Geomorphology Symposium 2005 Abstracts
Geomorphology Symposium 2005 Pages
Table of Contents
- Holocene Terraces within the Larger Context of the Pleistocene Record of Grand Canyon, J. Pederson
Jump to Abstract - Effects of Tributary Debris on the Longitudinal Profile and Incision of the Colorado River in Grand Canyon, T.C. Hanks and R.H. Webb
Jump to Abstract - Debris Flows in Grand Canyon: Modeling Changes in the Longitudinal Profile Of the Colorado River, R.H. Webb, P.G. Griffiths, and C. S. Magirl
Jump to Abstract - Climatic Variability and Water Resources in the Colorado River Basin With an Emphasis on Effects on Grand Canyon, R.H. Webb
Jump to Abstract - Computation and Analysis of the Instantaneous-Discharge Record for the Colorado River at Lees Ferry, Arizona: May 8, 1921 through September 30, 2000, D.J. Topping
Jump to Abstract - The Degraded Reach: Rate and Pattern of Bed and Bank Adjustment of the Colorado River in the 25 km immediately Downstream from Glen Canyon Dam, P.E. Grams, J.C. Schmidt and D.J. Topping
Jump to Abstract - System-Wide Changes in the Distribution of Fine Sediment in the Colorado River Corridor between Glen Canyon Dam and Bright Angel Creek, Arizona J.C. Schmidt, D.J. Topping, P.E. Grams and J.E. Hazel
Jump to Abstract - Holocene Aggradation of the Colorado River in Grand Canyon, S.W. Davis and M.E. Davis
Jump to Abstract - Late Holocene Alluvial History of the Colorado River in Grand Canyon R. Hereford
Jump to Abstract - Terrace Stratigraphy, Geomorphology, And Climate in Cataract Canyon as a Control for Analogous Grand Canyon Settings, A.R. Potochnik, K.S. Thompson, G.R. O'Brien and L.A. Neal
Jump to Abstract - Use of Sedimentary Structures to Infer Geomorphic and Hydrologic History of Channel-Margin Deposits, D.M. Rubin, A.E. Draut, R.E. Hunter, T.S. Melis, F.L. Nials, J.C. Schmidt, D.J. Topping
Jump to Abstract - A Geomorphic Classification for Archeological Sites and Description of Small Catchment Processes along the Colorado River in Grand Canyon, A.R. Potochnik and K.S. Thompson
Jump to Abstract - A Quantitative Model of the Erosional Vulnerability of Archeological Sites on Holocene Fluvial Terraces from Local Runoff, Colorado River, A.R. Potochnik, K.S. Thompson and R. Ryel
Jump to Abstract - Twentieth Century Precipitation History of the Colorado Plateau and Northern Arizona, Relation to Increased Erosion of Prehistoric Colorado River Terraces in Grand Canyon, R. Hereford
Jump to Abstract - Gully Erosion of Holocene Terraces in Grand Canyon-Results of Recent Study, J. Pederson
Jump to Abstract - Monitoring Arroyos with Conventional Survey Techniques in Grand Canyon: 1996-2004, J. Hazel, M. Kaplinski, and R. Parnell
Jump to Abstract - Modeling of the Effects of Water and Sand Discharge on Sand Deposition in Archeologically Significant Reaches of the Colorado River in Grand Canyon S. Wiele and M. Torrizo
Jump to Abstract - The Role of Aeolian Sediment Transport in the Preservation of Archaeological Sites, Grand Canyon: Developing Criteria for Evaluating Dam Impact, A.E. Draut, D.M. Rubin and T. Melis
Jump to Abstract
Holocene Terraces within the Larger Context of the Pleistocene Record of Grand Canyon
J. Pederson, Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT 84322-5210, bolo@cc.usu.edu
Abstract
One of the classic themes in geomorphology is the scaling of time and space scales in terms of cause-and-effect in landscapes. If one is studying a localized feature such as a gully, then the causual processes are short in duration. If one is studying the entire long-profile of a river, the pertinent controls on that profile are similarly long in duration. Because of this characteristic of the science, the longer geomorphic record of Grand Canyon is valuable for providing a context for the distinct and shorter Holocene record that most research has focused on.
To summarize the Pleistocene record of eastern Grand Canyon: There is a well exposed set of deposits spanning the last ~400 ky that can be dated by a combination of optically-stimulated luminescence, uranium-series, and cosmogenic-nuclide dating. A long-term bedrock incision rate of 142 m/my can be extracted by linking those episodes in time when the Colorado River is on bedrock. Superimposed upon this long-term incision are very high amplitude cycles of aggradation and incision that are clearly controlled by climate-induced changes in hydrology and sediment supply. Finally, the records from local tributary catchments versus the mainstem Colorado River are unexpectedly different.
The recent history and functioning of the river corridor has been intensively studied, and there is general agreement that the Colorado is mostly an alluvial river in the present day. But it is valuable to note that over 100-ky or longer timescales, the Colorado is effectively a bedrock river that has incised through an elevated orogenic plateau, cutting a steep, bedrock-dominated landscape. Episodes of being an alluvial river comprise only a fraction of the rivers total history. The longer, cyclic record suggests the river is at the start of a several-thousand year episode of incision into underlying gravels that were deposited towards the end of the Last Glacial Maximum. Lastly, the nature of the river's sediment load and hydrology, its basic channel geometry, and the relative importance of debris fans have all changed significantly through time.
In summary, it is to be expected that the controls on gullying, the controls on debris fans and terraces, and the controls on the overall cutting of Grand Canyon will all be different. As the spatial scale of the problem gets smaller, the controlling processes become more episodic and temporary in their geologic context, but not necessarily in their human context.
Selected References:
Anders, M.D., Pederson, J.L., Rittenhour, T.M., Sharp, W.D., Gosse, J.C., Goble, R.J., Stockli, L., Yang, G., Karlstrom, K.E., And Crossey, L.C., In Press, Middle-Late Pleistocene Geomorphology And Alluvial Geochronology Of Eastern Grand Canyon-Unexpected Linkages Of Landscape Components During Climate Changes: Quaternary Science Reviews.
Pederson, J., Karlstrom, K., Sharp, W., And Mcintosh, W., 2002, Differential Incision Of Grand Canyon Related To Quaternary Faulting-Constraints From U-Series And Ar/Ar Dating: Geology, V. 30, No. 8, P. 739-742.
Pederson, J., Karlstrom. K., Sharp, W., And Mcintosh, W., 2003, Reply To Comment By Hanks, T.C. And Blair, J.L.., On Differential Incision Of The Grand Canyon Related To Quaternary Faulting - Constraints From U-Series And Ar/Ar Dating: Geology, P. E16-E17. DOI 10.1130/0091-7613(2003)31<E17:R>2.0.CO;2
Pederson, J.L., Schmidt, J.C., And Anders, M.D., 2003, Pleistocene And Holocene Geomorphology Of Marble And Grand Canyons, Canyon Cutting To Adaptive Management, In Easterbrook, D. J, Ed., Field Trip Guidebook For The Xvith INQUA Congress: Denver, Geological Society Of America, P. 407-438.
Pederson, J.L., 2001, Searching For The Pre-Grand Canyon Colorado River-The Muddy Creek Formation North Of Lake Mead: Young, R.A., And Spamer, E.E., Eds., The Colorado River: Origin And Evolution: Grand Canyon, Arizona, Grand Canyon Association Monograph 12, P. 71-75.
Pederson, J.L. And Karlstrom, K.E., 2001, Relating Differential Incision Of Grand Canyon To Slip Along The Hurricane-Toroweap Fault System: Young, R.A., And Spamer, E.E., Eds., The Colorado River: Origin And Evolution: Grand Canyon, AZ, Grand Canyon Association Monograph 12, P. 159-163.
Pederson, J.L. And Anders, M.D., Rittenhour, T.M., Sharp, W.D., Gosse, J.C., Karlstrom, K.E., Crossey, L.C., Goble, R.J., In Review, Using Fill Terraces To Understand Incision Rates And Evolution Of The Colorado River In Eastern Grand Canyon, Arizona: Journal Of Geophysical Research-Earth's Surface.
Related Student Theses:
Anders, Matt, MS 2002, Quaternary Geology And Landscape Evolution Of Eastern Grand Canyon, Arizona.
Mackley, Rob, MS 2005, Relating Large-Scale Bedrock Resisting And Hydraulic Driving Forces Along The Colorado River In Glen And Grand Canyons, Utah And Arizona.
