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The State of Natural and Cultural Resources in the Colorado River Ecosystem:

JUNE 30, 1999 DRAFT REPORT
Grand Canyon Monitoring and Research Center
Flagstaff, AZ 86001
Updated: 30 June 1999

Table of Contents

Physical Resources and Processes

  • (Streamflow, Sediment-Transport and Related Geomorphic Processes)
    • Greater Grand Canyon Climate Data:
      • Colorado River Corridor -(Example of Available Data)
        • Phantom Ranch Air Temperature
        • Phantom Ranch Precipitation
      • North and South Rims - (Long-Term Records in Northern Arizona)
        • Ashfork, Cameron, Desert View Ranger Station, Flagstaff, Grand Canyon National Park, Lees Ferry, Mt. Trumbull, Page, Seligman, Tuweep, Williams

GLEN CANYON DAM OPERATIONS (Water Years):

COLORADO RIVER STREAMFLOW AND SEDIMENT DATA (Water Years):

  • Colorado River -
  • -below Glen Canyon Dam (1989-1993);
  • -at Lees Ferry (1923-current);
  • -above the Little Colorado River near Desert View (1983-84, 1985-86 and 1990current);
  • -near Grand Canyon (1922-current);
  • -above National Canyon near Supai (1983-84, 1985-86, 1990-1993, and 1996);
  • -above Diamond Creek near Peach Springs (1983-84, 1985-86, 1990-current)

GAGED TRIBUTARY STREAMFLOW AND SEDIMENT DATA (Water Years):

REACH AVERAGED UNGAGED-TRIBUTARY SEDIMENT AND FLOW:

  • 10-Year Averages for Sediment Inputs, Research in Progress (Webb et al., USGS)
  • Tributary Debris-Flow Potential (Griffiths et al., USGS)

MAIN CHANNEL BED GRAIN-SIZE DATA:

  • Time Series of Grain-Size Evolution, Research in Progress (Topping et al., USGS)

SAND BAR AND MAIN CHANNEL SAND-STORAGE EVOLUTION:

HISTORICAL AND RECENT CHANGES IN DEBRIS FANS AND RAPIDS:

SYNTHESIS OF HISTORICAL HYDROLOGIC AND GEOMORPHIC DATA:

CURRENT MAIN-CHANNEL MAPPING EFFORTS:

GCMRC 1998-99 MONITORING AND RESEARCH PROJECTS:

1. Northern Arizona University (Parnell et al.) Annual Change Detection Monitoring for Sand-Storage in the Main Channel of the Colorado River below Glen Canyon Dam;

2. Utah State University (Schmidt et al.) Historical Synthesis of Hydrologic, Sediment-Transport and Geomorphic Data for the Colorado River Between Lees Ferry and Phantom Ranch, AZ;

3. U.S. Geological Survey (Webb et al.) Estimation of Averaged Long-Term Sediment Inputs and Impacts from Ungaged Tributaries of the Colorado River Below Glen Canyon Dam;

4. U.S. Geological Survey (Hornewer et al.) Monitoring and Research of Mainstem and Gaged Tributary Sediment-Transport, Streamflow and Water Quality Below Glen Canyon Dam;

5. U.S. Geological Survey (Topping) Development of Predictive Capabilities for Streamflow and Sediment-Transport Associated with the Little Colorado River.

PROPOSED GCMRC 2000 MONITORING AND RESEARCH PROJECTS:

A. Continuation of monitoring as described above, with emphasis on research related to fine-sediment budgeting.

B. Initial development of a long-term monitoring plan for streamflow, sediment-transport and related geomorphic processes.

C. New monitoring initiative for daily to quasi-daily sampling of suspended-sediment and channel-bed grain-size at the Grand Canyon gage near Phantom Ranch, AZ.

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Figure P1.1:

Greater Grand Canyon Climate Data:

Colorado River Corridor -(Example of Available Data)

Figure P1.1: Monthly minimum and maximum air temperatures (oC) at Phantom Ranch, Grand Canyon National Park, 1988-1997. Data from NOAA, updated 4 December 1998.

