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Sediment transport in rivers is controlled by both the flow and the upstream sediment supply. Changes in either the flow or the upstream sediment supply will therefore change the sediment transport rate and the locations where sediment will either get deposited or eroded. 

This project conducts research on the physical interactions between the flow, upstream sediment supply, channel geometry, and bed-sediment grain size in bedrock-canyon rivers with intermittent, limited supplies of sediment, and in alluvial rivers with relatively unlimited supplies of sediment. Because this research requires accurate measurement of sediment transport, we have also focused on evaluating errors associated with conventional sampling techniques and also on developing new approaches to collecting continuous high-resolution sediment-transport data. 

This work has had led to: (1) improved understanding of how the flow and upstream sediment supply interact with channel geometry and bed-sediment grain size, (2) improved and new methods for accurately measuring sediment transport over long timescales, (3) improved methods for serving and visualizing river flow and sediment data on the web. These advances have led to the rapid transfer of new and more accurate information to river managers so that they can best manage sediment in their river systems.

This project has conducted research on rivers throughout the western United States, with most of this research occurring within the Colorado River and Rio Grande basins. Active research efforts are currently underway on: 

1. The Colorado River and its tributaries in and around Grand Canyon National Park, Arizona,
2. The Green, Yampa, and Little Snake rivers in and upstream from Dinosaur National Monument, Colorado and Utah, 
3. The Colorado and Green rivers in Canyonlands National Park, Utah, 
4. The Green River in and upstream from the Ouray National Wildlife Refuge, Utah, 
5. The Rio Grande and its tributaries in Big Bend National Park, Texas, and 
6. The Rio Grande upstream from Elephant Butte Reservoir, New Mexico. 

Past research has included work in the Colorado River Delta along the international border downstream from Yuma, Arizona.

Publications

2023

AuBuchon, J., Abraham, D., Posner, A., Brown, J., Jackson, T., and Griffiths, R.E., 2023, Acoustic measurements on a shallow, sand-bed river: A case study from the Rio Grande: Proceedings of SEDHYD 2023, the Federal Interagency Sedimentation and Hydrologic Modeling Conference, May 8 – 12, 2023, St. Louis, Missouri, https://www.sedhyd.org/2023Program/1/82.pdf

Salter, G., Topping, D.J., Wright, S.A., Nelson, J.M., Mueller, E.R., and Grams, P.E., Numerical modeling of mud transport, storage, and release on the Colorado River, Arizona: Proceedings of SEDHYD 2023, the Federal Interagency Sedimentation and Hydrologic Modeling Conference, May 8 – 12, 2023, St. Louis, Missouri, https://www.sedhyd.org/2023Program/1/20.pdf

Wood, M., Groten, J., Straub, T., Whealdon-Haught, D., Griffiths, R., Boldt, J.A., Lucena, Z., Brown, J., Suttles, S., and Dickhudt, P., 2023, State of the science and decision support for measuring suspended sediment with acoustic instrumentation: Proceedings of SEDHYD 2023, the Federal Interagency Sedimentation and Hydrologic Modeling Conference, May 8 – 12, 2023, St. Louis, Missouri, https://www.sedhyd.org/2023Program/1/15.pdf

2022

Dean, D.J., Topping, D.J., Buscombe, D.D., Groten, J.T., Ziegeweid, J., Fitzpatrick, F.A., Lund, J.W., and Coenen, E.N., 2022, The use of continuous sediment-transport measurements to improve sand-load estimates in a large sand-bedded river: The lower Chippewa River, Wisconsin: Earth Surface Processes and Landforms, v. 47, p. 2006–2023, https://doi.org/10.1002/esp.5360. (Additional supporting information downloadable from the journal website.)

Deemer, B.R., Yackulic, C.B., Hall, R.O., Dodrill, M.J., Kennedy, T.A., Muehlbauer, J., Topping, D.J., Voichick, N., and Yard, M., 2022, Experimental reductions in subdaily flow fluctuations increased gross primary productivity for 425 river kilometers downstream: Proceedings of the National Academy of Sciences NEXUS, v. 1, p. 1–12, https://doi.org/10.1093/pnasnexus/pgac094. (Additional supporting information downloadable from the journal website.)

Grams, P.E., Friedman, J.M., Dean, D.J., and Topping, D.J., 2022, The effects of requested flows for native fish on sediment dynamics, geomorphology, and riparian vegetation for the Green River in Canyonlands National Park, Utah: U.S. Geological Survey Open-File Report 2022–1019, 20 p., https://doi.org/10.3133/ofr20221019

LeCoz, J., Perret, E., Camenen, B., Topping, D.J., Buscombe, D.D., Leary, K.C.P, Dramais, G., and Grams, P.E., Mapping 2-D bedload rates throughout a sand-bed river reach from high-resolution acoustical surveys of migrating bedforms: Water Resources Research, v. 58, e2022WR032434, https://doi.org/10.1029/2022WR032434. (Additional supporting information downloadable from the American Geophysical Union.)

Sabol, T.A., Topping, D.J., Griffiths, R.E., and Dramais, G., 2022, Field investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements: U.S. Geological Survey Open-File Report 2022–1077, 14 p., https://doi.org/10.3133/ofr20221077

2021

Topping, D.J., Grams, P.E., Griffiths, R.E., Dean, D.J., Wright, S.A., and Unema, J.A., 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, v. 126, e2020JF005565, https://doi.org/10.1029/2020JF005565. (Additional supporting information downloadable from the American Geophysical Union.)