Effects of Tributary Debris on the Longitudinal Profile and Incision of the Colorado River in Grand Canyon
T. C. Hanks1 and R. H. Webb2
1345 Middlefield Road, Menlo Park, CA 94025, thanks@usgs.gov
2 U.S. Geological Survey, 520 N. Park Avenue, Tucson, AZ 85719, rhwebb@usgs.gov
Abstract
The Colorado River in Grand Canyon has long been known as a "rapids-and-pools" river, with rapids forming primarily where tributary debris flows and related fans enter the river, constricting the channel laterally and raising its bed elevation. The rapids are short-wavelength (~1 km), small-amplitude ( ~5 m) convexities in the river's longitudinal profile, arising from the shallow gradient in the upstream pool and the steep gradient through the rapid itself. Analysis of the entire longitudinal profile through Grand Canyon reveals two long-wavelength (~100 km), large-amplitude (15 to 30 m) river-profile convexities: the eastern canyon convexity between River Mile (RM) 30 and RM 80 and the western canyon convexity between RM 160 and RM 250. These large-amplitude convexities have strong spatial correlations with high probabilities of debris-flow occurrence, high densities of debris fans, and the largest debris fans along the river. Convexities of intermediate scale are also identified in the longitudinal profile. River-profile convexities are unstable and require an active and powerful geologic process to maintain them, in this case the abundant, frequent, and voluminous debris-flow activity in Grand Canyon. For all of the Holocene and at least some of the late Pleistocene, the Colorado River has been expending its energy transporting sediment within Grand Canyon, integrating short-wavelength convexities into long-wavelength convexities, with little or no bedrock incision. The several known episodes of late-Quaternary aggradation and subsequent incision of the Colorado River, with most of the Holocene devoted to its aggradation, suggest that distinctions must now be made between "debris-fill incision" and "bedrock incision", as we admit the possibility that debris-fill incision might occur in the absence of bedrock incision. Mostly because the subaqueous geometry of the river channel and its debris fill is so poorly known, even at the present time, these distinctions will not be easy to quantify. Any incision rate involving a depth of incision of the order of the (unknown) river-geometry dimensions is subject to large uncertainties, comparable to the incision rate itself. Such must be the case for most mid-to-late Quaternary incision rates determined for the Colorado River in Grand Canyon.
Key Words: Colorado River, Grand Canyon, river-profile convexities, debris flows, incision rates
Selected References:
Hanks, T.C., And R.H. Webb (2005). Effects Of Tributary Debris On The Longitudinal Profile And Incision Of The Colorado River In Grand Canyon, J. Geophys. Res., Submitted.
Debris Flows in Grand Canyon: Modeling Changes in the Longitudinal Profile Of the Colorado River
R. H. Webb1, P. G. Griffiths2, and C. S. Magirl3, U.S. Geological Survey, 520 N. Park Avenue, Tucson, AZ 85719, 1rhwebb@usgs.gov, 2pggriffi@usgs.gov, 3csmagirl@usgs.gov
Abstract
Debris flows occur in 736 tributaries of the Colorado River in Grand Canyon between Lee's Ferry and the Grand Wash Cliffs in Arizona (river miles 0 to 276). An episodic type of flash flood, debris flows transport poorly-sorted particles ranging from clay to boulders to the Colorado River. Debris flows create and maintain debris fans and the hundreds of associated riffles and rapids that control the geomorphic framework of the river. Interpretation of considerable repeat photography spanning 120 years, supplemented with aerial photography made between 1935 and 1990, yielded information on the historical frequency of debris flows in 168 of the 736 tributaries (23%). Of the 168 tributaries, 96 contain evidence of post-1872 debris flows, whereas 72 tributaries have not had a debris flow during the last century. The frequency of debris flows ranges from one every 10 to 15 years in certain eastern tributaries to less than one per century in other drainage basins. On average, debris flows may recur approximately every 30 to 50 years in individual tributaries, although adjacent tributaries may have considerably different histories. On average, repeat photography shows that 5.0 debris flows per year occur in Grand Canyon, compared with a direct observational record of 5.1 debris flows per year from 1984 through 2003. The oldest Holocene debris fan in Grand Canyon dated by the 14C method is 5.4 ka. Using dissolution-pit dating, the oldest known surfaces are about 7.3 ka, surfaces commonly dated between 0.5 and 7.3 ka. Using 3He and 14C, debris flows occurred at Lava Falls Rapid at 0.5, 2.2, and 3.0 ka. Considered together, Holocene ages of debris flows suggests they may not be completely random in time; instead, debris-flow activity is probably related to periods of increased regional storm frequency.
Sediment yield from debris flow was modeled by combining a frequency model with data on debris-flow magnitude and particle-size distribution. Using logistic regression with the extensive repeat-photography record of debris flows, we calculated logistic probabilities using 22 morphometric, lithologic, and climatic parameters as the independent variables. The probability that a debris flow occurred during the past 100 years was estimated for each of the 736 tributaries, explaining about 74% of observed data. We used a frequency factor approach to convert the logistic probabilities to a lognormal distribution. Using total volumes of historical debris flows measured in Grand Canyon, we developed an enveloping curve relating debris-flow volumes to tributary drainage area. Combining the frequency-factor relation and magnitude data, we estimated total debris-flow sediment yield per decade for each debris-flow producing tributary in Grand Canyon and modeled their effects on the drop through rapids.
Debris flows deliver between 0.12 and 0.25.106 Mg/yr of sediment to debris fans between Lee's Ferry and Lake Mead and between 0.46 and 0.96 . 106 Mg/yr in Marble Canyon alone. Measured boulder content of historical debris flows averages 13.8±18.7%. Debris flows produce from 5,000 to 18,000 Mg of boulders every decade that accumulate on debris fans. We used our stochastic model to accumulate sediments on debris fans over 10 centuries; all particles finer than boulders are assumed to be reworked by the pre-dam Colorado River, leaving a lag of boulders in the river to form rapids. Average calculated bed rise at tributary junctures is 2.25 m/kyr, which is greater than the average drop of 1.58 m. The only tributaries on the list of 25 largest rapids in 1923 and the list of 30 largest bed rises are Bright Angel Creek and Prospect Canyon (Lava Falls Rapid). The list of tributaries with the largest predicted rises include South Canyon (1), Bright Angel Creek (2), and Tiger Wash (4), and half of the top 30 predicted rises occur at tributaries that currently have no rapids. Using one-dimensional flow modeling, we show that debris flows can affect the river corridor for many river miles, drowning out upstream rapids and creating low-velocity conditions that may promote fine-grained deposition along channel margins in the interval between debris flow and reworking flood. Our model of boulder delivery to the corridor is incomplete, but preliminary results show a promising approach to predicting the locations of future debris flows as well as explaining Holocene changes in the grade of the Colorado River.
Selected References:
Griffiths, P.G., Webb, R.H., And Melis, T.S., 1997, Initiation Of Debris Flows In Bedrock Canyons Of The Colorado River, USA, In Chen, Cheng-Lung (Editor), Debris-Flow Hazards Mitigation: Mechanics, Prediction, And Assessment: New York, American Society Of Civil Engineers, P. 12-20.
Griffiths, P.G., Webb, R.H., And Melis, T.S., 2004, Initiation And Frequency Of Debris Flows In Grand Canyon, Arizona: Journal Of Geophysical Research, Surface Processes, V. 109, F04002, Doi:10.1029/2003JF000077, 14 P.
Magirl, C.S., Webb, R.H., And Griffiths, P.G., 2004, Long-Term Change In The Water-Surface Profile Of The Colorado River In Grand Canyon, Arizona: Water Resources Research, In Press.
Marzolf, G.R., Valdez, R.A., Schmidt, J.C., And Webb, R.H., 1998, Perspectives On River Restoration In The Grand Canyon: Bulletin Of The Ecological Society Of America, V. 79, No. 4, P. 250-254.
Melis, T.S., Webb, R.H., And Griffiths, P.G., 1997, Debris Flows In Grand Canyon National Park: Peak Discharges, Flow Transformations, And Hydrographs, In Chen, Cheng-Lung (Editor), Debris-Flow Hazards Mitigation: Mechanics, Prediction, And Assessment: New York, American Society Of Civil Engineers, P. 727-736.
Melis, T.S., And Webb, R.H., 1993, Debris Flows In Grand Canyon National Park, Arizona C Magnitude, Frequency And Effects On The Colorado River, In Shen, H.W., Su, S.T., And Wen, F., (Editors), Hydraulic Engineering >93: New York, American Society Of Civil Engineers, Proceedings Of The ASCE Conference, San Francisco, California, P. 1290-1295.
Melis, T.S., Webb, R.H., Griffiths, P.G, And Wise, T.J., 1994, Magnitude And Frequency Data For Historic Debris Flows In Grand Canyon National Park And Vicinity, Arizona: U.S. Geological Survey Water Resources Investigations Report 94-4214, 285 P.
Pizzuto, J.E., Webb, R.H., Griffiths, P.G., Elliott, J.G, And Melis, T.S., 1999, Entrainment And Transport Of Cobbles And Boulders From Debris Fans, In Webb, R.H., Schmidt, J.C., Marzolf, G.R., And Valdez, R.A., The Controlled Flood In Grand Canyon: Scientific Experiment And Management Demonstration: Washington, D.C. American Geophysical Union, Geophysical Monograph 110, P. 53-70.
Schmidt, J.C., Grams, P.E., And Webb, R.H., 1995, Comparison Of The Magnitude Of Erosion Along Two Large Regulated Rivers: Water Resources Bulletin, V. 31, P. 617-631.
Webb, R.H., Pringle, P.T., Reneau, S.L., And Rink, G.R., 1988, The 1984 Monument Creek Debris Flow: Implications For The Formation Of Rapids On The Colorado River In Grand Canyon National Park: Geology, V. 16, P. 50-54.
Webb, R.H., Pringle, P.T., And Rink, G.R., 1989, Debris Flows In Tributaries Of The Colorado River In Grand Canyon National Park, Arizona: U.S. Geological Survey Professional Paper 1492, 39 P.
Webb, R.H., 1996, Grand Canyon, A Century Of Change: Tucson, University Of Arizona Press, 320 P.