Figure P1.2:

Figure P1.2: Daily precipitation (mm) at Phantom Ranch, Grand Canyon National Park, 1988-1997. Data from NOAA, updated 4 December 1998.

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North and South Rims

{PROPOSED NEW FIGURE HERE - [Location map showing long-term climate stations for greater Grand Canyon region. Data available through NOAA.] UNDER CONSTRUCTION FOR SCORE 2000}

GLEN CANYON DAM OPERATIONS - (Water Years)

Historical Daily Streamflows at Lees Ferry, (1920-current)

Figure P2.1:

Figure P2.1: Mean daily flow at Lees Ferry, Arizona, 1921-1998. Daily minimum and maximum flow data are presented from 1987-1998. Data from USGS, updated 6 December 1998.

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Dam Operations Measured at Lees Ferry, Water Years (1996-1998)

Figure P2.2:

Figure P2.2: Minimum and maximum daily flow (cfs) at the U.S.G.S. streamflow gauge at Lees Ferry, AZ, Water Years 1996-1998. Data from USGS; updated 6 December 1998.

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Ramping Rates (SCADA) at Glen Canyon Dam, Water Years (1996-1998)

Figure. P2.3:

Figure. P2.3: Daily minimum and maximum ramping rates (cfs/hr), Water Years 1996-1998. Data courtesy of W. Vernieu from Bureau of Reclamation SCADA; updated 6 December 1998.

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Dam Operations Measured at Glen Canyon Gage, Water Years (1989-1993)

{PROPOSED NEW FIGURE HERE - [Minimum and maximum daily flow (cfs) at the U.S.G.S. streamflow gauge below Glen Canyon Dam, AZ, Water Years 1989-1993. Data from USGS.] UNDER CONSTRUCTION FOR SCORE 2000}

Summary of Mainstream Hydrograph for Water Years (1996-1998)

Discharge from Glen Canyon Dam from WYs 1995 through 1998, reflects transition from Interim Flows to Record-of-Decision (ROD) actions of the Department of Interior Secretary, and a transition from a relatively average to higher runoff year in the Upper Colorado River basin (Fig. P2.1-2.2). Dam releases in 1996, generally varied between 8,000 cfs and 19,000 cfs, with higher fluctuating flows predominating prior to, and after the 1996 BHBF-Test. During the late March/early April BHBF-Test, discharge at Glen Canyon Dam was maintained at 45,000 cfs for 7 days. High snowpack forecasted snowpack in the headwaters during winters of 1996-98, increased the likelihood of surplus runoff into Lake Powell, and resulted in discharge levels from Glen Canyon Dam being increased to constant 27,000 cfs in late February and March 1997. High constant flow of 24,000 predominated in March and April 1997, and was maintained at nearly constant flows of 20,000 to 21,000 cfs from May through August 1997. A 3-day constant 8,000 cfs flow aerial photography overflight was conducted from August 30 through 1 September (Labor Day) 1997, to record resource conditions, such as sandbar size and distribution, relative to that of previous years. A 31,000 cfs peak-powerplant test release was conducted November 3-5, 1997. This test release was implemented to assess possible benefits to sand conservation through non-spill main channel flows following significant inputs of sand and finer sediment by the Paria River. The winter 1997, releases were kept at relatively high levels in January through March 1998, to create additional Lake Powell storage in anticipation of late, high spring inflows associated with the 1997-98 ENSO warming event in the Eastern Pacific Ocean.

Flows in 1998 were generally high and steady to prevent spills from Lake Powell. A constant 15,000 cfs constant flow was conducted over the Labor Day weekend 1998, for aerial photography of the river corridor. Ramping rates exceeded ROD levels several times in 1998, but with no detectable effect downstream (Fig. P2.3). Under currently adopted Hydrologic Triggering Criteria for implementing Beach/Habitat-Building Flows, there were no opportunities for such managed floods in Water Years 1997 through 1999.

