River Geomorphology, Sediment Storage, Sandbar and Campsite Monitoring in Grand Canyon
River channels and their adjacent floodplains are ever evolving in form and composition in response to changing patterns of streamflow, the quantity and size of supplied sediment, and feedbacks with the riparian and aquatic ecosystems. Changes in channel form affect aquatic and riparian habitats, which are important for plants, animals, and insects. Erosion and deposition of river channels and river banks also dramatically affects land used by people, including private property and resources on public lands. Many floodplains and river deposits also include historic and ancient artefacts and cultural sites important to human heritage.
Project Overviews
The River Geomorphology and Geomorphic Change project at the Southwest Biological Science Center's Grand Canyon Monitoring and Research Center (GCMRC) includes a range of studies concerned with describing, quantifying, and predicting geomorphic changes, mostly on large rivers in the western United States.
We use a variety of techniques to make high-resolution measurements of river channel bathymetry and topography, including laser-scanning, photogrammetry, conventional and GPS surveying, and single- and multi-beam echo sounders. We also employ a wide range of analytical tools for topographic modeling, change detection, and classification of river bottom substrate and measurement of sediment grain size.
The projects outlined on this page include:
~ Grand Canyon Sandbar Monitoring
~ Sediment Storage in Grand Canyon — Mapping the Colorado River and measuring the sand budget
~ River Campsites in Grand Canyon National Park
~ a link to the High-Flow Experiment webpage
Geomorphology Projects in Grand Canyon National Park
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,” from Lake Powell, the reservoir formed by Glen Canyon Dam.
The sediment and geomorphology projects at GCMRC include the collection and processing of data to provide information needed to conduct controlled floods and the research and monitoring needed to evaluate the outcome of each controlled flood and the long-term effects of controlled floods and normal dam operations on sediment-related resources.
Grand Canyon Sandbar Monitoring
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.
Topographic surveys are conducted annually at a collection of long-term sandbar monitoring sites to track trends in sandbar size. The data are available through interactive plots of sandbar area and volume spanning 1990 to the most recent survey.
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.
Our Findings
Five High-Flow Experiments (HFEs) 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
Access sandbar monitoring photographs (including responses to High-Flow Experiments) here:
Sediment Storage in Grand Canyon
The sandbars exposed along the shoreline of the Colorado River represent only a small fraction of the sand deposits in Grand Canyon, most of which are on the bed of the river in eddies and the channel. Monitoring of sediment storage is conducted to track changes in the supply of sand available to build sandbars.
Current management practice includes efforts to maintain and build sandbars by releasing high flows from Glen Canyon Dam that are timed to coincide with periods of fine-sediment supply from tributaries (High-flow Protocol Environmental Assessment).
The success of this approach to build sandbars depends on the maintenance of a sufficient supply of sand within the channel for rebuilding sandbars. The purpose of the sediment-storage monitoring project is to track long-term trends in sand storage and thereby provide a robust measure of whether or not the supply of sand available for building sandbars is increasing, decreasing, or remaining stable over time-scales of years to decades.
Monitoring Sediment Storage
We measure changes in sediment storage directly by making repeat topographic maps of the river bed and banks. The maps are made by surveying exposed sediment deposits with conventional total station. These measurements involve the use of a survey instrument set on a known benchmark to measure the location and elevation of points on the ground selected by a rodman equipped with a reflective target. However, most of the sediment is underwater and is measured with sonar. Multibeam sonar is the most efficient method, because it is capable of mapping wide swaths of the riverbed. Singlebeam sonar measures depths directly below the instrument and is used to map areas too shallow for the multibeam equipment, but too deep for conventional survey. All of the sonar measurements are positioned by shore-based robotic total stations that track boat position in real time. GPS is not used for any of the measurements, because satellite signals are not sufficiently reliable in the deep canyon environment.
Measurements of changes in sediment storage are also made by measuring sediment concentration in the water (see interactive web app Discharge, Sediment, and Water Quality Monitoring.)
Findings
Initial results from efforts to monitor long-term trends in sediment storage indicate that storage did not decline between 2002 and 2009. This period was one of average to above average tributary sand inputs and average to below average release of water from Glen Canyon Dam. These findings are based on a period that was favorable to sand accumulation.
