SEDIMENT FLOW IN

FARMINGTON CANYON

 

Ryan McBride

GIS in Water Resources

Fall 2003

 

 

INTRODUCTION

The focus of this project was to study sedimentation in Farmington Canyon.  Three other undergrad students studied this project as part of our senior design project, which we felt could benefit from using GIS.  We each took different parts of the project to research and explore.  We combined our efforts to map the watershed as a whole and to see how sedimentation affects the canyon.  Our study also included how much sediment yield will be washed out of the canyon during a rainstorm or snowmelt.  Two methods were utilized in this project.  The PSIAC (Pacific Southwest Inter Agency Committee) Method and the MUSLE (Modified Universal Soil Loss Equation) Equation were used to find sediment yield. 

 

AREA OF STUDY

Farmington Canyon is a small watershed located 20 minutes North of Salt Lake City.  This canyon covers 10 mi^2 in area.  It has steep slopes that are prone to erosion and has a past history of loss of sediment. 

                                                                                                                                   

                                                                                                     Location of project

PROCESS

The PSIAC method is used to find annual sediment load.  The procedure considers nine factors that depend on surface geology, soils, climate, runoff, topography, ground cover, land use, channel erosion, and upland erosion. (http://www.forester.net/ec_0009_gis.html).  This method is some what subjective and depends upon the characteristics observed.  Each of the 9 factors is given a rating that is then calculated to give a sediment yield. 

Number

Factors

Rating

1

Surface Geology

0-10 (0 for hard rock)

2

Soil

0-10 (0 for rock soil)

3

Climate/Precipitation

0-10 (0 for snow melt)

4

Runoff

0-10 (0 for low peak)

5

Topography

0-20 (0 for mile slope)

6

Ground Cover

(-)10-10 (-10 for 100%protection)

7

Land Use

(-)10-10 (-10 for unused)

8

Upland Erosion

0-25 (0 for no evidencee of slope erosion)

9

Channel Erosion

0-25 (0 for bedrock/complete protection)

                                                                   Sedimentation engineering by William Rahmeyer

ANNUAL YIELD = 0.0833 e^(0.0359 FR)

FR=Rating Factor

On our field trip to Farmington canyon we each rated the different factors.  The results are as follows.

PSIAC Method for determining yield**

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Brad

Sefa

Ryan

Katie

Jeff

 

North*

South*

North*

South*

North*

South*

North*

South*

North*

South*

F1

8

8

4

3

8

7

8

8

7

7

F2

7

7

8

5

6

7

8

6

7

8

F3

0

0

0

0

0

0

2

2

1

0

F4

2

2

1

1

0

0

10

10

2

0

F5

15

15

10

13

20

20

15

18

18

18

F6

5

-5

-4

-6

0

-10

0

-5

-2

-10

F7

8

8

-2

0

0

0

9

5

-2

-2

F8

10

5

10

12

15

10

19

10

10

7

F9

10

10

5

5

10

10

10

10

10

7

Sum

65

50

32

33

59

44

81

64

51

35

Classification

3

4

4

4

3

4

 

 

3

4

Annual Yield in acre ft/square mile/annual year

0.859154314

0.501422244

0.262761966

0.27236649

0.692666435

0.404256084

1.525913535

0.82885775

0.51975032

0.29264157

Annual Yield in tons per annual year

30929.55529

18051.2008

9459.430767

9805.19364

24935.99168

14553.21903

54932.88727

29838.879

18711.0116

10535.0965

 

 

 

 

 

 

 

 

 

 

 

*This is the North side and South side of the watershed and not the "North Facing" and "South Facing" sides.

 

 

 

 

**Please see explanation on this method in the paper

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

North*

South*

 

 

 

 

 

 

 

 

Average

27793.77533

16556.7178

 

 

 

 

 

 

 

 

Final Yield=

44350.49313

Tons/year

 

 

 

 

 

 

 

-Based on average between all group members

 

 

 

 

 

 

 

Along with the PSIAC method the MUSLE equation is also used to calculate sediment yield.  By use of the MUSLE equation we were able to determine how much soil is lost due to sedimentation.   We each took a part of the MUSLE equation to find out the sediment yield in the canyon.  The MUSLE equation is as follows.

gs=a[Q*qp]^b*K*LS*CP*SDR
 
 

 

 


Q = Storm Runoff (acre-ft)

qp= Peak runoff (cfs)

K=Soil Erodibilty Factor      Brad Taylor

LS=Slope Factor                 Jeff Jensen

CP=Ground Cover Factor    Iosefa Matagi

 

