SEDIMENT DELIVERY FROM UNGAGED TRIBUTARIES TO THE COLORADO

RIVER IN GRAND CANYON

Robert H. Webb

Peter G. Griffiths

U.S. Geological Survey

1675 W. Anklam Road

Tucson, AZ 85745

Theodore S. Melis

Grand Canyon Monitoring and Research Center

2255 N. Gemini Drive

Flagstaff, AZ 86001

DRAINAGE AREAS OF UNGAGED TRIBUTARIES IN GRAND CANYON

0

5

10

15

20

25

30

35

Range in Drainage Area (km2)

ESTIMATING STREAMFLOWSEDIMENT YIELD

Use multiple techniques to constrain estimates:

• Regional sediment yield data;

• Empirical sediment yield relations;

• Flood-frequency rating-curve technique.

REGIONAL SEDIMENT YIELD DATA (mostly from east of Grand Canyon)

Source Area Sediment load Sediment yield(km2) (106 Mg/yr) (Mg/yr/ km2)

25 small reservoirs (Hains, et al. 1952) 0.2-47.1 <0.003 5.7-628Moenkopi Wash #1 29.2 0.0069 237Yellow Water Wash #1 52.2 0.034 643Coal Mine Wash #1 77.1 0.019 245Yellow Water Wash #2 109.1 0.017 158Coal Mine Wash #2 112.7 0.0095 84Paria River at Lees Ferry 3,650 3.0 820Moenkopi Wash, Tuba City 4,219 0.65 155Little Colorado River near Cameron 68,600 9.2 130Colorado River at Lees Ferry 290,000 65. 220Colorado River near Grand Canyon 366,000 84. 230

RED NAMES indicate previously unused data from Black Mesa.

EMPIRICAL METHODS FOR ESTIMATING SEDIMENT YIELD

Estimated Sediment yield

Source Original Equation Units (106 Mg/yr) (Mg yr-1 km-2)

Renard (1972) 0.001846 A-0.1187 ac-ft/ac/yr 0.67 204

Strand (1975) 1130 A0.77 m3/yr 1.62 494

Dendy and Bolton (1976) 1280 Q0.46 (1.43-0.26 log A) tons/mi2/yr 0.81 247Flaxman (1972) log(Y+100) = 6.21301 - ac-ft/mi2/yr 0.14 42.6

2.19113 log (X1+100) + 0.06034 log (X2+100) - 0.01644 log (X3+100) + 0.04250 log (X4+100)

Soil Conservation Svc. (1975) PSIAC method ac-ft/mi2/yr 13.5 4,110Howard and Dolan (1981) 780 A Mg/km2/yr 2.56 780Randle and Pemberton (1987) 1750 A-0.24 m3/km2/yr 2.4 731

Graf (1987) 1200 A1.0 m3/yr 3.9 1,190

n = 219 ungaged tributaries

FLOOD FREQUENCY TECHNIQUE

We combine:

• Sediment-rating curves from 5 small drainages on Black Mesa;

• Flood hydrographs for 22 summer and 20 winter flows above base discharge on Bright Angel Creek;

• Regional flood-frequency relations developed for Arizona (Roeske, 1978);

• Qs = Q10 + 2 . Q5 + 5 . Q2

STREAMFLOW SEDIMENT-YIELDBY ALL THREE METHODS

100

101

102

103

104

105

106

107

10-2

10-1

100

101

102

103

Regional data

Regression through regional data

Renard (1972) Equation

Flood frequency method Moenkopi Wash #1)

Drainage Area (km2)

n = 768 tributaries

(r = 0.86)

STREAMFLOW SEDIMENT-YIELD ESTIMATES

Drainage Sediment yield (103 Mg/yr)

Sediment-yield reach area Regional Renard Flood- (km2) data equation frequency

A: Lake Powell – Paria R. 321 65 76 45

B: Paria R. – LCR 2,953 610 593 457

C: LCR – Bright Angel Cr. 494 98 127 82

D: Bright Angel – Kanab Cr. 1,640 332 375 240

E: Kanab – Havasu Cr. 276 57 64 41

F: Havasu – Diamond Cr. 3,958 821 779 488

G: Diamond Cr. – Lake Mead 3,236 669 633 397

TOTAL 12,878 2,650 2,650 1,750

A DEBRIS-FLOW SEDIMENT-YIELD MODEL

We combine:• Frequency model based on logistic regression (Griffiths et

al., 1996);

• Magnitude model based on monitoring of debris flows from 1984 through 1998 (Melis et al., 1994);

• Reworking of debris fans by Colorado River floods (Melis, 1997; Webb et al., 1997, 1999).