Gray, J.R., Schwarz, G.E., Dean, D.J., Czuba, J.A., and Groten, J.T., 2021, Instruments, methods, rationale, and derived data used to quantify and compare the trapping efficiencies of four types of pressure-difference bedload samplers: U.S. Geological Survey Open-File Report 2021–1064, 61 p., https://doi.org/10.3133/ofr20211064

Sabol, T.A., Griffiths, R.E., Topping, D.J., Mueller, E.R., Tusso, R.B., and Hazel, J.E., Jr., 2021, Strandlines from large floods on the Colorado River in Grand Canyon National Park, Arizona: U.S. Geological Survey Scientific Investigations Report 2021-5048, 41 p., https://doi.org/10.3133/sir20215048

Unema, J.A., Topping, D.J., Kohl, K.A., Pillow, M.J., and Caster, J.J., 2021, Historical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries: U.S. Geological Survey Scientific Investigations Report 2021–5049, 34 p., https://doi.org/10.3133/sir20215049

2020

Dean, D.J., Topping, D.J., Grams, P.E., Walker, A.E., and Schmidt, J.C., 2020, Does channel narrowing by floodplain growth necessarily indicate sediment surplus? Lessons from sediment transport analyses in the Green and Colorado Rivers, Canyonlands, Utah: Journal of Geophysical Research: Earth Surface, v. 125, e2019JF005414, https://doi.org/10.1029/2019JF005414. (Additional supporting information downloadable from the American Geophysical Union.)

Grams, P.E., Dean, D.J., Walker, A.E., Kasprak, A., and Schmidt, J.C., 2020, The roles of flood magnitude and duration in controlling channel width and complexity on the Green River in Canyonlands, Utah, USA: Geomorphology, v. 371, 107438, https://doi.org/10.1016/j.geomorph.2020.107438. (Additional supporting information downloadable from the journal website.)

Rubin, D.M., Buscombe, D., Wright, S.A., Topping, D.J., Grams, P.E., Schmidt, J.C., Hazel, J.E., Jr., Kaplinski, M.A., and Tusso, R., 2020, Causes of variability in suspended-sand concentration evaluated using measurements in the Colorado River in Grand Canyon: Journal of Geophysical Research: Earth Surface, v. 125, e2019JF005226, https://doi.org/10.1029/2019JF005226. (Additional supporting information downloadable from the American Geophysical Union.)

Walker, A.E., Moore, J.N., Grams, P.E., Dean, D.J., and Schmidt, J.C., 2020, Channel narrowing by inset floodplain formation of the lower Green River in the Canyonlands region, Utah: Geological Society of America Bulletin, v. 132, p. 2333–2352, with additional supporting material in the Geological Society of America Data Repository, https://doi.org/10.1130/B35233.1

2019

Topping, D.J., Grams, P.E., Griffiths, R.E., Hazel, J.E., Jr., Kaplinski, M., Dean, D.J., Voichick, N., Unema, J.A., and Sabol, T.A., 2019, Optimal timing of high-flow experiments for sandbar deposition. U.S. Bureau of Reclamation, Glen Canyon Dam Adaptive Management Program. High-Flow Experiments Assessment Extended Abstracts, March 2019 Annual Reporting Meeting, March 6–7, Tempe, AZ, p. 3–9, https://pubs.usgs.gov/publication/70203738 or https://www.usbr.gov/uc/progact/amp/amwg/2019-03-06-amwg-meeting/20190301-HFE_Extended_Abstracts-Combined_FINAL.pdf. 

Dean, D.J., and Topping, D.J., 2019, Geomorphic change and biogeomorphic feedbacks in a dryland river: The Little Colorado River, Arizona, USA, Geological Society of America Bulletin, v. 131, n. 11-12, p. 1920-1242, doi: 10.1130/B35047.1, with additional supporting material in the Geological Society of America Data Repository, https://doi.org/10.1130/B35047.1.

Dramais, G., Camenen, B., Le Coz, J., Topping, D.J., Peteuil, C., and Pierrefeu, G., 2019, A physically based method of combining ADCP velocity data with point samples to compute suspended-sand discharge – Application to the Rhone River, France, Proceedings of the 4th Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 24 – 28, 2019, Peppermill Hotel, Reno, Nevada, https://www.sedhyd.org/2019/openconf/modules/request.php?module=oc_proceedings&action=view.php&id=120&file=1/120.pdf&a=Accept.

Grams, P.E., Buscombe, D., Topping, D.J., Kaplinski, M., and Hazel, J.E., Jr., 2019, How many measurements are required to construct an accurate sand budget in a large river? Insights from analyses of signal and noise, Earth Surface Processes and Landforms, v. 44, p. 160-178, doi: 10.1002/esp.4489, https://doi.org/10.1002/esp.4489.

Leonard, C.M., Schmidt, J.C., Topping, D.J., and Griffiths, R.E., 2019, Interpreting flux-based sediment budgets in a habitat context: Linking precise temporal- resolution measurements of sediment flux to spatially robust characterization of channel change, Proceedings of the 4th Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 24 – 28, 2019, Peppermill Hotel, Reno, Nevada, https://www.sedhyd.org/2019/openconf/modules/request.php?module=oc_proceedings&action=view.php&id=179&file=1/179.pdf&a=Accept

2018

Topping, D.J., Mueller, E.R., Schmidt, J.C., Griffiths, R.E., Dean, D.J., and Grams, P.E., 2018, Long-term evolution of sand transport through a river network:  Relative influences of a dam versus natural changes in grain size from sand waves, Journal of Geophysical Research: Earth Surface, v. 123,https://doi.org/10.1029/2017JF004534. (Additional supporting information downloadable from the American Geophysical Union.)