Rain storm           

a = 95

b= .56
 

 

 

 

 

 

 

 

 

 

                                               

 

 

 

 

 

 

My main objective was to find storm runoff.  The majority of my time was spent finding Q and qp. The other group members cover the factors of K, LS and CP in detail.  Their information can be found on the links next to the MUSLE factors.  There are many methods to estimative peak runoff rates.  To find Q, I used the Rational Equation.  This equation is used to determine peak discharge from a drainage basin runoff.  There are some limitations to this equation that affect the outcome.  It is recommended that the drainage area be no larger than 2000 acres.  Since the area of Farmington Canyon was over 6000 acres, it needed to be divided up into smaller catchments. ( Bernie Engel (engelb@ecn.purdue.edu)

 

 

Q=CIA
 
 

 

 

 

 

Q=Runoff

C=Runoff Coefficient

I=Intensity of rainfall (assume 1 in/hr)

A=Area of Catchment
 
 

 

 

 

 

 

 

 

 

 

 


The Rational Method coefficient C is a function of soil type and ground cover.  The C value can range from .05 to .95 depending on conditions.  It is a value that represents how much runoff will occur in a certain area.  The runoff coefficient depends upon what type of soil the water is being infiltrated in and also the kind of vegetation that is present.  The C value gets lower as infiltration increases.  The following chart gives a basic break down of different C values with their corresponding ground cover.

 

 

Ground Cover

Runoff Coefficient, c

Lawns

0.05 - 0.35

Forest

0.05 - 0.25

Cultivated land

0.08-0.41

Meadow

0.1 - 0.5

Parks, cemeteries

0.1 - 0.25

Unimproved areas

0.1 - 0.3

Pasture

0.12 - 0.62

Residential areas

0.3 - 0.75

Business areas

0.5 - 0.95

Industrial areas

0.5 - 0.9

Asphalt streets

0.7 - 0.95

Brick streets

0.7 - 0.85

Roofs

0.75 - 0.95

Concrete streets

0.7 - 0.95

 

(http://www.lmnoeng.com/Hydrology/rational.htm)

 

 

Farmington Canyon had a wide variety of vegetation and ground cover.  It ranged from sparsely covered grassland to densely covered forest.

In choosing a C value it is next to impossible to obtain one for each single area.  I decided to break up the canyon into the North Side and the South Side.  I chose this breakup because the South Side had mostly thick vegetation, which would have a smaller C value.  The North Side was mostly covered with short grass and weeds.  Due to the fact that the North Side is not as dense, and has a Higher C value, it has a higher tendency to release sedimentation.

 

SOUTH SIDE

 

 

 

 

C=.17

 

NORTH SIDE

 

 

 

C=.3

 

The variable I is the intensity of the storm.  For my calculations I assumed a storm of 1 in/hr and that it was uniform in space and time over the catchment area.  In determining the area of the watershed GIS was a valuable resource.  Because the watershed needed to be divided into sub catchments GIS was useful in being able to separate the basin into 44 separate catchments.  After obtaining the sub catchments I was able to attain area information for each one.

HYDROID

SHAPE_AREA

 

m2

17

2187672.4

18

1827676.07

34

794251.8245

35

962325.7698

36

562951.7855

39

395773.3481

40

411073.2211

41

605251.029

43

171898.8484

44

928349.7853

45

488700.6879

47

88197.95131

49

857024.57

50

668248.822

51

689400.2

52

263251.8937

53

409723.4542

55

1004400.746

56

1044451.201

57

518175.7148

61

443026.7672

65

395324.5536

66

217799.2478

67

228824.122

69

604800.5427

70

269774.1187

 

                    CATCHMENT AREA

 

 

                                                         

 

 

 

 

 

 

 

 

 

 

After finding the necessary information for each sub catchment I entered it into Excel.  By finding the values of .3 and .17 for C, using 1 in/hr for I, and gathering the different areas from GIS, I was able to calculate Q.  By obtaining Q I will be then able to tell how much runoff will occur during an assumed storm.  This will assist me in solving for the Sediment yield.

