THESIS

GEOMORPHIC ANALYSIS OF THE MIDDLE RIO GRANDE –

ELEPHANT BUTTE REACH, NEW MEXICO

Submitted by

Tracy Elizabeth Owen

Department of Civil and Environmental Engineering

In partial fulfillment of the requirements

For the Degree of Master of Science

Colorado State University

Fort Collins, Colorado

Spring 2012

Master’s Committee: Advisor: Pierre Julien Christopher Thornton Sara Rathburn

Copyright by Tracy Elizabeth Owen 2012

All Rights Reserved

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ABSTRACT

GEOMORPHIC ANALYSIS OF THE MIDDLE RIO GRANDE –

ELEPHANT BUTTE REACH, NEW MEXICO

The Elephant Butte Reach spans about 30 miles, beginning from the South Boundary

of the Bosque del Apache National Wildlife Refuge (River Mile 73.9) to the “narrows” of

the Elephant Butte Reservoir (River Mile 44.65), in central New Mexico. Sediment plugs

occasionally form along the Middle Rio Grande, completely blocking the main channel

of the river. In 1991, 1995, and 2005, the Tiffany Plug was initiated at the upstream end

of the Elephant Butte Reach. In 2008, the Bosque del Apache Plug formed just upstream

of the Elephant Butte Reach. Sediment plugs occur at the location of a constriction or

channel aggradation (Burroughs 2011). As aggradation within the Elephant Butte Reach

is known to contribute to a decrease in channel capacity (Reclamation 2007), it is

important to understand the influences of Elephant Butte Reservoir levels on channel

aggradation/degradation in order to decrease the potential for future sediment plug

formation. Further understanding of the historical and spatial changes within Elephant

Butte Reach, along with a better understanding of the influences of Elephant Butte

Reservoir levels on channel aggradation/degradation, are essential for improvement in

future river management practices along the Middle Rio Grande. Using aerial

photographs, survey data, reservoir water surface elevation data, and bed material data,

the following objectives are addressed in this study:

1. Quantify temporal changes in channel widths and sinuosity from 1935 to 2010.

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2. Quantify change in channel slope temporally.

3. Quantify rate of aggradation/degradation in response to a change in base-level

(i.e., change in reservoir water surface elevation).

4. Quantify aggradation/degradation wave propagation upstream.

5. Quantify spatial and temporal trends in bed material grain size.

From 1935 to 2010, channel widths and sinuosity decrease over time. The

majority of the Reach’s channel slope decreases from 1935 to 2010; the downstream-

most stretch of the channel, closest to Elephant Butte Reservoir, alternates between

increasing and decreasing channel slopes.

As the Elephant Butte Reservoir level (base-level) increases, the channel aggrades

in response. As the base-level decreases, the channel degrades. The rates of aggradation

and degradation vary between different periods of base-level changes, and are quantified

within the report. When the base-level changes a wave of aggradation/degradation

travels upstream. The rate of wave propagation upstream varies relative to the rate of

base-level change, and is quantified within the report for four sets of

aggradation/degradation waves.

Bed material samples obtained from cross-section surveys and at the San Acacia

and San Marcial gauges showed a coarsening at a rate of about 0.03 mm/year. In the

downstream direction, bed material became slightly finer. The median bed material grain

size ranged from 0.11 mm to 0.26 mm.

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ACKNOWLEDGEMENTS

I would first like to thank the U.S. Bureau of Reclamation in Albuquerque for

providing me with this project and the incredible amount of data. I would especially like

to thank Jonathan Aubuchon, of the Albuquerque office, and Drew Baird, of the Denver

office, for their insights about the river. Dr. Rathburn and Dr. Thornton, thank you for

serving on my committee and providing thoughtful comments to improve my Thesis.

Thanks to my advisor, Dr. Pierre Julien, for his constant guidance and encouragement.

Special thanks to Seema Shah-Fairbank for answering all of my questions and

guiding me through the vast database. Many thanks to Katharine Anderson who helped

me with planform delineations, range line cross-section plots, sinuosity calculations,

etc… Thanks to Ted Bender for reading this report and for gracefully listening to my

frustrations during those challenging times. Thanks also to Kiyoung Park for his insight

and ideas regarding the river’s behavior.

And finally, I would like to thank my family and Ben Mapes for supporting me

every step of the way. Mom, thanks for always being available for a phone call. Dad and

Janet, thanks for your encouragement and belief in me. Will, thanks for being a great

role model, setting the example at every stage in life. Ben, I can’t even begin to express

my thanks for your support and understanding throughout this entire process. Without

you I would have never left my computer and would have missed countless adventures; I

look forward to more adventures with you.

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TABLE OF CONTENTS

Abstract ............................................................................................................................... ii Acknowledgements ............................................................................................................ iv Table of Contents ................................................................................................................ v List of Figures .................................................................................................................... vi List of Tables ..................................................................................................................... ix List of Appendices .............................................................................................................. x Section 1:  Introduction ................................................................................................... 1 

1.1  Habitat and Endangered Species .......................................................................... 2 1.2  Sediment Plugs ..................................................................................................... 5 

Section 2:  Site Description and Background ................................................................. 7 2.1  Elephant Butte Reach ........................................................................................... 7 2.2  Subreach Definition.............................................................................................. 8 2.3  Available Data .................................................................................................... 18 

2.3.1  Survey Lines and Dates ...............................................................................18 2.3.2  Discharge Data .............................................................................................21 2.3.3  Bed Material.................................................................................................24 2.3.4  Suspended Sediment Data............................................................................24 

Section 3:  Reservoir Level Analysis ............................................................................ 26 3.1.1  Reservoir Level Analysis .............................................................................26 

Section 4:  Channel Analysis ........................................................................................ 30 4.1  Channel Planform Analysis from Aerial Photographs ....................................... 30 

4.1.1  Channel Delineation .....................................................................................30 4.1.2  Channel Widths from GIS ...........................................................................37 4.1.3  Sinuosity ......................................................................................................39 

4.2  Aggradation and Degradation from Agg/Deg Surveys ...................................... 45 4.2.1  Channel Thalweg Profile from Agg/Deg Surveys .......................................45 4.2.2  Change in Channel Thalweg Elevation from Agg/Deg Surveys .................48 

4.3  Aggradation and Degradation from Range Line Surveys .................................. 55 4.3.1  Channel Thalweg Profile from Range Line Surveys ...................................55 4.3.2  Change in Thalweg and Average Bed Elevation from Range Line Surveys66 4.3.3  Rate of Aggradation/Degradation from Range Line Surveys ......................75 4.3.4  Rate of Wave Propagation Upstream from Range Line Surveys ................80 

4.4  Bed Material Analysis ........................................................................................ 86 4.4.1  Grain Size Distributions ...............................................................................86 4.4.2  Median Grain Size .......................................................................................93 

4.5  Suspended Sediment Data .................................................................................. 96 Section 5:  Summary and Conclusions ....................................................................... 100 References ....................................................................................................................... 103 Appendices ...................................................................................................................... 105 

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LIST OF FIGURES Figure 1.1 Map of the Rio Grande Watershed (MRGBI 2009) ......................................... 1 Figure 1.2 Historical Timeline of Middle Rio Grande (Modified After Makar 2011, Pers. Comm.) ............................................................................................................................... 4 Figure 1.3: Rio Grande Silvery Minnow and Southwestern Flycatcher ............................ 5 Figure 1.4 Aerial View of Tiffany Plug in 2005 ................................................................ 6 Figure 2.1: Location of the Elephant Butte Reach from Google Maps ............................. 7 Figure 2.2 Profile of Elephant Butte Reach Widths and Thalweg at Agg/Deg Lines ....... 9 Figure 2.3 2008 Aerial Photo of Subreach 1 .................................................................... 11 Figure 2.4 2008 Aerial Photo of Subreach 2 .................................................................... 12 Figure 2.5 2008 Aerial Photo of Subreach 3 .................................................................... 13 Figure 2.6 2008 Aerial Photo of Subreach 4 .................................................................... 14 Figure 2.7 2008 Aerial Photo of Subreach 5 .................................................................... 15 Figure 2.8 2008 Aerial Photo of Subreach 6 .................................................................... 16 Figure 2.9 2008 Aerial Photo of Elephant Butte Reservoir ............................................. 17 Figure 2.10 Subreach Definitions and Agg/Deg Line Locations (2008 GIS Elephant Butte Reach Delineation Shown) ...................................................................................... 19 Figure 2.11 Subreach Definitions and Range Line Locations (2008 GIS Elephant Butte Reach Delineation Shown) ............................................................................................... 20 Figure 2.12 Location of Gauges ....................................................................................... 22 Figure 2.13: Daily Discharge of the Rio Grande in 1999 ................................................. 23 Figure 2.14 Comparison of Annual Peak Flows at San Acacia and San Marcial Gauges24 Figure 2.15: Annual Suspended Sediment Yield at San Acacia and San Marcial Gauges25 Figure 3.1 Elephant Butte Reservoir Level Time Series ................................................. 27 Figure 3.2 Elephant Butte Reservoir Historical Sediment Survey Longitudinal Profile (Reclamation, 2008) .......................................................................................................... 29 Figure 4.1 Channel Planforms from Aerial Photography ................................................ 31 Figure 4.2 Subreach 1 Channel Planforms from Aerial Photography ............................. 32 Figure 4.3 Subreach 2 Channel Planforms from Aerial Photography ............................. 32 Figure 4.4 Subreach 3 Channel Planforms from Aerial Photography ............................. 33 Figure 4.5 Subreach 4 Channel Planforms from Aerial Photography ............................. 34 Figure 4.6 Subreach 5 Channel Planforms from Aerial Photography ............................. 35 Figure 4.7 Subreach 6 Channel Planforms from Aerial Photography ............................. 36 Figure 4.8 Channel Widths from GIS (1918 - 2010) ....................................................... 38 Figure 4.9 Channel Widths from GIS (1962 - 2010) ....................................................... 39 Figure 4.10 Subreach Lengths and Total Lengths as Measured From GIS Data ............ 40 Figure 4.11 Temporal Sinuosity Trends .......................................................................... 43 Figure 4.12 Thalweg Elevation Profile From Agg/Deg Surveys ..................................... 46 Figure 4.13 Bed Slope from Agg/Deg Surveys ............................................................... 47 Figure 4.14 Change in Channel Thalweg Elevation from Agg/Deg Surveys .................. 49 Figure 4.15 Change in Channel Thalweg Elevation (1962 – 1972) Based on Agg/Deg Surveys .............................................................................................................................. 50 Figure 4.16 Change in Channel Thalweg Elevation (1972 – 1992) Based on Agg/Deg Surveys .............................................................................................................................. 50 

