Sediment budget for the 2000 LSSF Experiment, in context of the last half century

Sediment budget for the 2000 LSSF Experiment, in context of the last half century David J. Topping, David M. Rubin, Nancy J. Hornewer, Gregory G. Fisk, James R. Allen, Elizabeth Fuller, and Jamie P. Macy (USGS)

REVIEW

HYPOTHESES • UNDER NORMAL POWERPLANT OPERATIONS, NEWLY INPUT TRIBUTARY SAND WILL BE EXPORTED FROM MARBLE CANYON WITHIN SEVERAL MONTHS • SAND WILL ACCUMULATE IN THE REACH DOWNSTREAM FROM LEES FERRY WHEN DISCHARGES ARE HELD BELOW 9,000 cfs

MARBLE CANYON NET CHANGE • -900,000 to - 2,100,000 metric tons, without estimates for additional inputs • -500,000 to -1,700,000 metric tons, with estimates for additional inputs • 500,000 metric tons is equivalent to 3 cm of erosion spread over the entire area of Marble Canyon

CONCLUSIONS • SAND BUDGET FOR MARBLE CANYON WAS NEGATIVE DURING AUGUST 1999-SEPTEMBER 2000 • 1999 PARIA RIVER SAND INPUTS WERE EXPORTED FROM MARBLE CANYON WITHIN 1-3 MONTHS • SAND DID ACCUMULATE IN MARBLE CANYON DURING THE STEADY 8,000 cfs FLOWS, BUT NOT AS MUCH AS WAS ERODED DURING THE MAY SPIKE

BECAUSE THE MARBLE CANYON SAND BUDGET WAS SLIGHTLY NEGATIVE FROM PRE-MAY SPIKE TO PRE-SEPT SPIKE, SAND CONCENTRATIONS WERE 20% LOWER DURING THE SEPTEMBER SPIKE • BECAUSE THE SAND EXPORT FROM MARBLE CANYON WAS VERY SIMILAR TO THE SAND EXPORT PAST THE GRAND CANYON GAGE, VERY LITTLE CAN BE SAID ABOUT THE SAND BUDGET IN UPPER GRAND CANYON • SILT AND CLAY CAN ALSO ACCUMULATE WHEN THE FLOWS ARE KEPT AT 8,000 cfs • BETA SUGGESTS THAT THE CHANNEL AND EDDIES BELOW 8,000 cfs WERE MORE DEPLETED IN JUNE-JULY 2000 THAN AT ANY OTHER TIME

Sediment budget for the 2000 LSSF Experiment, in context of the last half century

Sediment budget for the 2000 LSSF Experiment, in context of the last half century

Presentation Transcript

The 21 st Century Context for

Major Events during the First Half of the Nineteenth Century

The 21 st Century Context for

Half a century with The Beatles

Rocking the british stage in the last century

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The Second Half of the Nineteenth Century

the Last Decade of the twentieth Century

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Sediment Bottle Experiment

The Climate of the Last 2000 Years

An autobiographical vision of different modes of activism in the last half century

Half a century with The Beatles

Revolutions in the First Half of the 19th Century

ORGANIZATIONS FOR THE NEXT CENTURY 2000

The 21st Century Context for Learning Mathematics

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