Periods when dam release volumes are greater and tributary sediment inputs are less frequent will likely result in less sand accumulation. Results have also demonstrated that measurements of channel change made in short reaches (less than a few miles in length) can be used to track changes in deposits and transfers of sand among the storage locations, but the results cannot be extrapolated to long segments of the river (over 10 miles in length), because the size and distribution of sand storage locations is highly variable.
Resources
Web application for viewing maps of the riverbed: https://grandcanyon.usgs.gov/portal/home/webmap/viewer.html?webmap=a599ee6e49be4adcbb7f042bcf0fb544
River Campsites in Gand Canyon National Park
Sandbars have been used as campsites by river runners and hikers since the first expeditions to the region more than 100 years ago. Sandbar campsites continue to be an important part of the recreational experience for the more than 25,000 hikers and river runners that visit the Colorado River corridor each year.
Because the Colorado River is dominated by bedrock cliffs and steep talus slopes, sandbars provide unique areas along the river that are flat, relatively free of vegetation, easily accessible by river runners, and able to withstand high usage with negligible impact.
Campsite Monitoring
Since 1990, the Grand Canyon Monitoring and Research Center in cooperation with Northern Arizona University has been monitoring sandbars by topographic survey (https://www.usgs.gov/apps/sandbar/).
Beginning in 1998, 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 an 8-degree slope), smooth (not rocky), and clear of dense vegetation. This monitoring has shown changes in campsite area caused by vegetation expansion and sandbar erosion/deposition.
Data and Resources
-
Web application for viewing campsites and other geospatial data in Grand Canyon: https://grandcanyon.usgs.gov/gisapps/cmv-app-master-wret/viewer/index.html
-
Web application for viewing the predicted level of inundation for a 41,000 ft3/s high-flow experiment: https://grandcanyon.usgs.gov/portal/home/webmap/viewer.html?webmap=13c8070db92046d4ac3825decb1f0ca7
-
Sandbar and campsite monitoring photographs: https://grandcanyon.usgs.gov/gisapps/sandbarphotoviewer/RemoteCameraTimeSeries.html
-
Grand Canyon River Guides Adopt-a-beach photographs: https://grandcanyon.usgs.gov/gisapps/adopt-a-beach/index.html
High-Flow Experiments
To manage limited sand resources in Grand Canyon, experimental high flows, which are much higher than base-operations flows, are periodically conducted.
High-flow experiments are designed to determine if limited sediment resources can be managed to maintain or increase sandbar size. The Grand Canyon Monitoring and Research Center conducts monitoring and research studies of these experimental flows.
Click on the links below to learn about related science projects.
Rio Grande/Rio Bravo Research
River Sediment Dynamics
High-Flow Experiments on the Colorado River
Grand Canyon Streamflow and Sediment Project
Airborne Remote Sensing in Grand Canyon
Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
Geospatial Science and Technology
Connectivity of Sand Resources Along the Colorado River in Grand Canyon
GCMRC Online Maps
GCMRC Data, Web Applications, and Tools
River Valley Sediment Connectivity Data, Colorado River, Grand Canyon
Geomorphology and Campsite Data, Colorado River, Marble and Grand Canyon, Arizona
Associations between riparian plant morphological guilds and fluvial sediment dynamics along the regulated Colorado River in Grand Canyon
Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona
Geomorphology and vegetation change at Colorado River campsites, Marble and Grand Canyons, 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
Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009
Riparian vegetation, Colorado River, and climate: five decades of spatiotemporal dynamics in the Grand Canyon with river regulation
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
Colorado River campsite monitoring, Grand Canyon National Park, Arizona, 1998-2012
Monitoring fine-sediment volume in the Colorado River ecosystem, Arizona: construction and analysis of digital elevation models
Predicted Shorelines for High Flows on the Colorado River Application
This application highlights modeled flows of the Colorado River for a discharge of 41,000 cubic feet per second (cfs) that is approximate to recent (2012 - 2018) and future anticipated water releases associated with a High Flow Experiments conducted from Glen Canyon Dam near Page, Arizona. These data are to help visualize the water levels during High Flow Events in relation to othe
APPLICATION - Discharge, Sediment, and Water Quality Monitoring Application
This link launches the Grand Canyon Monitoring and Research Center’s discharge, sediment and water quality monitoring application gateway. Sediment and water quality information can be accessed from here for our on-going monitoring taking place across the Southwest U.S.