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Figure 4.17 Change in Channel Thalweg Elevation from 1992 – 2002 Based on Agg/Deg Surveys .............................................................................................................................. 51 Figure 4.18 Change in Channel Thalweg Elevation from 1962 – 2002 Based on Agg/Deg Surveys .............................................................................................................................. 51 Figure 4.19 Temporal Trend in Thalweg Elevation at Agg/Deg Lines ........................... 54 Figure 4.20 Rate of Channel Aggradation between 1972 and 1992 ................................ 55 Figure 4.21 Thalweg Elevation Profile From Range Line Survey Data .......................... 57 Figure 4.22 Subreach 1 Average Channel Thalweg Slope: Temporal Trend .................. 58 Figure 4.23 Subreach 2 Average Channel Thalweg Slope: Temporal Trend .................. 58 Figure 4.24 Subreach 3 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.25 Subreach 4 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.26 Subreach 5 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.27 Subreach 6 Average Channel Thalweg Slope: Temporal Trend .................. 60 Figure 4.28 Subreach 1: SO-1641 Surveyed Cross-Sections ........................................... 62 Figure 4.29 Subreach 2: SO-1683 Surveyed Cross-Sections ........................................... 62 Figure 4.30 Subreach 3: EB-10 Surveyed Cross-Sections............................................... 63 Figure 4.31 Subreach 3: EB-10 (w/Floodplain) Surveyed Cross-Sections...................... 63 Figure 4.32 Subreach 4: EB-13 Surveyed Cross-Sections............................................... 64 Figure 4.33 Subreach 5: EB-20 Surveyed Cross-Sections............................................... 64 Figure 4.34 Subreach 6: EB-29 Surveyed Cross-Sections............................................... 65 Figure 4.35 Subreach 6: EB-29 (w/Floodplain) Surveyed Cross-Sections...................... 65 Figure 4.36 Subreach 6: EB-41 Surveyed Cross-Sections............................................... 66 Figure 4.37 Change in Thalweg Elevation at Range Lines (1980 – 2010) ...................... 67 Figure 4.38 Change in Average Channel Bed Elevation at Range Lines (1988-2010) ... 73 Figure 4.39 Change in Channel Thalweg Elevations at Range Lines (1988-2010) ......... 74 Figure 4.40 Magnitude of Aggradation and Degradation at Range Lines (2003-2004) .. 76 Figure 4.41 Magnitude of Aggradation and Degradation at River Miles (2003-2004) .... 76 Figure 4.42 Magnitude of Aggradation and Degradation at Range Lines (2004-2005) .. 77 Figure 4.43 Magnitude of Aggradation and Degradation at River Miles (2004 to 2005) 78 Figure 4.44 Change in Thalweg Elevation from 2004 to 2009........................................ 78 Figure 4.45 Magnitude of Degradation from 2004 to 2009 ............................................. 79 Figure 4.46 Magnitude of Aggradation from 2004-2009 ................................................ 80 Figure 4.47 Reservoir Water Surface Elevation Change from 2009-2010 Resulting in Wave 1 Channel Degradation ........................................................................................... 81 Figure 4.48 Rate of Wave 1 Propagation Upstream ........................................................ 81 Figure 4.49 Reservoir Water Surface Elevation Change from 2004-2009 Resulting in Wave 2 Channel Aggradation ........................................................................................... 82 Figure 4.50 Rate of Wave 2 Propagation Upstream ........................................................ 83 Figure 4.51 Reservoir Water Surface Elevation Change from 1997-2004 Resulting in Wave 3 Channel Degradation ........................................................................................... 84 Figure 4.52 Rate of Wave 3 Propagation Upstream ........................................................ 84 Figure 4.53 Reservoir Water Surface Elevation Change from 1990-1995 Resulting in Wave 4 Channel Aggradation ........................................................................................... 85 Figure 4.54 Rate of Wave 4 Propagation Upstream ........................................................ 86 Figure 4.55 EB-10 1992 Bed Material Grain Size Distributions ..................................... 88 Figure 4.56 San Acacia Gauge: Annual Bed Material Grain Size Distributions ............. 89 

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Figure 4.57 San Marcial Gauge: Annual Bed Material Grain Size Distributions ........... 89 Figure 4.58 Subreach 1 (SO-1641): Annual Bed Material Grain Size Distributions ...... 90 Figure 4.59 Subreach 2 (SO-1683): Annual Bed Material Grain Size Distributions ...... 90 Figure 4.60 Subreach 3 (EB-10): Annual Bed Material Grain Size Distributions .......... 91 Figure 4.61 Subreach 4 (EB-13): Annual Bed Material Grain Size Distributions .......... 91 Figure 4.62 Subreach 5 (EB-18): Annual Bed Material Grain Size Distributions .......... 92 Figure 4.63 Subreach 6 (EB-24): Annual Bed Material Grain Size Distributions .......... 92 Figure 4.64 Average Median Bed Material Grain Size Temporal Trends ....................... 94 Figure 4.65 Average Median Bed Material Grain Size: Subreach Temporal Trends ...... 94 Figure 4.66 Water Discharge Single Mass Curve (Larsen et al. 2007) ........................... 96 Figure 4.67 Suspended Sediment Discharge Single Mass Curve (Larsen et al. 2007) ........................................................................................................... 97 Figure 4.68 Suspended Sediment Concentration Double Mass Curves (Larsen et al. 2007) ........................................................................................................... 98 

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LIST OF TABLES Table 2-1: Available Daily Discharge Data ..................................................................... 21 Table 2-2: Available Suspended Sediment Data ............................................................. 25 Table 4-1 Subreach Length and Total Length Values as Measured From GIS Data ...... 41 Table 4-2 Sinuosity Values .............................................................................................. 44 Table 4-3 Average Bed Slope from Agg/Deg Surveys .................................................... 48 Table 4-4 Change in Channel Thalweg Elevation Values from Agg/Deg Surveys ......... 49 Table 4-5 Average, Maximum and Minimum Change in Channel Thalweg Elevation Based on Agg/Deg Surveys .............................................................................................. 52 Table 4-6 Average Channel Thalweg Slopes for Subreaches 1 through 6 ...................... 60 Table 4-7 Change in Thalweg Elevation Between Select Year Sets ................................ 70 Table 4-8 Representative Range Lines for Each Subreach .............................................. 87 Table 4-9 Water Discharge (Larsen et al. 2007) .............................................................. 97 Table 4-10 Suspended Sediment Discharge (Larsen et al. 2007) .................................... 98 Table 4-11 Suspended Sediment Concentration (Larsen et al. 2007) .............................. 99 

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LIST OF APPENDICES

 Appendix A: Range Line Survey Dates ......................................................................... 106 Appendix B: Daily Discharge Hydrographs……………………………………….…..117 Appendix C: Dates and Locations of Bed Material Samples………………………….125 Appendix D: Dates and Locations of USGS Gauge Bed Material Samples…………..127 Appendix E: Aerial Photograph Survey Dates and Information………………………129 Appendix F: Range Line Cross-Section Plots…………………………………………131 Appendix G: Change in Thalweg Elevation vs. River Mile Plots……………………..157 Appendix H: Bed Material Grain Size Distribution Plots……………………………..166

1

SECTION 1: INTRODUCTION

The Rio Grande is about 1890 miles long (3040 kilometers), making it one of the

longest rivers in the United States (Kammerer 1990). The headwaters of the Rio Grande

begin in southern Colorado near Camby Mountain. The river then flows south through

New Mexico, and then becomes a dividing border between Texas and Mexico. For

purposes of this report, the Middle Rio Grande is defined as the 180 mile stretch of the

Rio Grande River that extends from Cochiti Dam to the narrows of Elephant Butte

Reservoir. Figure 1.1 provides a map of the Rio Grande.

Figure 1.1 Map of the Rio Grande Watershed (MRGBI 2009)

Human activities have had an impact on the river for thousands of years. However,

it was not until the late 14th century when the Spanish settled near the Rio Grande that

humans began to dramatically influence the river (Finch 2004). Since then, the water

2

discharge, sediment discharge, and cross sectional geometry have changed as a result of

human colonization. Devastating floods were very common on the Rio Grande up until

the early 1900’s when large dams and reservoirs were constructed. In addition, large

stretches of the river were channelized. These projects helped regulate the water and

prevent extensive flooding. Mining, logging and grazing in the beginning of the 20th

century destroyed much of the vegetation, resulting in dramatic erosion and a subsequent

increase in the sediment load in the river (Scurlock 1998). The increased erosion and

sediment load caused a l3% loss of capacity within Elephant Butte Reservoir by the mid

1930’s (Clark 1987). The increased sediment and decreased flow also lead to severe

aggradation along the river. Between 1880 and 1924, the bed of the river rose 9 feet at

the San Marcial gauging station (Scurlock 1998).

1.1 Habitat and Endangered Species

Exotic plants like the Russian olive, Russian thistle, Siberian elm, tree-of-heaven,

and tamarisk, whose roots added extra shear strength to the sand near the river, were

introduced to try to keep the river more stable (Mussetter Engineering 2001). However,

due to the addition of these foreign plants, riparian vegetation, such as native cottonwood

trees and willow trees, have declined (Finch 2004, Earick 1999). New animals such as

the barbary sheep, ibex, and oryx were also introduced to the area (Finch 2004). Human

influences have caused several native species of animals that use the Rio Grande as their

habitat, such as the Rio Grande silvery minnow, Rio Grande cutthroat trout, southwestern

willow flycatcher, and whooping crane, to teeter on the brink of extinction. Human

impacts, coupled with natural events such as droughts, have also led to increased soil

erosion along much of the Middle Rio Grande (Scurlock 1998).

3

In order to resolve many problems regarding the Rio Grande, the Middle Rio

Grande Conservancy District (MRGCD) was formed in 1923. The purpose of the

MRGCD was to “provide flood protection from the Rio Grande, and make the

surrounding area hospitable for urbanization and agriculture” (MRGCD 2006). Between

1923 and 1935, one storage dam, four diversion dams, and 817 miles of drainage and

irrigation channels had been constructed by the MRGCD (MRGCD 2006). The work

completed by the MRGCD was successful in controlling the river’s floods, and the

Bureau of Reclamation and the Army Corps of Engineers continued to repair and update

the structures established by the MRGCD. Several new levees and Cochiti dam have

been constructed to combat flooding and sedimentation problems along the river

(MRGCD 2006). A historical timeline of the Middle Rio Grande is shown in Figure 1.2.