Voichick, N., Topping, D.J., and Griffiths, R.E., 2018, Technical note--False low turbidity readings during high suspended-sediment concentrations: Hydrology and Earth System Sciences, v. 22, p. 1767-1773, doi: 10.5194/hess-22-1767-2018, https://doi.org/10.5194/hess-22-1767-2018

2017

Griffiths, R.E., and Topping, D.J., 2017, Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets: Geomorphology, v. 296, p. 59-73, doi: 10.1016/j.geomorph.2017.08.037, https://doi.org/10.1016/j.geomorph.2017.08.037.

Mueller, E.R., Schmidt, J.C., Topping, D.J., Shafroth, P.B., Rodríguez-Burgueño, J.E., Ramírez-Hernández, J., and Grams, P.E., 2017, Geomorphic change and sediment transport during a small artificial flood in a transformed post-dam delta: The Colorado River delta, United States and Mexico:  Ecological Engineering, v. 106, p. 757-775,https://doi.org/10.1016/j.ecoleng.2016.08.009. 

Norman, L. M., Sankey, J. B., Dean, D. J., Caster, J., DeLong, S. B., DeLong, W. M., and Pelletier, J., 2017, Quantifying geomorphic change at ephemeral stream restoration sites using a coupled-model approach: Geomorphology, v. 283, p. 1-16, doi: 10.1016/j.geomorph.2017.01.017, https://doi.org/10.1016/j.geomorph.2017.01.017

VanderKooi, S.P., Kennedy, T.A., Topping, D.J., Grams, P.E., Ward, D.L., Fairley, H.C., Bair, L.S., Sankey, J.B., Yackulic, C.B., and Schmidt, J.C., 2017, Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan: U.S. Geological Survey Open-File Report 2017-1006, 18 p., https://doi.org/10.3133/ofr20171006

2016

Topping, D.J., and Wright, S.A., 2016, Long-term continuous acoustical suspended-sediment measurements in rivers—Theory, application, bias, and error:  U.S. Geological Survey Professional Paper 1823, 98 p., https://doi.org/10.3133/pp1823.

Topping, D.J., Wright, S.A., Griffiths, R.E., and Dean, D.J., 2016, Long-term continuous acoustical suspended-sediment measurements in rivers – Theory, evaluation, and results from 14 stations on five rivers, in Constantinescu, G., Garcia, M., and Hanes, D., eds., River Flow 2016, CD-ROM Proceedings of the International Conference on Fluvial Hydraulics, St. Louis, Missouri, USA, July 11-14, 2016, ISBN 978-1-138-2913-2 for set of Book and CD-ROM, ISBN 978-1-315-64447-9 for eBook PDF, p. 1510-1518 on CD-ROM.

Dean, D.J., Topping, D.J., Schmidt, J.C., Griffiths, R.E., and Sabol, T.A., 2016, Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads:  Journal of Geophysical Research Earth Surface, v. 121, n. 1, p. 82-110, doi: 10.1002/2015JF003436, with additional supporting information downloadable from the American Geophysical Union, https://doi.org/10.1002/2015JF003436

Voichick, N., Kennedy, T., Topping, D., Griffiths, R., and Fry, K., 2016, Water clarity of the Colorado River—Implications for food webs and fish communities:  U.S. Geological Survey Fact Sheet 2016-3053, 4 p., https://doi.org/10.3133/fs20163053

2015

Topping, D.J., Wright, S.A., Griffiths, R.E., and Dean, D.J., 2015, Physically based method for measuring suspended-sediment concentration and grain size using multi-frequency arrays of single-frequency acoustic-Doppler profilers:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 833-846, https://acwi.gov/sos/pubs/3rdJFIC/Contents/5B-Topping.pdf.

Dean, D.J., Topping, D.J., Griffiths, R., Sabol, T.A, Schmidt, J.C., and Bennett, J., 2015, Using 15-minute acoustic data to analyze suspended-sediment dynamics in the Rio Grande in the Big Bend region:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 1234-1245, https://acwi.gov/sos/pubs/3rdJFIC/Contents/7A-Dean.pdf.

Grams, P.E., Buscombe, D., Topping, D.J., Hazel, J.E., Jr., and Kaplinski, M., 2015, Use of flux and morphologic sediment budgets for sandbar monitoring on the Colorado River in Marble Canyon, Arizona:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 1144-1155, https://acwi.gov/sos/pubs/3rdJFIC/Contents/6D-Grams.pdf.

Grams, P.E., Schmidt, J.C., Wright, S.A., Topping, D.J., Melis, T.S., and Rubin, D.M., 2015, Building sandbars in the Grand Canyon:  EOS, Transactions of the American Geophysical Union, v. 96, 11 p., doi:10.1029/2015EO030349, https://eos.org/wp-content/uploads/2015/06/2015EO11.pdf?adaf16, html version (missing some illustrations) located at https://eos.org/features/building-sandbars-in-the-grand-canyon.

Griffiths, R.E., and Topping, D.J., 2015, Inaccuracies in sediment budgets arising from estimations of tributary sediment inputs:  An example from a monitoring network on the southern Colorado Plateau:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 583-594, https://acwi.gov/sos/pubs/3rdJFIC/Contents/4A-Griffiths.pdf.

Mueller, E.R., Schmidt, J.C., Topping, D.J., and Grams, P.E., 2015, Geomorphic change in the limitrophe reach of the Colorado River in response to the 2014 delta pulse flow, United States and Mexico:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 1501-1512, https://acwi.gov/sos/pubs/3rdJFIC/Contents/8D-Mueller.pdf.

Sibley, D., Topping, D.J., Hines, M., and Garner, B., 2015, User-interactive sediment budgets in a browser: A web application for river science and management:  Proceedings of the 3rd Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, April 19-23, 2015, Peppermill Hotel, Reno, Nevada, p. 595-605, https://acwi.gov/sos/pubs/3rdJFIC/Contents/4A-Sibley.pdf.

