Grand Canyon Monitoring and Research Cent

Revisiting Experimental Flow Desi

Sediment and Fishery Resour

WY 2005 and Beyond
Southwest Biological Science Center - 

Experimenting with Sand

Sand Export and Conservation For any 

monthly volume, a steady flow should transport less sand than any diurnal fluctuating flow regime (true for a flume, but perhaps not for the CRE owing to the confounding issue of hundreds of eddies that act as both “sinks” & “sources.”)

Main Channel Flume at St. Anthony Falls Laboratory

Minneapolis, MN on the Mississippi River
Southwest Biological Science Center - 

Experimenting with Sand

Scenario #2

Sand Bars within Eddies Might increase in 

size during brief periods of fluctuating flows following sand inputs from the Paria River (temporarily increasing sand availability prior to controlled floods that occur shortly thereafter)

Eminence Reattachment Bar – April 23, 2004
Southwest Biological Science Center - 

Experimenting with Sand

Scenarios 1 & 3

Sand Storage in the Main Channel in 

scenario #1 is optimized throughout the system by flows that equate to the pre-dam mean, daily discharge (scenario #3 may have limited potential owing to the fact that large Winter sand inputs from the Paria River are relatively rare)
Southwest Biological Science Center - 

Why Pursue the “Blocked” 

Approach for Fish?

Sorting Out Sand Options is relatively easier 

with respect to establishing cause & effect compared with answering fishery questions (the current sediment experiments build on the knowledge gained from the 1996 test and the monitoring since 1999)

-4.0-3.0-2.0-1.0

0.01.02.03.04.0

05,00010,00015,00020,00025,00030,00035,00040,000

MASS-BALANCE SAND BUDGET

BETWEEN LEES FERRY AND THE GRAND CANYON GAGE

AUG 1999

OCT 1999

DEC 1999

FEB 2000

APR 2000

JUN 2000

AUG 2000

OCT 2000

DEC 2000

FEB 2001

APR 2001

JUN 2001

AUG 2001

OCT 2001

DEC 2001

FEB 2002

APR 2002

JUN 2002

AUG 2002

OCT 2002

DEC 2002

FEB 2003

APR 2003

JUN 2003

AUG 2003

OCT 2003

MASS-BALANCE UNCERTAINTY ENVELOPE

WATER DISCHARGE

SAND MASS IN REACH RELATIVE TO 

THAT ON AUG 15, 1999 (million metric tons)

DISCHARGE AT THE LEES FERRY GAGE (ft3/s)

PARIA RIVER FLOODS LCR FLOOD

PARIA RIVER FLOOD

ACCUMULATION

EROSION
Southwest Biological Science Center - 

Why Pursue the 

“Blocked” Approach?

Long-Term Implementation is focused on Flow 

Non-Flow treatments that are related to ReasonabPrudent Alternatives, as well as Non-RPA ideas aelements of ecosystem changes in the post-dam eras introduced non-native fish and reduced turbidi
Southwest Biological Science Center - 

The Original “Blocked” Approa

of 2002, with Five Treatment

Increased

Fluctuations

In Daily Flows

(Jan – Mar)

Mechanical

Removal of Rainbow 

Trout in GC

(Jan-Mar, Jul - Dec)

Stable-Low

Flows in Fall

(Aug – Dec)

TCD

(Future)

WY2002-03 WY2003-04WY2004-05WY2005-06WY2006-07WY2007-08WY2008-09WY2009-10WY2010-11WY2011-12WY2012-13WY2013-14WY2014-15WY2015-16WY2016-17WY2017-18
Southwest Biological Science Center - 

The Revised “Blocked” Strategy w

Controlled and Two Randomized Tr

Water Year

Flow Treatment

(Jan – Apr,

Aug– Dec)

Mechanical Removal of 

Rainbow Trout in GC

(Jan-Mar, Jul - Dec)

Temperature

Control Device/Low 

Reservoir Releases

B

B

WY2002-03 Fluctuating Remove Fish Random WY2003-04 Fluctuating Remove Fish Random WY2004-05 Stable Remove Fish Random WY2005-06 Stable Remove Fish Random WY2006-07 Fluctuating Do Not Remove Fish Random WY2007-08 Fluctuating Do Not Remove Fish Random WY2008-09 Stable Do Not Remove Fish Random WY2009-10 Stable Do Not Remove Fish Random WY2010-11 Fluctuating Remove Fish Random WY2011-12 Fluctuating Remove Fish Random WY2012-13 Stable Remove Fish Random WY2013-14 Stable Remove Fish Random WY2014-15 Fluctuating Do Not Remove Fish Random WY2015-16 Fluctuating Do Not Remove Fish Random WY2016-17 Stable Do Not Remove Fish Random WY2017-18 Stable Do Not Remove Fish Random