These dams and levees were able to control the flow of the river and altered the

seasonal flooding patterns that used to exist. The magnitude of the floods within the Rio

Grande was greatly reduced due to the construction of these structures. These floods

were essential for several species’ reproduction habitats. The Rio Grande silvery

minnow, shown in Figure 1.3, used the swampy flooded terrain as the ideal reproduction

habitat (Earick 1999; Borgan 2006). The Rio Grande silvery minnow used to flourish

within the river from Espanola, NM to the Gulf of Mexico, however, now it is present in

only 5% of its former range (Earick 1999; MRGESA 2006a). Today, about 95% of the

Rio Grande silvery minnow population is concentrated below the San Acacia diversion

dam in the San Acacia Reach of the Middle Rio Grande. It no longer exists below the

Elephant Butte Reservoir, and was placed on the endangered species list in 1994

(MRGCD 2002).

4

Figure 1.2 Historical Timeline of Middle Rio Grande (Modified After Makar 2011, Pers. Comm.)

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The southwestern willow flycatcher (Figure 1.3) also uses the Rio Grande’s

riparian vegetation and wetlands to raise their young chicks. The altered flooding patterns

and reduced reproduction habitat have negatively impacted their population as well. In

1995 the southwestern willow flycatcher was placed on the endangered species list as a

response to their declining population (MRGCD 2002; MRGESA 2006b).

1.2 Sediment Plugs

Historically, sediment plugs have formed along the Middle Rio Grande,

completely blocking the main channel of the river. In 1991, 1995, and 2005, the Tiffany

Plug formed in the upstream end of the Elephant Butte Reach at Agg/Deg 1683 (River

Mile 70.23), as seen in Figure 1.4. In 2008, the Bosque del Apache Plug formed between

Agg/Deg 1531 and 1550 (River Mile 82.5 – 80.81), about 7 miles upstream of the

Elephant Butte Reach. Little is known about the formation of sediment plugs; why they

form, where they form, and how best to manage river flows to prevent the formation of

sediment plugs. The consequences of sediment plugs in the Middle Rio Grande are

significant. The presence of sediment plugs blocks the main channel of the Rio Grande

6

and prevents water from reaching Elephant Butte Reservoir due to increased infiltration

and evapotranspiration induced by the plugs. The current practice with sediment plugs

by the United States Bureau of Reclamation (Reclamation) is to excavate a pilot channel

through the plug to encourage water to flow again and re-channelize; this method is

expensive and time consuming. Sediment plugs occur at the location of a constriction or

channel aggradation (Burroughs 2011). As aggradation within the Elephant Butte Reach

is known to contribute to a decrease in channel capacity (Reclamation 2007), it is

important to understand the influences of Elephant Butte Reservoir levels on channel

aggradation/degradation in order to decrease the potential for future sediment plug

formation.

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Apache Plug formed just upstream of the Elephant Butte Reach. Further understanding

of the influences of Elephant Butte Reservoir levels on channel aggradation/degradation

will provide insight into proper river management practices in order to decrease the

potential for sediment plug formation.

The objectives of this study include the following:

1. Quantify temporal changes in channel widths and sinuosity from 1935 to 2010.

2. Quantify change in channel slope temporally.

3. Quantify rate of aggradation/degradation in response to a change in base-level

(i.e., change in reservoir water surface elevation).

4. Quantify aggradation/degradation wave propagation upstream.

5. Quantify spatial and temporal trends in bed material grain size.

2.2 Subreach Definition

To thoroughly evaluate the significant changes in the study area, the reach was

divided into six subreaches. The subreach definitions were determined by initial

assessments of the channel widths and planforms from aerial photos and channel slope.

To determine the subreach divisions, the active channel widths, as measured from

edge of vegetation to edge of vegetation, were plotted for the entire Elephant Butte Reach

for years 1962, 1972, 1992, and 2002. The thalweg at each Agg/Deg-line was also

plotted for each set of years, as shown on Figure 2.2. The subreaches were chosen based

on the 2002 dataset because of the abundance of both GIS and Agg/Deg Cross-section

data during this year, but subreaches were confirmed using the 1962, 1972, and 1992

datasets.

Figurre 2.2 Profile off Elephant Butte

9

e Reach Widths and Thalweg att Agg/Deg Lines

10

There are no major slope distinctions along the Elephant Butte Reach in 2002;

therefore, subreaches were primarily selected based on width trends. Subreaches 1, 3,

and 5 tend to be wider than Subreaches 2, and 4 (based on 2002 data). Subreach 6 is a

transitional subreach, which is sometimes river, and sometimes reservoir, depending on

the level of Elephant Butte Reservoir. The first subreach begins at the south boundary of

the Bosque del Apache NWR, Agg/Deg 1637, and extends to Agg/Deg 1672. The

second subreach begins at Agg/Deg 1672 and ends at Agg/Deg 1696. The third subreach

begins at Agg/Deg 1696 and ends at Agg/Deg 1728. The fourth subreach begins at

Agg/Deg 1728 and ends at Agg/Deg 1751. The fifth subreach begins at Agg/Deg 1751

and ends at Agg/Deg 1794. The sixth, and last, subreach begins at Agg/Deg 1794 and

extends to Elephant Butte Reservoir.

Figure 2.3 through Figure 2.9 show the 2008 aerial photographs of the study area

and its subreaches. Notice the low-flow conveyance channel located on the west bank of

the river. The previous temporary outfall of the low-flow conveyance channel was at

Agg/Deg 1794, which marks the end of Subreach 5 and the beginning of Subreach 6.

The Black Mesa geologic feature is located east of Subreach 3. Levee construction along

the West side of the river has prevented the river from excessive meandering. The

Tiffany Plug location is shown on Figure 2.4; the Bosque del Apache Plug is located

about 7 miles upstream of the study reach and is, therefore, not shown.

11

Figure 2.3 2008 Aerial Photo of Subreach 1

12

Figure 2.4 2008 Aerial Photo of Subreach 2

Tiffany Plug (1991, 1995, 2005)

13

Figure 2.5 2008 Aerial Photo of Subreach 3

14

Figure 2.6 2008 Aerial Photo of Subreach 4

15

Figure 2.7 2008 Aerial Photo of Subreach 5

16

Figure 2.8 2008 Aerial Photo of Subreach 6

17

Figure 2.9 2008 Aerial Photo of Elephant Butte Reservoir

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2.3 Available Data

The data used in this study was received from a number of different agencies:

United States Bureau of Reclamation (Reclamation), National Oceanic and Atmospheric

Administration (NOAA), the United States Geological Survey (USGS), and the Middle

Rio Grande database compiled at Colorado State University for Reclamation.

2.3.1 Survey Lines and Dates

Cross-sectional survey data was collected by Reclamation using both

Aggradation/Degradation line (Agg/Deg-line) surveys; Socorro range line (SO-line), and

Elephant Butte range line (EB-line) surveys. Agg/Deg-line elevations were derived using

photogrammetry. The Agg/Deg-lines are spaced about 500 feet apart and were surveyed

in 1962, 1972, 1992, and 2002. This information was used for the hydraulic and GIS

analyses to follow. Figure 2.10 shows the entire Elephant Butte Reach with each of the

six defined subreaches, and the Agg/Deg-lines with the 2008 GIS Elephant Butte Reach

delineation.

The range lines (SO-lines and EB-lines) were field surveyed by Reclamation

beginning in 1980. These surveys are more detailed than the channel cross-sections that

were developed from the aerial photographs (i.e., Agg/Deg lines). The spacing of these

surveys is greater than that of the Agg/Deg lines, but the field surveyed cross section

locations typically coincide with Agg/Deg line locations. Range line survey data was

available from 1980 to 2010 from Reclamation. 18 SO-lines and 102 EB-lines are

located within the reach. Figure 2.11 shows the location of the SO- and EB-lines and

Appendix A provides the dates of available survey data at each SO- and EB-line.

19

Figure 2.10 Subreach Definitions and Agg/Deg Line Locations (2008 GIS Elephant Butte Reach Delineation Shown)

Agg/Deg 1637

Agg/Deg 1672 Agg/Deg 1696

Agg/Deg 1728

Agg/Deg 1751

Agg/Deg 1794

Tiffany Plug Agg/Deg 1683 (1991, 1995, 2005)

20

Figure 2.11 Subreach Definitions and Range Line Locations (2008 GIS Elephant Butte

Reach Delineation Shown)

Agg/Deg 1637

Agg/Deg 1672 Agg/Deg 1696

Agg/Deg 1728

Agg/Deg 1751

Agg/Deg 1794

Tiffany Plug Agg/Deg 1683 (1991 – 1995, 2005

21

2.3.2 Discharge Data

Mean daily discharge data was primarily used from two USGS gauges: the San

Marcial gauge (08358400, primary gauge), located in the upstream end of the study

reach, and the San Acacia gauge (08354900, secondary gauge), located approximately 44

miles upstream of the study reach. The gauge numbers and their dates of available

discharge data are shown in Table 2-1.

Table 2-1: Available Daily Discharge Data USGS Gauging Station USGS Gauge Number Dates Available

RG at San Marcial 8358400 1949- current

RG at San Acacia 8354900 1958-current

The Elephant Butte Dam gauge (8361000), located approximately 34 miles

downstream of the Elephant Butte Reach, measures regulated reservoir releases, and was

therefore not useful in this study. The San Antonio gauge (8355490), located

approximately 25 miles upstream of the Elephant Butte reach, only contains discharge

data for recent years (2005 – Sep 2008), and therefore was not considered. An additional

gauge is located at the Escondida Bridge, approximately 16 miles upstream of the

Elephant Butte reach. However, this gauge only records real-time discharge and not the

historical data needed for this study. Figure 2.12 shows the locations of the nearby

gauges.

22

Figure 2.12 Location of Gauges

An example hydrograph for the San Acacia and San Marcial gauges for the year

1999 is shown in Figure 2.13. The hydrograph demonstrates that there are typically two

distinct peaks on the Middle Rio Grande. The first peak occurs between mid-May until

the end of June and the second peak occurs in August. As demonstrated in Figure 2.13,

23

significant evapotranspiration losses from the river largely contribute to the typically

lower discharge measurements at the San Marcial Gauge, compared to the San Acacia

Gauge (Baird, D., Pers. Comm.). Additional daily discharge graphs from the years 1990-

2010 are available in Appendix B.