Webb, R.H., Griffiths, P.G., Melis, T.S., Elliott, J.G., And Pizzuto, J.E., 1999, Reworking Of Debris Fans By The 1996 Controlled Flood In Grand Canyon, In Webb, R.H., Schmidt, J.C., Valdez, R.A., And Marzolf, G.R., The 1996 Flood In Grand Canyon: Scientific Experiment And Management Demonstration: Washington, D.C. American Geophysical Union, Geophysical Monograph, P. 37-51.
Webb, R.H., Wegner, D.L., Andrews, E.D., Valdez, R.A., And Patten, D.T., 1999, Downstream Effects Of Glen Canyon Dam On The Colorado River In Grand Canyon: A Review, In Webb, R.H., Schmidt, J.C., Marzolf, G.R., And Valdez, R.A., The Controlled Flood In Grand Canyon: Scientific Experiment And Management Demonstration: Washington, D.C. American Geophysical Union, Geophysical Monograph 110, P. 1-21.
Webb, R.H., Schmidt, J.C., Marzolf, G.R., And Valdez, R.A. (Editors), 1999, The Controlled Flood In Grand Canyon: Scientific Experiment And Management Demonstration: Washington, D.C. American Geophysical Union, Geophysical Monograph 110, 367 P.
Webb, R.H., Melis, T.S., Griffiths, P.G., Elliott, J.G., Cerling, T.E., Poreda, R.J, Wise, T.W, And Pizzuto, J.E., 1999, Lava Falls Rapid In Grand Canyon, Effects Of Late Holocene Debris Flows On The Colorado River: U.S. Geological Survey Professional Paper 1591, 90 P.
Webb, R.H., Griffiths, P.G., Melis, T.S., And Hartley, D.R., 2000, Sediment Delivery By Ungaged Tributaries Of The Colorado River In Grand Canyon: U.S. Geological Survey Water Resources Investigations Report 00-4055, 67 P.
Webb, R.H., Griffiths, P.G., And Hartley, D.R., 2001, Techniques For Estimating Sediment Yield Of Ungaged Tributaries On The Southern Colorado Plateau: Reno, Nevada, Proceedings Of The Seventh Federal Interagency Sedimentation Conference, P. I-24 To I-31.
Webb, R.H., And Griffiths, P.G., 2001, Sediment Delivery By Ungaged Tributaries Of The Colorado River In Grand Canyon, U.S. Geological Survey Fact Sheet FS-018-01, 4 Pp.
Webb, R.H., And Griffiths, P.G., 2001, Monitoring Of Coarse Sediment Inputs To The Colorado River In Grand Canyon, U.S. Geological Survey Fact Sheet FS-019-01, 4 Pp.
Webb, R.H., Melis, T.S., And Valdez, R.A., 2002, Observations Of Environmental Change In Grand Canyon: U.S. Geological Survey Water Resources Investigations Report 02-4080, 33 P.
Webb, R.H., Melis, T.S., And Griffiths, P.G., 2003, Debris Flows And The Colorado River, In Beus, S.S., And Morales, M., Grand Canyon Geology, 2nd Edition: New York, Oxford University Press, P. 371-390.
Webb, R.H., Griffiths, P.G., And Melis, T.S., 2004, Debris Flows And Rapids In Grand Canyon: Implications For Erosion Rates And Evacuation Of Sediment From Tributary Canyons, In Young, R.A., And Spamer, E.E. (Eds.), 2001, The Colorado River: Origin And Evolution: Grand Canyon, Arizona, Grand Canyon Association Monograph 12, P. 183-188.
Climatic Variability and Water Resources in the Colorado River Basin With an Emphasis on Effects on Grand Canyon
R.H. Webb, U.S. Geological Survey, 520 N. Park Ave., Tucson, AZ 85745, rhwebb@usgs.gov
Abstract
Climatic fluctuations have profound effects on water resources in the western United States, particularly runoff in the Colorado River basin. Since the start of persistent drought conditions in about 2000, inflows to Lake Powell on the Colorado River have been below average, leading to drawdown of Lake Mead and Lake Powell, the primary means of storage on the river. Winter and spring frontal systems originating in the North Pacific Ocean provide the largest and most important source of moisture for runoff, and this is the moisture source most affected by global-scale climatic fluctuations. El Niño-Southern Oscillation (ENSO) conditions in the Pacific Ocean, which oscillate over a 4-7 year period have been linked to floods (El Niño) and droughts (La Niña) across the western United States. Warm-winter storms can be enhanced during El Niño conditions, causing above-average runoff in the Colorado River basin, as occurred in 1982-1983. The occurrence of La Niña conditions is frequently, though not always, associated with below-average flow in the Colorado River. Another longer-term index of climatic variability is the Pacific Decadal Oscillation (PDO), which varies on a scale of 30-50 years and is strongly related to ENSO. During the 20th century, the PDO had several phases: warm from 1923-1943 and from 1976-1998, cool from 1944-1975, cool from 1999-2001, and warm from 2002 to the present. Finally, drought occurrence in the United States has been linked with fluctuations in the Atlantic Multidecadal Oscillation (AMO), an index of Atlantic Ocean sea-surface temperature that varies on a scale of 20-35 years. AMO "cool" phase occurred from 1902-1925 and from 1964-1994, whereas a "warm" phase occurred almost continuously from 1926-1963 and was associated with persistent regional drought. The AMO entered a persistent warm phase in 1996 and is associated with the current drought.
No single index of the global climate system-ENSO, PDO, AMO-explains a significant amount of the variation of river flow in the Colorado River. Flow in the Colorado River at Lees Ferry or entering Lake Powell varied significantly during the 20th century. Not accounting for consumptive use, which increased during the 20th century upstream of Lake Powell, the average annual volume was 12.4 million acre-feet (MAF) from 1895 through 2003. The annual flow volume decreased by about 0.5 MAF per decade from 1895 through 2003, is due, in part, to upstream water use. The period 1905-1922 had the highest long-term annual flow volume in the 20th century, averaging 16.1 MAF at Lees Ferry. The highest annual flow volume occurred in 1984 (22.2 MAF), and the highest 3-year average is 20.3 MAF for the period 1983-1985. The lowest annual flow volume is 3.8 MAF in 2002, followed by 3.9 MAF in 1934 and 4.8 MAF in 1977. Flow averaged only 5.4 MAF during 2001-2003; the lowest previous 3-year average flows were 7.3 MAF from 1954 through 1956 and 8.0 MAF from 1933 through 1935.
Preliminary data from the Bureau of Reclamation, which adjusts for upstream consumptive use, indicate that 2002-2004 had the lowest 3-year average flow (9.2 MAF), compared with the previous low of 9.8 MAF during 1953-1955. Tree-ring reconstructions of precipitation in northern Utah indicate that, since 1226 A.D., nine droughts have occurred lasting 15-20 years and four droughts have occurred lasting more than 20 years. Such findings from the tree-ring record, coupled with new findings about the connection between the AMO and drought frequency, suggest that the current drought could continue for several more years. Alternatively, the three droughts that affected the basin during the 20th century each lasted from 4 to 11 years, indicating that the current dry conditions could shift to wetter conditions at any time.
Selected References
Cayan, D.R., And Webb, R.H., 1992, El Niño/Southern Oscillation And Streamflow In The Western United States, In Diaz, H.F., And Markgraf, V., (Editors), El Niño, Historical And Paleoclimatic Aspects Of The Southern Oscillation: Cambridge, England, Cambridge University Press, P. 29-68.
Collier, M., And Webb, R.H., 2002, Floods, Droughts, And Climate Change: Tucson, University Of Arizona Press, 153 P.
Hereford, Richard, And Webb, R.H., 1992, Historic Variation In Warm-Season Rainfall On The Colorado Plateau, U.S.A.: Climatic Change, V. 22, P. 239-256.
Hereford, R., Webb, R.H., And Graham, S., 2002, Precipitation History Of The Colorado Plateau Region, 1900-2000: U.S. Geological Survey Fact Sheet 119-02, 4 P.
Hereford, R., Webb, R.H., And Longpré, C.I., 2004, Precipitation History Of The Mojave Desert Region, 1893-2001: U.S. Geological Survey Fact Sheet 117-03, 4 P.
Schmidt, K.M., And Webb, R.H., 2001, Researchers Consider U.S. Southwest's Response To Warmer, Drier Conditions: EOS, V. 82, No. 41, P. 475, 478.
Webb, R.H., Mccabe, G.J., Hereford, R., And Wilkowske, C., 2004, Climatic Fluctuations, Drought, And Flow Of The Colorado River: U.S. Geological Survey Fact Sheet 2004-3062, 4 P.