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.
River channels and their adjacent floodplains are ever evolving in form and composition in response to changing patterns of streamflow, the quantity and size of supplied sediment, and feedbacks with the riparian and aquatic ecosystems. Changes in channel form affect aquatic and riparian habitats, which are important for plants, animals, and insects. Erosion and deposition of river channels and river banks also dramatically affects land used by people, including private property and resources on public lands. Many floodplains and river deposits also include historic and ancient artefacts and cultural sites important to human heritage.
Project Overviews
The River Geomorphology and Geomorphic Change project at the Southwest Biological Science Center's Grand Canyon Monitoring and Research Center (GCMRC) includes a range of studies concerned with describing, quantifying, and predicting geomorphic changes, mostly on large rivers in the western United States.
We use a variety of techniques to make high-resolution measurements of river channel bathymetry and topography, including laser-scanning, photogrammetry, conventional and GPS surveying, and single- and multi-beam echo sounders. We also employ a wide range of analytical tools for topographic modeling, change detection, and classification of river bottom substrate and measurement of sediment grain size.
The projects outlined on this page include:
~ Grand Canyon Sandbar Monitoring
~ Sediment Storage in Grand Canyon — Mapping the Colorado River and measuring the sand budget
~ River Campsites in Grand Canyon National Park
~ a link to the High-Flow Experiment webpage
Geomorphology Projects in Grand Canyon National Park
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,” from Lake Powell, the reservoir formed by Glen Canyon Dam.
The sediment and geomorphology projects at GCMRC include the collection and processing of data to provide information needed to conduct controlled floods and the research and monitoring needed to evaluate the outcome of each controlled flood and the long-term effects of controlled floods and normal dam operations on sediment-related resources.
Grand Canyon Sandbar Monitoring
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.
Topographic surveys are conducted annually at a collection of long-term sandbar monitoring sites to track trends in sandbar size. The data are available through interactive plots of sandbar area and volume spanning 1990 to the most recent survey.
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.
Our Findings
Five High-Flow Experiments (HFEs) 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
Access sandbar monitoring photographs (including responses to High-Flow Experiments) here:
Sediment Storage in Grand Canyon
The sandbars exposed along the shoreline of the Colorado River represent only a small fraction of the sand deposits in Grand Canyon, most of which are on the bed of the river in eddies and the channel. Monitoring of sediment storage is conducted to track changes in the supply of sand available to build sandbars.
Current management practice includes efforts to maintain and build sandbars by releasing high flows from Glen Canyon Dam that are timed to coincide with periods of fine-sediment supply from tributaries (High-flow Protocol Environmental Assessment).
The success of this approach to build sandbars depends on the maintenance of a sufficient supply of sand within the channel for rebuilding sandbars. The purpose of the sediment-storage monitoring project is to track long-term trends in sand storage and thereby provide a robust measure of whether or not the supply of sand available for building sandbars is increasing, decreasing, or remaining stable over time-scales of years to decades.
Monitoring Sediment Storage
We measure changes in sediment storage directly by making repeat topographic maps of the river bed and banks. The maps are made by surveying exposed sediment deposits with conventional total station. These measurements involve the use of a survey instrument set on a known benchmark to measure the location and elevation of points on the ground selected by a rodman equipped with a reflective target. However, most of the sediment is underwater and is measured with sonar. Multibeam sonar is the most efficient method, because it is capable of mapping wide swaths of the riverbed. Singlebeam sonar measures depths directly below the instrument and is used to map areas too shallow for the multibeam equipment, but too deep for conventional survey. All of the sonar measurements are positioned by shore-based robotic total stations that track boat position in real time. GPS is not used for any of the measurements, because satellite signals are not sufficiently reliable in the deep canyon environment.
Measurements of changes in sediment storage are also made by measuring sediment concentration in the water (see interactive web app Discharge, Sediment, and Water Quality Monitoring.)
Findings
Initial results from efforts to monitor long-term trends in sediment storage indicate that storage did not decline between 2002 and 2009. This period was one of average to above average tributary sand inputs and average to below average release of water from Glen Canyon Dam. These findings are based on a period that was favorable to sand accumulation.
