Since the completion of Glen Canyon Dam in 1963, the amount of sand supplied to Grand Canyon National Park has been reduced by more than 90 percent. The Paria River, a tributary to the Colorado River 15 miles downstream from the dam, is now the single most important supplier of sand to the Colorado River within the Park. This large reduction in sand supply has resulted in substantial decrease in the number and size of sandbars. Sandbars are important because they serve as campsites for river runner and hikers, provide important aquatic and riparian habitats, and are the source of sand that may help protect archaeological sites. The information collected by this project will be used to determine whether dam operations, including High-flow Experiments, cause increases or decreases in sandbars and associated campsites in Grand Canyon National Park.
The Sandbar Monitoring Data
Currently, topographic maps are made at a set of monitoring sites annually using conventional survey equipment. These surveys are used to calculate the size of each sandbar in terms of the area of exposed sand and the volume of sand contained in the bar. Both of these calculations are relative to an elevation of interest.
Recent Findings
Each of the five High-flow Experiments (HFEs) that has been released from Glen Canyon Dam between November 2012 and November 2018 resulted in deposition at more than 50 percent of 44 long-term sandbar monitoring sites in Marble Canyon and Grand Canyon. That deposition also resulted in small cumulative increases in sandbar volume at those same monitoring sites. Cumulative increases in sand volume between 2003 and 2018 are significant at two sandbar types—reattachment bars and upper pool bars. Hydrograph shape appears to affect sandbar topography for at least some sites. The lower downramp rate used in 2012 resulted in sandbar topography that was less steep compared to the downramp rate used in the 2008 HFE. However, because the adjusted hydrograph with lower downramp rate was tested in only one year and because topographic surveys were only available for three sites, it is uncertain whether this response would be consistent among many sites or repeatable in future HFEs.
In four out of the five years with HFEs, the sand mass balance for the July 1 to December 1 accounting period for all five account years has been significantly positive and in one year the sand mass balance was indeterminant. Thus, the objective HFEs to cause deposition on sandbars and increases in sandbar size without causing decreases in sand storage in Marble Canyon was achieved or exceeded each year.
Data and Resources
Sandbar monitoring data: GCMRC - Sandbar Monitoring (usgs.gov)
Sandbar monitoring photographs (including responses to High-flow Experiments): https://grandcanyon.usgs.gov/gisapps/sandbarphotoviewer/RemoteCameraTimeSeries.html
Below are other science projects associated with this project.
River Geomorphology and Geomorphic Change
Sediment Storage in Grand Canyon
River Campsites in Grand Canyon National Park
High-Flow Experiments on the Colorado River
Below are data or web applications associated with this project.
River Valley Sediment Connectivity Data, Colorado River, Grand Canyon
Below are publications associated with this project.
Quantifying and forecasting changes in the areal extent of river valley sediment in response to altered hydrology and land cover
Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona
Automated remote cameras for monitoring alluvial sandbars on the Colorado River in Grand Canyon, Arizona
Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon
Using oblique digital photography for alluvial sandbar monitoring and low-cost change detection
Long-term monitoring of sandbars on the Colorado River in Grand Canyon using remote sensing
Building sandbars in the Grand Canyon
Use of flux and morphologic sediment budgets for sandbar monitoring on the Colorado River in Marble Canyon, Arizona
The influence of controlled floods on fine sediment storage in debris fan-affected canyons of the Colorado River basin
A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change
2008 High-flow experiment at Glen Canyon Dam: Morphologic response of eddy-deposited sandbars and associated aquatic backwater habitats along the Colorado River in Grand Canyon National Park
Sandbar response in Marble and Grand Canyons, Arizona, following the 2008 high-flow experiment on the Colorado River
Below are data or web applications associated with this project.
APPLICATION - Grand Canyon Sandbar Monitoring
Several applications related to the Grand Canyon Monitoring and Research Center’s long-term sandbar monitoring project can be accessed here, including the sandbar area and volume tool and applications highlighting changes to sandbars as a result of High-Flow Events (HFEs) conducted by Glen Canyon Dam near Page, Arizona.
Below are partners associated with this project.