Figure 2.13: Daily Discharge of the Rio Grande in 1999

The annual peak flow information for the San Acacia and San Marcial gauges was

obtained from the USGS website. Figure 2.14 displays a comparison of the peak flows at

the San Acacia Gauge and the San Marcial Gauge.

24

Figure 2.14 Comparison of Annual Peak Flows at San Acacia and San Marcial Gauges

2.3.3 Bed Material

Bed material data was collected by Reclamation from 1986-2007 at SO- and EB-

range lines. The dates and locations of the collected bed material data are provided in

Appendix C. Additional bed material data was also obtained from the USGS gauging

stations at San Acacia, located approximately 44 miles upstream of Elephant Butte

Reach, and San Marcial, located within the Elephant Butte Reach

(http://nwis.waterdata.usgs.gov). The dates and locations of the data recorded are

provided in Appendix D.

2.3.4 Suspended Sediment Data

As part of this study, the suspended sediment data was used from the Escondida

Reach Report (Larsen et al. 2007). This was used since no new sediment data is available

on the USGS website for the San Acacia and San Marcial guages. Daily suspended

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1959

1961

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

Annual Peak Discharge

 (cfs)

Year

San Acacia

San Marcial

25

sediment data was used for this analysis. Figure 2.15 shows the annual suspended

sediment load at each gauge. Continuous suspended sediment data was not always

available for all parameters at each gauge. A blank year indicates that complete sediment

data was not available for that year.

Figure 2.15: Annual Suspended Sediment Yield at San Acacia and San Marcial Gauges

Table 2-2 gives the dates of continuous, available data at each gauge.

Table 2-2: Available Suspended Sediment Data

USGS GAUGING STATION DATES

RG at San Marcial

Oct. 1956 - July 1962 Sep. 1962 - Aug. 1966 Oct. 1966 - Sep. 1989 Oct. 1991 - Sep. 1995

RG at San Acacia

Jan 1959 - Sep. 1959 Jan 1960 - Sep. 1961

July 1961 April 1962 - July 1962 Aug 1962 - Sep. 1962

March 1963 - Sep. 1996

0

2000000

4000000

6000000

8000000

10000000

12000000

1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994

Year

San Marcial San Acacia

26

SECTION 3: RESERVOIR LEVEL ANALYSIS

3.1.1 Reservoir Level Analysis

A reservoir level analysis was performed for the Elephant Butte Reservoir,

located at the downstream end of the Elephant Butte Reach. Figure 3.1 shows the

Elephant Butte Reservoir level time series. Elephant Butte Dam construction began in

1908 and was completed in 1916, with water storage operations beginning in January of

1915 (Reclamation, 2008). The maximum water surface elevation (WSE) of Elephant

Butte Reservoir is 4407.0 ft. Since its inception, the WSE behind Elephant Butte Dam

has varied more than 150 ft in elevation. The reservoir was not completely filled until

1942, at which point the reservoir level dropped about 150 ft between 1942 and 1954,

due to a drought which lasted from about 1942 to about 1974 (Figure 1.2). The low flow

conveyance channel (LFCC), which was built to hydraulically efficiently transport water

to Elephant Butte Reservoir and runs the entire length of Elephant Butte Reach, was in

operation by 1955 and operated until 1986. With the operation of the LFCC during the

drought, the reservoir WSE averaged between El 4331 and El 4404. By about 1977 the

reservoir began to fill again until it was full, or essentially full, from 1985 to 1999, at

which point another drought impacted the reservoir level, which decreased to an average

WSE of about 4340 ft in 2010.

27

Figure 3.1 Elephant Butte Reservoir Level Time Series

4200

4250

4300

4350

4400

4450

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

WSE (ft)

Annual Mean WSE Annual Max WSE Annual Min WSE

DROUGHT DROUGHT

LFCC OPERATION

28

Figure 3.2 shows the historical sediment survey longitudinal profile with reservoir

sediment surveys completed in 1915, 1988, 1999, and 2007. Comparing the survey

between 1915 and 1988, up to 50 ft of aggradation has occurred within Elephant Butte

Reservoir. The decrease in longitudinal profile elevation from 1999 to 2007 can be

attributed to the consolidation of the deposited sediment during the low reservoir levels in

response to a second drought from 1999 to 2005.

In 1915, when the reservoir had just begun to fill, had the reservoir been at its

maximum WSE, then the upstream extent of the reservoir would have reached RL 10 (or

the upstream end of Subreach 3). By 2007, the upstream extent of the reservoir at its

maximum WSE would have been about RL 20 (or the upstream end of Subreach 6). This

means the maximum upstream extent of the reservoir would have shifted downstream

approximately 6 miles. The level of the reservoir impacts Elephant Butte Reach, due to

sediment deposition as a result of an increased base-level. The longitudinal profile of

Elephant Butte Reach is base-level controlled; with an increase in base-level, the channel

adjusts vertically by way of sediment deposition, resulting in channel aggradation.

29

Figure 3.2 Elephant Butte Reservoir Historical Sediment Survey Longitudinal Profile (Reclamation, 2008)

MAX WSE

AVG. WSE

2010 AVGWSE

SR3 SR4 SR5 SR

30

SECTION 4: CHANNEL ANALYSIS

4.1 Channel Planform Analysis from Aerial Photographs

Using ArcGIS and aerial photographs supplied by Reclamation, the study reach’s

active channel was delineated for 1918, 1935, 1949, 1962, 1972, 1985, 1992, 2001, 2002,

2003, 2004, 2005, 2006, 2008 and 2010. These active channel delineations will be

referred to as planforms for purposes of this report; the active channel corresponds to the

area bounded by established vegetation. Aerial photographs were not available during

1985, and a delineation provided by Reclamation was used; the 2010 active channel was

delineated using a Digital Elevation Model (DEM). See Appendix E for survey dates and

additional information about the aerial photographs.

The active channel width was measured at each Agg/Deg line using the delineated

planforms. A mean width value was then obtained for each subreach and for the overall

reach using a weighted average method. Finally, the sinuosity was computed.

4.1.1 Channel Delineation

Figure 4.1 shows the channel planforms that were delineated in ArcGIS. Figure 4.2

through Figure 4.7 show magnified versions of Figure 4.1. Based on visual observations,

the overall channel has narrowed and changed from a multithread channel to a primarily

single-thread channel. Subreaches 1, 2, 5, and 6 have straightened and narrowed

primarily between 1918 and 1962, and have remained relatively unchanged since then.

The multithread characteristics of the river observed from 1928 to 1949 are not repeated

after the recession of the reservoir from 2001 to 2003, because Reclamation regularly

excavated pilot channels within Subreach 6 (Baird, D., Pers. Comm.).

31

Figure 4.1 Channel Planforms from Aerial Photography

32

Figure 4.2 Subreach 1 Channel Planforms from Aerial Photography

Figure 4.3 Subreach 2 Channel Planforms from Aerial Photography

33

Figure 4.4 Subreach 3 Channel Planforms from Aerial Photography

34

Figure 4.5 Subreach 4 Channel Planforms from Aerial Photography

35

Figure 4.6 Subreach 5 Channel Planforms from Aerial Photography

36

Figure 4.7 Subreach 6 Channel Planforms from Aerial Photography

37

Note that the difference between the first set of delineations, 1918-1949, is 31

years, the second set of delineations, 1962-1985, is 23 years, the third set of delineations,

1992-2002 is 10 years, and the fourth set of delineations, 2003-2010 is only 7 years.

Based on a qualitative visual analysis, the first delineation comparison covers the longest

time period and shows the most change and the last delineation comparison shows the

shortest time period with the least change. Nevertheless, narrowing and straightening of

the reach is observed over time.

4.1.2 Channel Widths from GIS

The active channel width corresponds to the non-vegetated channel. The active

channel planforms were delineated from aerial photographs using this criterion, and

widths were measured at every Agg/Deg line and/or Range line for which the river

intersected. A distance-dependent, weighted average method was used to calculate the

average width at each subreach and for the total reach.

In general, Figure 4.8 illustrates a decreasing trend in the width over time for all

of the subreaches from 1935 to 1972. Subreaches 1 and 2 experienced an increase in

average width in 1949 due to the existence of a multithread channel; Subreach 1

increased from about 940 ft to about 1100 ft, and Subreach 2 increased from about 700 ft

to about 1700 ft. The decrease in channel width from 1935 to 1972 (on average, about

275 ft) may be attributed to lower than average discharges, a decrease in base-level, or a

combination of the two. The lower than average discharges and decrease in base-level

are both results of the drought, which lasted from 1942 to 1979. From 1935 to 2010, the

channel width decreased according to the following second order polynomial equation:

y = 0.2353x2 - 936.54x + 931904

38

Where, x is the year, and y is the average channel width (ft).

Figure 4.8 Channel Widths from GIS (1918 - 2010)

As seen in Figure 4.9, between 1972 and 1985, the average channel width

increased, on average, about 60 ft and the base-level increased by up to 125 ft. Between

1985 and 2000, the base-level remained relatively unchanged, changing no more than 27

ft, and the average channel width, on average, changed no more than 30 ft. Between

2000 and 2004, the base-level decreased by up to 100 ft, and the average channel width

increased 26 ft from 2001 to 2003 and decreased 45 ft from 2003 to 2004. The large

decrease in channel width between 2003 and 2004 was due to mechanical excavation of

narrow pilot channels by Reclamation (Baird, D. Pers. Comm.). The base-level increased

by about 50 ft between 2004 and 2010, and the average channel width increased about 55

ft between 2004 and 2006, and decreased about 55 ft between 2006 and 2010. In general,

y = 0.2353x2 ‐ 936.54x + 931904R² = 0.9299

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Average

 Width (ft)

YearSubreach 1 Subreach 2 Subreach 3

Subreach 4 Subreach 5 Subreach 6

Total (SR 1‐5) Total (SR 1‐6) Poly. (Total (SR 1‐6))

39

based on this dataset, the channel width tends to increase with a rise in base-level, and

decrease with a drop in base-level.

Figure 4.9 Channel Widths from GIS (1962 - 2010)

4.1.3 Sinuosity

Sinuosity of the entire Elephant Butte Reach, as well as the six subreaches, was

computed using aerial photographs in ArcGIS. The sinuosity was determined by using

the following equation:

Where S is the sinuosity, Lc is the length of the channel, and Lv is the length of the

valley.

The length of the channel, and each of the six subreaches, was measured along the

river thalweg, an estimated delineation from aerial photographs and channel delineations.

