Difference between revisions of "GCDAMP Sediment"

Latest revision as of 15:30, 17 September 2026

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

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

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

Metrics

Performance Metric:

Sand Bar Volume (includes multiple “sub-metrics”, e.g., normalized sandbar volume by type, mean sand bar response to HFEs)

Surveillance Metrics:

Sand Supply By River Segment (Sand Mass Balance)
Silt & Clay Retention by River Segment (Turbidity)

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Updates
https://www.usbr.gov/uc/progact/amp/twg/2022-01-13-twg-meeting/20220113-AnnualReportingMeeting-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf https://www.usbr.gov/uc/progact/amp/twg/2022-01-13-twg-meeting/20220113-AnnualReportingMeeting-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR3_Grams.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/15jun11/Attach_02,.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR02_Grams.pdf
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]
How long is sand stored on the bed of the river?
Bedrock-canyon rivers tend to be supply limited because they are efficient transporters of sediment and not because the upstream supply of sediment is small. Following episodic tributary floods that supply finer sand, sand migrates quickly downstream in the form of a wave in which large systematic changes in bed-sand grain size occur. The tributary fine-sediment (i.e., sand, silt, and clay) supply to the Colorado River in our study area is bimodal, with a clay primary mode and a sand-silt secondary mode. The tributary sand supply grades smoothly into the silt-and-clay supply such that the sand-size sediment comprises the coarser part of this secondary mode, which occurs in very fine sand (0.0625–0.125 mm) for the Paria River and in medium silt (0.0156–0.0312 mm) for the LCR. Both tributaries supply more silt and clay to the Colorado River than they do sand. During sediment years 1998–2017, silt and clay comprised 60.6% and 88.1% of the fine sediment supplied by the Paria River and LCR, respectively. Of the total amount of sand supplied since 2011, the Paria River has contributed 57%, the LCR has contributed 21%, and all other tributaries combined have contributed 22%. The largest quantities of sand are supplied by the Paria River and LCR during summer thunderstorm-generated floods that last hours to a day. Large sand loads are rare during winter and spring months on both rivers. Our late-1990s observations suggested that tributary floods generated sand waves that split into two packets, A and B: packet A was finer than packet B and migrated downstream in the Colorado River with a celerity slightly slower than the water velocity. Packet B migrated much more slowly than packet A; the amalgamated front of packet B had migrated only ∼10 km in the 3 and 10 days after two Paria River floods. The primary peak in QSAND—1/βQ cross covariance decays to background within 7–20 days of a tributary flood at all but the RK49 station, thus indicating that much of packet A exits our study area quickly. The lower celerity of packet B causes the secondary cross-covariance peak to become distinct from the primary peak with increasing distance downstream. Following a Paria River flood, the secondary peak (packet B) separates from the primary peak (packet A) between the RK49 and RK99 stations, and it takes ∼198 and ∼290 days for the tail of packet B to respectively reach these stations. Following an LCR flood, packet B separates from packet A upstream from the RK141 station, and it takes ∼261 days for the tail of packet B to reach this station. [3]
Sediment Augmentation
Randle, T.J., Lyons, J.K., Christensen, R.J., and Stephen, R.D., 2007, Colorado River ecosystem sediment augmentation appraisal engineering report: Bureau of Reclamation, Technical Service Center, Sedimentation and River Hydraulics Group, Denver, Colorado, 71 p. Grand Canyon sediment augmentation would have two primary purposes: Seasonally increase the turbidity of the Colorado River to provide cover for native and endangered fish during the months of May through December. This is the period when young-of-the year humpback chub emerge from the Little Colorado River and then rear in the Colorado River (U.S. Department of the Interior, Bureau of Reclamation, 1995). These native fish evolved in a turbid environment and may use it for cover from potential predators. Annually increase the sand supply to the Colorado River during beach-building flows to build larger sandbars, especially in Marble Canyon, through fluvial processes. Sediment slurry pipelines that would deliver sediment from the Navajo Canyon arm of Lake Powell to the Colorado River below Glen Canyon Dam or near Lees Ferry are believed to be technically feasible. Five sediment augmentation alternatives have been formulated and evaluated. Alternatives are available to deliver fine sediment and sand to the Colorado River, either below Glen Canyon Dam or near Lees Ferry. Attempts have been made to formulate each alternative to minimize environmental impacts and to avoid cultural resource impacts. No major environmental impacts for any of the five alternatives have been identified at this time. Sediment source areas in Lake Powell seem to be the most logical choice because of cost and because the sediments in Lake Powell would have naturally reached the Colorado River below the site of Glen Canyon Dam. Sediment source areas in Navajo Canyon are much closer to Glen Canyon Dam than other major source areas in Lake Powell. Laboratory analysis of one sediment sample from Navajo Canyon did not detect any contaminants above background levels. A more intensive sediment sampling program would be needed to verify if this finding is applicable to more of the sediments within Navajo Canyon. Although the present and future sedimentation volumes in Navajo Canyon may not be enough to sustain a Grand Canyon sediment augmentation program over the long term, the volumes should be sufficient for one or two decades (see figure 8). Sediments in Navajo Canyon could be dredged first and then the submerged slurry pipelines and floating pumping stations could be moved to an upstream source such as the Escalante River or San Juan River deltas. Sediment slurry pipelines can deliver large quantities of sediment, and over long distances, much more efficiently and at less cost than barges or trucks. Submerging sediment slurry pipelines in Lake Powell appears to be a viable option with much less impact than overland routes from major sediment source areas in Lake Powell where no direct roads presently exist. The augmentation of fine sediment should be considered in conjunction with alternatives that would increase the summer water temperatures released from Glen Canyon Dam (e.g., selective withdrawal of water from Lake Powell). Native and endangered fish in Grand Canyon National Park are impacted by less turbidity and colder water temperatures in summer compared to natural conditions (U.S. Department of the Interior, Bureau of Reclamation, 1995). Turbidity may provide native fish with cover from predation. In the absence of turbid conditions, native fish tend not to be active during the day (U.S. Department of the Interior, Bureau of Reclamation, 1995). Although, colder water temperatures may impact young-of-the-year native fish in summer, the colder temperatures may also keep non-native warm-water fish from migrating upstream through Grand Canyon National Park. If water temperatures are increased, there is a concern that non-native warm-water fish may have the advantage (U.S. Department of the Interior, Bureau of Reclamation, 1995). The augmentation of fine sediment may provide the necessary cover for native and endangered fish.