Computation and Analysis of the Instantaneous-Discharge Record for the Colorado River at Lees Ferry, Arizona: May 8, 1921 through September 30, 2000
D. Topping, USGS Water Resources Division, National Research Program, 2255 N. Gemini Dr., Flagstaff, AZ 86001, dtopping@usgs.gov
Abstract
A gaging station has been operated by the U.S. Geological Survey at Lees Ferry, Arizona, since May 8, 1921. In March 1963, Glen Canyon Dam was closed 15.5 miles upstream, cutting off the upstream sediment supply and regulating the discharge of the Colorado River at Lees Ferry for the first time in history. To evaluate the pre-dam variability in
the hydrology of the Colorado River, and to determine the effect of the operation of Glen Canyon Dam on the downstream hydrology of the river, a continuous record of the instantaneous discharge of the river at Lees Ferry was constructed and analyzed for the entire period of record between May 8, 1921, and September 30, 2000. This effort involved retrieval from the Federal Records Centers and then synthesis of all the raw historical data collected by the U.S. Geological Survey at Lees Ferry. As part of this process, the weak discharges of the two largest historical floods at Lees Ferry, the 1884 and 1921 floods, were reanalyzed and recomputed. This reanalysis indicates that the peak discharge of the 1884 flood was 210,000+30,000 cubic feet per second (ft3/s) and the peak discharge f the 1921 flood was 170,000+20,000 ft3/s. These values are indistinguishable from the peak discharges of these floods originally estimated or published by the U.S. Geological Survey, but are substantially less than the currently accepted peak discharges of these floods. The entire continuous record of instantaneous discharge of the Colorado River at Lees Ferry can now be requested from the U.S. Geological Survey Grand Canyon Monitoring and Research Center, Flagstaff, Arizona, and is also available electronically at. This record is perhaps the longest (almost 80 years) high-resolution (mostly 15- to 30-minute precision) times series of river discharge available. Analyses of these data, therefore, provide an unparalleled characterization of both the natural variability in the discharge of a river and the effects of dam operations on a river. Following the construction and quality-control checks of the continuous record of instantaneous discharge, analyses of flow duration, sub-daily flow variability, and flood frequency were conducted on the pre- and post-dam parts of the record. These analyses indicate that although the discharge of the Colorado River varied substantially prior to the closure of Glen Canyon Dam in 1963, operation of the dam has caused changes in discharge that are more extreme than the pre-dam natural variability. Operation of the dam has eliminated flood flows and base flows, and thereby has effectively "flattened" the annual hydrograph. Prior to closure of the dam, the discharge of the Colorado River at Lees Ferry was lower than 7,980 ft3/s half of the time. Discharges lower than about 9,000 ft3/s were important for the seasonal accumulation and storage of sand in the pre- river downstream from Lees Ferry. The current operating plan for Glen Canyon Dam no longer allows sustained discharges lower than 8,000 ft3/s to be released. Thus, closure of the dam has not only cut off the upstream supply of sediment, but operation of the dam has also largely eliminated discharges during which sand could be demonstrated to accumulate in the river. In addition to radically changing the hydrology of the river, operation of the dam for hydroelectric-power generation has introduced large daily fluctuations in discharge. During the pre-dam era, the median daily range in discharge was only 542 ft3/s, although daily ranges in discharge exceeding 20,000 ft3/s were observed during the summer thunderstorm season. Relative to the pre-dam period of record, dam operations have increased the daily range in discharge during all but 0.1 percent of all days. The post-dam median daily range in discharge, 8,580 ft3/s, exceeds the pre-dam median discharge of 7,980 ft3/s. Operation of the dam has also radically changed the frequency of floods in the Colorado River at Lees Ferry. The frequency of floods with peak discharges larger than about 29,000 ft3/s has greatly decreased, while the frequency of smaller floods, with peak discharges between 18,500 and 29,000 ft3/s, as increased substantially. Operation of the dam has greatly extended the duration of smaller floods; for example, each of the four longest periods of sustained flows in excess of 18,500 ft3/s occurred after closure of the dam.
Selected References
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.
Rubin, D.M., And Topping, D.J., 2001, 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. 37, P. 133-146.
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.
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.
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.
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.
The Degraded Reach: Rate and Pattern of Bed and Bank Adjustment of the Colorado River in the 25 km immediately Downstream from Glen Canyon Dam
P. E. Grams1, J. C. Schmidt2, and D. J. Topping3
1,2Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT, 1grams@cc.usu.edu ,2 jschmidt@cc.usu.edu
3 USGS Water Resources Division, National Research Program, Flagstaff, AZ 86001, dtopping@usgs.gov
Abstract
The 25-km reach of the Colorado River immediately downstream from Glen Canyon Dam is a classic example of a channel whose bed has degraded and armored in response to flow and sediment regulation caused by a dam. Although the evacuation of bed sediment from this reach was reported upon nearly 30 yrs ago (Pemberton, 1976), the complete array of channel adjustments has not been described previously. This study uses the abundance of historical data available for this river segment and field measurements made in the last decade in a comprehensive analysis of channel change. We add 25 years to the record of previously reported bed elevation measurements, such that the long-term trend in channel bed adjustment can now be understood. These measurements are supplemented with (1) new analyses of long-term records of bed and bank elevation at U. S. Geological Survey stream gaging stations, (2) mapping of historical aerial photographs that depict changes in the channel-side alluvial deposits, and (3) a pre-dam sediment budget for Glen Canyon. These data depict in detail the processes of the transformation of the Colorado River in Glen Canyon from an alluvial sand-bedded river with a large reservoir of fine-sediment storage to a pool-and-riffle, gravel-bed trout stream.
Although bed degradation began when the cofferdam was installed in 1959, the greatest proportion of degradation occurred in 1965 when the U. S. Bureau of Reclamation intentionally released high flows from the dam in a series of pulses intended to scour the reach downstream from the dam. This event evacuated a reach-average of 2.6 m of sediment from the center of the channel. Continued erosion occurred in the downstream half of the study area during emergency power plant-bypass releases of the mid-1980s. There were small adjustments in bed elevation in the 1990s, but the channel bed today is much the same as it was 15 years ago. The total volume of bed sediment evacuated from the study reach is equivalent to one-third the pre-dam annual sediment load and is two orders of magnitude greater than estimated post-dam sediment inputs to the reach. The average size of bed material has increased from 0.2 mm in 1956 to over 20 mm as measured in 1999.
The widespread bed degradation has resulted in the emergence of additional channel controls, which frequently occur at the mouths of tributary canyons. This is evidenced by the development of a stepped low-water longitudinal profile from the smooth profile that existed in the pre-dam era. The magnitude of degradation in riffles decreases with distance downstream from the dam, consistent with general models of bed degradation downstream from dams. The magnitude of sediment evacuation from pools, however, does not decrease systematically, but fluctuates in magnitude and extends much farther downstream.
The alluvial deposits in Glen Canyon include a complex suite of pre- and post-dam fine- and coarse-grained deposits that occur at a variety of elevations above the active river channel. Many deposits are pre-dam remnants, specifically associated with the lowering of the channel. These include pre-dam fine-sediment deposits that are now perched high above the present active channel and mid- and side-channel gravel and cobble bars that occur in segments where degradation was concentrated in one part of the channel, leaving exposed large areas of the pre-dam riverbed. The reach also includes narrow strips of fine-grained post-dam flood deposits. Both pre- and post-dam fine-grained deposits have been colonized and stabilized by invasive exotic riparian vegetation, resulting in a net decrease in bankfull channel width of about 6% throughout the study area.
Some erosion of channel-side deposits has occurred in the study reach, although the magnitude of this erosion is small compared to the evacuation of sediment from the bed. Most of this erosion has been concentrated in a few pre-dam terraces that eroded dramatically for brief periods and have become armored and stabilized. The area of alluvium represented by eddy deposits has not changed significantly, but the elevation of these deposits has decreased resulting in net erosion from eddy storage environments.
Selected References
Grams, P.E., Schmidt, J.C., Topping, D.J., and Goeking, S., 2004. The Degraded Reach: Rate And Pattern Of Bed And Bank Adjustment Of The Colorado River In The 25 Km Immediately Downstream From Glen Canyon Dam, Final Report, Grand Canyon Monitoring and Research Center, Flagstaff, Arizona.
System-Wide Changes in the Distribution of Fine Sediment in the Colorado River Corridor between Glen Canyon Dam and Bright Angel Creek, Arizona
J. C. Schmidt1, D. J. Topping2, P. E. Grams1, and J. E. Hazel3
1Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT 84322-5210, jschmidt@cc.usu.edu, grams@cc.usu.edu
2USGS Water Resources Division, National Research Program, c/o GCMRC, 2255 N Gemini Dr, Flagstaff, AZ 86001, dtopping@usgs.gov
3Northern Arizona University, Dept. of Geology, Flagstaff, AZ 86001, Joseph.Hazel@nau.edu
Abstract
The riverine ecosystem of the Colorado River between Glen Canyon Dam and Bright Angel Creek had less fine sediment on its bed, in eddies, and as channel-margin deposits in 2001 than it did prior to completion of the dam. Changes in dam operations in the 1990s did not arrest this trend.
Eddies are now the primary storage site of fine sediment. Eddies have always been a very large storage site for fine sediment, but the bed once played a more important role than it does today. The bed has been significantly lowered in Glen Canyon, but the bed has only degraded in pools and ponded backwaters in Marble and Upper Grand Canyons. There is no evidence that fine sediment aggrades on the main channel bed or in the deep parts of eddies for longer than a few weeks to a few months, and these parts of the river respond quickly to changes in flow and sediment transport. These areas evacuate fine sediment during flows typical of the 1990s.
Post-dam flood deposits have a longer response time and adjust over a period of years to decades to changes in dam operations. These deposits are only constructed by dam releases that exceed power plant capacity. They are subject to large erosion rates during the first months following flood recession, but erosion rates thereafter decrease. The area of these deposits caused by the 1996 Controlled Flood lasted about 5 years, although some individual deposits remain large today.