Hall, R. O. Jr., Yackulic, C. B., Kennedy, T. A., Yard, M. D., Rosi-Marshall, E. J., Voichick, N., & Behn, K. E., 2015, Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon:  Limnology and Oceanography, v. 60, n. 2, p. 512-526, doi: 10.1002/lno.10031, https://doi.org/10.1002/lno.10031

2014

Griffiths, R.E., Topping, D.J., Anderson, R.S., Hancock, G.S., and Melis, T.S., 2014, Design of a sediment-monitoring gaging network on ephemeral tributaries of the Colorado River in Glen, Marble, and Grand Canyons, Arizona:  U.S. Geological Survey Open-File Report 2014-1137, 21 p., https://doi.org/10.3133/ofr20141137

Voichick, N., and Topping, D.J., 2014, Extending the turbidity record: making additional use of continuous data from turbidity, acoustic-Doppler, and laser diffraction instruments and suspended-sediment samples in the Colorado River in Grand Canyon:  U.S. Geological Survey Scientific Investigations Report 2014-5097, 31 p., https://doi.org/10.3133/sir20145097

2013

Grams, P.E., Topping, D.J., Schmidt, J.C., Hazel, J.E., Jr., and Kaplinski, M., 2013, Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: Issues of scale, geomorphic setting, and sampling design:  Journal of Geophysical Research Earth Surface, v. 118, n. 2, p. 361-381, doi: 10.1002/jgrf.20050, https://doi.org/10.1002/jgrf.20050

Sabol, T.A., and Topping, D.J., 2013, Evaluation of intake efficiencies and associated sediment-concentration errors in US D-77 bag-type and US D-96-type depth-integrating suspended-sediment samplers:  U.S. Geological Survey Scientific Investigations Report 2012-5208, 88 p., https://doi.org/10.3133/sir20125208

Sabol, T.A., and Springer, A.E., 2013, Transient simulation of groundwater levels within a sandbar of the Colorado River, Marble Canyon, Arizona, 2004: U.S. Geological Survey Open-File Report 2013-1277, 22 p., https://doi.org/10.3133/ofr20131277

2012

Griffiths, R.E., Topping, D.J., Andrews, T., Bennett, G.E., Sabol, T.A., and Melis, T.S., 2012, Design and maintenance of a network for collecting high-resolution suspended-sediment data at remote locations on rivers, with examples from the Colorado River:  U.S. Geological Survey Techniques and Methods 8-C2, 44 p., https://pubs.usgs.gov/tm/tm8c2/

2011

Topping, D.J., Rubin, D.M., Wright, S.A., and Melis, T.S., 2011, Field evaluation of the error arising from inadequate time averaging in the standard use of depth-integrating suspended-sediment samplers:  U.S. Geological Survey Professional Paper 1774, 95 p., https://pubs.usgs.gov/pp/1774/

2010      

Topping, D.J., Rubin, D.M., Grams, P.E., Griffiths, R.E., Sabol, T.A., Voichick, N., Tusso, R.B., Vanaman, K.M., and McDonald, R.R., 2010, Sediment transport during three controlled-flood experiments on the Colorado River downstream from Glen Canyon Dam, with implications for eddy-sandbar deposition in Grand Canyon National Park: U.S. Geological Survey Open-File Report 2010-1128, 111 p, https://pubs.usgs.gov/of/2010/1128/

Melis, T.S., Topping, D.J., Grams, P.E., Rubin, D.M., Wright., S.A., Draut, A.E., Hazel, J.E., Jr., Ralston, B.E., Kennedy, T.A., Rosi-Marshall, E., Korman. J., Hilwig, K.D., and Schmit, L.M., 2010, 2008 High-Flow Experiment at Glen Canyon Dam Benefits Colorado River Resources in Grand Canyon National Park: U.S. Geological Survey Fact Sheet 2010-3009, 4 p, https://pubs.usgs.gov/fs/2010/3009/

Draut, A.E., Topping, D.J., Rubin, D.M., Wright, S.A., and Schmidt, J.C., 2010, Grain-size evolution in suspended sediment and deposits from the 2004 and 2008 controlled-flood experiments in Marble and Grand Canyons, Arizona: Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/P_DRAUT_GRANDCYN_FINAL.pdf   

Grams, P.E., Hazel, J.E., Schmidt, J.C., Kaplinski, M., Wright, S.A., Topping, D.J., and Melis, T.S., 2010, Geomorphic response of sandbars to the March 2008 high-flow experiment on the Colorado River downstream from Glen Canyon Dam: Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/5D_Grams.pdf

Grams, P.E., Schmidt, J.C., and Topping, D.J., 2010, Bed incision and channel adjustment of the Colorado River in Glen Canyon National Recreation Area downstream from Glen Canyon Dam, in Melis, T.S., Hamill, J.F., Bennett, G.E., Coggins, L.G., Jr., Grams, P.E., Kennedy, T.A., Kubly, D.M., and Ralston, B.E., eds., Proceedings of the Colorado River Basin Science and Resource Management Symposium, November 18–20, 2008, Scottsdale, Arizona: U.S. Geological Survey Scientific Investigations Report 2010–5135, p. 167-176, https://pubs.usgs.gov/sir/2010/5135/

Griffiths, R.E., Topping, D.J., McDonald, R.R., and Sabol, T.A., 2010, The use of the multi-dimensional surface-water modeling system (MD_SWMS) in calculating discharge and sediment transport in remote ephemeral streams:  Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/P40_Griffiths_paper.pdf

Rubin, D.M., Topping, D.J., Chezar, H., Hazel, J.E., Schmidt, J.C., Breedlove, M., Melis, T.S., and Grams, P.E., 2010, 20,000 grain-size observations from the bed of the Colorado River, and implications for sediment transport through Grand Canyon: Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/3C_Rubin_03_08_10.pdf

