Surface Water

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Surface Water
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The Lane Diagram
WATER
SEDIMENT

 
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I. Events During PrecipitationA. InterceptionB.
Stem Flow C. Depression StorageD. Hortonian
Overland Flow E. Interflow F. Throughflow -gt
Return Flow G. Baseflow
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II. HydrographA. General
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II. HydrographA. General B. Storm Hydrograph
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II. HydrographA. General B. Storm Hydrograph
1. Shape and Distribution of events
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direct ppt., runoff, baseflow, interflow
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II. HydrographA. General B. Storm Hydrograph
1. Shape and Distribution of 2. Hydrograph
Separation
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II. HydrographA. General B. Storm Hydrograph
1. Shape and Distribution of 2. Hydrograph
SeparationC. Predicting the rate of Baseflow
Recession after a storm
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vs.
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Why care?
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Predicting the rate of Baseflow Recession after a
storm
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Predicting the rate of Baseflow Recession after a
storm
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An example problem.
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Gaining and Losing Streams..
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III. Rainfall-Runoff Relationships
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III. Rainfall-Runoff RelationshipsA. Time of
Concentration
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationThe time required for overland
flow and channel flow to reach the basin outlet
from the most distant part of the catchment
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationThe time required for overland
flow and channel flow to reach the basin outlet
from the most distant part of the catchment
tc L 1.15 7700 H 0.38
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationThe time required for overland
flow and channel flow to reach the basin outlet
from the most distant part of the catchment
tc L 1.15 7700 H 0.38
tc time of concentration (hr) L length of
catchment (ft) along the mainstream from basin
mouth to headwaters (most distant ridge) H
difference in elevation between basin outlet and
headwaters (most distant ridge)
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III. Rainfall-Runoff RelationshipsA. Time of
Concentration example problem
L 13,385 ft H 380 ft
tc L 1.15 7700 H 0.38
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L 31,385 ft H 380 ft
Tc 0.75 hrs, or 45 minutes
tc (13,385) 1.15 7700 (380) 0.38
tc time of concentration (hr) L length of
catchment (ft) along the mainstream from basin
mouth to headwaters (most distant ridge) H
difference in elevation (ft) between basin outlet
and headwaters (most distant ridge)
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational EquationIf the period
of ppt exceeds the time of concentration, then
the Rational Equation applies
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation
QCIA
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation
QCIA Where Qpeak runoff rate (ft3/s) C
runoff coeffic. I ave ppt intensity
(in/hr) A drainage area (ac)
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First solve for time of concentration
(Duration) THEN solve for rainfall intensity
for a given X year storm.
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
The drainage basin that ultimately flows past the
JMU football stadium is dominated by an
industrial park with flat roofed buildings,
parking lots, shopping malls, and very little
open area. The drainage basin has an area of 90
acres. Find the peak discharge during a storm
that has a 25 year flood return interval.
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First solve for time of concentration
(Duration) THEN solve for rainfall intensity
for a given X year storm. 45 minutes from
previous exercise
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
The drainage basin that ultimately flows past the
JMU football stadium is dominated by an
industrial park with flat roofed buildings,
parking lots, shopping malls, and very little
open area. The drainage basin has an area of 90
acres. Find the peak discharge during a storm
that has a 25 year flood return interval.
Q ciA
