SEDIMENT DELIVERY FROM UNGAGED TRIBUTARIES TO THE COLORADO RIVER IN GRAND CANYON - PowerPoint PPT Presentation

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SEDIMENT DELIVERY FROM UNGAGED TRIBUTARIES TO THE COLORADO RIVER IN GRAND CANYON

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  1. 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

  2. DRAINAGE AREAS OF UNGAGED TRIBUTARIES IN GRAND CANYON

  3. ESTIMATING STREAMFLOWSEDIMENT YIELD Use multiple techniques to constrain estimates: • Regional sediment yield data; • Empirical sediment yield relations; • Flood-frequency rating-curve technique.

  4. 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 5.7-628 Moenkopi Wash #1 29.2 0.0069 237 Yellow Water Wash #1 52.2 0.034 643 Coal Mine Wash #1 77.1 0.019 245 Yellow Water Wash #2 109.1 0.017 158 Coal Mine Wash #2 112.7 0.0095 84 Paria River at Lees Ferry 3,650 3.0 820 Moenkopi Wash, Tuba City 4,219 0.65 155 Little Colorado River near Cameron 68,600 9.2 130 Colorado River at Lees Ferry 290,000 65. 220 Colorado River near Grand Canyon 366,000 84. 230 RED NAMES indicate previously unused data from Black Mesa.

  5. 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 0.81 247 Flaxman (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 4,110 Howard and Dolan (1981) 780 A Mg/km2/yr 2.56 780 Randle 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

  6. 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

  7. STREAMFLOW SEDIMENT-YIELDBY ALL THREE METHODS (r = 0.86)

  8. 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

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

  10. DEBRIS FLOW VOLUMESIN GRAND CANYON 100,000 ) 3 10,000 Debris Flow Volume (m 1,000 Debris-FlowVolumes . 0.294 2 V = 11,808 A , R = 0.89 max . 0.278 2 V = 5728 A , R = 0.47 avg 100 0.1 1 10 100 1000 2 Drainage Area (km )

  11. DEBRIS-FLOW SEDIMENT YIELDESTIMATES Reach Drainage 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.

  12. 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 Total 2,947 2,793 10 5

  13. SEDIMENT SOURCES TO THE COLORADO RIVER 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

  14. 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.

  15. PARTICLE-SIZE DISTRIBTION OF STREAMFLOW SAND

  16. SAND DELIVERED TO THE RIVERFollowing Debris Fan Reworking 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

  17. 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.