Sabol, T.A., Topping, D.J., and Griffiths, R.E., 2010, Field evaluation of sediment-concentration errors arising from non-isokinetic intake efficiency in depth-integrating suspended-sediment bag samplers:  Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada., https://acwi.gov/sos/pubs/2ndJFIC/Contents/P23_SABOL_02_23_10.pdf

Tusso, R., Rubin, D.M., Topping, D.J., Chezar, H., and Breedlove B., 2010, Using changes in bed-surface grain size as a proxy for changes in bed sand storage, Colorado River, Grand Canyon, in Melis, T.S., Hamill, J.F., Bennett, G.E., Coggins, L.G., Jr., Grams, P.E., Kennedy, T.A., Kubly, D.M., and Ralston, B.E., eds., Proceedings of the Colorado River Basin Science and Resource Management Symposium, November 18–20, 2008, Scottsdale, Arizona: U.S. Geological Survey Scientific Investigations Report 2010–5135, p. 347-355, https://pubs.usgs.gov/sir/2010/5135/

Voichick, N., and Topping, D.J., 2010, Use of specific conductance in estimating salinity and as a natural tracer of water parcels in the Colorado River between Glen Canyon Dam and Diamond Creek, northern Arizona, in Melis, T.S., Hamill, J.F., Bennett, G.E., Coggins, L.G., Jr., Grams, P.E., Kennedy, T.A., Kubly, D.M., and Ralston, B.E., eds., Proceedings of the Colorado River Basin Science and Resource Management Symposium, November 18–20, 2008, Scottsdale, Arizona: U.S. Geological Survey Scientific Investigations Report 2010–5135, p. 357-362, https://pubs.usgs.gov/sir/2010/5135/

Voichick, N., and Topping, D.J., 2010, Comparison of turbidity to multi-frequency sideways looking acoustic-Doppler data and suspended-sediment data in the Colorado River in Grand Canyon:  Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/P34_Voichick_FISC_Paper.pdf

Wright, S.A., Topping, D.J., Rubin, D.M., and Melis, T.S., 2010, An approach for modeling sediment budgets in supply-limited rivers:  Water Resources Research, v. 46, W10538, 18 p., doi:10.1029/2009WR008600, https://doi.org/10.1029/2009WR008600

Wright, S.A., Topping, D.J., Rubin, D.M., and Melis, T.S., 2010, Modeling long-term sediment budgets in supply-limited rivers: Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/3B_Wright_12_29_09_paper.pdf

Wright, S.A., Topping, D.J., and Williams, C.A., 2010, Discriminating silt-and-clay from suspended-sand in rivers using sidelooking acoustic profilers:  Proceedings of the Joint Federal Interagency Conference on Sedimentation and Hydrologic Modeling, June 27- July 1, 2010, Riviera Hotel, Las Vegas, Nevada, https://acwi.gov/sos/pubs/2ndJFIC/Contents/2C_Wright_03_01_10_paper.pdf

2009

Wright, S.A., Anderson, C.R., and Voichick, N., 2009, A simplified water temperature model for the Colorado River below Glen Canyon Dam:  River Research and Applications:  v. 25, p. 675-686, doi: 10.1002/rra.1179, https://doi.org/10.1002/rra.1179

2008

Topping, D.J., Rubin, D.M., and Schmidt, J.C., 2008, Update on regulation of sand transport in the Colorado River by changes in the surface grain size of eddy sandbars over multiyear timescales: U.S. Geological Survey Scientific Investigations Report 2008–5042, 24 p, https://pubs.usgs.gov/sir/2008/5042/

Akahori, R., Schmeeckle, M.W., Topping, D.J., and Melis, T.S., 2008, Erosion properties of cohesive sediments in the Colorado River in Grand Canyon: River Research and Applications, v. 24, p. 1160-1174, doi: 10.1002/rra.1122, https://doi.org/10.1002/rra.1122

Draut, A. E., Rubin, D. M., Dierker, J. L., Fairley, H. C., Griffiths, R. E., Hazel, J. E. Jr., Hunter, R. E., Kohl, K., Leap, L. M., Nials, F. L., Topping, D. J., and Yeatts, M., 2008, Application of sedimentary-structure interpretation to geoarchaeology in the Colorado River corridor, Grand Canyon, Arizona, USA: Geomorphology, v. 101, n. 3, p. 497-509, doi: 10.1016/j.geomorph.2007.04.032, https://doi.org/10.1016/j.geomorph.2007.04.032

Rubin, D.M., and Topping, D.J., 2008, Correction to “Quantifying the relative importance of flow regulation and grain-size regulation of suspended-sediment transport α, and tracking changes in bed-sediment grain size β”: Water Resources Research, v. 44, W09701, 5 p., doi: 10.1029/2008WR006819, https://doi.org/10.1029/2008WR006819

Voichick, N., 2008, Specific conductance in the Colorado River between Glen Canyon Dam and Diamond Creek, northern Arizona, 1988–2007:  U.S. Geological Survey Data Series 364, 16 p, https://pubs.usgs.gov/ds/364/

Wright, S.A., Schmidt, J.C., Melis, T.S., Topping, D.J., and Rubin, D.M., 2008, Is there enough sand? Evaluating the fate of Grand Canyon sandbars: GSA Today, v. 18, no. 8, p. 4-10, doi: 10.1130/GSATG12A.1, https://doi.org/10.1130/GSATG12A.1