Links and Information
GCMRC Annual Reports page GCMRC Grand Canyon Sandbar Monitoring The High Flow Experiment (HFE) Page Recreation Page Aeolian Sand Transport Page Turbidity Page Over Flights Page
Projects
Sandbar Monitoring Campsite Monitoring Suspended Sediment Transport Automated Substrate Classification Using Swath Mapping Systems Sediment Storage Underwater Photography to Measure Bed Grain Size
Sediment Gages
Water Holes Canyon above the mouth Paria River near Kanab, UT Paria River at Lees Ferry, AZ Colorado River at Lees Ferry Badger Creek below highway 89A near Vermillion Cliffs, AZ Tanner Wash below highway 89A near Bitter Springs, AZ House Rock Wash above Emmett Wash near Cliff Dwellers, AZ North Canyon near Cliff Dwellers, AZ Shinumo Wash in Twentynine Mile Canyon near Cedar Ridge, AZ Colorado River near river mile 30 Colorado River above Little Colorado River near Desert View, AZ Moenkopi Wash near Cameron, AZ Little Colorado River at Grand Falls, AZ Little Colorado River at Cameron, AZ Little Colorado River near Cameron, AZ Little Colorado River above the mouth near Desert View, AZ Colorado River near Grand Canyon, AZ Bright Angel Creek near Grand Canyon, AZ Shinumo Creek Kanab Creek above the mouth near Supai, AZ Havasu Creek above the mouth near Supai, AZ Colorado River above National Canyon near Supai, AZ Colorado River above Diamond Creek near Peach Springs, AZ
Sand Mass Balance Reaches in Grand Canyon
Upper Marble Canyon Lower Marble Canyon Eastern Grand Canyon East Central Grand Canyon West Central Grand Canyon Western Grand Canyon and the Lake Mead Delta
Presentations and Papers
2026 Interdisciplinary Sediment, Riparian Vegetation, and Cultural Resource Science Evaluation of LTEMP sand management Riverbed and Sandbar Response to Glen Canyon Dam Operations and High-Flow Experiments Evaluation of LTEMP sand management Reservoir Operational Strategies for Sustainable Sand Management in the Colorado River 2025 Goal 7 Metrics: Sediment Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem 2024 Project B Update and Riverbed and sandbar response to dam operations and high-flow experiments Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem Effects of Reservoirs and Stock Ponds on Surface Water Runoff in the Little Colorado River Basin Assessing geomorphic change for 454 river km of the Colorado River in Grand Canyon, AZ via continuous and high-resolution water surface and bed profiles Hydrodynamic modeling of the Colorado River between Glen Canyon Dam and Lees Ferry, Arizona 2024 Griffiths et al., 2024, Changes in sand storage in the Colorado River in Grand Canyon National Park from July 2017 through June 2020 Channel Response to High Flows in Western Grand Canyon Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem Project B Update and Riverbed and sandbar response to dam operations and high-flow experiments 2023 A Continuous High-Resolution Profile of the Riverbed and Water Surface for 460-km of the Colorado River in Grand Canyon Project A: Streamflow, Sediment, and Vegetation Dynamics; Implications for Geomorphic Change in the Colorado River and its Tributaries Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem Numerical Modeling of Mud Transport, Storage, and Release on the Colorado River, Arizona 2022 Multi-Decadal Sandbar Response to Flow Management Downstream from a Large Dam-The Glen Canyon Dam on the Colorado River in Marble and Grand Canyons, AZ Summary of Sediment and Sandbar Projects GCMRC Projects A and B LTEMP Goal 7 Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem 2021 Argonne. 2021. Evaluation of Sand Augmentation for Stabilizing Recreational Beaches and Storing Sand in Glen Canyon National Recreation Area A simple morphodynamic model to rapidly evaluate sandbar rebuilding during controlled floods Topping et al. 2021, Self-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size: Journal of Geophysical Research: Earth Surface Alvarez et al. 2021, An eddy-resolving numerical model to study turbulent flow, sediment, and bed evolution using detached eddy simulation in a lateral separation zone at the field-scale: Journal of Geophysical Research—Earth Surface Sand Supply, Transport and Deposition 2020 Rubin et al., 2020, Causes of variability in suspended‐sand concentration evaluated using measurements in the Colorado River in Grand Canyon: JGR Earth Surface GCMRC 2019 Annual Reporting Meeting Overview – Part 3 Chapman et al., 2020, Estimating the contribution of tributary sand inputs to controlled flood deposits for sandbar restoration using elemental tracers, Colorado River, Grand Canyon National Park, Arizona: GSA Bulletin Associated data Project B: Effects of dam releases on in-channel sediment storage and sandbar dynamics Ashley et al., 2020, Estimating bedload from suspended load and water discharge in sand bed rivers: Water Resources Research. Geomorphic Change and Biogeomorphic Feedbacks in the Little Colorado River, Arizona 2019 Dean, D.J., and Topping, D.J., 2019, Geomorphic change and biogeomorphic feedbacks in a dryland river--The Little Colorado River, Arizona, USA: GSA Bulletin 2018 Sand tells a story Sankey et al., 2018, Sand classifications along the Colorado River in Grand Canyon derived from 2002, 2009, and 2013 high-resolution multispectral airborne imagery: U.S. Geological Survey data release GCMRC Science Updates PPT Hadley et al., 2018, Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona: River Research and Applications Key drivers of sand transport and storage in the Colorado River Ecosystem PPT Voichick, N. et al., 2018, Technical note--False low turbidity readings during high suspended-sediment concentrations: Hydrology and Earth System Sciences Grams et al., 2018, Automated remote cameras for monitoring alluvial sandbars on the Colorado River in Grand Canyon, Arizona: Open-File Report 2017 Chapman, K., 2017, Determining the tributary sediment contribution to experimental flood deposits on the Colorado River in Marble Canyon, Grand Canyon, Arizona: Flagstaff, Northern Arizona University, MS thesis Hamill, D., 2017, Quantifying riverbed sediment using recreational-grade side scan sonar: Logan, Utah State University, MS thesis Buscombe et al., 2017, Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds: Journal of Geophysical Research: Earth Surface Griffiths and Topping, 2017, Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets: Geomorphology Kaplinski et al. 2017. Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009: U.S. Geological Survey Open-File Report 2017–1030 Project 1: Streamflow, Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem Project 2: Hydrologic Change and the Geomorphic Transformation of the Little Colorado River: Implications for Sediment Delivery to the Grand Canyon Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent High-flow Experiments and Long-term Trends 2016 Topping et al. 2016. Long-term continuous acoustical suspended-sediment measurements in rivers — Theory, application, bias, and error: U.S. Geological Survey Professional Paper 1823 Sandbar Modeling Project Update Status of Sediment Resources – August 2016 Grand Canyon Monitoring and Research Center Science Updates and PPT (BO Compliance, Trout Updates, Green Sunfish, Fisheries PEP, Partners in Science) Observations of sand dune migration on the Colorado River in Grand Canyon using high-resolution multibeam bathymetry Project 2: Streamflow, Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent high-flow Experiments and Long-Term Trends 2015 Grams et al. 2015. Building Sandbars in the Grand Canyon, EOS, Trans. Am. Geophys. Union Alvarez. 2015. Turbulence, Sediment Transport, Erosion, and Sandbar Beach Failure Processes in Grand Canyon. Ph.D. Dissertation, Arizona State University, Tempe, AZ GCMRC Science Update - Sediment GCMRC Science Update - Sediment Updates on 2014 HFE, Paria sediment inputs, and sediment mass balance Glen Canyon Tailwater Fishery “Integrating Fish and Channel Mapping” GCMRC’s Online Mapping and GIS Resources Streamflow, Water Quality, and Sediment Transport in the Colorado River Ecosystem Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent High-flow Experiments and Long-term Trends 2014 Science Updates - Recent Research on Sand, Bugs, and Fish Sandbars and Sand Storage in Marble and Grand Canyons (Grams) Processing fine sediment transport data: procedures, processing, and bottlenecks (Griffiths) 2013 Alvarez and Schmeeckle. 2013. Erosion of river sandbars by diurnal stage fluctuations in the Colorado river in the Marble and Grand Canyons: Full-scale laboratory experiments GCMRC Update - Status of Resources and Sediment Conditions Present Status of Sediment Resources-August 2013 Science Updates - Overflights, Riparian Vegetation, and Sediment 2013 Overflight Wrap up GCMRC Science Update on Sediment and Fisheries Sediment Monitoring Program: Sediment Delivery from Tributaries and Sediment Transport by Colorado River Sandbar Monitoring for November 2012 Controlled Flood 2012 GCMRC Updates and Sediment Update E-mail to TWG with Sediment Model Link GCMRC Updates and PPT Sandbars and In-Channel Sand Storage: Short-Term Dynamics and Long-Term Trends Physical controls on sediment deposition, erosion, and transport Geomorphic Framework & Role of Debris Flows Suspended-Sediment Transport and Sandbars Glen Canyon Dam Operations -Post-EIS Summary A Conversation about Rivers and Dams Modeling 101 2011 GCMRC Updates Update on Sand Mass Balance with Modeling 2010 Wright, S.A., and Grams, P.E., 2010, Evaluation of Water Year 2011 Glen Canyon Dam flow release scenarios on downstream sand storage along the Colorado River in Arizona: U.S. Geological Survey Open-File Report 2010-1133 Update on Water Quality and 2010 Sand Input Grand Canyon Monitoring and Research Updates and the Following Open File Reports: 1) Evaluation of Water Year 2011 Glen Canyon Dam Flow Release Scenarios on Downstream Sand Storage Along the Colorado River in Arizona, and 2) An Approach to Modeling Sediment Budgets in Supply-limited Rivers Report on Sediment Modeling to Support Development of 2011 Hydrograph Update on 2010 Sediment Inputs Temperature Control Device and Sediment Augmentation Report TWG Chair Temperature Control Device/Sediment Augmentation Minutes from June 21, 2010, TWG Webinar/Conference Call with Memo from John Hamill to Shane Capron dated May 17, 2010, Subject: TWG and stakeholder requests for GCMRC to evaluate the effects of various dam operation scenarios on sediment storage and loss in the Grand Canyon with Open File Report 2010-1133 Mechanics and Modeling of Flow, Sediment Transport and Morphologic Change in Riverine Lateral Separation Zones Sediment and Temperature Modeling Update PPT as presented at January 2010 Annual Reporting Meeting AIF: Temperature Control Device and Sediment Augmentation and PPT 2009 Selective Withdrawal and Sediment Augmentation Update PPT Grand Canyon Monitoring and Research Center Updates Sandbar Evolution: Extending the Historical Perspective PPT AIF: Grand Canyon Monitoring and Research Center (GCMRC) Update Water Quality and Sediment, 2008 High Flow Experiment, and Integrated Flow, Temperature, and Sediment Modeling PPT Grand Canyon Monitoring and Research Center updates by Program Managers Diamond Creek Gage Discontinuation 2008 Is there enough sand? Evaluating the fate of Grand Canyon sandbars 2007 Randle et al. 2007. Colorado River Ecosystem Sediment Augmentation Appraisal Engineering Report 2003 Topping et al. 2003. Computation and analysis of the instantaneous-discharge record for the Colorado River at Lees Ferry, Arizona, May 8, 1921 through September 30, 2000: U.S. Geological Survey Professional Paper 1677 1999 Floods and Sandbars in the Grand Canyon, a publication of the Geological Society of America (published in GSA Today, April 1999) 1988 Schmidt and Graf, 1988, Aggradation and degradation of alluvial sand deposits, 1965 to 1986, OFR 87-561
Other Stuff
Eddies occur adjacent to rapids and the flow in the eddy is related to the flow characteristics in the rapid. Sand bars were typically larger before the dam.(Science Background for HFE Planning- Jack Schmidt, GCMRC_KA 2013) Sediment Presentation- AMWG Jan 2002 Sediment White Paper- AMWG Jan 2002 The United States Geological Survey estimates that the Colorado River below Glen Canyon Dam only has 6 percent of the sediment that it received before the Glen Canyon Dam was built in the 1960s. Flash Flood videos Paria River Flash Flood 8/3/16 Buckskin Gulch Flash Flood 8/4/16 Buckskin Wash Flash Flood / Debris Flow 2013 Paria River Flash Flood / Debris Flow 8/19/12 Glen Canyon and Page Arizona Flooding May 22 2009