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
The drainage basin that ultimately flows past the
JMU football stadium is dominated by an
industrial park with flat roofed buildings,
parking lots, shopping malls, and very little
open area. The drainage basin has an area of 90
acres. Find the peak discharge during a storm
that has a 25 year flood return interval.
Q ciA Q (0.85)(2.5 in/hr)(90 acres)
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
The drainage basin that ultimately flows past the
JMU football stadium is dominated by an
industrial park with flat roofed buildings,
parking lots, shopping malls, and very little
open area. The drainage basin has an area of 90
acres. Find the peak discharge during a storm
that has a 25 year flood return interval.
Q 191.3 ft3/s
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
The drainage basin that ultimately flows past the
JMU football stadium is dominated by an
industrial park with flat roofed buildings,
parking lots, shopping malls, and very little
open area. The drainage basin has an area of 90
acres. Find the peak discharge during a storm
that has a 25 year flood return interval.
Calculate the mean velocity if the cross
sectional area of the channel is 40 ft2.
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
An industrial park with flat roofed buildings,
parking lots, and very little open area has a
drainage basin area of 90 acres. The 25 year
flood has an intensity of 2 in/hr. Find the peak
discharge during the storm.
Calculate the mean velocity if the cross
sectional area of the channel is 40
ft2. Discharge Velocity x Area
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III. Rainfall-Runoff RelationshipsA. Time of
ConcentrationB. Rational Equation example
problem
An industrial park with flat roofed buildings,
parking lots, and very little open area has a
drainage basin area of 90 acres. The 25 year
flood has an intensity of 2 in/hr. Find the peak
discharge during the storm.
Calculate the mean velocity if the cross
sectional area of the channel is 40
ft2. Discharge Velocity x Area 191.3 ft3/s
40ft2 V V 4.8 ft/s
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Calculate the mean velocity if the cross
sectional area of the channel is 40
ft2. Discharge Velocity x Area 191.3 ft3/s
40ft2 V V 4.8 ft/s or 146.3 cm/s If the
channel is made of fine sand, will it remain
stable?
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Hjulstrom Diagram
146.3 cm/s
0.10-0.25 mm (fine sand) size range
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III. Measurement of Streamflow
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III. Measurement of StreamflowA. Direct
MeasurementsB. Indirect Measurements
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III. Measurement of StreamflowA. Direct
Measurements
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III. Measurement of StreamflowA. Direct
Measurements 1. Price /Gurley/Marsh-McBirney
Current Meters
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III. Measurement of StreamflowA. Direct
Measurements 1. Price or Gurley Current
Meter 2. Weirs
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Weirsrectangular Q 1.84 (L 0.2H)H
3/2Where L length of weir crest (m), H ht
of backwater above weir crest (m), Q
m3/snote eq. 2.16B in Fetter isincorrect
(exponent is 3/2 asshown above)
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WeirsV notch Q1.379 H 5/2 Where H ht of
backwater above weir crest (m)Q m3/s
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III. Measurement of Streamflow B. Indirect
Measurements
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III. Measurement of Streamflow B. Indirect
Measurements 1.Manning Equation
V R 2/3 S ½ n
Where V average flow velocity (m/s) R
hydraulic radius (m) S channel slope
(unitless) n Manning roughness coefficient
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1.Manning Equation
V R 2/3 S ½ n
Where V average flow velocity (m/s) R
hydraulic radius (m) S channel slope
(unitless) n Manning roughness coefficient
R A/P A Area (m2) P Wetted
Perimeter (m)
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1.Manning Equation
If using English units..
V 1.49 R 2/3 S ½ n
Where V average flow velocity (ft/s) R
hydraulic radius (ft) S channel slope
(unitless) n Manning roughness coefficient
R A/P A Area (ft2) P Wetted
Perimeter (ft)
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V R 2/3 S ½ n
If Q V A, then
Q A R 2/3 S ½ n
Where Q average flow discharge (m3/s) A
area of channel (m2) R hydraulic radius (m) S
channel slope (unitless) n Manning roughness
coefficient
R A/P A Area P Wetted Perimeter