The thalweg delineation was approximate and accuracy was, in some cases, further

0

50

100

150

200

250

300

1960 1970 1980 1990 2000 2010

Average

 Width (ft)

Year

Subreach 1 Subreach 2 Subreach 3 Subreach 4

Subreach 5 Subreach 6 Total (SR 1‐5) Total (SR 1‐6)

Lv

LcS

40

limited by the clarity and quality of the aerial photographs. The 1985 and 1918

planforms delineated by Reclamation were used to estimate the length of the channel and

the length of the valley. For each year, the length of the valley was measured as the

straight-line distance between the upstream and downstream extents of the reach and

subreaches, as dictated by major geologic features, such as the Black Mesa. The channel

length measurements are plotted in Figure 4.10 and presented in Table 4-1. The channel

length decreased about 0.0126 miles/year between 1935 and 2010.

Figure 4.10 Subreach Lengths and Total Lengths as Measured From GIS Data

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

1910 1930 1950 1970 1990 2010

Chan

nel Length (miles)

YearSubreach 1 Subreach 2 Subreach 3Subreach 4 Subreach 5 Subreach 6Total Reach SB (1‐5) Total Reach SB (1‐6)

41

Table 4-1 Subreach Length and Total Length Values as Measured From GIS Data

Reach Measured Lengths (mi) 

1918  1935  1949  1962  1972  1985  1992  2001  2002  2003  2004  2005  2006  2008  2010 

Subreach 1  3.46  3.92  4.07  3.52  3.56  3.30  3.38  3.34  3.34     3.42  3.34  3.30  3.27  3.32 

Subreach 2  1.51  1.54  1.59  2.39  2.21  2.25  2.27  2.26  2.28     2.31  2.28  2.27  2.31  2.27 

Subreach 3  1.56  3.87  3.54  3.25  3.24  3.10  3.18  3.18  3.21  3.17  3.19  3.17  3.14  3.26  3.20 

Subreach 4     2.04  2.12  2.14  2.13  2.13  2.13  2.13  2.13  2.13  2.15  2.15  2.13  2.14  2.11 

Subreach 5     4.74  4.97  4.21  4.26  4.13  4.36  4.24  4.30  4.27  4.38  4.32  4.23  4.36  4.26 

Subreach 6     17.39  16.11  18.12  16.14  5.56  2.04  2.03  7.67  16.73  16.93  16.48  16.48  17.11  0.79 

Total Reach SR (1‐5)  6.52  16.10  16.29  15.52  15.41  14.92  15.33  15.15  15.26  9.57  15.45  15.25  15.07  15.35  15.16

Total Reach SR (1‐6)  6.52  33.48  32.40  33.64  31.55  20.48  17.37  17.18  22.93  26.31  32.38  31.73  31.55  32.46  15.96

Agg/Deg Start  1637  1637  1637  1637  1637  1637  1637  1637  1637  1692  1637  1637  1637  1637  1637 

Agg/Deg End  1708  1962  1948  1962  1958  1849  1811  1811  1875  1962  1962  1960  1960  1962  1962 

42

Figure 4.11 shows the sinuosity for the Elephant Butte Reach and each of the

subreaches, values are presented in Table 4-2. From 1918 to 1935 sinuosity increased for

the entire channel; though the overall sinuosity remains low, less than 1.3, Subreach 1 is

more sinuous than Subreach 2 by about 15 percent. There is not enough planform

delineated in Subreach 3 in 1918 to be considered representative of the entire subreach,

so this portion was disregarded. No planform data exists below Subreach 3 in 1918, so

sinuosity data is unavailable. From 1935 to 1949, the sinuosity for the entire channel,

and for each subreach, decreased by less than 6 percent, except Subreach 5, which

increased about by about 4 percent. Subreach 2 remained less sinuous, by about 15

percent on average and up to 20 percent, than the remaining Subreaches, which ranged in

sinuosity from 1.18 to 1.29. From 1949 to 1962, the sinuosity of Subreaches 1, 3, 4, and

5 decreased between 10 and 20 percent, while Subreaches 2 and 6 increased between 5

and 10 percent. From 1962 to 2010 sinuosity tends to increase and decrease repetitively

between a range of 1.0 and 1.15 for Subreaches 1 through 5, while Subreach 6 tends to

have a higher sinuosity than the other subreaches from 1962 to 2010 and ranges from

1.12 to 1.24. The higher sinuosities observed in Subreach 6 in the mid-2000s is because

Reclamation mechanically introduced a sinuous channel to Subreach 6 by excavating a

pilot channel after the lowering of Elephant Butte Reservoir (Baird, D., Pers. Comm.). In

general, it can be said that this channel has experienced relatively low sinuosity (less than

1.25) since 1962. From 1935 to 2010, the channel sinuosity can be described using the

following second order polynomial:

y = 6E-05x2 - 0.2196x + 219.57

Where, x is year, and y is channel sinuosity (ft/ft).

43

Figure 4.11 Temporal Sinuosity Trends

y = 6E‐05x2 ‐ 0.2196x + 219.57R² = 0.8398

1

1.05

1.1

1.15

1.2

1.25

1.3

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

2015

Sinuosity

Year

Subreach 1 Subreach 2 Subreach 3

Subreach 4 Subreach 5 Subreach 6

Total Reach (SR 1‐5) Total Reach (SR 1‐6) Poly. (Total Reach (SR 1‐5))

44

Table 4-2 Sinuosity Values

Reach Year 

1918  1935  1949  1962  1972  1985  1992  2001  2002  2003  2004  2005  2006  2008  2010 

Subreach  1  1.118  1.222  1.180 1.039 1.110 1.027 1.052  1.017  1.037    1.062 1.039 1.003 1.050 1.067 

Subreach   2  1.032  1.054  1.014 1.106 1.013 1.013 1.075  1.024  1.010    1.002 1.025 1.055 1.091 1.073 

Subreach  3  1.049  1.259  1.182 1.054 1.004 1.016 1.052  1.017  1.134 1.035 1.008 1.061 1.013 1.086 1.066 

Subreach  4  ‐‐  1.293  1.280 1.026 1.034 1.033 1.031  1.010  1.047 1.018 1.012 1.057 1.019 1.100 1.084 

Subreach  5  ‐‐  1.233  1.280 1.062 1.069 1.028 1.124  1.087  1.113 1.104 1.145 1.109 1.076 1.128 1.101 

Subreach  6  ‐‐  1.194  1.181 1.246 1.137 1.225 1.158  1.182  1.121 1.149 1.162 1.145 1.145 1.176   

Total Reach (SR 1‐5)  ‐‐  1.213  1.200 1.078 1.081 1.037 1.079  1.063  1.080    1.095 1.068 1.083 1.077 1.064 

Total Reach (SR 1‐6)  1.108  1.210  1.202 1.176 1.121 1.098 1.093  1.089  1.098 1.140 1.135 1.119 1.117 1.146 1.064 

Agg/Deg Start  1637  1637  1637  1637  1637  1637  1637  1637  1637  1692  1637  1637  1637  1637  1637 

Agg/Deg End  1708  1962  1948  1962  1958  1849  1811  1811  1875  1962  1962  1960  1960  1962  1794 

45

4.2 Aggradation and Degradation from Agg/Deg Surveys

4.2.1 Channel Thalweg Profile from Agg/Deg Surveys

The channel thalweg profile from the Agg/Deg survey data was utilized to

demonstrate how the minimum elevation and slope of the reach has changed over time, as

shown in Figure 4.12. The average bed slope for each subreach and for the entire reach

was determined by first plotting the thalweg profile versus downstream distance, as

measured along the estimated thalweg in GIS, and fitting a linear regression trendline to

each subreach. The slope of the linear regression line was considered the average bed

slope of the respective subreach. A linear regression trendline was also fit to the total

reach thalweg profile, from which the slope of the regression trendline was considered

the average bed slope of the total reach. This method was used for 1962, 1972, 1992, and

2002. The average bed slope for each subreach and for the entire reach is shown in

Figure 4.13.

438

440

442

444

446

448

450

Elevation (ft)

80

00

20

40

60

80

00

0

SR1

Figure 4

20,000 4

D

SR2

4.12 Thalweg E

40,000 60

Distance Downstre

SR3 SR4

46

Elevation Profil

0,000 80,

eam of South Boun

SR5 4

e From Agg/De

,000 100,

ndary of Bosque d

SR6

eg Surveys

000 120,0

del Apache NWR (ft

000 140,00

t)

1962 Th

1972 Th

1992 Th

2002 Th

00 160,00

alweg Profile

alweg Profile

alweg Profile

alweg Profile

0

47

Figure 4.13 Bed Slope from Agg/Deg Surveys

Between the years 1962 and 1972, the bed slope increased between 15 and 30

percent for Subreaches 1, 2, and 3; bed slope decreased 40 and 20 percent for Subreaches

4 and 5, respectively. From 1972 to 1992, bed slope decreased between 10 and 45

percent for all subreaches. From 1992 to 2002, Subreach 2 increased 10 percent and

Subreach 6 increased fourfold; all other subreaches decrease between 3 and 15 percent.

The overall decrease in bed slope along the entire reach suggests aggradation has

occurred between 1962 and 2002. The decrease in bed slope from 1972 to 1992 in

Subreach 6 could be caused by the increased Elephant Butte Reservoir level (base-level),

which increased by about 130 ft. The fourfold increase in bed slope from 1992 to 2002 in

Subreach 6 could be due to the drop base-level, which dropped about 85 feet between

1992 and 2002. The longitudinal profile of Elephant Butte Reach is base-level

controlled; with an increase in base-level, the channel adjusts vertically by way of

sediment deposition, resulting in channel aggradation and a decrease in channel slope. It

is important to note, however, that these trends could also be due to the lack of data in

Subreach 6, especially in 1972 and 1992, which could skew the calculated bed slope

0.0000

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

1960 1970 1980 1990 2000 2010

Bed Slope

Year

Subreach 1Subreach 2Subreach 3Subreach 4Subreach 5Subreach 6Total Reach (1‐5)

48

value to be inaccurate. Table 4-3 shows the average values of the channel slope for each

subreach and the overall reach.

