Difference between revisions of "GCDAMP Sediment"

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*[https://www.usbr.gov/uc/progact/amp/amwg/2021-02-11-amwg-meeting/20210211-SandSupplyTransportDeposition-508-UCRO.pdf Sand Supply, Transport and Deposition ]
  
 
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Revision as of 15:15, 31 March 2021


The Paria River flowing into the mainstem Colorado River‎


Sediment and Geomorphology

Erosion of sandbars (beaches) along the Colorado River in Grand Canyon was first reported in the early 1970s, approximately 10 years after completion of Glen Canyon Dam. Since then, scientific studies have been conducted to monitor changes in sandbars and changes in the amount of sand stored on the bed of the river. One of the outcomes of these studies has been the implementation of flow experiments intended to rebuild eroded sandbars, especially by the release of controlled floods, also called High Flow Experiments, or HFEs, from Glen Canyon Dam. The sediment and geomorphology projects at Grand Canyon Monitoring and Research Center include the collection and processing of data to provide information needed to conduct controlled floods and to evaluate the outcome of each controlled flood and the long-term effects of controlled floods and normal dam operations on sediment-related resources. [1]

Beginning in 1998, recreational campsite area has also been measured on a subset of the sandbar monitoring sites. Campsite areas are defined as areas that are flat (less than 8 degree slope), smooth (not rocky), and clear of dense vegetation. Monitoring data show that vegetation expansion and sandbar erosion/deposition contribute to reductions in campsite area.

LTEMP Resource Goal for Sediment

Increase and retain fine sediment volume, area, and distribution in the Glen, Marble, and Grand Canyon reaches above the elevation of the average base flow for ecological, cultural, and recreational purposes.

Desired Future Condition for Sediment-Related Resources

High elevation open riparian sediment deposits along the Colorado River in sufficient volume, area, and distribution so as to provide habitat to sustain native biota and desired ecosystem processes
• Nearshore habitats for native fish
• Marsh and riparian habitat for fish (food chain maintenance)
• Cultural resource preservation
• Maintenance of camping beaches

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Updates

Sediment transport and river discharge

When the discharge of the Colorado River was lower than about 9,000 ft3/s, sand accumulated in the reach in Marble and upper Grand Canyons. At discharges higher than about 9,000 ft3/s, however, sand-transport rates at the Grand Canyon gaging station generally equaled those at the Lees Ferry gaging station, and at discharges higher than about 16,000 ft3/s, sand-transport rates at the Grand Canyon gaging station generally either equaled or exceeded those at the Lees Ferry gaging station. Thus, at discharges greater than about 9,000 ft3/s, sand was either conveyed through or eroded from the reach in Marble and upper Grand Canyons.

As discharges less than 9,000 ft3/s became less common, the discharge of the river became progressively more conducive to the conveyance of sand through or the erosion of sand from Marble and upper Grand Canyons. [2]

Links and Information

Projects

Sediment Gages

Sand Mass Balance Reaches in Grand Canyon

Presentations and Papers

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2003

1999

1988

Other Stuff


Flash Flood videos