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Q A R 2/3 S ½ N
Where Q average flow discharge A area of
channel r hydraulic radius s channel slope
(unitless) n Manning roughness coefficient
R A/P A Area P Wetted Perimeter

Example Problem A flood that occurred in a
mountain stream comprised of cobbles, pebbles,
and few boulders creates a high water mark of 3
meters above the bottom of the channel, and
temporarily expands the channel width to 6 m. The
slope of the water surface is 100 meters of drop
per 1 km of distance. Determine V in
m/s Determine Q in m3/s
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B. Indirect Measurements 1.Manning Equation 2.
SuperElevation Method 3. Measurement of Cobbles
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B. Indirect Measurements 1.Manning Equation 2.
SuperElevation Method
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B. Indirect Measurements 1.Manning Equation 2.
SuperElevation Method
Q A(RcgcosS tanT) ½
Q discharge,A average radial cross section
in the bend,Rc radius of curvature S slope of
channel (degrees)T angle between high water
marks on opposite banks (degrees)
Example Problem
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B. Indirect Measurements 3. Measurement of
Cobbles
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B. Indirect Measurements 3. Measurement of
Cobbles
The Costa Equation
V 0.18d 0.49 Where V m/s, dmm where 50 lt
d lt 3200 mm Measure the 5 largest boulders,
intermediate axis, take the average
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B. Indirect Measurements 3. Measurement of
Cobbles
V 0.18d 0.49 Where V m/s, dmm and 50 lt d lt
3200 mm Measure the 5 largest boulders,
intermediate axis And hc V
1.5 4.5(S 0.001)0.17 Where V
velocity, in m/s S energy slope (decimal
form) hc competent flood depth (m)
Example Problem Average of five largest
boulders 3.2m x 2.3m x 1.6 m Average slope 5.5
degrees Find average velocity and depth of flow
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V. Hydraulic Geometry A. The relationships
Q VA Q V w d w aQb d cQ f v kQ m
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V. Hydraulic Geometry A. The relationships
B. at a station C. distance
downstream
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M 0.26
A. Hydraulic Geometry
M 0.4
at a station trends
M 0.34
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M 0.5
A. Hydraulic Geometry
M 0.4
distance downstream trends
M 0.1
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Distance Downstream
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VI. Flood Frequency A. Flood Frequency
Analysis B. Flow Duration Curves
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VI. Flood Frequency A. Flood Frequency
Analysis
Flood recurrence interval (R.I.) use Weibull
Method - calculates the R.I. by taking the
average time between 2 floods of equal or
greater magnitude. RI (n
1) / m where n is number of
years on record, m is
magnitude of given flood
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VI. Flood Frequency A. Flood Frequency
Analysis
What does this mean??? the curve estimates the
magnitude of a flood that can be expected within
a specified period of time   The probability
that a flow of a given magnitude will occur
during any year is P 1/RI. EX a
50 year flood has a 1/50th chance, or 2 percent
chance of occurring in any given year .
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VI. Flood Frequency A. Flood Frequency
Analysis
For multiple years q 1- ( 1-1/RI)n
where q probability of flood
with RI with a specified number of years
n
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VI. Flood Frequency A. Flood Frequency
Analysis
For multiple years q 1- (
1-1/RI)n where q
probability of flood with RI with a specified
number of years n EX a 50 year flood has an 86
chance of occurring over 100 years
Example Problem Determine the water height
during a 100 year storm at the Harrison Gaging
Station near Grottoes, Virginia.
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VI. Flood Frequency A. Flood Frequency
Analysis
Example Problem Determine the water height
during a 100 year storm at the Harrison Gaging
Station near Grottoes, Virginia.

• Method
• Access data at www.usgs.gov select water tab
• Select water watch under streams, lakes,
  rivers option
• Choose the current stream flow map,
• your state and the respective station location
• Open station page by clicking on the station
  number
• Select surface water - peak streamflow option
• Choose tab separated file format
• Highlight, copy, and paste (special) your data to
  Excel
• for analysis.

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VI. Flood Frequency A. Flood Frequency
Analysis
Example Problem Determine the water height
during a 100 year storm at the Harrison Gaging
Station near Grottoes, Virginia.

• Method (continued)
• Clean up data so that only Year , Q, and
  Gage Ht. are present
• Sort data based on Q in descending order
• Add magnitude (m) ranking (highest 1)
• Add RI formula, where RI (n1)/m
• Create graph depicting RI vs. Q
• Create graph of Q vs. Gage Ht.
• Determine Gage Height with respect to the given
  RI

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Year Q (cfs) Gage Ht (ft) Magnitude RI (yrs)
9/6/1996 28900 15.57 1 73.0
11/4/1985 28100 15.47 2 36.5
10/15/1942 23100 17.2 3 24.3
9/19/2003 22000 14.41 4 18.3
6/21/1972 21300 15.25 5 14.6
1924-05-00 21000 16.6 6 12.2
9/6/1979 16200 13.47 7 10.4
10/5/1972 15300 13.24 8 9.1
3/18/1936 12600 13.07 9 8.1
3/19/1975 12400 12.2 10 7.3
9/28/2004 12300 12.26 11 6.6
8/16/1940 12100 12.91 12 6.1
4/17/2011 11900 12.15 13 5.6
4/26/1937 11700 13 14 5.2
9/18/1945 11300 12.8 15 4.9
8/20/1969 11100 12.72 16 4.6
1/25/2010 11100 11.9 17 4.3
11/29/2005 10900 11.84 18 4.1
3/19/1983 10300 11.44 19 3.8
9/20/1928 10100 11.9 20 3.7
2/17/1998 10000 11.59 21 3.5
4/22/1992 9840 11.8 22 3.3
5/30/1971 9460 11.93 23 3.2
10/17/1932 8700 11.5 24 3.0
12/1/1934 8340 11.3 25 2.9
9/19/1944 8340 11.33 26 2.8
10/9/1976 8250 10.62 27 2.7
2/14/1984 8250 10.6 28 2.6
4/17/1987 8120 11.08 29 2.5
6/18/1949 7980 11.06 30 2.4
1/26/1978 7800 10.38 31 2.4
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VI. Flood Frequency B . Flow Duration Curves
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VI. Flood Frequency B. Flow Duration
Curves shows the percentage of time that a
given flow of a stream will be equaled or
exceeded.
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B . Flow Duration Curves shows the percentage
of time that a given flow of a stream will be
equaled or exceeded.
P m n1
(100)
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B . Flow Duration Curves shows the percentage
of time that a given flow of a stream will be
equaled or exceeded.
(100)
P m n1
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VI. Flood Frequency B. Flow Duration
Example Problem Determine the discharge that
can be expected 80 of the time at the Harrison
Gaging Station near Grottoes, Virginia.