DEBRIS FLOW VOLUMESIN GRAND CANYON

100

1,000

10,000

100,000

0.1 1 10 100 1000

Debris-Flow Volumes

Vmax

= 11,808 . A

0.294, R

2 = 0.89

Vavg

= 5728 . A

0.278, R

2 = 0.47

Deb

ris

Flo

w V

olu

me

(m3)

Drainage Area (km2)

DEBRIS-FLOW SEDIMENT YIELDESTIMATES

ReachDrainage Area Sediment Yield (103 Mg/year)

(km2) Vmax model Vavg model

A: Lake Powell – Paria R. 321 0* 0*

B: Paria R. – LCR 2,953 80, 38

C: LCR – Bright Angel Cr. 494 30 14

D: Bright Angel – Kanab Cr. 1,640 50 24

E: Kanab – Havasu Cr. 276 5 3

F: Havasu – Diamond Cr. 3,958 72 34

G: Diamond Cr. – Lake Mead 3,236 58 28

TOTAL 12,878 295 141* Tributaries in Reach A (Glen Canyon) do not produce debris flows.

COMBINED SEDIMENT YIELD(STREAMFLOW + DEBRIS FLOW)

Sediment Yield Debris flow contribution

Reach (103 Mg/year) (%)

Vmax model Vavg model Vmax model Vavg model

A: Lake Powell – Paria R 65 65 0 0

B: Paria R. – LCR 691 648 12 6

C: LCR – Bright Angel Cr. 127 112 23 13

D: Bright Angel – Kanab Cr. 381 356 13 7

E: Kanab – Havasu Cr. 062 059 9 4

F: Havasu – Diamond Cr. 893 855 8 4

G: Diamond Cr. – Lake Mead 728 698 8 4

Total2,947 2,793 10 5

Sediment load

Source (103 Mg/yr)

Colorado River at Lee’s Ferry (pre-dam) 65,000

Little Colorado River 9,200

Paria River 3,000

Moenkopi Wash 2,700

Kanab Creek 800

Moenkopi Wash 700

Ungaged tributaries in Marble Canyon 600

Ungaged tributaries in Glen Canyon 70

SEDIMENT SOURCES TO THE COLORADO RIVER

SAND CONTENT OF STREAMFLOW SEDIMENT YIELD

Tributary Sand (%) Reference

General 15 Randle and Pemberton (1987)

Little Colorado River 0.7-22.6 Garrett et al., 1993

1-50 Rote et al., 1997

Bright Angel Creek 87*† Garrett et al., 1993

1-64 Rote et al., 1997

Kanab Creek 0.1-14.5 Garrett et al., 1993

0-36 Rote et al., 1997

Havasu Creek 1-89 Rote et al., 1997

National Canyon 81-99*† Garrett et al., 1993

*Not a gaging station; miscellaneous tributary flow in 1983 (Garret et al., 1993).†Calculated from silt+clay % and assuming no particles >2 mm were transported.

PARTICLE-SIZE DISTRIBTION OF STREAMFLOW SAND

0

20

40

60

80

100

Reach A (n = 6)Reach B (n = 71)Reach C (n = 6)Reach D (n = 3)Reach F (n = 3)

Pe

rcen

t F

iner

Th

an

2 1 0.5 0.25 0.125 0.063

Particle Size (mm)

Drainage Area Sediment Yield

Reach (km2) (103 Mg/year)

Minimum Maximum Average

A: Lake Powell – Paria R 321 10 49 30

B: Paria R. – LCR 2,953 93 462 288

C: LCR – Bright Angel Cr. 494 15 75 47

D: Bright Angel – Kanab Cr. 1,640 51 251 156

E: Kanab – Havasu Cr. 276 9 43 27

F: Havasu – Diamond Cr. 3,958 125 619 385

G: Diamond Cr. – Lake Mead 3,236 102 505 314

Total 12,878 404 2,002 1,247

SAND DELIVERED TO THE RIVERFollowing Debris Fan Reworking

CONCLUSIONS• Ungaged tributaries in Grand Canyon deliver nearly 3 . 106 Mg/yr of

sediment to the Colorado River. This is comparable to the sediment load of a major tributary.

• As debris fans are reworked, an average of 1 . 106 Mg/yr of sand is made available to the regulated river throughout Grand Canyon.

• In Glen and Marble Canyons, an average of 0.32 . 106 Mg of sand is delivered to the river annually. This is:

– 20% of the sand supplied by the Paria River each year;

– twice the sand estimated for this reach in the 1995 EIS.

• Debris flows contribute between 5 and 10% of total sediment, and no more than 8% of sand; but they deliver 100% of coarse sediment (boulders and cobbles) that create critical habitat and zones of fine sediment storage.

• Efforts are underway by the GCMRC to verify streamflow estimates by gaging several small drainages in Marble Canyon.