Difference between revisions of "GCDAMP Sediment"

Latest revision as of 15:30, 17 September 2026

Sediment and Geomorphology

LTEMP Resource Goal

Desired Future Condition

Metrics

Updates

Sediment transport and river discharge

How long is sand stored on the bed of the river?

Sediment Augmentation

Links and Information

Projects

Sediment Gages

Sand Mass Balance Reaches in Grand Canyon

Presentations and Papers

Other Stuff

Flash Flood videos

Navigation menu

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@@ Line 16: / Line 16: @@
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-[[File:Paria at mainstem.jpg|300px‎]]
+[[File:Paria at mainstem.jpg|center|thumbnail|400px|The Paria River flowing into the mainstem Colorado River‎]]<br>
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-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 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.
+==[http://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Home_Page.aspx '''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 [http://gcdamp.com/index.php?title=The_HFE_Page '''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. [https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Home_Page.aspx]
+Beginning in 1998, [http://gcdamp.com/index.php?title=RECREATION '''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.
+==[http://gcdamp.com/index.php?title=Long-term_Experimental_and_Management_Plan_(LTEMP) '''LTEMP Resource Goal''']==
+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:'''<br>
+==[http://gcdamp.com/index.php?title=Portal:Desired_Future_Conditions_-DFCs '''Desired Future Condition''']==
 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<br>
 • Nearshore habitats for native fish<br>
@@ Line 30: / Line 42: @@
 • Cultural resource preservation<br>
 • Maintenance of camping beaches<br>
+==[[Media:USGS GCMRC Status of LTEMP Metrics Report Dec11 2025-508Comp.pdf| '''Metrics''']]==
+Performance Metric:
+*Sand Bar Volume (includes multiple “sub-metrics”, e.g., normalized sandbar volume by type, mean sand bar response to HFEs)
+Surveillance Metrics:
+*Sand Supply By River Segment (Sand Mass Balance)
+*Silt & Clay Retention by River Segment (Turbidity)
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-! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#000; padding:0.2em 0.4em;">Updates</h2>
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#000; padding:0.2em 0.4em;"> Updates  </h2>
+|-
+|style="color:#000;"|
+[[File:SedimentSustainability.PNG|center|thumbnail|500px|https://www.usbr.gov/uc/progact/amp/twg/2022-01-13-twg-meeting/20220113-AnnualReportingMeeting-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf ]]
+[[File:LongtermDecline.PNG|center|thumbnail|500px|https://www.usbr.gov/uc/progact/amp/twg/2022-01-13-twg-meeting/20220113-AnnualReportingMeeting-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf ]]
+[[File:SandbarMonitoring2016.jpg|center|thumbnail|500px|[https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR3_Grams.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR3_Grams.pdf] ]]
+[[File:2012 2014 HFE response.jpg|center|thumbnail|500px|[https://www.usbr.gov/uc/rm/amp/twg/mtgs/15jun11/Attach_02,.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/15jun11/Attach_02,.pdf] ]]
+[[File:2016 SedimentSummary.jpg|center|thumbnail|500px|[https://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR02_Grams.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR02_Grams.pdf] ]]
+|-
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;"> Sediment transport and river discharge </h2>
 |-
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-[[File:Sandbars 1990 2014.jpg|600px]]
+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. [https://pubs.usgs.gov/pp/pp1677/pdf/pp1677.pdf]
+|-
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;"> How long is sand stored on the bed of the river? </h2>
+|-
+|style="color:#000;"|
+Bedrock-canyon rivers tend to be supply limited because they are efficient transporters of sediment and not because the upstream supply of sediment is small. Following episodic tributary floods that supply finer sand, sand migrates quickly downstream in the form of a wave in which large systematic changes in bed-sand grain size occur. The tributary fine-sediment (i.e., sand, silt, and clay) supply to the Colorado River in our study area is bimodal, with a clay primary mode and a sand-silt secondary mode. The tributary sand supply grades smoothly into the silt-and-clay supply such that the sand-size sediment comprises the coarser part of this secondary mode, which occurs in very fine sand (0.0625–0.125 mm) for the Paria River and in medium silt (0.0156–0.0312 mm) for the LCR. Both tributaries supply more silt and clay to the Colorado River than they do sand. During sediment years 1998–2017, silt and clay comprised 60.6% and 88.1% of the fine sediment supplied by the Paria River and LCR, respectively. Of the total amount of sand supplied since 2011, the Paria River has contributed 57%, the LCR has contributed 21%, and all other tributaries combined have contributed 22%. The largest quantities of sand are supplied by the Paria River and LCR during summer thunderstorm-generated floods that last hours to a day. Large sand loads are rare during winter and spring months on both rivers.
+Our late-1990s observations suggested that tributary floods generated sand waves that split into two packets, A and B: packet A was finer than packet B and migrated downstream in the Colorado River with a celerity slightly slower than the water velocity. Packet B migrated much more slowly than packet A; the amalgamated front of packet B had migrated only ∼10 km in the 3 and 10 days after two Paria River floods. The primary peak in QSAND—1/βQ cross covariance decays to background within 7–20 days of a tributary flood at all but the RK49 station, thus indicating that much of packet A exits our study area quickly. The lower celerity of packet B causes the secondary cross-covariance peak to become distinct from the primary peak with increasing distance downstream. '''Following a Paria River flood, the secondary peak (packet B) separates from the primary peak (packet A) between the RK49 and RK99 stations, and it takes ∼198 and ∼290 days for the tail of packet B to respectively reach these stations. Following an LCR flood, packet B separates from packet A upstream from the RK141 station, and it takes ∼261 days for the tail of packet B to reach this station.''' [https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2020JF005565]
+|-
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;"> Sediment Augmentation </h2>
+|-
+|style="color:#000;"|
+[http://www.riversimulator.org/Resources/USBR/LTEP/Randle2007.pdf Randle, T.J., Lyons, J.K., Christensen, R.J., and Stephen, R.D., 2007, Colorado River ecosystem sediment augmentation appraisal engineering report: Bureau of Reclamation, Technical Service Center, Sedimentation and River Hydraulics Group, Denver, Colorado, 71 p.]
+Grand Canyon sediment augmentation would have two primary purposes:
+#Seasonally increase the turbidity of the Colorado River to provide cover for native and endangered fish during the months of May through December. This is the period when young-of-the year humpback chub emerge from the Little Colorado River and then rear in the Colorado River (U.S. Department of the Interior, Bureau of Reclamation, 1995). These native fish evolved in a turbid environment and may use it for cover from potential predators.
+#Annually increase the sand supply to the Colorado River during beach-building flows to build larger sandbars, especially in Marble Canyon, through fluvial processes.
+Sediment slurry pipelines that would deliver sediment from the Navajo Canyon arm of
+Lake Powell to the Colorado River below Glen Canyon Dam or near Lees Ferry are
+believed to be technically feasible. Five sediment augmentation alternatives have been
+formulated and evaluated. Alternatives are available to deliver fine sediment and sand to
+the Colorado River, either below Glen Canyon Dam or near Lees Ferry.