Table 4-3 Average Bed Slope from Agg/Deg Surveys Subreach  Agg/Deg Lines  1962  1972  1992  2002 

1  1637 ‐ 1672  0.000509  0.000675  0.000523  0.000441 

2  1672 ‐ 1696  0.000823  0.000830  0.000480  0.000532 

3  1696 ‐ 1728  0.000699  0.000797  0.000564  0.000538 

4  1728 ‐ 1751  0.000855  0.000537  0.000498  0.000417 

5  1751 ‐ 1794  0.000730  0.000600  0.000550  0.000532 

6  1794 ‐ 1875  0.000370  0.000370  0.000205  0.000819 

Total (1‐6)  1637 ‐ 1875  0.000594  0.000684  0.000535  0.000495 

Total (1‐5)  1637 ‐ 1794  0.000710  0.000720  0.000562  0.000481 

4.2.2 Change in Channel Thalweg Elevation from Agg/Deg Surveys

A weighted average of the change in thalweg elevation was computed for the

entire reach, as well as each subreach, for each year of available Agg/Deg survey data.

The average change in thalweg elevation was then compared between years to determine

the change in elevation over time. Figure 4.14 shows the average change in thalweg

elevation for each subreach, and the overall reach over time; the tabulated values are

displayed in Table 4-4. The results show that the average change in the channel thalweg

elevation decreased between 0.7 and 3.5 ft from 1962 to 1972 for all subreaches except

Subreaches 5 and 6; Subreaches 5 and 6 increased in elevation by about 0.2 to 0.4 ft. The

average change in channel thalweg elevation has been increasing since 1972. An

increase in channel thalweg elevation indicates aggradation, whereas a decrease indicates

degradation. The entire reach has been aggrading since 1972.

49

Figure 4.14 Change in Channel Thalweg Elevation from Agg/Deg Surveys

Table 4-4 Change in Channel Thalweg Elevation Values from Agg/Deg Surveys

Δ Channel Thalweg Elevation (ft) 

Weighted Average  1962 ‐ 1972  1972 ‐ 1992  1992 ‐ 2002  1962 ‐ 2002 

U/S OF EB REACH  0.79  3.36  1.76  5.91 

SUBREACH 1  ‐0.67  5.73  1.85  6.93 

SUBREACH 2  ‐2.65  8.33  3.67  9.39 

SUBREACH 3  ‐3.45  11.57  4.20  12.31 

SUBREACH 4  ‐3.53  14.07  5.88  16.39 

SUBREACH 5  0.43  15.06  7.21  22.50 

SUBREACH 6  0.26  17.68  6.53  20.01 

TOTAL REACH  ‐1.33  11.42  4.79  15.95 

Analyses were done using the Agg/Deg data to show the change in thalweg

elevation at each Agg/Deg line (see Figure 4.15 to view the changes from 1962-1972,

Figure 4.16 for 1972-1992, Figure 4.17 for 1992-2002, and Figure 4.18 for 1962-2002).

Recall that Agg/Deg data does not have surveys available at every Agg/Deg line during

the years 1962, 1972, and 1992, therefore the plots only show the Agg/Deg lines for

‐5

0

5

10

15

20

25

1962 ‐ 1972 1972 ‐ 1992 1992 ‐ 2002 1962 ‐ 2002

Chan

ge in

 Chan

nel Thalweg Elevation (ft)

SUBREACH 1 SUBREACH 2 SUBREACH 3 SUBREACH 4

SUBREACH 5 SUBREACH 6 TOTAL REACH

50

which data exists. Table 4-5 shows the average, maximum and minimum changes in

channel thalweg elevation with their respective Agg/Deg line for each group of years.

Figure 4.15 Change in Channel Thalweg Elevation (1962 – 1972) Based on Agg/Deg

Surveys

Figure 4.16 Change in Channel Thalweg Elevation (1972 – 1992) Based on Agg/Deg

Surveys

‐6

‐5

‐4

‐3

‐2

‐1

0

1

2

3

4

1637

1645

1652

1662

1670

1678

1688

1695

1707

1733

1750

1777

1792

1804

1820

Chan

ge in

 Chan

nel Invert Elevation (ft)

Agg/Deg #

1962 ‐ 1972

0

5

10

15

20

25

1637

1645

1652

1662

1670

1678

1688

1695

1707

1733

1750

1762

1786

1798

1809

Chan

ge in

 Chan

nel Invert Elevation (ft)

Agg/Deg #

1972 ‐ 1992

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

51

Figure 4.17 Change in Channel Thalweg Elevation from 1992 – 2002 Based on Agg/Deg

Surveys

Figure 4.18 Change in Channel Thalweg Elevation from 1962 – 2002 Based on Agg/Deg

Surveys

0

1

2

3

4

5

6

7

8

9

1637

1645

1652

1662

1670

1678

1688

1695

1703

1731

1747

1751

1777

1792

1804

Chan

ge in

 Chan

nel Invert Elevation (ft)

Agg/Deg #

1992 ‐ 2002

0

5

10

15

20

25

30

1637

1645

1652

1662

1670

1678

1688

1695

1703

1731

1747

1762

1786

1798

1809

1827

1848

1875

Chan

ge in

 Chan

nel Invert Elevation (ft)

Agg/Deg #

1962 ‐ 2002

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

52

Table 4-5 Average, Maximum and Minimum Change in Channel Thalweg Elevation Based on Agg/Deg Surveys

Year:  1962 ‐ 1972  1972 ‐ 1992  1992 ‐ 2002  1962 ‐ 2002 

Δ Thalweg El (ft) 

Agg/Deg # 

Δ Thalweg El (ft) 

Agg/Deg # 

Δ Thalweg El (ft) 

Agg/Deg # 

Δ Thalweg El (ft) 

Agg/Deg # 

Subreach 1 

Max  1.30  1641  7.70  1652  3.14  1673.0  8.34  1662 

Min  ‐3.10  1670  3.50  1645  0.84  1652.0  4.95  1645 

Average ‐0.67  5.73  1.85  6.93 

Subreach 2 

Max  ‐1.30  1692  10.60  1695  4.35  1683.0  11.28  1692 

Min  ‐4.30  1678  7.10  1678  2.58  1695.0  7.00  1678 

Average ‐2.65  8.33  3.67  9.39 

Subreach 3 

Max  ‐2.40  1707  13.90  1731  4.99  1731.0  14.19  1731 

Min  ‐4.70  1731  10.20  1707  3.68  1707.0  11.47  1707 

Average ‐3.45  11.57  4.20  12.31 

Subreach 4 

Max  ‐1.70  1747  14.60  1751  6.36  1747.0  18.66  1747 

Min  ‐5.50  1733  14.00  1747  5.53  1733.0  14.13  1733 

Average ‐3.53  14.07  5.88  16.39 

Subreach 5 

Max  2.60  1762  16.30  1777  7.92  1777.0  23.78  1762 

Min  ‐1.20  1777  14.50  1762  6.68  1762.0  23.02  1777 

Average 0.43  15.06  7.21  22.50 

Subreach 6 

Max  1.40  1820  19.80  1798.00  7.80  1804.0  24.30  1809 

Min  ‐0.90  1798  16.70  1804  5.20  1798.0  11.50  1875 

Average 0.26  17.68  6.53  20.01 

Total Reach 

Max  2.60  1762  19.80  1798  7.92  1777.0  24.30  1809 

Min  ‐5.50  1733  3.50  1645  0.84  1652.0  4.95  1645 

Average ‐1.33  11.42  4.79  15.95 

53

From 1962 to 1972 degradation occurred in all subreaches. The upstream half of

Subreach 1 aggraded from 1962 to 1972, along with five sections in Subreach 5 and

Subreach 6. Since 1972, the channel has been aggrading along all subreaches. From

1962 to 2002, a maximum aggradation of 24.30 feet has occurred at Agg/Deg 1809, at the

downstream end of the reach, with a minimum aggradation of 4.95 ft at Agg/Deg 1645, at

the upstream end of the reach. From Figure 4.18, it is clear that aggradation increases in

the downstream direction. Within Subreach 6, however, there tends to be a decrease in

aggradation in the downstream direction. The overall aggradation of the reach is due to

the increase in base-level between 1972 and 1985, at which point the base-level changed

less than 30 ft between 1985 and 2000. Between 1992 and 2002, aggradation continued

in the upstream portions of the reach, still in response to the increase in base-level

between 1972 and 1985. However, the downstream portion of Subreach 6 (Agg/Deg

1827 to Agg/Deg 1875) did not aggrade as much as the upstream portion of Subreach 6,

because of the drop in base-level of about 80 ft between 2000 and 2002.

Figure 4.19 shows the change in the thalweg elevation at selected Agg/Deg lines

from 1962 – 1992. Only Agg/Deg lines with sufficient years of sample data were plotted.

It can be inferred from this plot that as the reservoir level increases, the channel thalweg

elevation increases at each Agg/Deg line, and that the increase in channel thalweg

elevation is more pronounced in the downstream direction, closer to the reservoir.

54

Figure 4.19 Temporal Trend in Thalweg Elevation at Agg/Deg Lines

4320

4340

4360

4380

4400

4420

4440

4460

4480

4500

1950 1960 1970 1980 1990 2000 2010 2020

Elevation (ft)

Year

1625

1628

1633

1637

1641

1645

1648

1652

1658

1662

1666

1670

1673

1678

1683

1688

1692

1695

1703

1707

1731

1733

1747

1750

1751

1762

1777

1786

1792

1798

1804

1809

1820

1827

1835

1848

1856

1864

1875

1883

1887

1894

1908

EB Res

55

Figure 4.20 shows the rate of aggradation between 1972 and 1992 at each

Agg/Deg line for which there is data. A second order polynomial trendline was fit to the

data. For an increase in base-level (Reservoir WSE) of up to 13.4 ft/yr, the following

second order polynomial describes the rate of aggradation from 1972 to 1992 for the

Elephant Butte Reach:

Rate of Aggradation = -0.0014x2 + 0.0649x + 0.1832

Where, x is the distance in miles downstream of Agg/Deg 1637 (or the upstream end of

Elephant Butte Reach).

Figure 4.20 Rate of Channel Aggradation between 1972 and 1992

4.3 Aggradation and Degradation from Range Line Surveys

4.3.1 Channel Thalweg Profile from Range Line Surveys

Figure 4.21 shows the thalweg elevation profile of the entire reach. Only years

with enough range line survey data were plotted. Not all years are presented, because the

lines on the plot would be too dense to see trends if all the years were plotted, so certain

years were chosen to represent changes. The thalweg elevation profile shows a general

y = ‐0.0014x2 + 0.0649x + 0.1832R² = 0.9334

0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20

Rate of Aggradation (ft/yr)

Miles Downstream from Agg/Deg 1637

56

trend of varying aggradation and degradation over time. One of the most notable trends

from this plot is the flattening of the channel slope from 2004 to 2009 in the downstream

half of the reach, which is due to the aggradation induced by a rise in base-level from

2004 to 2009. Also noteworthy is the significant aggradation in 2005 upstream of EB-10

(Agg/Deg 1707). The Tiffany Plug formed in 2005 at SO-1683 (Agg/Deg 1683), just

upstream of EB-10, which can be seen in the profile. In 1995, severe degradation can be

seen downstream of SO-1683 (Agg/Deg 1683), and virtually no change at SO-1683, even

though a sediment plug had formed upstream of SO-1683 in 1995. This is likely

explained by the timing of the survey, which seems to have occurred after the sediment

plug was mechanically removed by Reclamation.