Selected References
Schmidt, John C., Topping, David J., Grams, Paul E., and Hazel, Joseph E., October 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 (available at USGS Grand Canyon Monitoring and Research Center, Flagstaff, AZ)
Holocene Aggradation of the Colorado River in Grand Canyon
S. W. Davis and M. E. Davis, Davis Consulting Earth Scientists, PO Box 734, Georgetown, CA 95634, davis2consulting@sbcglobal.net
Abstract
Holocene deposits of fine sand and silt outcrop frequently along the river corridor in Grand Canyon, to a height of ~10 m above present river level. Known as the Archeological Unit (AU) for the prehistoric artifacts they contain, the surfaces of these deposits were farmed extensively by Ancestral Puebloans in the late Holocene. These deposits are devoid of the coarse quartzite and porphyry gravels so typical of both older and younger river deposits and point to a Colorado River (CR) in the mid-to-late Holocene in a low-energy, depositional regime that filled the present channel to overflowing with fine sand and silt. Tributary fans and terraces also aggrade to the top of and interfinger with the AU. In eastern Grand Canyon, previously published radiometric ages of charcoal in hearths and buried soils date to 4460 yr BP at ~2 m below the top of the remnant surfaces. Similar materials of greater but unknown age extend to below present river grade. Many tools and pottery fragments scattered on top of the surfaces are identified as artifacts associated with the Pueblo II cultures (1,000 yr BP). However, radiometric ages associated with buried soils containing maize pollen are contemporaneous only with late-Archaic (>3,000 yr BP) through Basketmaker II and III cultures (~3,000 - 1200 yr BP). Ancestral Puebloan people abandoned the Grand Canyon by ~ 700 yr BP. Our data suggest Colorado River incision likely began ~1200 to 1000 yr BP, as evidence for Pueblo II farming along the main stem is lacking. This does not preclude the possibility of occasional overbank flood deposits that post-date the beginning of incision, but diversion of CR water onto corn fields appears to have ceased prior to Pueblo II - time. Events that triggered the aggradation were likely climatically induced and probably began in the late-Pleistocene or early-Holocene.
Late Holocene Alluvial History of the Colorado River in Grand Canyon
R. Hereford, U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, rhereford@usgs.gov
Abstract
Topographically controlled large-scale surficial geologic mapping was undertaken at seven localities (Ninemile Wash, Lees Ferry, Nankoweap Rapids, Palisades Creek, Tanner Rapids, "Forbidden zone," and Granite Park) to elucidate the late Quaternary geology of the Colorado River corridor. The mapping emphasized the late Holocene alluvial history (i.e., the past several thousand years) of the river, the relation of terraces to archeologic sites and features, and the age and origin of tributary debris fans. In addition, field observations and measurements were made at 16 tributary debris fans. The debris fans range in age from around 7,000 to 700 cal yr B.P. and were deposited during five essentially canyon-wide episodes of fan forming debris flow activity. The alluvial deposits consist of seven terraces and related alluvial deposits that range in age from around 4,500 B.P. to the present. For operational purposes, these deposits are conveniently divided into those of pre- and post-dam (1963) age.
The pre-dam alluvium is typically very fine-grained poorly sorted sand that was deposited by floods on incipient floodplains or floodplain-like features near and around tributary debris fans. Geologic mapping established the relative age of the pre-dam deposits based on height above the river at 140 m3/s discharge and cross-cutting, erosional stratigraphic relations. Radiocarbon dating and archeologic content were used to estimate their absolute age. The pre-dam deposits are referred to as the striped alluvium (ca. 2,500 B.C. to A.D. 300, 13-17 m above river), the alluvium of Pueblo-II age (A.D. 700-1200, 8-13 m above river), the upper mesquite alluvium (A.D. 1400-1880, 5-8 m above river), the lower mesquite alluvium (A.D. 1880-1922, 5-6 m above river), and the pre-dam alluvium (A.D. 1922-1958, 4-5 m above river). The terminology refers to the characteristic feature (i.e., color, archeology, or vegetation) of the deposit or its relative elevation. The striped alluvium and alluvium of Pueblo-II age are particularly relevant as the terraces and deposits of these units contain important archeologic material. Generally, the pre-dam alluvial history of the Colorado River in Grand Canyon is similar to its major tributaries on the southern Colorado Plateau, suggesting a regional climatic control on alluvial activity. The post-dam deposits consist of three deposits and terrace-like features that formed during distinctive discharge regimens controlled by operation of Glen Canyon Dam. These deposits are the flood sand of 1983, the high flow sand of 1984, and the fluctuating flow sand. The post-dam deposits are slightly coarser grained and are deficient in silt and clay compared with the pre-dam alluvium, the result of decreased fine-grained sediment load during the post-dam era.
Selected References
Burke, K.J., Fairley, H.C., Hereford, Richard, And Thompson, K.S., 2003, Holocene Terraces, Sand Dunes, And Debris Fans Along The Colorado River In Grand Canyon, In, Beus, S.S., And Morales, Michael, Eds., Grand Canyon Geology: London, Oxford University Press, P. 352-370.
Fairley, H.C., And Hereford, Richard, 2002, Geoarcheological Research Along The Colorado River In Grand Canyon, Arizona, In, Phillips, B.P., Ed., Culture And Environment In The American Southwest: Papers In Honor Of Robert C. Euler: Phoenix, Arizona, SWCA Anthropological Research Paper Number 8, P. 39-48.
Hereford, Richard, 1996, Map Showing Surficial Geology And Geomorphology Of The Palisades Creek Area, Grand Canyon National Park, Arizona: U.S. Geological Survey Miscellaneous Investigations Map I-2449, Scale 1:2,000, (With Discussion).
Hereford, Richard, Thompson, K.S., Burke, K.J., And Fairley, H.C., 1996, Tributary Debris Fans And The Late Holocene Alluvial Chronology Of The Colorado River, Eastern Grand Canyon, Arizona: Geological Society Of America Bulletin, V. 108, P. 3-19.
Hereford, Richard, Burke, K.J., And Thompson, K.S., 1998, Map Showing Quaternary Geology And Geomorphology Of The Nankoweap Rapids Area, Marble Canyon, Arizona: U.S. Geological Survey Miscellaneous Investigations Map I-2608, Scale 1:2,000 (With Discussion).
Hereford, Richard, Thompson, K.S., And Burke, K.J., 1998, Numerical Ages Of Holocene Tributary Debris Fans Inferred From Dissolution Pitting On Carbonate Boulders In The Grand Canyon Of Arizona: Quaternary Research, V. 50, P. 139-147.
Hereford, Richard, Burke, K.J., And Thompson, K.S., 2000, Map Showing Quaternary Geology And Geomorphology Of The Lees Ferry Area, Marble Canyon, Arizona: U.S. Geological Survey Miscellaneous Investigation Series Map I-2663, Scale 1:2,000 (With Discussion).
Hereford, Richard, Burke, K.J., And Thompson, K.S, 2000, Map Showing Quaternary Geology And Geomorphology Of The Granite Park Area, Grand Canyon, Arizona: U.S. Geological Survey Miscellaneous Investigation Series Map I-2662, Scale 1:2,000.
Hereford, Richard, And Webb, R.H., 2004, Map Showing Quaternary Geology And Geomorphology Of The Lone Dell Reach Of The Paria River, Lees Ferry, Arizona With Accompanying Pamphlet, Comparative Landscape Photographs Of The Lonely Dell Area And The Mouth Of The Paria River By Robert H. Webb And Richard Hereford: U.S. Geological Survey Geologic Investigations Series I-2771, Scale 1:5,000.
Terrace Stratigraphy, Geomorphology, And Climate in Cataract Canyon as a Control for Analogous Grand Canyon Settings
A.R. Potochnik1,, K.S. Thompson2, G.R. O'Brien3, and L.A. Neal4, 2005.
1Mesa Butte Consultants, 18 East Juniper Ave., Flagstaff, AZ 86001, arp4@infomagic.net
2PO Box 1611, Dolores, CO 81323, katethompson@frontier.net
3787 N. 1500 E., Logan, UT 84321, grandobrien@yahoo.com
4Envirosystems, Inc., 2101 N. 4th St., Flagstaff, AZ 86001, lneal@esmaz.com
Abstract
Fluvial terrace stratigraphy and small catchments between tributary canyons are identified and surveyed in Cataract Canyon of the Colorado River, Utah, to establish control localities for analogous settings in Grand Canyon. Pre-dam alluvial and eolian geomorphic processes are studied to determine possible links to accelerated erosion of archeologic sites seen in the post-dam environment of Grand Canyon. A distinct tier of five alluvial river terraces are present in Cataract Canyon. The relative age of each terrace is estimated using a combination of driftwood strand elevations, vegetation types and maturity, dendrochronology; and correlation with known large flood events from the historical record. The front edge of the tread of the highest terrace (T1) is overtopped by the 1884 annual flood and the lowest terrace is formed by the 1999 annual flood. Upper areas of the highest terrace contain diagnostic pre-Puebloan points (300-500 AD) contemporaneous with artifacts recognized on the highest terraces in Grand Canyon, the alluvium of Puebloan age (AP), and "striped" alluvium (SA).Thirteen small catchments are mapped and surveyed in four "geomorphic settings" analogous to those found in Grand Canyon (i.e., alluvial fan, tributary plain, talus slope, and debris lobe). Three small catchments are compared from analogous reaches in both canyons. Grand Canyon catchments show 50% greater gully density, 400% greater gully depth, and 200% more river-based drainages than Cataract Canyon. Records of mean annual precipitation, mean precipitation for peak month of monsoon season, and number of days in monsoon season with >25mm of precipitation from 8 weather stations in the region are sufficiently similar for possible weather-driven affects to be compared. The difference in weather data from the two areas is small compared to more pronounced differences in the magnitude of terrace erosion. Detailed topographic surveys of the three Cataract Canyon catchment areas before and after the 1999 annual flood show the infilling of new sand within previously formed gullies was ubiquitous but that the volumes of new sand varied widely between surveyed locations. The buttressing of terrace sequences with variable amounts of new sand below the annual flood stage demonstrates the dynamic interface between gully erosion from small catchments and the restorative potential of new sand deposition from large annual river flood events.