2007

Topping, D.J., Rubin, D.M., and Melis, T.S., 2007, Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River:  Relative importance of changes in bed-sand grain size and bed-sand area:  Sedimentary Geology, 24 p., doi: 10.1016/j.sedgeo.2007.03.016, https://doi.org/10.1016/j.sedgeo.2007.03.016

Topping, D.J., Wright, S.A., Melis, T.S., and Rubin, D.M., 2007, High-resolution measurements of suspended-sediment concentration and grain size in the Colorado River in Grand Canyon using a multi-frequency acoustic system: Proceedings of the Tenth International Symposium on River Sedimentation, August 1-4, 2007, Moscow, Russia, v. 3, p. 330-339, https://www.riversimulator.org/Resources/GCMRC/PhysicalResources2/Topping2007b.pdf

Grams, P.E., Schmidt, J.C., and Topping, D.J., 2007, The rate and pattern of bed incision and bank adjustment on the Colorado River in Glen Canyon downstream from Glen Canyon Dam:  Geological Society of America Bulletin, v. 119, p. 556-575, doi: 10.1130/B25969.1, with additional supporting material in the Geological Society of America Data Repository, https://doi.org/10.1130/B25969.1

Hazel, J.E., Jr., Kaplinski, M., Parnell, R., Kohl, K., and Topping, D.J., 2007, Stage-discharge relations for the Colorado River in Glen, Marble, and Grand Canyons, Arizona, 1990-2005:  U.S. Geological Survey Open-File Report 2006-1243, 19 p., https://pubs.usgs.gov/of/2006/1243/

Melis, T.S., Topping, D.J., Rubin, D.M., Wright, S.A., 2007, Research furthers conservation of Grand Canyon sandbars:  U.S. Geological Survey Fact Sheet 2007-3020, 4 p,https://pubs.usgs.gov/fs/2007/3020/

Rubin, D.M., Chezar, H., Topping, D.J., Melis, D.J., and Harney, J., 2007, Two new approaches for measuring spatial and temporal changes in bed-sediment grain size:  Sedimentary Geology, 7 p., doi: 10.1016/j.sedgeo.2007.03.020, https://doi.org/10.1016/j.sedgeo.2007.03.020

Schmidt, J.C., Topping, D.J., Rubin, D.M., Hazel, J.E., Jr., Kaplinski, M., Wiele, S.M., and Goeking, S.A., 2007, Streamflow and sediment data collected to determine the effects of Low Summer Steady Flows and Habitat Maintenance Flows in 2000 on the Colorado River between Lees Ferry and Bright Angel Creek, Arizona:  U.S. Geological Survey Open-File Report 2007-1268, 79 p., https://pubs.usgs.gov/of/2007/1268/

Voichick, N., and Wright, S.A., 2007, Water-temperature data for the Colorado River and tributaries between Glen Canyon Dam and Spencer Canyon, northern Arizona, 1988–2005: U.S. Geological Survey Data Series 251, 24 p., https://pubs.usgs.gov/ds/2007/251/

2006

Topping, D.J., Rubin, D.M., Schmidt, J.C., Hazel, J.E., Jr., Melis, T.S., Wright, S.A., Kaplinski, M., Draut, A.E., and Breedlove, M.J., 2006, Comparison of sediment-transport and bar-response results from the 1996 and 2004 controlled-flood experiments on the Colorado River in Grand Canyon:  CD-ROM Proceedings of the 8^th Federal Inter-Agency Sedimentation Conference, Reno, Nevada, April 2-6, 2006, ISBN 0-9779007-1-1, https://pubs.usgs.gov/misc/FISC_1947-2006/pdf/1st-7thFISCs-CD/8thFISC/Session%201B-3_Topping.pdf

Topping, D.J., Wright, S.A., Melis, T.S., and Rubin, D.M., 2006, High-resolution monitoring of suspended-sediment concentration and grain size in the Colorado River using laser-diffraction instruments and a three-frequency acoustic system:  CD-ROM Proceedings of the 8^th Federal Inter-Agency Sedimentation Conference, Reno, Nevada, April 2-6, 2006, ISBN 0-9779007-1-1.

Hazel, J., Jr., Topping, D.J., Schmidt, J.C., and Kaplinski, M., 2006, Influence of a dam on fine-sediment storage in a canyon river:  Journal of Geophysical Research, v. 111, F01025, 16 p, doi: 10.1029/2004JF000193, https://doi.org/10.1029/2004JF000193

Rubin, D.M., Chezar, H., Harney, J.N., Topping, D.J., Melis, T.S., and Sherwood, C.R., 2006, Underwater microscope for measuring spatial and temporal changes in bed-sediment grain size: U.S. Geological Survey Open-File Report 2006-1360, https://pubs.usgs.gov/of/2006/1360/

2005

Topping, D., Rubin, D., and Melis, T., 2005, Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River, in Flemming, B.W., Hartmann, D., and Delafontaine, M.T., eds., From Particle Size to Sediment Dynamics International Workshop, Hanse Institute for Advanced Study, Delmenhorst (Germany), April 15-18, 2004:  Research Centre Terramare Reports, No. 13, p. 153-158.