57

Figure 4.21 Thalweg Elevation Profile From Range Line Survey Data

4380

4400

4420

4440

4460

4480

4500

1600 1650 1700 1750 1800 1850 1900 1950 2000

Thalweg Elevation (ft)

Agg/Deg Line

1988

1991

1994

1995

1999

2004

2005

2009

Tiffany Plug, 2005, SO-1683 (Agg/Deg 1683)

Elephant Butte Reservoir Max WSE, El 4454 (Project Datum)

SR 2SR 1 SR 3 SR 4 SR 5 SR 6

Agg

/Deg

163

7

Agg

/Deg

167

2

Agg

/Deg

169

6

Agg

/Deg

172

8

Agg

/Deg

175

1

Agg

/Deg

179

4

58

The channel thalweg profile from the range line survey data was utilized to

demonstrate how the minimum elevation and slope of the reach has changed over time.

The average bed slope for each subreach was determined by first plotting the thalweg

profile versus river mile, and then fitting a linear regression trendline to each subreach.

The slope of the linear regression line was considered the average bed slope of the

respective subreach. This method was used for all years for which range line survey data

was available. The average channel thalweg slopes for each Subreach 1 through

Subreach 6 are presented in Figure 4.22 through Figure 4.27, respectively. Table 4-6

presents the values of the average channel thalweg slopes for each subreach.

Figure 4.22 Subreach 1 Average Channel Thalweg Slope: Temporal Trend

Figure 4.23 Subreach 2 Average Channel Thalweg Slope: Temporal Trend

0

1

2

3

4

5

6

7

8

1985 1990 1995 2000 2005 2010

Avg Thalweg Slope (ft/m

i)

Year

0

1

2

3

4

5

6

7

8

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Avg Thalweg Slope (ft/m

i)

Year

59

Figure 4.24 Subreach 3 Average Channel Thalweg Slope: Temporal Trend

Figure 4.25 Subreach 4 Average Channel Thalweg Slope: Temporal Trend

Figure 4.26 Subreach 5 Average Channel Thalweg Slope: Temporal Trend

0

1

2

3

4

5

6

1985 1990 1995 2000 2005 2010

Avg Thalweg Slope (ft/m

i)

Year

0

1

2

3

4

5

6

1975 1980 1985 1990 1995 2000 2005 2010 2015

Avg Thalweg Slope (ft/m

i)

Year

0

1

2

3

4

5

6

1985 1990 1995 2000 2005 2010 2015

Avg Thalweg Slope (ft/m

i)

Year

60

Figure 4.27 Subreach 6 Average Channel Thalweg Slope: Temporal Trend

Table 4-6 Average Channel Thalweg Slopes for Subreaches 1 through 6

Channel Thalweg Slope (ft/mi) 

Year  SR 1  SR 2  SR 3  SR 4  SR 5  SR 6 

2010  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  3.3058  3.9285  2.7865 

2009  3.819  2.5421  14.345  3.191  4.7156  2.8378 

2008  2.3551  3.2975  2.1491  3.6395  4.2458  2.9771 

2007  1.5905  3.215  3.4676  3.6845  4.1554  3.1211 

2006  3.3542  3.0568  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  3.4361 

2005  0.1714  5.4088  0.2545  3.7804  4.8768  3.4627 

2004  2.1619  3.6974  4.9293  3.7213  3.1183  4.1643 

2003  0.7829  3.3695  2.9158  3.6717  2.9102  4.2159 

2002  2.7047  2.8284  1.9506  3.99  2.5376  4.2891 

2001  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  2.3077 

2000  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  5.0078  2.9984  2.7499 

1999  3.3741  2.7141  1.147  5.0078  2.9984  3.2324 

1998  4.1195  2.5813  4.1364  3.7546  3.2622  3.567 

1997  2.3206  4.9367  4.3273  4.2125  1.6368  3.4796 

1996  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  2.5278  2.1193  4.2534 

1995  6.8687  7.3103  ‐6  4.3334  1.949  4.2116 

1994  4.3434  2.2019  3.0909  4.3229  3.9316  3.5435 

1993  2.303  ‐‐‐‐  4.7273  4.0989  2.6817  3.6434 

1992  4.1414  ‐‐‐‐  3.6364  3.053  2.5  4.6557 

1991  6.4848  ‐‐‐‐  2.5273  4.4329  5.5  ‐‐‐‐ 

1990  3.6869  ‐‐‐‐  2.9455  3.3211  2.8516  4.1049 

1989  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  3.9154 

1988  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  4.4677  3.0734  1.7771 

1987  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  5.1043  ‐‐‐‐  ‐‐‐‐ 

1986  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  5.1482  ‐‐‐‐  ‐‐‐‐ 

1980  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  3.8767  ‐‐‐‐  ‐‐‐‐ 

0

1

2

3

4

5

1985 1990 1995 2000 2005 2010 2015

Avg Thalweg Slope (ft/m

i)

Year

61

Subreaches 1 through 5 don’t appear to have a trend relating average channel

thalweg slope to time. Subreach 6, however, has a decreasing trend from 1995 to 2001

and again from 2002 to 2010. From 1995 to 2001, the channel slope decreases at a rate

of 0.32 ft/mi/yr; from 2002 to 2010, the channel slope decreases at a rate of 0.21 ft/mi/yr.

From 1995 to 2001, the base-level drops about 35 ft, while Subreach 6’s slope decreases.

From 2001-2004, the base-level drops another 60 ft, and from 2004 to 2009, the base-

level increases about 35 ft, all while the channel slope decreases. Therefore, the channel

slope is not dependent on the base-level changes within the same time-frame. Rather, the

channel slope decrease from 1995 to 2001 is due to the increase in base-level from 1982

to 1986, or from the increase in base-level from 1990 to 1995. And, the channel slope

decrease from 2001 to 2010 is due to the increase in base-level from 2004 to 2009. The

sudden jump in channel slope from 2.3 ft/mile, in 2001, to 4.3 ft/mile, in 2002, is likely a

result of the decrease in base-level between 1995 and 2004, during which the base-level

dropped by about 100 ft.

Cross-sections were plotted at select range lines for all years of available data and

are presented in Appendix F. Figure 4.28 through Figure 4.36 show representative cross-

sections of Elephant Butte Reach. SO-1683, Figure 4.29, is located in Subreach 2. From

2004 to 2005 the channel aggraded by about 8 ft and then degraded by about 8 ft from

2005 to 2006. This is the location of the Tiffany Sediment Plug in 2005. The sediment

plug was removed by excavating a pilot channel, which accounts for the decrease in bed

elevation from 2005 to 2006. EB-41, Figure 4.36, is located in Subreach 6. When the

reservoir was full from 1985 to 2000, this range line was inundated by the reservoir,

which is why there is only data available beginning in 2004.

62

Figure 4.28 Subreach 1: SO-1641 Surveyed Cross-Sections

Figure 4.29 Subreach 2: SO-1683 Surveyed Cross-Sections

4486

4488

4490

4492

4494

4496

4498

4500

50 100 150 200 250

Elevation (ft)

Station (ft)

SO‐16412009

2008

2007

2006

2005

2004

2003

2002

2001

1999

1998

1997

4474

4476

4478

4480

4482

4484

4486

4488

4490

4492

0 50 100 150 200

Elevation (ft)

Station (ft)

SO‐16832009

2008

2007

2006

2005

2004

2003

2002

1999

1998

1997

1995

1994

1993

1990

63

Figure 4.30 Subreach 3: EB-10 Surveyed Cross-Sections

Figure 4.31 Subreach 3: EB-10 (w/Floodplain) Surveyed Cross-Sections

4462

4464

4466

4468

4470

4472

4474

4476

4478

4480

4482

500 600 700 800 900 1000

Elevation (ft)

Station (ft)

EB‐1020102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980

4450

4455

4460

4465

4470

4475

4480

4485

4490

0 500 1000 1500 2000 2500

Elevation (ft)

Station (ft)

EB‐10 (w/Floodplain)20102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980

Active Channel

64

Figure 4.32 Subreach 4: EB-13 Surveyed Cross-Sections

Figure 4.33 Subreach 5: EB-20 Surveyed Cross-Sections

4460

4462

4464

4466

4468

4470

4472

4474

4476

1950 2000 2050 2100 2150 2200 2250 2300

Elevation (ft)

Station (ft)

EB‐132009

2008

2007

2005

2004

2002

2000

1998

1992

1988

1987

1986

4435

4440

4445

4450

4455

4460

4465

150 200 250 300 350 400 450

Elevation (ft)

Station (ft)

EB‐20200920082007200520042002200019991998199719951994199319921991199019881980

65

Figure 4.34 Subreach 6: EB-29 Surveyed Cross-Sections

Figure 4.35 Subreach 6: EB-29 (w/Floodplain) Surveyed Cross-Sections

4425

4430

4435

4440

4445

4450

5000 5100 5200 5300 5400 5500 5600

Elevation (ft)

Station (ft)

EB‐292009

2008

2007

2005

2004

2002

2000

1999

1997

1995

1993

1989

4425

4430

4435

4440

4445

4450

4455

3750 4250 4750 5250 5750 6250 6750

Elevation (ft)

Station (ft)

EB‐29 (w/Floodplain) 2009

2008

2007

2005

2004

2002

2000

1999

1997

1995

1993

1989

Active Channel

66

Figure 4.36 Subreach 6: EB-41 Surveyed Cross-Sections

4.3.2 Change in Thalweg and Average Bed Elevation from Range Line Surveys

As seen in Figure 4.28 through Figure 4.36 aggradation and degradation occur

across the entire channel bed, not just the thalweg. Therefore, the following analyses

focus on the change in thalweg elevation temporally and spatially. Figure 4.37 shows the

change in the thalweg elevation at selected range lines from 1980-2010. Only range lines

with sufficient years of sample data were plotted.