COLORADO RIVER STREAMFLOW AND SEDIMENT-TRANSPORT DATA -

{SEVERAL PROPOSED NEW FIGURES HERE - [Historical time series of annual-peak streamflows data for six stations along the main channel Colorado River below Glen Canyon Dam. Data from USGS.] UNDER CONSTRUCTION FOR SCORE 2000}

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GAGED TRIBUTARY STREAMFLOW DATA -

Paria River near Lees Ferry, AZ, Water Years (1924-1998)

Figure. P3.1:

Figure. P3.1: Paria River flow, 1924-1998. Data from the USGS, updated 6 December1998.

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Little Colorado River near Cameron, AZ, Water Years (1948-1998)

Figure. P3.2:

Figure. P3.2: Daily mean flow of the Little Colorado River at Cameron, AZ, 1947-1998. Minimum and maximum flow data are presented from 1995-1998. A record historical flow of approximately 100,000 cfs occurred on the LCR in August 1923. Data from USGS, updated 6 December 1998.

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{SEVERAL PROPOSED NEW FIGURES HERE - [Additional historical annual-peak streamflows data for gaged tributaries of the Colorado River below Glen Canyon Dam, Bright Angel Creek, Kanab Creek, Havasu Creek, and Diamond Creek. Data from USGS.] UNDER CONSTRUCTION FOR SCORE 2000}

REACH AVERAGED UNGAGED-TRIBUTARY SEDIMENT AND FLOW -

10-Year Averages for Sediment Inputs

{PROPOSED NEW FIGURE HERE - [Reach-averaged estimates (10-yr) of sediment inputs from ungaged tributaries below Glen Canyon Dam. Data from USGS, Webb et al., in progress.] UNDER CONSTRUCTION FOR SCORE 2000}

Tributary Debris-Flow Potential

{PROPOSED NEW FIGURE HERE - [Statistically derived probabilities for future occurrences of debris flows from ungaged tributaries below Glen Canyon Dam. Data from USGS, Griffiths et al., in progress.] UNDER CONSTRUCTION FOR SCORE 2000}

MAIN-CHANNEL BED GRAIN-SIZE DATA -

Time Series of Grain-Size Evolution

{PROPOSED NEW FIGURES HERE - [Time Series of channel-bed grain-size data for the main channel of the Colorado River. Data from USGS, Topping et al., in progress.] UNDER CONSTRUCTION FOR SCORE 2000}

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SAND BAR AND MAIN CHANNEL SAND-STORAGE EVOLUTION -

Sand Bar and Eddy Changes

Figure P4.1:

Figure P4.1: Upper graph - channel sand storage above river mile 61(Marble Canyon) and below the Little Colorado River confluence, 1991-1998, data from Kaplinski et al. (1998), courtesy of J. Hazel, NAU Geology Department, updated 1 July 1998. Lower Graph - sand inputs from the Paria and Little Colorado Rivers, Water Years 1990-1998, data from USGS.

 

Figure. P4.2:

Figure. P4.2: Sediment discharge from the Paria River, Water Years 1990-1998, showing exceptional sand inputs from summer monsoon storms in late summer of 1997 and 1998.

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Figure. P4.3 : 1/2 Figure. P4.3 : 2/2

Figure. P4.3 : Sand bar volume (upper graph) and area (lower graph) upstream and downstream from the Little Colorado River, 1990-1998. Error bars are + 1 se. Data courtesy of J. Hazel, M. Kaplinski and R. Parnell, NAU Geology Dept., updated 6 December 1998.

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Mainstream Sediment Transport and the 1996 BHBF-Test

In 1996 the Bureau of Reclamation's Glen Canyon Environmental Studies and its cooperators conducted an experimental controlled flood from Glen Canyon Dam. This release is described as a Beach/Habitat-Building Flow (BHBF-Test) in the Operation of Glen Canyon Dam - Final EIS. A comprehensive volume on the results of this experiment has been published by the American Geophysical Union (Monograph #110; editors: Webb, Schmidt, Valdez and Marzolf). This large scale experiment was successful in increasing the height and volume of many sand bars. Although successful as a sand management event, the 1996 event was not of sufficient magnitude to rejuvenate the large return-current channel, termed backwaters, which are believed to be important to early life stages of native fish. Kearsley (1999), reports that the 1996 BHBF-Test significantly increased the availability of campsites, particularly in what she termed critical reaches below Glen Canyon Dam.