Selected References
Thompson, K.S., And Potochnik, A.R., 2000, Development Of A Geomorphic Model To Predict Erosion Of Pre-Dam Colorado River Terraces Containing Archaelogical Resources: Grand Canyon Monitoring And Research Center Contract Under Bureau Of Reclamation Cooperative Agreement No. 1425-98-FC-40-22610; SWCA Project No. 2362-1383.
Use of Sedimentary Structures to Infer Geomorphic and Hydrologic History of Channel-Margin Deposits
D.M. Rubin1, A.E. Draut2, R.E. Hunter2, T.S. Melis3, F.L. Nials4, J.C. Schmidt5, D.J. Topping3
1 US Geological Survey, Pacific Science Center, 400 Natural Bridges Dr., Santa Cruz, CA 95060, drubin@usgs.gov
2 University of California, USGS Pacific Science Center, 400 Natural Bridges Dr., Santa Cruz, CA 95060, adraut@usgs.gov
3 USGS Water Resources Division, National Research Program, c/o GCMRC, 2255 N. Gemini Dr., Flagstaff, AZ 86001, tmelis@usgs.gov, dtopping@usgs.gov
4 GeoArch, Inc., 10450 W. 8th Place, Lakewood CO 80215, fnials@earthlink.net
5 Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT 84322-5210. jschmidt@cc.usu.edu
Abstract
The present surface of geomorphic features along the Colorado River represents only a tiny fraction of the information such landforms contain about their origin, evolution, geomorphology, hydrology, and archaeology. Every sedimentary layer within channel-margin deposits records a previous surface of that landform or the reworking of an older landform. Stratigraphy within terraces and other alluvial deposits thus provides a natural record of geomorphic history.
Sedimentary structures also provide information about the depositional setting, and fluvial and eolian flow processes that deposited sediment that created the landforms. Where sedimentary structures are well preserved, extremely detailed reconstructions of geomorphic and hydrologic history are possible. For example, sedimentary structures can be used to determine which strata within a terrace or other channel-margin landform were deposited by the Colorado River, by slopewash or small tributaries, or by eolian redistribution of Colorado River sediment. Where individual flood deposits can be traced laterally, the stage of the flood that produced the deposit can often be determined. Directions of ripple migration preserved within deposits can be used to distinguish deposits of recirculating eddies from deposits on levees and other areas where flow was directed downstream. Preserved wave-ripple deposits can be used to map prior locations of wave-washed beaches. Textural changes within flood deposits can also be used to infer pre-historic hydrologic conditions. For example, upward coarsening of flood deposits has been used to document that the winnowing of sediment on the river bed occurred not just during the 1996 experimental flood, but also in the pre-dam river.
Sedimentology is not merely useful; it is essential to understanding geomorphic history, because he geomorphic surface does not always represent the depositional origin of channel-margin deposits. For example, many terraces formed by high flows in 1984, 1985, and 1986 were not deposited by those flows; they were formed when those flows eroded older (1983) deposits. Similarly, some terraces that support wind-blown dunes were deposited by floods of the Colorado River; the eolian deposits are merely a thin skim of reworked river sand on the terrace surface.
Archaeology is also an important part of understanding the history of channel-margin deposits. Archaeology can be used to date sediment deposits, and the sediment deposits can be used to understand the origin of the substrate on which prehistoric people lived.
A Geomorphic Classification for Archeological Sites and Description of Small Catchment Processes along the Colorado River in Grand Canyon
A.R. Potochnik1, and K.S Thompson2, 2005.
1Mesa Butte Consultants, 18 East Juniper Ave., Flagstaff, AZ 86001, arp4@infomagic.net
2PO Box 1611, Dolores, CO 81323, katethompson@frontier.net
Abstract
Prehistoric and historic peoples inhabiting the Colorado River corridor selected places for habitation and other activities in strategic areas close to the river but above areas of frequent inundation. As evidenced by the distribution of known sites, these areas tend to be on the higher flat sand terraces rarely inundated by large river floods. Since geomorphic context is critical for their location, it is helpful to develop a geomorphic basis for classification of sites. Here we use the term small catchment (SC) geomorphic system to represent all the local runoff basins between the large, rim-headed tributary canyons. Runoff from these areas drains onto the high river terraces where most sites are located. We identify and classify discrete settings within the SC geomorphic system to better understand the variety and range of hillslope/SC processes acting on the high river terraces. These five settings are: alluvial fan, tributary plain, talus slope, debris lobe, and dune field. We identify a type locality and four reference localities for each of these five settings. SCs range in area from 102 m2 to 180,363 m2 and none originate at the rim of Grand Canyon. Every small catchment has a point of impingement on a fluvial terrace. Gully initiation and propagation in sand terraces from SC runoff that erodes archeologic sites is a combination/permutation of three processes: alluvial fan progradation, ponding and overflow, and infiltration and piping. We examine and classify 119 small catchments located in 36 archeologically-rich areas in four sections of the Grand Canyon. We establish control for Grand Canyon in 13 analogous small catchments in Cataract Canyon where climatic patterns are similar but river processes are pre-dam in nature. Each catchment is surveyed for parameters that are intrinsic or extrinsic to the SC. Intrinsic parameters are factors within each SC that either drive or resist gully erosion of the terraces. Driving factors in the catchments include: drainage area, stream length, runoff efficiency, catchment length, runoff slope, and the shale factor. Resisting factors in the terraces include: ground cover, grain size distribution, permeability, terrace width, terrace height, sand depth, and number of terraces. Extrinsic parameters are factors that may impact a SC from outside and include: human mitigation efforts, eolian infilling, flood flow infilling, side canyon overflow, and human visitation impact. Each of these intrinsic and extrinsic factors is measured for all 119 small catchments for the purpose of developing a quantitative predictive model for erosion of archeologically rich terraces in Grand Canyon.
Selected References
Hereford, R. Fairley, H.C., Thompson, K.S., And Balsom, J.R., 1993, Surficial Geology, Geomorphology, And Erosion Of Archeologic Sites Along The Colorado River, Eastern Grand Canyon, Grand Canyon National Park, Arizona. U.S. Geological Survey Open-File Report 97-167. USGS, Flagstaff.
Potochnik, A.R. And Reynolds, S.J., 2003, Side Canyons Of The Colorado River In Grand Canyon. In Grand Canyon Geology, Edited By S.S. Bues And M. Morales, Pp. 391-406.
Thompson, K.S., And Potochnik, A.R., 2000, Development Of A Geomorphic Model To Predict Erosion Of Pre-Dam Colorado River Terraces Containing Archaelogical Resources: Grand Canyon Monitoring And Research Center Contract Under Bureau Of Reclamation Cooperative Agreement No. 1425-98-FC-40-22610; SWCA Project No. 2362-1383.
A Quantitative Model of the Erosional Vulnerability of Archeological Sites on Holocene Fluvial Terraces from Local Runoff, Colorado River
A.R. Potochnik1, K.S. Thompson2, and R. Ryel3, 2005.
1Mesa Butte Consultants, 18 East Juniper Ave., Flagstaff, AZ 86001, Arp4@infomagic.net
2PO Box 1611, Dolores, CO 81323, katethompson@frontier.net
31649 N. 1000 E., North Logan, UT, 84341, range@cc.usu.edu
Abstract
Archeologic sites located on high river terraces in Grand Canyon are eroding at an increasingly rapid rate principally through gully erosion from small catchments between large tributary canyons. Most sites are located in four wide reaches of the river in Marble Canyon, Furnace Flats, the Aisles, and western Grand Canyon below the Muav gorge. Since not all archeologic areas are equally vulnerable, a mathematical model is developed to predict relative vulnerability to erosion for the purpose of increasing efficiency of monitoring, mitigation, and data recovery efforts. Field analyses of 119 small catchments in 36 archeologically-rich areas include measuring a suite of geomorphic parameters and observing the range and types of processes, particularly at the dynamic interface between the small catchment, eolian, and fluvial systems. Development of a conceptual geomorphic model provides the foundation for a mathematical model developed by assigning numeric values to different parameters of the small catchment geomorphic system and river terraces. Each parameter modifies the basic model, which is described as a catchment "funnel" emptying water (driving force) onto a sand terrace "sponge" (resisting force). The model produces terrace vulnerability values of 1 to 100 with 100 being a terrace most vulnerable to gully erosion. The model applies a hypothetical 25mm rainfall event in a 24 hour period to each catchment to rate its vulnerability. Each catchment receives a vulnerability value for its uppermost terrace. Each catchment also receives an average vulnerability value that incorporates the sum effect of all terraces present at a catchment mouth. Each catchment is described, evaluated, and rated as to its geomorphic setting, susceptibility to dam operations, restoration potential by a beach building flow, and erosional vulnerability from local runoff. Gully depth ratio is an easily measured parameter that reflects an upper terrace's degree of gully development and can be easily measured by monitoring teams to test the efficacy of this predictive model. We recommend monitoring 25 catchments, including 1 type locality and 4 reference localities for each of five geomorphic setting to test and refine this model. We test three hypotheses to explain the rapid rate of gullying in river terraces; null, climatic variation, and base level hypotheses. Results show that climatic variation and dam presence/operations have both exacerbated gully erosion. We use "restorative base level" hypothesis to emphasize that although lowered base levels of the river post dam certainly drive gully erosion, high, sediment-rich releases from the dam in concert with eolian redistribution can act to slow erosion rates and perhaps restore terraces containing archeological sites.