Periods when dam release volumes are greater and tributary sediment inputs are less frequent will likely result in less sand accumulation. Results have also demonstrated that measurements of channel change made in short reaches (less than a few miles in length) can be used to track changes in deposits and transfers of sand among the storage locations, but the results cannot be extrapolated to long segments of the river (over 10 miles in length), because the size and distribution of sand storage locations is highly variable.
Resources
Web application for viewing maps of the riverbed: https://grandcanyon.usgs.gov/portal/home/webmap/viewer.html?webmap=a599ee6e49be4adcbb7f042bcf0fb544
River Campsites in Gand Canyon National Park
Sandbars have been used as campsites by river runners and hikers since the first expeditions to the region more than 100 years ago. Sandbar campsites continue to be an important part of the recreational experience for the more than 25,000 hikers and river runners that visit the Colorado River corridor each year.
Because the Colorado River is dominated by bedrock cliffs and steep talus slopes, sandbars provide unique areas along the river that are flat, relatively free of vegetation, easily accessible by river runners, and able to withstand high usage with negligible impact.
Campsite Monitoring
Since 1990, the Grand Canyon Monitoring and Research Center in cooperation with Northern Arizona University has been monitoring sandbars by topographic survey (https://www.usgs.gov/apps/sandbar/).
Beginning in 1998, 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 an 8-degree slope), smooth (not rocky), and clear of dense vegetation. This monitoring has shown changes in campsite area caused by vegetation expansion and sandbar erosion/deposition.
Data and Resources
-
Web application for viewing campsites and other geospatial data in Grand Canyon: https://grandcanyon.usgs.gov/gisapps/cmv-app-master-wret/viewer/index.html
-
Web application for viewing the predicted level of inundation for a 41,000 ft3/s high-flow experiment: https://grandcanyon.usgs.gov/portal/home/webmap/viewer.html?webmap=13c8070db92046d4ac3825decb1f0ca7
-
Sandbar and campsite monitoring photographs: https://grandcanyon.usgs.gov/gisapps/sandbarphotoviewer/RemoteCameraTimeSeries.html
-
Grand Canyon River Guides Adopt-a-beach photographs: https://grandcanyon.usgs.gov/gisapps/adopt-a-beach/index.html
High-Flow Experiments
To manage limited sand resources in Grand Canyon, experimental high flows, which are much higher than base-operations flows, are periodically conducted.
High-flow experiments are designed to determine if limited sediment resources can be managed to maintain or increase sandbar size. The Grand Canyon Monitoring and Research Center conducts monitoring and research studies of these experimental flows.
Click on the links below to learn about related science projects.
Rio Grande/Rio Bravo Research
River Sediment Dynamics
High-Flow Experiments on the Colorado River
Grand Canyon Streamflow and Sediment Project
Airborne Remote Sensing in Grand Canyon
Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
Geospatial Science and Technology
Connectivity of Sand Resources Along the Colorado River in Grand Canyon
GCMRC Online Maps
GCMRC Data, Web Applications, and Tools
River Valley Sediment Connectivity Data, Colorado River, Grand Canyon
Geomorphology and Campsite Data, Colorado River, Marble and Grand Canyon, Arizona
Associations between riparian plant morphological guilds and fluvial sediment dynamics along the regulated Colorado River in Grand Canyon
Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona
Geomorphology and vegetation change at Colorado River campsites, Marble and Grand Canyons, 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
Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009
Riparian vegetation, Colorado River, and climate: five decades of spatiotemporal dynamics in the Grand Canyon with river regulation
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
Colorado River campsite monitoring, Grand Canyon National Park, Arizona, 1998-2012
Monitoring fine-sediment volume in the Colorado River ecosystem, Arizona: construction and analysis of digital elevation models
Predicted Shorelines for High Flows on the Colorado River Application
This application highlights modeled flows of the Colorado River for a discharge of 41,000 cubic feet per second (cfs) that is approximate to recent (2012 - 2018) and future anticipated water releases associated with a High Flow Experiments conducted from Glen Canyon Dam near Page, Arizona. These data are to help visualize the water levels during High Flow Events in relation to othe
APPLICATION - Discharge, Sediment, and Water Quality Monitoring Application
This link launches the Grand Canyon Monitoring and Research Center’s discharge, sediment and water quality monitoring application gateway. Sediment and water quality information can be accessed from here for our on-going monitoring taking place across the Southwest U.S.
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.