In addition, various papers are being presented in other peer-reviewed journals. In one such paper, Rubin et al. (1998) reported that flood deposits produced by the 1996 BHBF-Test, as well as those from pre-dam terraces, coarsen upwards. This pattern indicates that fine sediment supplies are depleted relatively rapidly during Grand Canyon floods. This information suggests that system-wide storage potential for sand is relatively limited. One implication of limited sand-storage potential in the main channel is that new inputs from tributaries have a limited residence time in the system once storage potential is full. Hence, to maximize sediment conservation in sand bars and related habitats, future BHBFs might be more effectively released soon after floods from the Paria and Little Colorado Rivers occur. Another implication of these findings is that future planned floods may need to be of shorter duration to prevent excess export of fine sediments. In terms of physical science outcomes, the most critical result of the BHBF-Test was recognition and documentation by USGS scientists that stable rating-curve approaches to estimating storage and export of sand are not appropriate for the Colorado River below Glen Canyon Dam. The implication of this fact is that long-term monitoring and sand-transport model development in the main channel must include considerations of periodic tributary sediment inputs, and channel-bed grain-size evolution, as well as sand-storage volume changes.

Paria River Sediment Transport

During GCES Phase II, Topping (1997 and draft USGS report) evaluated Paria River flow and sediment transport, and developed a flow-based model for estimating inputs of sand, silt and clay to the Colorado River. He compared modeled estimates for inputs during 4 large floods in August and September 1997, with measured sediment loads which ranged up to 115 m3/s and delivered 2.2 million tons of sand and 2.7 million tons of silt and clay to the Colorado River. Modeled inputs for sand were within 10-15 percent of measured values reported by USGS for water year 1997. A later Paria River flood in September 1998, exceeded the peak magnitude of all of the floods in 1997, (6,500 cfs) adding about 800,000 tons of sand to the mainstream in the Marble Canyon reach. Model results for this significant flood agreed closely with sand-input values published by USGS. The Paria River flow and sediment model continues to be refined to improve estimates for inputs of silt and clay. A similar predictive capability is currently being developed in cooperation with USGS (Topping) for sediment inputs from the Little Colorado River. Both models are scheduled to be fully developed by the end of FY 2000. These models will allow managers to obtain accurate, preliminary estimates of changes in main channel sediment storage that occur from gaged tributary floods. Accurately modeled sediment inputs from the Paria and Little Colorado Rivers will also support ongoing efforts to develop a 1-dimensional sand transport model for the main channel relative to operations of Glen Canyon Dam.

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HISTORICAL AND RECENT CHANGES IN DEBRIS FANS AND RAPIDS -

{PROPOSED NEW TABLE HERE - [Listing of sites below Glen Canyon Dam where tributary debris flows have impacted the geomorphic framework of the main channel of the Colorado River since 1872. Data from USGS, Melis et al.] UNDER CONSTRUCTION FOR SCORE 2000}

Historical Event Data Since 1872

Debris flows are extraordinary floods in which large quantities of rock and other debris slurry down tributary canyons, sometimes reaching the Colorado River. More than 700 ungaged tributaries in Marble and Grand Canyon reaches of the Colorado River produce debris flows, on average, about once every 20-200 years (Melis et al., 1994). Recently, Griffiths et al. (1996) and Melis et al. (1994), reported Grand Canyon debris flow activity and mapped debris flow frequency in all the tributaries of Grand Canyon. Additionally, Griffiths (1996) reported statistically modeled debris-flow probabilities for all ungaged tributaries.

Debris fans at tributary confluences with the main channel Colorado River are primarily responsible for all but two of the Colorado River's world-renown whitewater rapids. Glen Canyon Dam has reduced the likelihood of exceptionally large flows (>100,000 cfs), floods which in pre-dam time cleared rapids of tributary-input debris that includes large boulders. Therefore, a continuing concern exists regarding the increasing navigational severity of Grand Canyon rapids. On average, severa1debris flows reach the Colorado River each year, and 1998 was no exception. Debris flows in July 1996, at Monument and Hermit Creeks (RM 94 and 95, respectively), aggraded existing debris fans, and increased the navigational difficulty of Hermit Rapid. Large debris flows occurred in the lower Grand Canyon in August and September 1998. A large debris flow at 194 Mile Canyon in mid-August narrowed the river considerably, but failed to create new navigational difficulties. Another debris flow during the same period altered navigational conditions at 209-Mile Rapid.