Selected References
Thompson, K.S., And Potochnik, A.R., 2000, Development Of A Geomorphic Model To Predict Erosion Of Pre-Dam Colorado River Terraces Containing Archaelogical Resources. Grand Canyon Monitoring And Research Center Contract Under Bureau Of Reclamation Cooperative Agreement No. 1425-98-FC-40-22610; SWCA Project No. 2362-1383.
Thompson, K.S., Burke, K.J., And Hereford, R., 1996, Topographic Map Showing Drainage Basins Associated With Pre-Dam Terraces In The Granite Park Area, Grand Canyon, Arizona. U.S. Geological Survey Open-File Report 96-298. USGS, Flagstaff.
Twentieth Century Precipitation History of the Colorado Plateau and Northern Arizona, Relation to Increased Erosion of Prehistoric Colorado River Terraces in Grand Canyon
R. Hereford, U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, rhereford@usgs.gov
Abstract
Precipitation varied substantially in the twentieth century, particularly during the latter part. Periods of drought (1893-1904) or drought-like conditions (1942-1977) alternated with episodes of above normal precipitation (1904-1941 and 1978-1998). This multidecadal variability was evidently caused by fluctuations of the Pacific Decadal Oscillation (PDO), a phenomenon of the Northern Pacific Ocean that alters the climate of the Southwest for periods of 20-30 years. Generally, multidecadal droughts and wet spells are synchronous with negative and positive phases of the PDO, respectively. The recent positive phase of the PDO from the mid-1970s through the mid-1990s produced some of the wettest climate of the twentieth century in northern Arizona and the Colorado Plateau. This wet climate also produced large floods in rivers and creeks throughout the southern Colorado Plateau region.
In the 1980s, Park Service archeologists began to observe and record increased exposure of archeologic features and sites associated with prehistoric terraces of the Colorado River. Much of the erosion occurred where short tributary channels cross the terraces. These washes were reactivated by the unusually wet weather and abundant runoff beginning in the late 1970s. The net effect was headward extension and widening of the channels where they crossed the terraces. Although the increased hillslope runoff was the immediate cause of the erosion, the presence of Glen Canyon Dam might have exacerbated arroyo cutting. In sediment laden, unregulated streams such as the Paria River and many others, short channels crossing terraces are filled episodically at their mouths during mainstem floods. These deposits effectively raise the baselevel of the catchment retarding upstream erosion. It seems likely that this process was active along the Colorado River before closure of Glen Canyon Dam. The more than eight-fold reduction of sediment load and lack of floods in the post-dam era precluded the characteristic high-level alluvial filling at the mouths of tributary channels. During the frequent hilllslope runoff of the late twentieth century, tributary washes established channels through and into the pre-dam deposits as the channels drained to a lower effective baselevel. This would have increased the effects of arroyo cutting and erosion of prehistoric terraces.
Selected References
Hereford, Richard, And Webb, R.H., 1992, Historic Variation Of Warm-Season Rainfall, Southern Colorado Plateau, Southwestern U.S.A.: Climatic Change, V. 23, P. 239-256.
Hereford, Richard, Fairley, H.C., Thompson, K.S., And Balsom, J.R., 1993 Surficial Geology, Geomorphology, And Erosion Of Archeologic Sites Along The Colorado River, Eastern Grand Canyon, Grand Canyon National Park, Arizona: U.S. Geological Survey Open-File Report 93-517, 46 P. 23 Figs., 4 Tables, 4 Plates.
Hereford, Richard, 1996, Map Showing Surficial Geology And Geomorphology Of The Palisades Creek Area, Grand Canyon National Park, Arizona: U.S. Geological Survey Miscellaneous Investigations Map I-2449, Scale 1:2,000, (With Discussion).
Hereford, Richard, Webb, R.H., And Graham, Scott, 2002, Precipitation History Of The Colorado Plateau Region, 1900-2000: U.S. Geological Survey Fact Sheet 119-02.
Gully Erosion of Holocene Terraces in Grand Canyon-Results of Recent Study
J. Pederson, Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT 84322-5210, bolo@cc.usu.edu
Abstract
Cultural sites along the Colorado River corridor in Grand Canyon tend to be in sandy Holocene deposits, and they are subject to damage by gully erosion. Driven by the need to protect these cultural resources, recent study has assessed the performance of erosion-control structures, tested photogrammetry as a tool for monitoring gullies, and provided a better geomorphic understanding of the erosion. We performed detailed total-station surveys, conducted remote-sensing analyses with dedicated, high-resolution aerial photographs, and collected several types of geomorphic field data (including infiltration capacity, soil shear strength, grain size, and vegetation density) before and after the 2002 summer monsoon for 22 gullies in Grand Canyon.
Focusing on the results pertaining to the geomorphology of gully erosion, data confirm that it is happening by the processes of infiltration-excess overland flow and minor piping. Gully erosion is concentrated at knickpoints, with steeper drainages have more knickpoints and new knickpoints tending to form in relatively steep reaches. Importantly, soil shear strength and infiltration capacity vary significantly with sediment texture, vegetation, and soil crusts, and these factors influence the initiation and extent of erosion. At Lees Ferry, preliminary data indicate a positive, but nonlinear, relation between precipitation and erosion, with a threshold rainfall intensity for erosion falling between 3 and 5.5 cm/hr.
A slope-area gully initiation threshold can be defined for the study sites based on gully heads. With detailed terrain models from remote sensing, this empirical threshold was applied in a preliminary GIS-based model to successfully identify locations sensitive to gully erosion. An abundance of false positive predictions belie the simplicity of this initial model, but it could be greatly improved by the addition of spatially distributed infiltration, soil strength, and vegetation information to the detailed topographic template. Such a numerical model could then employ prescribed precipitation events and predict the extent of gully erosion, which could be validated by observations. This would be a powerful tool for cultural site management and protection, and sensitivity analysis using an improved model may be the only practical way to quantify the relative importance of different controls on the erosion--including base level.
Selected References
Pederson, J.L., Petersen, P.A., Macfarlane, W.W., Gonzales, M.F., And Kohl, K., 2003, Mitigation, Monitoring, And Geomorphology Related To Gully Erosion Of Cultural Sites In Grand Canyon: Report To The U.S. Geological Survey, Grand Canyon Monitoring And Research Center, 241 P.
Pederson, J.L., Petersen, P. A., And Dierker, J.L., In Review, Gullying And Erosion Control At Archaeological Sites In Grand Canyon, Arizona: Earth Surface Processes And Landforms.
Petersen, P.A., Mcfarlane, W.W., Pederson, J.L., And Gonzales, M.F., Preparation, Accuracy And Utility Of Aerial Photogrammetry In Monitoring Gully Erosion Of Archeological Sites In Grand Canyon, Arizona: Catena.
Related Student Thesis:
Petersen, Paul, MS 2003, Mitigation, Monitoring, And Geomorphology Related To Gully Erosion Of Archeological Sites In Grand Canyon.
Monitoring Arroyos with Conventional Survey Techniques in Grand Canyon: 1996-2004
J. Hazel1, M. Kaplinski2 and R. Parnell3, Department of Geology, Northern Arizona University, PO Box 4099, Flagstaff, AZ 86011
1 Joseph.Hazel@nau.edu
2Matt.Kaplinski@nau.edu
3 Roderic.parnell@nau.edu
Abstract:
An important hypothesis listed in the Glen Canyon Dam-Environmental Impact Statement (GCD-EIS) is that occasional high flows could rebuild high elevation sand deposits and potentially preserve the cultural deposits in situ (U.S. Department of Interior, 1995). It was theorized that deposition in arroyo mouths would lessen or slow arroyo cutting and thus reduce impacts to cultural resources. The first test of a controlled flood as described in the GCD-EIS occurred in spring 1996, with a 7-day release of 1274 m3/s. A second test of this concept occurred in November 2004, with a 2.5-day release of 1161 m3/s.
In this study, we continued the arroyo monitoring initiated by Yeatts (1996; 1998) of four arroyos located in easternmost Grand Canyon, Arizona. The data collected at four arroyos in 1996 and 1997 by Yeatts were reanalyzed and compared to topographic mapping at the same sites collected in 1998 and 1999 (Hazel et al., 2000). Similar measurements were made at one of the arroyos during the November 2004 high experimental flow.