 

 

HYDROID

SHAPE_AREA

CN

I

 

Q

q

HYDROID

m2

ft2

acre

 

ft

 

acre-ft

cfs

17

2187672.4

23547887

540.58299

0.3

0.08

 

13.51457

40.88

18

1827676.07

19672922

451.62639

0.3

0.08

 

11.29066

34.15

34

794251.8245

8549247.2

196.26294

0.3

0.08

 

4.906574

14.84

35

962325.7698

10358378

237.79472

0.3

0.08

 

5.944868

17.98

36

562951.7855

6059556.7

139.10774

0.3

0.08

 

3.477693

10.52

39

395773.3481

4260064.7

97.797248

0.3

0.08

 

2.444931

7.40

40

411073.2211

4424751

101.57791

0.3

0.08

 

2.539448

7.68

41

605251.029

6514861.6

149.56006

0.17

0.08

 

2.118767

6.41

43

171898.8484

1850302

42.476924

0.17

0.08

 

0.601756

1.82

44

928349.7853

9992664.3

229.39911

0.17

0.08

 

3.249821

9.83

45

488700.6879

5260325.3

120.75998

0.17

0.08

 

1.710766

5.18

47

88197.95131

949353.93

21.794082

0.17

0.08

 

0.308749

0.93

49

857024.57

9224926.8

211.77435

0.17

0.08

 

3.000137

9.08

50

668248.822

7192963.5

165.12708

0.17

0.08

 

2.3393

7.08

51

689400.2

7420634.8

170.35367

0.17

0.08

 

2.413344

7.30

52

263251.8937

2833617.1

65.050643

0.17

0.08

 

0.921551

2.79

53

409723.4542

4410222.3

101.24438

0.17

0.08

 

1.434295

4.34

55

1004400.746

10811269

248.19162

0.3

0.08

 

6.204791

18.77

56

1044451.201

11242368

258.08826

0.17

0.08

 

3.65625

11.06

57

518175.7148

5577591.6

128.04338

0.3

0.08

 

3.201085

9.68

61

443026.7672

4768695.8

109.47377

0.3

0.08

 

2.736844

8.28

65

395324.5536

4255234

97.686349

0.17

0.08

 

1.38389

4.19

66

217799.2478

2344369.3

53.819104

0.17

0.08

 

0.762437

2.31

67

228824.122

2463040

56.543397

0.3

0.08

 

1.413585

4.28

69

604800.5427

6510012.6

149.44874

0.17

0.08

 

2.11719

6.40

70

269774.1187

2903821.6

66.662312

0.17

0.08

 

0.944383

2.86

 

 

After calculating Q I needed to find the peak runoff.   To find qp I related Peak flow of the Basin as a whole with the following equation.

.

* Peak Flow
 

 

 To find qp I found out how much accumulation occurs in each cell.  Using the Arc Hydro tool I was able to plot drainage points for each sub catchment.  This allowed me to find out how many cells drained into each specific drainage point.  With this information I was able to plot on GIS the drainage points and flow accumulation for each sub catchment.

 

 

 

To find qp I needed to get stream flow data.   I obtained the necessary stream flow data from the USGS website. (http://www.usgs.gov).  This site has flow data for gauging stations throughout the U.S.  From this website I was able to obtain peak stream flow data from 1950 to 1983.  From this data I graphed the numbers and determined that the average peak flow was about 300 cfs.  I wanted to use the highest peak flow as a worse case scenario.  The flow during 1983 was the largest, in which Utah received large amounts of precipitation and extensive flooding.  Using this number would symbolize using the scenario for a 100 year flood.  The max flow for this basin was 590 cfs.

 

 

 

CONCLUSION

Using this information I was able to calculate the qp for each sub catchment.  Solving for qp allowed me to have the peak runoff for each sub catchment. Having the peak runoff along with the runoff from the assumed storm allowed me to see how rainfall or snowmelt affects sedimentation.  Using these numbers along with my group members’ information we were able to use the MUSLE equation to solve for Sediment Yield.  The Calculations are shown in the table below.

 

Catchment

LS

K

CP

Q

q

Total Sediment

Q

q

Total Sediment

GridID

 

 

 

(acre-ft)

(cfs)

(tons/event)

(acre-ft)

(cfs)

(tons/event)