+Attempts have been made to formulate each alternative to minimize environmental
+impacts and to avoid cultural resource impacts. No major environmental impacts for any
+of the five alternatives have been identified at this time.
+Sediment source areas in Lake Powell seem to be the most logical choice because of cost
+and because the sediments in Lake Powell would have naturally reached the Colorado
+River below the site of Glen Canyon Dam. Sediment source areas in Navajo Canyon are
+much closer to Glen Canyon Dam than other major source areas in Lake Powell.
+Laboratory analysis of one sediment sample from Navajo Canyon did not detect any
+contaminants above background levels. A more intensive sediment sampling program
+would be needed to verify if this finding is applicable to more of the sediments within
+Navajo Canyon.
+Although the present and future sedimentation volumes in Navajo Canyon may not be
+enough to sustain a Grand Canyon sediment augmentation program over the long term,
+the volumes should be sufficient for one or two decades (see figure 8). Sediments in
+Navajo Canyon could be dredged first and then the submerged slurry pipelines and
+floating pumping stations could be moved to an upstream source such as the Escalante
+River or San Juan River deltas.
-[[File:Sandbars 2008 2016.jpg|600px]]
+Sediment slurry pipelines can deliver large quantities of sediment, and over long
+distances, much more efficiently and at less cost than barges or trucks. Submerging
+sediment slurry pipelines in Lake Powell appears to be a viable option with much less
+impact than overland routes from major sediment source areas in Lake Powell where no
+direct roads presently exist.
-[[File:2016 SedimentSummary.jpg|600px]]
+The augmentation of fine sediment should be considered in conjunction with alternatives
+that would increase the summer water temperatures released from Glen Canyon Dam
+(e.g., selective withdrawal of water from Lake Powell). Native and endangered fish in
+Grand Canyon National Park are impacted by less turbidity and colder water
+temperatures in summer compared to natural conditions (U.S. Department of the Interior,
+Bureau of Reclamation, 1995). Turbidity may provide native fish with cover from
+predation. In the absence of turbid conditions, native fish tend not to be active during the
+day (U.S. Department of the Interior, Bureau of Reclamation, 1995). Although, colder
+water temperatures may impact young-of-the-year native fish in summer, the colder
+temperatures may also keep non-native warm-water fish from migrating upstream
+through Grand Canyon National Park. If water temperatures are increased, there is a
+concern that non-native warm-water fish may have the advantage (U.S. Department of
+the Interior, Bureau of Reclamation, 1995). The augmentation of fine sediment may
+provide the necessary cover for native and endangered fish.
 |}
@@ Line 64: / Line 164: @@
 |style="color:#000;"|
 *[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09382000#/ '''Paria River sediment gage'''] Click here to calculate how much sediment has come in from the Paria River.
-*[http://gcdamp.com/index.php?title=The_HFE_Page '''The HFE Page'''] See summaries from past HFEs
+*[[GCDAMP The_HFE_Page '''The HFE Page''']] See summaries from past HFEs
 |-
@@ Line 72: / Line 172: @@
 |class="MainPageBG" style="width:45%; border:1px solid #cedff2; background:#f5faff; vertical-align:top;"|
 {| width="100%" cellpadding="2" cellspacing="5" style="vertical-align:top; background:#f5faff;"
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Links and Information</h2>
+|-
+|style="color:#000;"|
+*[http://gcdamp.com/index.php?title=Portal:GCDAMP_Knowlege_Assessments GCMRC Annual Reports page]
+*[https://www.gcmrc.gov/sandbar/ GCMRC Grand Canyon Sandbar Monitoring]
+*[http://gcdamp.com/index.php?title=The_HFE_Page The High Flow Experiment (HFE) Page]
+*[http://gcdamp.com/index.php?title=RECREATION Recreation Page]
+*[[Aeolian Sand Transport|  Aeolian Sand Transport Page]]
+*[http://gcdamp.com/index.php?title=Turbidity Turbidity Page]
+*[http://gcdamp.com/index.php?title=GCDAMP-_Over-Flights Over Flights Page]
+|-
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">[https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Home_Page.aspx Projects]</h2>
+|-
+|style="color:#000;"|
+*[https://www.gcmrc.gov/sandbar/ Sandbar Monitoring]
+*[https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Camp.aspx Campsite Monitoring]
+*[https://www.gcmrc.gov/discharge_qw_sediment/ Suspended Sediment Transport ]
+*[https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Home_Page.aspx Automated Substrate Classification Using Swath Mapping Systems]
+*[https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_storage.aspx Sediment Storage]
+*[https://www.gcmrc.gov/research_areas/sediment_geomorphology/sed/Sed_Geomorph_Home_Page.aspx Underwater Photography to Measure Bed Grain Size ]
+|-
 ! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Sediment Gages</h2>
 |-
 |style="color:#000;"|
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09380000 '''Colorado River at Lees Ferry''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-GCLT1 Water Holes Canyon above the mouth]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09382000#/ '''Paria River at Lees Ferry''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09381800 Paria River near Kanab, UT]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09383050 '''Colorado River at 30 mile''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09382000 Paria River at Lees Ferry, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09383100 '''Colorado River above LCR''']
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09380000 Colorado River at Lees Ferry]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09403000 '''Bright Angel Creek''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT1 Badger Creek below highway 89A near Vermillion Cliffs, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT6 '''Shinumo Creek''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT2 Tanner Wash below highway 89A near Bitter Springs, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09402352 '''Colorado River abv Lava Canyon rm66''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT3 House Rock Wash above Emmett Wash near Cliff Dwellers, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09403270 '''Colorado River bl rm127''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT5 North Canyon near Cliff Dwellers, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09403850 '''Kanab Creek''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT6 Shinumo Wash in Twentynine Mile Canyon near Cedar Ridge, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404115 '''Havasu Creek''']
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09383050 Colorado River near river mile 30]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404120 '''Colorado River abv National Canyon''']
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09383100 Colorado River above Little Colorado River near Desert View, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404200 '''Colorado River bl Diamond Creek''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09401500 Moenkopi Wash near Cameron, AZ]
-*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404220 '''Colorado River abv Spencer rm246''']
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09401000 Little Colorado River at Grand Falls, AZ]
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09401200 Little Colorado River at Cameron, AZ]
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09402000 Little Colorado River near Cameron, AZ]
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09402300 Little Colorado River above the mouth near Desert View, AZ]
+*[https://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09402500 Colorado River near Grand Canyon, AZ]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09403000 Bright Angel Creek near Grand Canyon, AZ]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/GCMRC-MCLT6 Shinumo Creek]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09403850 Kanab Creek above the mouth near Supai, AZ]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404115 Havasu Creek above the mouth near Supai, AZ]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404120 Colorado River above National Canyon near Supai, AZ]