Topping, D.J., Rubin, D.M., and Schmidt, J.C., 2005, Regulation of sand transport in the Colorado River by changes in the surface grain size of eddy sandbars over multi-year timescales:  Sedimentology, v.52, p. 1133-1153, doi: 10.1111/j.1365-3091.2005.00738.x, https://doi.org/10.1111/j.1365-3091.2005.00738.x

Draut, A.E., Rubin, D.M., Dierker, J.L., Fairley, H.C., Griffiths, R.E., Hazel, J.E., Jr., Hunter, R.E., Kohl, K., Leap, L.M., Nials, F.L., Topping, D.J., and Yeatts, M., 2005, Sedimentology and stratigraphy of the Palisades, Lower Comanche, and Arroyo Grande areas of the Colorado River corridor, Grand Canyon, Arizona:  U.S. Geological Survey Scientific Investigations Report 2005-5072, 68 p, https://pubs.usgs.gov/sir/2005/5072/

Gray, J.R., Melis, T.S, Patiño, Eduardo, Gooding, D.J., Topping, D.J., Larsen, M.C., and Rasmussen, P.P., 2005, U.S. Geological Survey suspended-sediment surrogate research on optic, acoustic, and pressure-difference technologies, 10 p., https://www.usgs.gov/publications/us-geological-survey-research-surrogate-measurements-suspended-sediment in Gray, J.R., ed., Proceedings of the Federal Interagency Sediment Monitoring Instrument and Analysis Workshop, September 9-11, 2003, Flagstaff, Arizona:  U.S. Geological Survey Circular 1276, 46 p. plus online extended abstracts, https://pubs.usgs.gov/circ/2005/1276/

Rubin, D.M., Chezar, H., Topping, D.J., Melis, D.J., and Harney, J., 2005, Two new approaches for measuring spatial and temporal changes in bed-sediment grain size, in Flemming, B.W., Hartmann, D., and Delafontaine, M.T., eds., From Particle Size to Sediment Dynamics International Workshop, Hanse Institute for Advanced Study, Delmenhorst (Germany), April 15-18, 2004:  Research Centre Terramare Reports, No. 13, p. 135-138. 

White, M.A., Schmidt, J.C., and Topping, D.J., 2005, Application of wavelet analysis for monitoring the hydrologic effects of dam operation:  Glen Canyon Dam and the Colorado River at Lees Ferry, Arizona:  River Research and Applications, v.21, p. 551-565, doi: 10.1002/rra.827, https://doi.org/10.1002/rra.827

Wright, S.A., Melis, T.S., Topping, D.J., and Rubin, D.M., 2005, Influence of Glen Canyon Dam operations on downstream sand resources of the Colorado River in Grand Canyon, in Gloss, S.P., Lovich, J.E., and Melis, T.S., eds., The state of the Colorado River ecosystem in Grand Canyon: U.S. Geological Survey Circular 1282, p. 17-31, https://pubs.usgs.gov/circ/1282/

2004

Topping, D.J., Melis, T.S., Rubin, D.M., and Wright, S.A., 2004, High-resolution monitoring of suspended-sediment concentration and grain size in the Colorado River in Grand Canyon using a laser-acoustic system, in Hu, C., and Tan, Y, eds., Proceedings of the Ninth International Symposium on River Sedimentation, October 18-21, 2004, Yichang, China:  People’s Republic of China, Tsinghua University Press, p. 2507-2514, https://www.iahr.org/library/infor?pid=17383

Schmidt, J.C., Topping, D.J., Grams, P.E., and Hazel, J.E., Jr., 2004, System-wide changes in the distribution of fine sediment in the Colorado River corridor between Glen Canyon Dam and Bright Angel Creek, Arizona: Final report to the USGS Grand Canyon Monitoring and Research Center, Flagstaff, Arizona, 107 p.

2003

Topping, D.J., J.C. Schmidt, and L.E. Vierra, Jr., 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, 118 p, https://pubs.usgs.gov/pp/pp1677/

Gray, J.R., Gooding, Melis, T.S., Topping, D.J., and Rasmussen, P.P., 2003, U.S. Geological Survey suspended-sediment surrogate research, Part II:  Optic technologies:  Proceedings of the Virginia Water Research Symposium 2003, Water Resource Management for the Commonwealth, Virginia Polytechnic Institute and State University, Blacksburg, October 8-10, 2003, pp. 58-64, https://vtechworks.lib.vt.edu/bitstream/handle/10919/55230/2003WaterResearchSymposium_proceedings.pdf?sequence=1 - page=65

Gray, J.R., Melis, T.S, Patiño, Eduardo, Larsen, M.C., Topping, D.J., Rasmussen, P.P., and Figueroa-Alama, Carlos, 2003, U.S. Geological Survey research on surrogate measurements for suspended sediment, in Renard, K.G., McElroy, S.A., Gburek, W.J., Canfield, H.E., and Scott, R.L., eds., Proceedings of the 1^st Interagency Conference on Research in Watersheds:  U.S. Department of Agriculture, Agricultural Research Service, October 27-30, 2003, Benson, Arizona, pp. 95-100, https://www.tucson.ars.ag.gov/icrw/Proceedings/Gray.pdf

Gray, J.R., Patiño, Eduardo, Rasmussen, P.P., Larsen. M.C., Melis, T.S., Topping, D.J., and Alamo, C.F., 2003, Evaluation of sediment surrogate technologies for computation of suspended-sediment transport:  Proceedings of the 1^st International Yellow River Forum on River Basin Management, October 21-24, 2003:  Zhengzhou, Henan Province, China, the Yellow River Conservancy Publishing House, Vol. III, pp. 314-323, https://water.usgs.gov/osw/techniques/yrcc_surrogates.pdf

Melis, T.S., Topping, D.J., and Rubin D.M., 2003, Testing laser-based sensors for continuous in situ monitoring of suspended sediment in the Colorado River, Arizona, in  Bogen, J., Fergus, T., and Walling, D.E., eds., Erosion and Sediment Transport Measurement in Rivers:  Technological and Methodological Advances:  Wallingford, Oxfordshire, United Kingdom, IAHS Press, IAHS Publication 283, p. 21-27, https://pubs.usgs.gov/publication/70025352