The results show that net deposition occurred in all four arroyos during the 1996 controlled flood. The depth of fill was greatest at or near the arroyo mouths where there was complete or nearly complete infilling of up to 1 m of sand. The deposits emplaced in the arroyo mouths were incised at 3 sites between 1996 and 1999, but the arroyo channels were not eroded to depths that existed prior to the flood. Infilling of the arroyos, at terrace elevations higher than the arroyo mouth deposits, caused gully depths to progressively decrease. Eolian redistribution of 1996-flood deposits or wind deflation of sand from other areas is a possible mechanism that can explain sediment renewal in the arroyos. Cross sections and cut and fill volumes suggest that this material was not derived from arroyo wall collapse. These results will be compared to similar measurements made at one of the arroyos during the November 2004 high experimental flow.
Selected References
Hazel, Jr., J.E., M. Kaplinski, M. Manone, And R. Parnell, 2000, Monitoring Arroyo Erosion Of Pre-Dam River Terraces In The Colorado River Ecosystem, 1996-1999, Grand Canyon National Park, AZ: Report On File At The Grand Canyon Monitoring And Research Center, Flagstaff, AZ., 29 P.
Hereford, R., 1996, Map Showing Surficial Geology And Geomorphology Of The Palisades Creek Area, Grand Canyon National Park, Arizona: U.S. Geological Survey Miscellaneous Investigations Series Map I-2499, Scale 1:2000 (With Discussion).
Pederson, J.L., P.A. Peterson, W.W. Macfarlane, M.F. Gonzales, And K. Kohl, 2003, Mitigation, Monitoring, And Geomorphology Related To Gully Erosion Of Cultural Sites In Grand Canyon: Report On File At The Grand Canyon Monitoring And Research Center, Flagstaff, AZ., 243 P.
Yeatts, M., 1996, High Elevation Sand Deposition And Retention From The 1996 Spike Flow: An Assessment For Cultural Resources Stabilization: Report On File At The Grand Canyon Monitoring And Research Center, Flagstaff, AZ., 32 P.
Yeatts, M., 1998, High Elevation Sand Retention Following The 1996 Spike: Report On File At The Grand Canyon Monitoring And Research Center, Flagstaff, AZ., 15 P.
Modeling of the Effects of Water and Sand Discharge on Sand Deposition in Archeologically Significant Reaches of the Colorado River in Grand Canyon
S. Wiele1 and M. Torrizo2
1 USGS, 520 N. Park Avenue, Tucson, AZ 85719, smwiele@usgs.gov
2 Vermont Agency of Natural Resources, Department of Environmental Conservation, 103 South Main St., Bld 10N, Waterbury, VT 05671
The development of gullies adjacent to the Colorado River in Grand Canyon has led to the exposure and destruction of archeological artifacts. Hereford and others (1991, 1993) proposed that the initiation and propagation of these gullies are related to the effects of Glen Canyon Dam on river stages and the main-stem sand supply. They also suggested that restoration of sand deposits at river level could lead to stabilization of the gullies and relieve or reduce future damage to the archeological artifacts. This study examines the response of sand deposits in four reaches mapped by Hereford and others (1991, 1993) to variations in dam releases and sand supply. Deposition rates and volumes resulting from two discharges and three sand conditions were computed using a model of flow, sand transport, and bed evolution (Wiele and others, 1996, 1999). The results for reaches dominated by recirculation zones show trends similar to those from previous studies of reaches with similar morphology, but show a greater variability of responses in reaches in which recirculation zones are minor. In addition to sand supply, the deposit volume and deposition rate is generally sensitive to the water discharge: higher discharges generate higher stages and larger deposition accommodation spaces with larger deposits as a result. Most cases show rapid initial responses in which the channel deposits reach a near-equilibrium within 1-2 days. Future dam releases designed to rebuild sand bars efficiently would yield the best results with high water discharges as well as high sand supplies. Recirculation zones tend to accumulate sand during high flows at rates and volumes proportional to sand supply and water discharge; other reaches with seemingly simpler geometry, however, show more varied responses.
Selected References
Wiele, S.M., Graf, J.B., And Smith, J.D., 1996, Sand Deposition In The Colorado River In The Grand Canyon From Flooding Of The Little Colorado River: Water Resources Research, V. 32, No. 12, P. 3579-3596.
Wiele, S.M., 1998, Modeling Of Flood-Deposited Sand Distributions In A Reach Of The Colorado River Below The Little Colorado River, Grand Canyon, Arizona: Water Resources Investigation Report 97-4168.
Wiele, S.M., Andrews, E.D., And Griffin, E.R., 1999, The Effect Of Sand Concentration On Depositional Rate, Magnitude, And Location, In Webb, R.H., Schmidt, J.C., Marzolf, G.R., And Valdez, R.A. (Eds.), The Controlled Flood In Grand Canyon: Washington, D.C., American Geophysical Union, Geophysical Monograph 110.
Wiele, S.M. And Torizzo, M., Modeling Of Sand Deposition In Archeologically Significant Reaches Of The Colorado River In Grand Canyon, USA, Bates, P., Lane, S., And Ferguson, R. (Eds.) Environmental Computational Fluid Dynamics, In Press.
Wiele, S.M., and Torizzo, M., 2003, A stage-normalized function for the synthesis of stage-discharge relations for the Colorado River in Grand Canyon, Arizona, USGS Water-Resources Investigations Report 03-4037. Online at http://az.water.usgs.gov/pubs/03-4037intro.html
The Role of Aeolian Sediment Transport in the Preservation of Archaeological Sites, Grand Canyon: Developing Criteria for Evaluating Dam Impact
A. E. Draut1, D. M. Rubin2, and T. Melis3
1,2 US Geological Survey, Pacific Science Center, 400 Natural Bridges Drive, Santa Cruz, CA 95060, 1 adraut@usgs.gov, 2 drubin@usgs.gov
3 Grand Canyon Monitoring and Research Center, 2255 N. Gemini Dr., Flagstaff, AZ 86001, tmelis@usgs.gov
Abstract
The condition of Holocene and Recent sediment deposits in the Colorado River Corridor has important implications for the preservation of archaeological sites. In conjunction with detailed stratigraphic analyses of such deposits (discussed by D. M. Rubin in a separate presentation),our team is investigating active aeolian sediment transport at selected archaeologically significant locations in Grand Canyon. This study presents initial results of an ongoing instrumentation program, in which aeolian sediment transport rates, wind magnitude and direction, and precipitation are measured at nine stations in the river corridor. These data allow resolution of seasonal and regional variability in wind intensity and direction, and the resultant aeolian sediment transport, as well as precipitation patterns. Such information can be used to evaluate the potential for aeolian reworking of new fluvial sand deposits, and restoration of higher-elevation aeolian deposits, following a beach/habitat building flow (BHBF). The combination of data from instrumented sites such as these with field assessment of the stratigraphic context in which archaeological sites occur provides a basis for managers to evaluate the degree to which Glen Canyon Dam may affect the condition of these cultural resources. The relative significance of various sedimentary and geomorphic processes can differ widely between sites; specific causes of archaeological site erosion, and specific measures needed to rectify erosion, must be determined on a site-by-site basis. We propose a series of questions that must be answered, and the types of data needed to address them, in order to determine the extent to which aeolian sediment deposition affects the preservation potential of archaeological sites. Several examples of specific sites will be discussed. Questions include:
- What is the depositional context of sediment on which the site is built?
- What is the depositional context of sediment that has buried/protected the site? If the answer to (2) is aeolian sediment:
- Is there evidence for loss of aeolian sediment that previously covered the site?
- What is the source of the aeolian sediment that has buried the site?
- Has there been a demonstrated reduction in the source area from which this aeolian sand is derived?
- Could renewed deposition of aeolian sand have a significant restorative effect on this site? If the answer to (6) is yes,
- How could this be accomplished (i.e., is there evidence that a beach/habitat building flow could help restore the source for aeolian sand at this site)?
Selected References:
Draut, A. E., Rubin, D. M., Dierker, J. L., Fairley, H. C., Griffiths, R., Hazel, J. E. Jr., Hunter, R. E., Kohl, K., Leap, L. M., Nials, F. L., Topping, D. J. And Yeatts, M. Sedimentology And Stratigraphy Of The Palisades, Lower Comanche, And Arroyo Grande Areas Of The Colorado River Corridor, Grand Canyon, Arizona. US Geological Survey Scientific Investigations Report, In Press.
Draut, A. E., Rubin, D. M., Balsom, J. R. And Melis, T. M. 2003. The Role Of Eolian Sediment Transport In The Preservation Of Archaeological Features: A New Research Initiative In Grand Canyon National Park. Glen Canyon Adaptive Management Program, The Colorado River: An Ecosystem Science Symposium. Tucson, Arizona, October 28-30, 2003.
Draut, A. E., Rubin, D. M., Dierker, J. L., Fairley, H. C., Hunter, R. E., Leap, L. M., Nials, F. L., Topping, D. J. And Yeatts, M. 2004. Sedimentology And Stratigraphy Of Three Archaeologically Significant Areas Of The Colorado River Corridor, Grand Canyon, Arizona. Geological Society Of America Abstracts With Programs 36 (5), 514.
Draut, A. E., Rubin, D. M., Fairley, H. C. And Melis, T. S. 2004. Predictive Tools For Evaluating Aeolian Sediment Redistribution After Experimental Floods: Monitoring Studies In The Colorado River Corridor, Grand Canyon, Arizona. EOS, Transactions Of American Geophysical Union Fall Meeting Supp. 85 (47), Abstract H53B-1246.