Summary of Sediment Synt

Support of Ad Hoc Desired Futur

Technical Workgroup Me

December 4, 2007

Grand Canyon Monitoring & 

Center, Flagstaff
Summary of Sediment Synt

Synthesis Research Conducted Schmidt and others, 2004 (available at www.gc- Sandbar Area Declined an average of 25% in the upper 1

and 2000 (areas mapped from imagery captured at 5,000 & 

-Highly Variable Sandbar Loss – in some areas the percenin other areas loss was as much as -55%,-Average annual sandbar erosion is difficult to quantify,-During the 1990s, 55 of 57 cross-sections monitored by ththe volume of sand in the sandbars below 8,000 cfs and in decreased by over 25% at the sites monitored by NAU in t
Summary of Sediment Synt

Geomorphic Research Re

Grams and others, 2004 & Grams and others 200Geomorphic channel changes in the Lees Ferry reach - Most of the channel changes occurred during higheJune 1965 and during spills and high releases of 198- Sediment eroded from the tailwaters reach included both sand and gravel- The channel has incised and altered the stage/dischthe upper part of the reach, but changes are less dow
Summary of Sediment Synt

Some Other Related Rep

Topping and others, 2000a and 2000b 

– Two Water R

articles describing sand-transport characteristics of the Cpre-dam era – documented flows associated with sand aTopping and others, 2003 - “Computation and AnalysInstantaneous Discharge Record for the Colorado River Lees Ferry, Arizona - May 8, 1921, through September Topping and others, 2005 - “Regulation of sand transpColorado River by changes in the surface grain size of emulti-year timescales ”
Review of Suspended Sand 

How do GCD Operations Rel

Downstream Transport of N

Supplies From Tributary Sou

Monthly and Annual Times

Rapid Changes in both Sedimen

& Discharge Must be 

Considered in Modeling E
-2.0

-1.0

0.01.02.03.0

SEDIMENT-YEAR 2003 MASS-BALANCE SAND 

BETWEEN LEES FERRY AND THE GRAND CAN

JUL 2002

SEP 2002

NOV 2002

JAN 2003

MAR 2003

MAY 2003

MASS-BALANCE UNCERTAINTY ENVELOPEWATER DISCHARGE

SAND MASS IN REACH RELATIVE TO 

THAT ON JUL 1, 2002 (million metric tons)

LITTLE COLORADO RIVER FLOOD

ACCUMULATION

EROSION
-2.0

-1.0

0.01.02.03.0

SEDIMENT-YEAR 2004 MASS-BALANCE SAND 

BETWEEN LEES FERRY AND THE GRAND CAN

JUL 2003

SEP 2003

NOV 2003

JAN 2004

MAR 2004

MAY 2004

MASS-BALANCE UNCERTAINTY ENVELOPEWATER DISCHARGE

SAND MASS IN REACH RELATIVE TO 

THAT ON JUL 1, 2003 (million metric tons)

PARIA RIVER FLOOD

ACCUMULATION

EROSION
Summary – Flows and Sand Tr

Flow 

Regime Months Volume (TAF) Inputs Expor

5 – 10

9 490 1.6 

± 0.40 0.2 

± 0.0

7 – 13 18 610 1.3 

± 0.33 0.4 

± 0.0

11 – 18 23 850 1.0 

± 0.25 2.4 

± 0.2

Preliminary data subject to review and revision

Low to moderate volumes/peaks reta

High volumes/peaks exported more sand 

Based on data fro
-2.0

0.02.04.06.08.0

SEDIMENT-YEAR 2005 MASS-BALANCE SAND 

BETWEEN LEES FERRY AND THE GRAND CAN

JUL 2004

SEP 2004

NOV 2004

JAN 2005

MAR 2005

MAY 2005

WATER DISCHAR

MASS-BALANCE UNCERTAINTY ENVELOPE

SAND MASS IN REACH RELATIVE TO 

THAT ON JUL 1, 2004 (million metric tons)

PARIA RIVER FLOOD

ACCUMUL

EROSIO

LARGE LCR FLOODS
-1.0

-0.5

0.00.51.01.5

SEDIMENT-YEAR 2006 MASS-BALANCE SAND 

BETWEEN LEES FERRY AND THE GRAND CAN

JUL 2005

SEP 2005

NOV 2005

JAN 2006

MAR 2006

MAY 2006

WATER DISCHARGEMASS-BALANCE UNCERTAINTY ENVELOPE

SAND MASS IN REACH RELATIVE TO 

THAT ON JUL 1, 2005 (million metric tons)

PARIA RIVER FLOODS

ACCUMUL

EROSIO
Monitoring Sand Transport

Between 2000 and 2004 – UCRB hydrology was charaand GCD releases were 8.23 MAF – sand inputs were were exported downstream by higher summer/winter From 2005 to Present – Sand inputs have been above Releases have remained 8.23 MAF – only under these have new sand inputs accumulated Sand Transport under 8.23 MAF & MLFF – Largest typically December, January, July and AugustCurrent Modeling Capabilities – Sand Export can onlOwing to variable boundary conditions and predictinfrom tributaries is not possible
Thank You

Questions?