2002

Melis, T.S., Topping, D.J., and Rubin, D.M., 2002, Testing laser-based sensors for continuous, in-situ monitoring of suspended sediment in the Colorado River, Grand Canyon, Arizona, in Appendix 2 of Gray, J.R., and Glysson, G.D., eds., Proceedings of the federal interagency workshop on turbidity and other sediment surrogates, April 30-May 2, 2002, Reno, Nevada:  U.S. Geological Survey Circular 1250 https://pubs.usgs.gov/circ/2003/circ1250/

 Rubin, D.M., Topping, D.J., Schmidt, J.C., Hazel, J., Kaplinski, K., and Melis, T.S., 2002, Recent sediment studies refute Glen Canyon Dam hypothesis:  EOS, Transactions, American Geophysical Union, v. 83, n. 25, p. 273, 277-278, doi: 10.1029/2002EO000191, https://doi.org/10.1029/2002EO000191

2001

Rubin, D.M., and Topping, D.J., 2001, Quantifying the relative importance of flow regulation and grain-size regulation of suspended-sediment transport (a), and tracking changes in bed-sediment grain size (b): Water Resources Research, v. 37, p. 133-146, doi: 10.1029/2000WR900250, https://doi.org/10.1029/2000WR900250

Rubin, D.M., and Topping, D.J., 2001, What regulates suspended-sediment transport in a given setting?  Grain size of bed sediment or flow:  Proceedings of the 7^th Inter-Agency Sedimentation Conference, v. 1, p. I-199 through I-205.

Rubin, D.M., Tate, G.M., Topping, D.J., and Anima, R.A., 2001, Use of rotating side-scan sonar to measure bedload:  Proceedings of the 7^th Inter-Agency Sedimentation Conference, v. 1, p. III-139 through III-143.

2000

Topping, D.J., Rubin, D.M., and Vierra, Jr., L.E., 2000, Colorado River sediment transport 1.  Natural sediment supply limitation and the influence of Glen Canyon Dam:  Water Resources Research, v. 36, p.515-542, doi: 10.1029/1999WR900285, https://doi.org/10.1029/1999WR900285

Topping, D.J., Rubin, D.M., Nelson, J.M., Kinzel, III, P.J., and Corson, I.C., 2000, Colorado River sediment transport 2.  Systematic bed-elevation and grain-size effects of sand supply limitation:  Water Resources Research, v. 36, p. 543-570, doi: 10.1029/1999WR900286, https://doi.org/10.1029/1999WR900286

pre-2000

Topping, D.J., 1993, Paleogeographic reconstruction of the Death Valley extended region:  Evidence from Miocene large rock-avalanche deposits in the Amargosa Chaos Basin, California: Geological Society of America Bulletin, v. 105, p. 1190-1213, doi: 10.1130/0016-7606(1993)105<1190:PROTDV>2.3.CO;2, https://doi.org/10.1130/0016-7606(1993)105<1190:PROTDV>2.3.CO;2

Topping, D.J., 1996, The tectonic significance of the Greater Amargosa Chaos - Buckwheat - Sperry Hills basin, in Reynolds, R.E., and Reynolds, J., eds., Punctuated Chaos in the Northeastern Mojave Desert, San Bernardino County Museum Association Quarterly, v. 43(1,2):  San Bernardino, California, San Bernardino County Museum Association, p. 143-146.

Topping, D.J., 1997, Flow, sediment transport, and channel geometric adjustment in the Grand Canyon, Arizona gage reach of the Colorado River during the 1996 Grand Canyon flood experiment, Proceedings of the Grand Canyon Monitoring and Research Center’s 1997 Symposium on the Glen Canyon Dam Beach / Habitat-building flow, p. 20-22.

Topping, D.J., 1997, Physics of flow, sediment transport, hydraulic geometry, and channel geomorphic adjustment during flash floods in an ephemeral river, the Paria River, Utah and Arizona:  University of Washington, unpublished Ph.D. thesis, Volume 1 and Volume 2, 406 p.

Topping, D.J., Melis, T.S., Pulwarty, R.S., 1998, ENSO and the Glen Canyon Dam Adaptive Management Program:  Eastern north Pacific forcing of Paria River floods in 1997: Proceedings of the 15^th Annual Pacific Climate (PACLIM) Workshop, p. 125-126.

Topping, D.J., Rubin, D.M., Nelson, J.M., Kinzel, III, P.J., and Bennett, J.P., 1999, Linkage between grain-size evolution and sediment depletion during Colorado River floods, in Webb, R.H., Schmidt, J.C., Marzolf, G.R., and Valdez, R.A., eds., The 1996 controlled flood in Grand Canyon:  Washington, D.C., American Geophysical Union, Geophysical Monograph 110, p. 71-98.

Holm, D.K., Pavlis, T.L., and Topping, D.J., 1994, Black Mountains crustal section, Death Valley, California, in McGill, S.F., and Ross, T.M., eds., Geological Investigations of an Active Margin, Geological Society of America Cordilleran Section Guidebook:  San Bernardino, California, San Bernardino County Museum Association, p. 31-54.

Nelson, J.M., Bennett, J.P., Topping, D.J., Parker, R.S., and Kinzel, III, P.J., 1998, Modeling flow and sediment transport to assess channel stability and evolution:  Proceedings of the Ninth Platte River Basin Ecosystem Symposium, 24-25 February 1998, Kearney, Nebraska, p. 74-75.

Rubin, D.M., Nelson, J.M., and Topping, D.J., 1998, Relation of inversely graded deposits to suspended-sediment grain-size evolution during the 1996 Flood Experiment in Grand Canyon:  Geology, v. 26, p. 99-102, doi: 10.1130/0091-7613(1998)​026<0099:ROIGDT>​2.3.CO;2, https://doi.org/10.1130/0091-7613(1998)026<0099:ROIGDT>2.3.CO;2