+*[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09404200 Colorado River above Diamond Creek near Peach Springs, AZ]
 |-
-! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Reports and Links </h2>
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Sand Mass Balance Reaches in Grand Canyon </h2>
 |-
 |style="color:#000;"|
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09380000/09383050 Upper Marble Canyon]
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09383050/09383100 Lower Marble Canyon]
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09383100/09402500 Eastern Grand Canyon]
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09402500/09404120 East Central Grand Canyon]
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09404120/09404200 West Central Grand Canyon]
+*[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09404200/Pearce%20Ferry Western Grand Canyon and the Lake Mead Delta]
+|-
-*[https://pubs.er.usgs.gov/publication/pp1825 '''Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam, Arizona''']
+! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;"> Presentations and Papers </h2>
-*[https://pubs.er.usgs.gov/publication/pp1823 '''Long-term continuous acoustical suspended-sediment measurements in rivers - Theory, application, bias, and error''']
+|-
-*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR01_Topping.pdf '''Project 2: Streamflow,  Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem''']
+|style="color:#000;"|
-*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR02_Grams.pdf '''Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent high-flow Experiments and Long-Term Trends''']
-*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/16jan26/documents/AR03_Buscombe.pdf '''Observations of sand dune migration on the Colorado River in Grand Canyon using high-resolution multibeam bathymetry''']
+'''2026'''
-*[https://drive.google.com/file/d/0BwY-Z2c3NTUGQURtV2s3eWJqRHM/view '''Updates on 2014 HFE, Paria sediment inputs, and sediment mass balance''']
+*[https://www.usbr.gov/uc/progact/amp/amwg/2026-02-26-amwg-meeting/uc-gcdamp-amwg-interdisciplinarysediment-508-20260226.pdf Interdisciplinary Sediment, Riparian Vegetation, and Cultural Resource Science]
-*[http://repository.asu.edu/items/30069 Alvarez, L.V. (2015) Turbulence, Sediment Transport, Erosion, and Sandbar Beach Failure Processes in Grand Canyon. Ph.D. Dissertation, Arizona State University, Tempe, AZ, 176pp.]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2026-02-26-amwg-meeting/uc-gcdamp-amwg-ltempsandmanagement-508-20260226.pdf Evaluation of LTEMP sand management]
-*[https://eos.org/features/building-sandbars-in-the-grand-canyon Grams, P. E., J. C. Schmidt, S. A. Wright, D. J. Topping, T. S. Melis, and D. M. Rubin (2015), Building Sandbars in the Grand Canyon, EOS, Trans. Am. Geophys. Union, 96(11), 12–16. ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2026-02-05-twg-meeting/uc-gcdamp-arm-riverbed-sandbarresponse-508-20260205.pdf Riverbed and Sandbar Response to Glen Canyon Dam Operations and High-Flow Experiments]
-*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/15jan20/Attach_01.pdf '''Streamflow, Water Quality, and Sediment Transport in the Colorado River Ecosystem''']
+*[https://www.usbr.gov/uc/progact/amp/twg/2026-02-05-twg-meeting/uc-gcdamp-arm-evaluationsandmanagement-508-20260205.pdf Evaluation of LTEMP sand management]
-*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/15jan20/Attach_02.pdf '''Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent High-flow Experiments and Long-term Trends''']
+*[https://www.usbr.gov/uc/progact/amp/twg/2026-02-05-twg-meeting/uc-gcdamp-arm-sandmanagement-508-20260205.pdf Reservoir Operational Strategies for Sustainable Sand Management in the Colorado River]
+'''2025'''
+*[https://www.usbr.gov/uc/progact/amp/twg/2025-04-10-twg-meeting/uc-gcdamp-twg-arm-goal7metrics-508-20250410.pdf Goal 7 Metrics: Sediment]
+*[https://www.usbr.gov/uc/progact/amp/twg/2025-04-10-twg-meeting/uc-gcdamp-twg-arm-projecta-508-20250410.pdf Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem]
+'''2024'''
+*[https://www.usbr.gov/uc/progact/amp/amwg/2024-02-29-amwg-meeting/20240229-ProjectB-UpdateRiverbedSandbarResponseDamOperationsHFE-508-UCRO.pdf Project B Update and Riverbed and sandbar response to dam operations and high-flow experiments ]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2024-02-29-amwg-meeting/20240229-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2024-01-25-twg-meeting/20240125-AnnualReportingMeeting-EffectsDamOperationsVegetationManagementPreservationGeomorphicConditionArchaeologicalSites-508-UCRO.pdf Effects of Reservoirs and Stock Ponds on Surface Water Runoff in the Little Colorado River Basin ]
+*[[Media:Sartain_AGU2023_poster_ARM.pdf| Assessing geomorphic change for 454 river km of the Colorado River in Grand Canyon, AZ via continuous and high-resolution water surface and bed profiles
+]]
+*[[Media:Kaplinski_Glen_canyon_flow_model_poster_20240114.pdf| Hydrodynamic modeling of the Colorado River between Glen Canyon Dam and Lees Ferry, Arizona]]
+'''2024'''
+*[https://doi.org/10.3133/ofr20231093 Griffiths et al., 2024, Changes in sand storage in the Colorado River in Grand Canyon National Park from July 2017 through June 2020]
+*[https://www.usbr.gov/uc/progact/amp/twg/2024-01-25-twg-meeting/20240125-AnnualReportingMeeting-ChannelResponseHighFlowsWesternGrandCanyon-508-UCRO.pdf Channel Response to High Flows in Western Grand Canyon ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2024-01-25-twg-meeting/20240125-AnnualReportingMeeting-ProjectAStreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem ]
+*[https://www.usbr.gov/uc/progact/amp/twg.html#:~:text=Project%20B%20Update%20and%20Riverbed%20and%20sandbar%20response%20to%20dam%20operations%20and%20high%2Dflow%20experiments Project B Update and Riverbed and sandbar response to dam operations and high-flow experiments ]
+'''2023'''
+*[https://www.usbr.gov/uc/progact/amp/twg/2023-01-26-twg-meeting/20230126-AnnualReportingMeeting-AContinuousHigh-ResolutionProfileRiverbedWaterSurface460-kmColoradoRiverGrandCanyon-508-UCRO.pdf A Continuous High-Resolution Profile of the Riverbed and Water Surface for 460-km of the Colorado River in Grand Canyon]
+*[https://www.usbr.gov/uc/progact/amp/twg/2023-01-26-twg-meeting/20230126-AnnualReportingMeeting-StreamflowSedimentVegetationDynamics-508-UCRO.pdf Project A: Streamflow, Sediment, and Vegetation Dynamics; Implications for Geomorphic Change in the Colorado River and its Tributaries]
+*[https://www.usbr.gov/uc/progact/amp/twg/2023-01-26-twg-meeting/20230126-AnnualReportingMeeting-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem]
+*[[Media:ARM_salter.pdf| Numerical Modeling of Mud Transport, Storage, and Release on the Colorado River, Arizona]]
+'''2022'''
+*[https://www.usbr.gov/uc/progact/amp/amwg/2022-08-18-amwg-meeting/20220818-Grams_Sandbars_AMWG_BAO_508.pdf Multi-Decadal Sandbar Response to Flow Management Downstream from a Large Dam-The Glen Canyon Dam on the Colorado River in Marble and Grand Canyons, AZ ]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2022-02-10-amwg-meeting/20220210-SummarySedimentSandbarProjects-508-UCRO.pdf Summary of Sediment and Sandbar Projects GCMRC Projects A and B LTEMP Goal 7 ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2022-01-13-twg-meeting/20220113-AnnualReportingMeeting-ProjectA-StreamflowWaterQualitySedimentTransportBudgetingColoradoRiverEcosystem-508-UCRO.pdf Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem ]
+'''2021'''
+*[[Media:Glen Canyon Sand Augmentation White Paper.pdf| Argonne. 2021. Evaluation of Sand Augmentation for Stabilizing Recreational Beaches and Storing Sand in Glen Canyon National Recreation Area]]