• Method
• Access data at www.usgs.gov select water tab
• Select water watch under streams, lakes,
  rivers option
• Choose the current stream flow map,
• your state and the respective station location
• Open station page by clicking on the station
  number
• Select daily data option,
• Then click mean discharge option
• Choose the earliest date of record through
  present
• Choose tab separated file format, and select
  go
• Highlight, copy, and paste (special) your data to
  Excel
• for analysis.

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VI. Flood Frequency A. Flood Frequency
Analysis
Example Problem Determine the discharge that
can be expected 80 of the time at the Harrison
Gaging Station near Grottoes, Virginia.

• Method (continued)
• Clean up data so that only Year , Q, and
  Gage Ht. are present
• Sort data based on Q in descending order
• Add magnitude (m) ranking (highest 1)
• Add P formula, where P m/(n1)
• Pick out desired probability value, and record
  the respective
• discharge

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P m 100 n1
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How much water would this value of discharge
yield for a full day?
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How much water would this value of discharge
yield for a full day?
81 ft3 3600 s 24 hr 6,998,400 ft3 of
water in one day s 1 hr 1 d
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V. Sediment Transport A. Shear Stress
tc critical boundary shear stress hc minimal
water depth required for flow ?w water density
(assume 1.00 g/cm3) g gravitational
acceleration (981 cm/s2) S slope (decimal
e.g., meters per meters)
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V. Sediment Transport A. Shear Stress
tc hc ?w g S
tc critical boundary shear stress (force per
unit area) (g/cm-s2) hc minimal water depth
required for flow (cm) ?w water density
(assume 1.00 g/cm3) g gravitational
acceleration (981 cm/s2) S slope (decimal,
e.g., meters per meters)
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V. Sediment Transport 1. Shear Stress 2. The
Shields Equation
tc hc ?w g S
tc tc (?s ?w)gD50
tc critical boundary shear stress hc
minimal water depth required for flow ?s, ?w
grain density (assume 2.65 g/cm3) and water
density g gravitational acceleration (981
cm/s2) D50 median bed material grain size
tc dimensionless critical shear stress (the
Shields number) 0.03 for sand, 0.047 for gravel
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Sediment Transport 1. Shear Stress 2. Shields
Equation
tc hc ?w g S
tc tc (?s ?w)gD50
hc (?s ?w) tc D50 ?wS
OR
tc critical boundary shear stress hc
minimal water depth required for flow ?s, ?w
grain density (assume 2.65 g/cm3) and water
density g gravitational acceleration (981
cm/s2) D50 median bed material grain size
tc dimensionless critical shear stress (the
Shields number) 0.03 for sand, 0.047 for gravel
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Problem A gravel bed stream of slope 2 m per 1
km has a median grain size of 60 mm. Caculate
1) the critical shear stress required for bedload
mobilization 2) The critical water depth to
initiate motion
tc hc ?w g S
tc tc (?s ?w)gD50
hc (?s ?w) tc D50 ?wS
OR
tc critical boundary shear stress hc
minimal water depth required for flow ?s, ?w
grain density (assume 2.65 g/cm3) and water
density g gravitational acceleration (981
cm/s2) D50 median bed material grain size
tc dimensionless critical shear stress (the
Shields number) 0.03 for sand, 0.047 for gravel