SYNTHESIS OF HISTORICAL HYDROLOGIC AND GEOMORPHIC DATA -

{SEVERAL PROPOSED NEW FIGURES HERE - [Time series of historical changes in sand bars and main channel streamflow and sediment transport between Lees Ferry and Phantom Ranch. (data derived from a variety of sources reported by Utah State University, Schmidt, Grams and Topping, study in progress] UNDER CONSTRUCTION FOR SCORE 2000}

Summary Results

Long-term data on the status of Grand Canyon sand bar changes relative to main channel streamflow and sediment transport are currently being synthesized through a cooperative research project with the Utah State University (Schmidt and Grams), and the U.S. Geological Survey (Topping et al.). Grams and Schmidt (1999) present a preliminary synthesis (1997 pilot study) of existing information on the status of six sites for which historical information is available. Their study sites are in wide reaches of the river from River Mile (RM) 44.0 (above the Little Colorado River (LCR) confluence) to RM 68.4 (below the LCR confluence). Their sources of data include analyses of aerial photography, bar cross-section data compiled by Howard and Dolan (1981), and the results of sand bar topographic monitoring projects by Northern Arizona University (e.g., Kaplinski et al. 1998). Schmidt (1992) demonstrated progressive loss of sand bar area and volume at Badger Rapid over the period of record. However, on the basis of existing data available for this initial synthesis research, Grams and Schmidt (1999) conclude that sites farther downstream do not shown progressive losses in either bar volume or area over post-dam time, despite closure and operation of Glen Canyon Dam in 1963. They conclude that the bars being monitored by NAU do characterize system dynamics, but the high variability of site-specific morphologies and sediment storage characteristics of individual eddies suggests that monitoring of sand bar erosion should be conducted at a large number of sites. Schmidt and Grams (1999) results suggest that a reach-averaged approach to sand bar change detection is needed to accurately track long-term trends in bar conditions in response to dam operations and other natural factors.

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CURRENT MAIN-CHANNEL MAPPING EFFORTS

{SEVERAL PROPOSED NEW FIGURES HERE - [Results of change detection analysis for main channel bed-substrate before and after the 1996 BHBF-Test, derived from side-scan sonar imaging. (data from USGS, Rubin and Anima, study in progress] UNDER CONSTRUCTION FOR SCORE 2000}

Use of Side-Scan Sonar Imagery for Change Detection of Bed Substrates and Classification (Anima and Rubin, USGS)

Recent side-scan SONAR and other analyses conducted by the U.S. Geological Survey's Marine and Coastal Geology Team (Geological Division), indicate that relatively less sand-storage exists on the channel bed outside of eddies than previously thought (D. Rubin, D. Topping and R. Anima, USGS, personal communication). The significance of this new information is that large contributions of sand, such those from recent Paria River floods in 1997 and 1998, are subject to relatively rapid export to Lake Mead. This export appears to occur over relatively short periods even under ROD operations, and presents a different paradigm from the one presented in the final EIS on Operations of Glen Canyon Dam (Topping et al., 1999; Topping, Rubin and Schmidt, 1999; Rubin and Topping, 1999 - AGU Monograph #110, and Grand Canyon Science Symposium 1999 abstract volume).

Results of 1999 Test of Multi-Beam, Hydro-Acoustic Bathymetry

{PROPOSED NEW FIGURE HERE - [Map product resulting from multi-beam bathymetry test of Glen Canyon reach. (data and map from GCMRC and NAU, assessment of test in progress] UNDER CONSTRUCTION FOR SCORE 2000}

GCMRC 1998-99, Monitoring and Research Projects -- .pdf format (71.9 KB)

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