equation
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Use fudge factor of 1.49 when units are feet
2
SLOPE
2
Wetted Perimeter
2
2
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http://wwwrcamnl.wr.usgs.gov/sws/f
ieldmethods/Indirects/nvalues/
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TIFF (Uncompressed) decompressor
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Clark Fork at Missoula,
Montana
Boundary Ck at Porthill,
Idaho
n = 0.030
n = 0.073
3
Flow Levels
Try to define in field using
observations
Bank full flow
About once a year
“Channel-forming flow”
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This is for alluvial channels
Extreme Floods
How does the Huntington Fit?
3
3
DEFINE
BASIN
AREA
COUNT BOXES
OR USE
DIGITIZER
4
Sediment Transport Through Rivers
Bedload -- material moving along the bed,
shear forces exerted by water sufficient to
move clasts -- rarely measured (at % level)
Suspended Load -- material kept in the water
column by turbulence and lift forces (easy to
measure in grab samples)
Dissolved Load -- material in solution
(easy to measure in grab samples)
Bedload usually <<< than suspended load and ignored
Dissolved load varies, usually < than suspended load
Sampling for suspended load…….
4
4
Mass Loadings and Erosion Rate
Estimation
Integrate suspended load over all flows (mass/time)
+
Integrate bedload load over all flows (mass/time)
+
Integrate dissolved load over all flows (mass/time)
Calcium, Rio Puerco
Load varies
over time
and
discharge
700
500
400
300
200
100
0
10/4/58
3/26/64
9/16/69
3/9/75
8/29/80
Date
2/19/86
8/12/91
2/1/97
Rio Puerco 1960-1990
10000
Discharge (cfs)
Ca (ppm or mg/kg)
600
8000
6000
4000
2000
y = -0.2709x + 1707.5
R2 = 0.012
0
0
500
1000
1500
2000
Dissolved Load (mg/kg)
2500
3000
USGS Water Quality Data on line
Dissolved and Suspended Load
http://nwis.waterdata.usgs.gov/nwis/qwdata?site_n
o=04282815&agency_cd=USGS&begin_date=&e
nd_date=&format=html_table&inventory_output=
0&rdb_inventory_output=file&date_format=YYY
Y-MMDD&rdb_compression=file&qw_sample_wide=0
&submitted_form=brief_list
4
Integration over all flows is a non
trivial problem!
Need Rating Curves (suspended, dissolved, bedload)
Suspended Load
Hysteresis loop
Other Approaches…Reservoir
trapping (may miss dissolved)
Nahal Yael, Negev Desert
4
SEDIMENT YIELD
- What comes out
= or ≠
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4
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Timescale
Steady state
Human impact
Episodic disturbance
SEDIMENT GENERATION
- Material generated by
erosion
River Lab Logistics
•
•
•
•
•
•
•
On Huntington, in water
Warm clothes, food, $, Daily Bread
Measure discharge - survey and velocity
Trace flow
Compare pools and riffles
Field estimate of bankfull stage
OLD TENNIS SHOES! Teva/toenail story
Downstream Organization
Survey one of each type
Calculate discharge for one of each type
Calculate roughness for one of each type
COMPARE