17

124.5

0.09

0.06

46.06

15.23

576.19

13.51

40.88

2192.95

18

74.3

0.09

0.06

38.48

12.72

308.68

11.29

34.15

1069.99

34

143.5

0.08

0.06

16.72

5.53

321.25

4.91

14.84

722.01

35

116

0.09

0.06

20.26

6.7

327.94

5.94

17.98

814.38

36

110.4

0.08

0.06

11.85

3.92

201.16

3.48

10.52

378.04

39

142.4

0.08

0.06

8.33

2.75

209.89

2.44

7.4

328.44

40

126

0.08

0.06

8.65

2.86

190.06

2.54

7.68

303.34

41

152.6

0.08

0.004

488.7

161.55

172.65

2.12

6.41

20

43

84.2

0.08

0.004

561.8

185.72

103.57

0.6

1.82

2.69

44

29.2

0.08

0.24

590

195.04

2216.98

3.25

9.83

370.25

45

120.6

0.09

0.004

429.89

142.11

142.15

1.71

5.18

13.99

47

91.5

0.09

0.06

405.53

134.06

1562.28

0.31

0.93

23.4

49

133.3

0.08

0.004

546.32

180.6

161.18

3

9.08

25.78

50

104.9

0.07

0.004

14.07

4.65

12.35

2.34

7.08

13.43

51

123

0.08

0.004

519.94

171.88

144.37

2.41

7.3

18.64

52

123

0.07

0.004

383.41

126.75

105.28

0.92

2.79

5.55

53

111.4

0.09

0.004

339.38

112.19

113.87

1.43

4.34

10.6

55

116.9

0.08

0.06

308.76

102.07

1505.72

6.2

18.77

765.23

56

130.8

0.07

0.004

21.99

7.27

20.14

3.66

11.06

27.62

57

98.9

0.08

0.06

10.91

3.61

171.45

3.2

9.68

308.63

61

49.5

0.09

0.06

9.32

3.08

87.85

2.74

8.28

145.78

65

135.7

0.08

0.004

8.32

2.75

13.33

1.38

4.19

11.04

66

81.3

0.08

0.004

279.28

92.32

65.78

0.76

2.31

3.39

67

84.2

0.08

0.004

263.78

87.2

65.8

1.41

4.28

7.01

69

127.4

0.08

0.004

12.73

4.21

16.15

2.12

6.4

16.67

70

80.5

0.08

0.004

246.23

81.4

60.36

0.94

2.86

4.27

74

85.1

0.08

0.06

182.75

60.41

800.37

4.71

14.25

409.11

80

185.7

0.09

0.004

157.37

52.02

119.74

1.75

5.28

22.03

81

85.7

0.09

0.004

57.79

19.1

30.3

1.87

5.67

11.01

84

47.1

0.08

0.004

134.11

44.33

24.52

1.79

5.43

5.12

85

31.4

0.09

0.004

17.31

5.72

5.39

2.88

8.71

6.53

90

118.7

0.08

0.004

8.21

2.71

11.57

1.37

4.13

9.51

91

139.4

0.08

0.004

38.3

12.66

34.23

0.54

1.63

3.95

100

86.7

0.08

0.004

15.32

5.07

12.29

2.55

7.71

13.97

101

91.1

0.09

0.004

19.73

6.52

16.9

3.28

9.92

21.91

106

55.8

0.07

0.004

18.35

6.07

7.71

3.05

9.23

9.62

107

112.7

0.07

0.004

104.96

34.7

44.33

1.43

4.33

8.33

117

31.8

0.06

0.06

17.06

5.64

53.98

2.84

8.58

64.89

118

36.7

0.15

0.004

79.29

26.21

26.17

2.78

8.41

12.24

127

13.7

0.15

0.004

27.83

9.2

5.22

0.15

0.44

0.17

128

105.4

0.1

0.06

14.54

4.81

271.21

2.42

7.31

300.01

129

44

0.12

0.004

19.94

6.59

10.96

3.32

10.03

14.29

131

34.7

0.15

0.004

9.17

3.03

6.78

1.52

4.61

5.9

135

49.8

0.15

0.004

17.78

5.88

14.46

2.96

8.94

17.76

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Snowmelt

 

 

Rainfall

 

 

 

 

 

 

Total Yield

10372.57

tons

Total Yield=

8539.48

tons

 

 

 

ASSUMPTIONS

·         Rainfall occurs uniformly over the entire watershed.

·         Rainfall occurs with a uniform intensity for duration equal to the time of concentration for the watershed.

·         The runoff coefficient, C, is dependent upon physical characteristics of the watershed, e.g. soil type.

·         The duration of storm is equal to 6 hours

·         Q=1.5qp

·         SDR = 1

·         That the slope data will be averaged over the area

WORKS CITED

 

·        “Use of GIS, Geo-Based Programs, and Computer Models for Watershed and Site Analyses.”  By Selena M. Forman, Martin J. Teal, David T. Williams, Leo R. Kreymborg, and Craig M. Burnett. (http://www.forester.net/ec_0009_gis.html) 4 Dec 2003

·        Rahmeyer, William “Sedimentation Engineering”

·         Engel,  Bernie (engelb@ecn.purdue.edu) 4 Dec 03

·        LMNO Engineering, Research, and Software, Ltd.http://www.lmnoeng.com/Hydrology/rational.htm

·        http://www.usgs.gov.  4 Dec 03