+*[https://www.usbr.gov/uc/progact/amp/twg/2021-10-14-twg-meeting/20211014-MorphodynamicModelEvaluateSandbarRebuilding-Presentation-508-UCRO.pdf A simple morphodynamic model to rapidly evaluate sandbar rebuilding during controlled floods]
+*[https://doi.org/10.1029/2020JF005565 Topping et al. 2021, Self-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size: Journal of Geophysical Research: Earth Surface]
+*[https://doi.org/10.1029/2021JF006149 Alvarez et al. 2021, An eddy-resolving numerical model to study turbulent flow, sediment, and bed evolution using detached eddy simulation in a lateral separation zone at the field-scale: Journal of Geophysical Research—Earth Surface]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2021-02-11-amwg-meeting/20210211-SandSupplyTransportDeposition-508-UCRO.pdf Sand Supply, Transport and Deposition ]
+'''2020'''
+*[https://doi.org/10.1029/2019JF005226 Rubin et al., 2020, Causes of variability in suspended‐sand concentration evaluated using measurements in the Colorado River in Grand Canyon: JGR Earth Surface]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2020-02-12-amwg-meeting/20200212-GCMRCScienceUpdatesPart3-Presentation-508-UCRO.pdf GCMRC 2019 Annual Reporting Meeting Overview – Part 3 ]
+*[https://doi.org/10.1130/B35642.1 Chapman et al., 2020, Estimating the contribution of tributary sand inputs to controlled flood deposits for sandbar restoration using elemental tracers, Colorado River, Grand Canyon National Park, Arizona: GSA Bulletin] [https://doi.org/10.5066/P9C0IN56 Associated data]
+*[https://www.usbr.gov/uc/progact/amp/twg/2020-01-13-twg-meeting/20200113-AnnualReportingMeeting-ProjectBEffectsDamReleaseSedimentStorageSandbarDynamics-Presentation-508-UCRO.pdf Project B: Effects of dam releases on in-channel sediment storage and sandbar dynamics ]
+*[https://doi.org/10.1029/2019WR025883 Ashley et al., 2020, Estimating bedload from suspended load and water discharge in sand bed rivers: Water Resources Research.]
+*[https://www.usbr.gov/uc/progact/amp/twg/2020-01-13-twg-meeting/20200113-AnnualReportingMeeting-GeomorphicChangeBiogeomorphicFeedbacksLittleColoradoRiver-Presentation-508-UCRO.pdf Geomorphic Change and Biogeomorphic Feedbacks in the Little Colorado River, Arizona ]
+'''2019'''
+*[https://doi.org/10.1130/B35047.1 Dean, D.J., and Topping, D.J., 2019, Geomorphic change and biogeomorphic feedbacks in a dryland river--The Little Colorado River, Arizona, USA: GSA Bulletin ]
+'''2018'''
+*[https://qcnr.usu.edu/wats/colorado_river_studies/files/documents/Rubin.pdf Sand tells a story]
+*[https://doi.org/10.5066/P99TN424 Sankey et al., 2018, Sand classifications along the Colorado River in Grand Canyon derived from 2002, 2009, and 2013 high-resolution multispectral airborne imagery: U.S. Geological Survey data release]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2018-08-22-amwg-meeting/Attach_12.pdf GCMRC Science Updates PPT]
+*[https://doi.org/10.1002/rra.3349 Hadley et al., 2018, Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona: River Research  and Applications]
+*[https://www.usbr.gov/uc/progact/amp/twg/2018-01-25-twg-meeting/AR02.pdf Key drivers of sand transport and storage in the Colorado River Ecosystem PPT]
+*[https://doi.org/10.5194/hess-22-1767-2018 Voichick, N. et al., 2018, Technical note--False low turbidity readings during high suspended-sediment concentrations: Hydrology and Earth System Sciences]
+*[https://doi.org/10.3133/ofr20181019 Grams et al., 2018, Automated remote cameras for monitoring alluvial sandbars on the Colorado River in Grand Canyon, Arizona: Open-File Report]
+'''2017'''
+*[[Media:Chapman 2017 Thesis-Determining tributary sediment exp flood deposits Marble Canyon ColRiv.pdf| Chapman, K., 2017, Determining the tributary sediment contribution to experimental flood deposits on the Colorado River in Marble Canyon, Grand Canyon, Arizona: Flagstaff, Northern Arizona University, MS thesis]]
+*[https://digitalcommons.usu.edu/etd/6635 Hamill, D., 2017, Quantifying riverbed sediment using recreational-grade side scan sonar: Logan, Utah State University, MS thesis]
+*[http://dx.doi.org/10.1002/2017JF004302 Buscombe et al., 2017, Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds: Journal of Geophysical Research: Earth Surface]
+*[https://doi.org/10.1016/j.geomorph.2017.08.037 Griffiths and Topping, 2017, Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets: Geomorphology]
+*[https://doi.org/10.3133/ofr20171030 Kaplinski et al. 2017. Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009: U.S. Geological Survey Open-File Report 2017–1030]
+*[https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR1_Topping.pdf Project 1: Streamflow, Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR2_Dean.pdf Project 2: Hydrologic Change and the Geomorphic Transformation of the Little Colorado River: Implications for Sediment Delivery to the Grand Canyon ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR3_Grams.pdf Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent High-flow Experiments and Long-term Trends ]
+'''2016'''
+*[https://pubs.er.usgs.gov/publication/pp1823 Topping et al. 2016. Long-term continuous acoustical suspended-sediment measurements in rivers — Theory, application, bias, and error: U.S. Geological Survey Professional Paper 1823]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2016-08-24-amwg-meeting/Attach_11a.pdf Sandbar Modeling Project Update]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2016-08-24-amwg-meeting/Attach_07b.pdf Status of Sediment Resources – August 2016]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2016-08-24-amwg-meeting/Attach_07a.pdf Grand Canyon Monitoring and Research Center Science Updates and PPT (BO Compliance, Trout Updates, Green Sunfish, Fisheries PEP, Partners in Science)]
+*[https://www.usbr.gov/uc/progact/amp/twg/2016-02-26-twg-meeting/AR03_Buscombe.pdf Observations of sand dune migration on the Colorado River in Grand Canyon using high-resolution multibeam bathymetry]
+*[https://www.usbr.gov/uc/progact/amp/twg/2016-02-26-twg-meeting/AR01_Topping.pdf Project 2: Streamflow,  Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem]
+*[https://www.usbr.gov/uc/progact/amp/twg/2016-02-26-twg-meeting/AR02_Grams.pdf Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent high-flow Experiments and Long-Term Trends]
+'''2015'''
+*[https://eos.org/features/building-sandbars-in-the-grand-canyon Grams et al. 2015. Building Sandbars in the Grand Canyon, EOS, Trans. Am. Geophys. Union]
+*[http://repository.asu.edu/items/30069 Alvarez. 2015. Turbulence, Sediment Transport, Erosion, and Sandbar Beach Failure Processes in Grand Canyon. Ph.D. Dissertation, Arizona State University, Tempe, AZ]
+*[https://drive.google.com/file/d/0BwY-Z2c3NTUGeUVIWEwyY1l6RUE/view GCMRC Science Update - Sediment]
+*[https://www.usbr.gov/uc/progact/amp/twg/2015-06-11-twg-meeting/Attach_02,.pdf GCMRC Science Update - Sediment]
+*[https://drive.google.com/file/d/0BwY-Z2c3NTUGQURtV2s3eWJqRHM/view Updates on 2014 HFE, Paria sediment inputs, and sediment mass balance]
+*[https://www.usbr.gov/uc/progact/amp/twg/2015-04-21-twg-meeting/Attach_11.pdf Glen Canyon Tailwater Fishery “Integrating Fish and Channel Mapping”]
+*[https://www.usbr.gov/uc/progact/amp/twg/2015-04-21-twg-meeting/Attach_13.pdf GCMRC’s Online Mapping and GIS Resources]
+*[https://www.usbr.gov/uc/progact/amp/twg/2015-01-20-twg-meeting/Attach_01.pdf Streamflow, Water Quality, and Sediment Transport in the Colorado River Ecosystem]
+*[https://www.usbr.gov/uc/progact/amp/twg/2015-01-20-twg-meeting/Attach_02.pdf Sandbars and Sediment Storage in Marble and Grand Canyons: Response to Recent High-flow Experiments and Long-term Trends]
+'''2014'''
+*[https://www.usbr.gov/uc/progact/amp/amwg/2014-08-27-amwg-meeting/Attach_04a.pdf Science Updates - Recent Research on Sand, Bugs, and Fish ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2014-01-30-twg-meeting/AR_Grams_Sandbar_Storage.pdf Sandbars and Sand Storage in Marble and Grand Canyons (Grams) ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2014-01-30-twg-meeting/AR_Griffiths_Processing.pdf Processing fine sediment transport data: procedures, processing, and bottlenecks (Griffiths) ]