Since the completion of Glen Canyon Dam in 1963, the amount of sand supplied to Grand Canyon National Park has been reduced by more than 90 percent. The Paria River, a tributary to the Colorado River 15 miles downstream from the dam, is now the single most important supplier of sand to the Colorado River within the Park. This large reduction in sand supply has resulted in substantial decrease in the number and size of sandbars. Sandbars are important because they serve as campsites for river runner and hikers, provide important aquatic and riparian habitats, and are the source of sand that may help protect archaeological sites. The information collected by this project will be used to determine whether dam operations, including High-flow Experiments, cause increases or decreases in sandbars and associated campsites in Grand Canyon National Park.
The Sandbar Monitoring Data
Currently, topographic maps are made at a set of monitoring sites annually using conventional survey equipment. These surveys are used to calculate the size of each sandbar in terms of the area of exposed sand and the volume of sand contained in the bar. Both of these calculations are relative to an elevation of interest.
Recent Findings
Each of the five High-flow Experiments (HFEs) that has been released from Glen Canyon Dam between November 2012 and November 2018 resulted in deposition at more than 50 percent of 44 long-term sandbar monitoring sites in Marble Canyon and Grand Canyon. That deposition also resulted in small cumulative increases in sandbar volume at those same monitoring sites. Cumulative increases in sand volume between 2003 and 2018 are significant at two sandbar types—reattachment bars and upper pool bars. Hydrograph shape appears to affect sandbar topography for at least some sites. The lower downramp rate used in 2012 resulted in sandbar topography that was less steep compared to the downramp rate used in the 2008 HFE. However, because the adjusted hydrograph with lower downramp rate was tested in only one year and because topographic surveys were only available for three sites, it is uncertain whether this response would be consistent among many sites or repeatable in future HFEs.
In four out of the five years with HFEs, the sand mass balance for the July 1 to December 1 accounting period for all five account years has been significantly positive and in one year the sand mass balance was indeterminant. Thus, the objective HFEs to cause deposition on sandbars and increases in sandbar size without causing decreases in sand storage in Marble Canyon was achieved or exceeded each year.
Data and Resources
Sandbar monitoring data: GCMRC - Sandbar Monitoring (usgs.gov)
Sandbar monitoring photographs (including responses to High-flow Experiments): https://grandcanyon.usgs.gov/gisapps/sandbarphotoviewer/RemoteCameraTimeSeries.html
Below are other science projects associated with this project.
River Geomorphology and Geomorphic Change
Sediment Storage in Grand Canyon
River Campsites in Grand Canyon National Park
High-Flow Experiments on the Colorado River
Below are data or web applications associated with this project.
River Valley Sediment Connectivity Data, Colorado River, Grand Canyon
Below are publications associated with this project.
Quantifying and forecasting changes in the areal extent of river valley sediment in response to altered hydrology and land cover
Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona
Automated remote cameras for monitoring alluvial sandbars on the Colorado River in Grand Canyon, Arizona
Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon
Using oblique digital photography for alluvial sandbar monitoring and low-cost change detection
Long-term monitoring of sandbars on the Colorado River in Grand Canyon using remote sensing
Building sandbars in the Grand Canyon
Use of flux and morphologic sediment budgets for sandbar monitoring on the Colorado River in Marble Canyon, Arizona
The influence of controlled floods on fine sediment storage in debris fan-affected canyons of the Colorado River basin
A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change
2008 High-flow experiment at Glen Canyon Dam: Morphologic response of eddy-deposited sandbars and associated aquatic backwater habitats along the Colorado River in Grand Canyon National Park
Sandbar response in Marble and Grand Canyons, Arizona, following the 2008 high-flow experiment on the Colorado River
Below are data or web applications associated with this project.
APPLICATION - Grand Canyon Sandbar Monitoring
Several applications related to the Grand Canyon Monitoring and Research Center’s long-term sandbar monitoring project can be accessed here, including the sandbar area and volume tool and applications highlighting changes to sandbars as a result of High-Flow Events (HFEs) conducted by Glen Canyon Dam near Page, Arizona.
Below are partners associated with this project.