+'''2013'''
+*[https://asu.pure.elsevier.com/en/publications/erosion-of-river-sandbars-by-diurnal-stage-fluctuations-in-the-co Alvarez and Schmeeckle. 2013. Erosion of river sandbars by diurnal stage fluctuations in the Colorado river in the Marble and Grand Canyons: Full-scale laboratory experiments]
+*[http://www.usbr.gov/uc/rm/amp/twg/mtgs/13nov06/Attach_02a.pdf GCMRC Update - Status of Resources and Sediment Conditions]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2013-08-08-amwg-meeting/Attach_06d.pdf Present Status of Sediment Resources-August 2013]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2013-08-08-amwg-meeting/Attach_06a.pdf Science Updates - Overflights, Riparian Vegetation, and Sediment]
+*[https://www.usbr.gov/uc/progact/amp/twg/2013-06-26-twg-meeting/Attach_07a.pdf 2013 Overflight Wrap up]
+*[https://www.usbr.gov/uc/progact/amp/twg/2013-06-26-twg-meeting/Attach_07b.pdf GCMRC Science Update on Sediment and Fisheries]
+*[https://www.usbr.gov/uc/progact/amp/twg/2013-01-24-twg-meeting/15_Topping.pdf Sediment Monitoring Program: Sediment Delivery from Tributaries and Sediment Transport by Colorado River]
+*[https://www.usbr.gov/uc/progact/amp/twg/2013-01-24-twg-meeting/16_Grams.pdf Sandbar Monitoring for November 2012 Controlled Flood]
+'''2012'''
+*[https://www.usbr.gov/uc/progact/amp/amwg/2012-08-29-amwg-meeting/Attach_04a.pdf GCMRC Updates and Sediment Update ]
+*[https://www.usbr.gov/uc/progact/amp/twg/2012-06-20-twg-meeting/Attach_09.pdf E-mail to TWG with Sediment Model Link]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2012-02-22-amwg-meeting/Attach_08.pdf GCMRC Updates and PPT]
+*[https://www.gcmrc.gov/about/ka/KA%202%20-%201-31-12/PM%20Talks/Grams%200400-0500.pdf Sandbars and In-Channel Sand Storage: Short-Term Dynamics and Long-Term Trends ]
+*[https://www.gcmrc.gov/about/ka/KA%202%20-%201-31-12/PM%20Talks/Topping%200200-0300.pdf Physical controls on sediment deposition, erosion, and transport ]
+*[https://www.gcmrc.gov/about/ka/KA%202%20-%201-31-12/PM%20Talks/Melis%200300-0400.pdf Geomorphic Framework & Role of Debris Flows Suspended-Sediment Transport and Sandbars Glen Canyon Dam Operations -Post-EIS Summary ]
+*[https://www.gcmrc.gov/about/ka/KA%202%20-%201-31-12/PM%20Talks/Schmidt%200100-0200.pdf A Conversation about Rivers and Dams ]
+*[https://www.gcmrc.gov/about/ka/KA%202%20-%202-1-12/PM%20Talks/Wright%200200-0300%20Modeling%20101.pdf Modeling 101 ]
+'''2011'''
+*[https://www.usbr.gov/uc/progact/amp/amwg/2011-08-24-amwg-meeting/Attach_06.pdf GCMRC Updates]
+*[https://www.usbr.gov/uc/progact/amp/twg/2011-06-28-twg-meeting/Attach_05.pdf Update on Sand Mass Balance with Modeling]
+'''2010'''
+*[https://pubs.usgs.gov/of/2010/1133/OFR_2010-1133.pdf Wright, S.A., and Grams, P.E., 2010, Evaluation of Water Year 2011 Glen Canyon Dam flow release scenarios on downstream sand storage along the Colorado River in Arizona: U.S. Geological Survey Open-File Report 2010-1133]
+*[https://www.usbr.gov/uc/progact/amp/twg/2010-11-15-twg-meeting/Attach_11d.pdf Update on Water Quality and 2010 Sand Input ]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2010-08-24-amwg-meeting/Attach_03a.pdf Grand Canyon Monitoring and Research Updates and the Following Open File Reports: 1) Evaluation of Water Year 2011 Glen Canyon Dam Flow Release Scenarios on Downstream Sand Storage Along the Colorado River in Arizona, and 2) An Approach to Modeling Sediment Budgets in Supply-limited Rivers]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2010-08-24-amwg-meeting/Attach_03b.pdf Report on Sediment Modeling to Support Development of 2011 Hydrograph]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2010-08-24-amwg-meeting/Attach_03c.pdf Update on 2010 Sediment Inputs]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2010-08-24-amwg-meeting/Attach_12a.pdf Temperature Control Device and Sediment Augmentation Report]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2010-08-24-amwg-meeting/Attach_12b.pdf TWG Chair Temperature Control Device/Sediment Augmentation]
+*[https://www.usbr.gov/uc/progact/amp/twg/2010-06-29-twg-meeting/Attach_01b.pdf Minutes from June 21, 2010, TWG Webinar/Conference Call with Memo from John Hamill to Shane Capron dated May 17, 2010, Subject: TWG and stakeholder requests for GCMRC to evaluate the effects of various dam operation scenarios on sediment storage and loss in the Grand Canyon with Open File Report 2010-1133]
+*[https://www.usbr.gov/uc/progact/amp/twg/2010-06-29-twg-meeting/Attach_10.pdf Mechanics and Modeling of Flow, Sediment Transport and Morphologic Change in Riverine Lateral Separation Zones]
+*[https://www.usbr.gov/uc/progact/amp/twg/2010-03-15-twg-meeting/Attach_07.pdf Sediment and Temperature Modeling Update PPT as presented at January 2010 Annual Reporting Meeting]
+*[https://www.usbr.gov/uc/progact/amp/twg/2010-01-21-twg-meeting/Attach_07.pdf AIF: Temperature Control Device and Sediment Augmentation and PPT]
+'''2009'''
+*[https://www.usbr.gov/uc/progact/amp/twg/2009-09-29-twg-meeting/Attach_14.pdf Selective Withdrawal and Sediment Augmentation Update PPT]
+*[https://www.usbr.gov/uc/progact/amp/twg/2009-09-29-twg-meeting/Attach_06.pdf Grand Canyon Monitoring and Research Center Updates]
+*[https://www.usbr.gov/uc/progact/amp/twg/2009-06-22-twg-meeting/Attach_04.pdf Sandbar Evolution: Extending the Historical Perspective PPT]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2009-04-29-amwg-meeting/Attach_03a.pdf AIF: Grand Canyon Monitoring and Research Center (GCMRC) Update]
+*[https://www.usbr.gov/uc/progact/amp/amwg/2009-04-29-amwg-meeting/Attach_03d.pdf Water Quality and Sediment, 2008 High Flow Experiment, and Integrated Flow, Temperature, and Sediment Modeling PPT]
+*[https://www.usbr.gov/uc/progact/amp/twg/2009-03-16-twg-meeting/Attach_05.pdf Grand Canyon Monitoring and Research Center updates by Program Managers]
+*[https://www.usbr.gov/uc/progact/amp/twg/2009-03-16-twg-meeting/Attach_10.pdf Diamond Creek Gage Discontinuation]
+'''2008'''
+*[http://www.riversimulator.org/Resources/Hydrology/WrightGSA2008.pdf Is there enough sand? Evaluating the fate of Grand Canyon sandbars]
+'''2007'''
+*[http://www.riversimulator.org/Resources/USBR/LTEP/Randle2007.pdf Randle et al. 2007. Colorado River Ecosystem Sediment Augmentation Appraisal Engineering Report]
+'''2003'''
+*[https://pubs.usgs.gov/pp/pp1677/pdf/pp1677.pdf Topping et al. 2003.  Computation and analysis of the instantaneous-discharge record for the Colorado River at Lees Ferry, Arizona, May 8, 1921 through September 30, 2000: U.S. Geological Survey Professional Paper 1677]
+'''1999'''
+*[https://www.usbr.gov/uc/rm/amp/twg/mtgs/10jun29/Attach_11.pdf Floods and Sandbars in the Grand Canyon, a publication of the Geological Society of America (published in GSA Today, April 1999)]
+'''1988'''
+*[https://pubs.usgs.gov/of/1987/0561/report.pdf Schmidt and Graf, 1988, Aggradation and degradation of alluvial sand deposits, 1965 to 1986, OFR 87-561]
 |-
@@ Line 114: / Line 404: @@
 |-
 |style="color:#000;"|
+----
 *Eddies occur adjacent to rapids and the flow in the eddy is related to the flow characteristics in the rapid.  Sand bars were typically larger before the dam.(Science Background for HFE Planning- Jack Schmidt, GCMRC_KA 2013)
@@ Line 120: / Line 412: @@
 *[http://www.nationalparkstraveler.com/2014/11/high-flows-through-grand-canyon-national-park-met-mixed-reactions25903 The United States Geological Survey estimates that the Colorado River below Glen Canyon Dam only has 6 percent of the sediment that it received before the Glen Canyon Dam was built in the 1960s.]
+==Flash Flood videos==
+*[https://www.youtube.com/watch?v=humwT6ivMt0 Paria River Flash Flood 8/3/16]
+*[https://www.youtube.com/watch?v=sJBl6GXf_EA Buckskin Gulch Flash Flood 8/4/16]
+*[https://www.youtube.com/watch?v=aZp_1KtrzjQ| Buckskin Wash Flash Flood / Debris Flow 2013]
+*[https://www.youtube.com/watch?v=iAw_zIg9BqI Paria River Flash Flood / Debris Flow 8/19/12]
+*[https://www.youtube.com/watch?v=580HhfKenws Glen Canyon and Page Arizona Flooding May 22 2009]
 |}