4398

4400

4402

4404

4406

4408

4410

4412

4414

4416

0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

EB‐41

2009

2008

2007

2004

67

Figure 4.37 Change in Thalweg Elevation at Range Lines (1980 – 2010)

4350

4400

4450

4500

4550

4600

4350

4360

4370

4380

4390

4400

4410

4420

4430

4440

4450

4460

4470

4480

4490

4500

1980 1985 1990 1995 2000 2005 2010

Reservoir W

SE (ft)

Chan

nel Thalweg Elevation (ft)

Year

SO‐1641

SO‐1652.7

SO‐1666

SO‐1673

S0‐1683

SO‐1692

SO‐1701.3

EB‐10

EB‐13

EB‐14

EB‐16

EB‐17

EB‐18

EB‐20

EB‐34

EB‐24

EB‐25

EB‐26

EB‐27

EB‐28

EB‐29

EB‐30

EB‐32

EB‐33

EB‐35

EB‐36

EB‐37

EB‐37.5

EB‐38

EB‐39

EB‐40

EB‐40.5

EB‐41

EB‐42

EB‐43

EB‐44

EB‐45

EB‐46

EB‐47

EB‐48

EB‐49

EB‐50

Reservoir Level

68

From 1980 to 1988, aggradation occurred at all range lines for which there is data.

From 1988 to 1994, the thalweg elevation alternated between increasing and decreasing

elevation, typically changing no more than 3 ft in either direction. From 1994 to 1995,

mostly aggradation occurs, up to 6.2 ft, near the upstream reservoir extent; degradation

occurs just downstream of the 1995 Tiffany Sediment Plug at SO-1692 and SO-1701.3,

7.6 ft and 3.6 ft, respectively. From 1995 to 2002, the change in channel thalweg

elevation varies between aggradation and degradation. From 2002 to 2003, aggradation

occurs from SO-1641 to EB-29, ranging between 1 ft and 4 ft; degradation occurs

downstream of EB-29, up to 3.5 ft. From 2003 to 2004, the channel degraded from SO-

1641 to SO-1692, and from EB-20 to EB-50 by up to 10.7 ft; the channel aggraded from

SO-1701.3 to EB-18 by up to 1 ft. From 2004 to 2007, aggradation occurred from SO-

1641 to SO-1692, up to 2.3 ft, and from EB-40 to EB-50, up to 7.6 ft; degradation

occurred from SO-1701.3 to EB-39, up to 11 ft. From 2007 to 2008, degradation

occurred from SO-1641 to EB-37.5, up to 2.7 ft; aggradation occurred from EB-38 to

EB-50, up to 1.4 ft. From 2008 to 2009, the channel degraded from SO-1641 to EB-37,

up to 2.6 ft; the channel aggraded from EB-37.5 to EB-50, up to 4.2 ft. From 2009 to

2010, the channel varied between aggradation and degradation, ranging between -1.8 ft

and 2.2 ft in elevation change.

A few notable changes occurred at EB-24. From 1990 to 1992 the thalweg

elevation decreased by about 12 ft, from 1992 to 1993 the thalweg elevation increased by

about 7.8 ft, and from 1994 to 1995, the thalweg elevation increased another 6.2 ft.

These changes are in direct response to the change in reservoir WSE, as the shape of the

69

thalweg elevation over time mimics the shape of the change in WSE over time, as seen in

Figure 4.37.

Table 4-7 shows the calculated values of change in thalweg elevation between

selected year sets at each range line for which there is data. The table is color-coded such

that cells highlighted with light red fill indicate degradation between the year set, while

cells highlighted with light green fill indicate aggradation, or in the case of the reservoir

level change, the colors indicate a drop in level and rise in level, respectively. A Cell

highlighted with blue fill and white text, or a cell under the area of the pink outline,

indicates the cross-section was inundated by the reservoir during the latter of the two

years associated with the year set. If the text within a cell reads “----”, then data was not

available at that range line during at least one of the two years associated with the year

set. A cell within the area of a red outline indicates the cell is associated with a “wave”

of degradation, while a cell within the area of a green outline indicates the cell is

associated with a “wave” of aggradation. If a cell is between the area of a red and green

outline, then the cell is considered a transitional area.

Four “waves” were analyzed from this dataset. The first wave is a wave of

degradation and is the result of a decrease in average reservoir level (base-level) from

2009 to 2010 of about 7 ft. The second wave is a wave of aggradation and is the result of

an increase in average base-level from 2004 to 2009 of about 35 ft. The third wave is a

wave of degradation and is the result of a decrease in average base-level from 1995 to

2004 of about 105 ft. The fourth and final wave analyzed, is a wave of aggradation and is

the result of an increase in average base-level from 1990 to 1995. No other waves were

analyzed in detail, due to the lack of available data between 1980 and 1990.

70

Table 4-7 Change in Thalweg Elevation Between Select Year Sets

 2009‐2010 

2008‐2009 

2007‐2008 

2004‐2007 

2003‐2004 

2002‐2003 

1999‐2002 

1998‐1999 

1997‐1998 

1995‐1997 

1994‐1995 

1993‐1994 

1992‐1993 

1991‐1992 

1990‐1991 

1990‐1992 

1988‐1990 

1980‐1988 

SO‐1641 

‐‐‐‐  0.73  ‐1.35  1.65  ‐0.17  1.26  ‐1.52  ‐0.12  1.81  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

SO‐1652.7 

‐‐‐‐  ‐0.81  ‐2.15  2.25  ‐1.62  1.92  ‐0.30  ‐0.57  ‐1.33  0.30  2.10  1.00  ‐0.60  ‐1.62  1.77  0.15  ‐‐‐‐  ‐‐‐‐ 

SO‐1666 

‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐0.16  1.43  ‐1.84  1.40  ‐0.40  ‐1.02  1.22  0.70  ‐1.00  ‐0.30  ‐‐‐‐  ‐‐‐‐ 

SO‐1673 

‐‐‐‐  ‐0.55  ‐1.22  0.26  ‐1.32  2.02  0.15  1.37  ‐2.22  3.70  0.50  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

SO‐1683 

‐‐‐‐  0.51  ‐0.52  ‐1.04  ‐2.21  2.61  1.36  0.67  ‐1.73  0.00  1.80  0.20  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

SO‐1692 

‐‐‐‐  0.66  ‐1.35  1.02  ‐1.84  1.16  ‐0.03  1.16  ‐‐‐‐  ‐‐‐‐  ‐7.60  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

SO‐1701.3 

‐‐‐‐  ‐0.15  ‐1.72  ‐2.74  1.22  2.38  ‐0.33  ‐0.58  1.80  3.50  ‐3.60  1.40  ‐0.60  ‐1.37  0.00  ‐1.37  ‐‐‐‐  ‐‐‐‐ 

EB‐10  1.27  ‐1.56  ‐0.99  ‐1.94  0.12  1.85  ‐0.77  1.06  1.91  ‐2.18  1.40  2.30  ‐1.20  ‐1.98  0.23  ‐1.75  1.25  8.10 

EB‐13  ‐0.18  ‐0.78  ‐0.70  ‐4.92  0.20  2.09  1.46  ‐0.61  ‐1.87  2.43  0.90  1.20  0.40  ‐2.19  ‐0.18  ‐2.37  1.47  12.10 

EB‐14  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  2.68  4.54  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  12.80 

EB‐16  ‐0.75  ‐0.39  ‐0.76  ‐5.89  0.49  2.17  0.34  0.40  2.28  ‐2.28  2.00  0.20  0.70  ‐‐‐‐  ‐‐‐‐  ‐1.88  3.18  11.00 

EB‐17  ‐0.15  0.06  ‐0.56  ‐4.33  ‐0.06  2.79  1.96  ‐1.90  1.01  1.49  0.30  1.20  ‐2.20  ‐0.22  ‐1.78  ‐2.00  2.70  11.90 

EB‐18  ‐0.79  0.25  ‐2.39  ‐6.27  0.02  3.35  ‐1.15  ‐0.67  4.37  ‐1.70  ‐1.80  3.40  ‐‐‐‐  ‐‐‐‐  ‐0.27  ‐‐‐‐  ‐0.36  2.80 

EB‐20  1.35  ‐2.58  ‐1.77  ‐7.37  ‐0.52  2.65  ‐0.71  2.90  ‐1.63  0.43  0.90  1.60  0.60  0.86  ‐2.91  ‐2.05  ‐‐‐‐  ‐‐‐‐ 

EB‐34  0.80  ‐0.53  ‐2.66  ‐8.56  ‐0.40  2.56  ‐0.13  ‐0.45  1.26  ‐1.21  2.50  0.70  0.90  ‐‐‐‐  ‐‐‐‐  ‐2.50  0.20  ‐‐‐‐ 

EB‐24  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐8.62  ‐2.11  2.38  2.23  ‐2.30  2.84  ‐2.74  6.20  ‐0.80  7.80  ‐6.36  ‐5.68  ‐12.04  ‐1.56  20.40 

EB‐25  0.05  ‐0.83  ‐1.20  ‐10.40  ‐0.62  2.26  ‐0.76  0.40  0.30  ‐0.10  0.60  ‐0.80  2.40  ‐‐‐‐  ‐‐‐‐  ‐0.86  0.86  ‐‐‐‐ 

EB‐26  ‐0.47  ‐0.29  ‐1.48  ‐11.13  0.44  1.01  0.45  ‐1.40  1.70  ‐3.80  1.20  ‐0.17  1.87  ‐‐‐‐  ‐‐‐‐  2.43  2.27  ‐‐‐‐ 

EB‐27  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐0.86  ‐1.30  ‐‐‐‐  ‐‐‐‐  1.10  2.30  ‐2.10  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  5.20 

EB‐28  ‐0.06  ‐0.27  ‐1.07  ‐1.86  ‐8.15  2.72  ‐1.51  ‐0.26  0.05  0.75  1.50  ‐0.70  3.30  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐29  ‐0.83  0.43  ‐2.15  ‐1.06  ‐10.69  4.12  ‐0.60  ‐2.47  3.04  0.80  0.30  ‐0.50  1.20  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐30  0.32  ‐0.66  0.85  ‐0.75  ‐4.24  ‐1.03  ‐4.53  2.47  1.03  2.00  0.90  ‐0.70  0.10  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

71

Table 4-7 Change in Thalweg Elevation Between Select Years (Part 2)

 2009‐2010 

2008‐2009 

2007‐2008 

2004‐2007 

2003‐2004 

2002‐2003 

1999‐2002 

1998‐1999 

1997‐1998 

1995‐1997 

1994‐1995 

1993‐1994 

1992‐1993 

1991‐1992 

1990‐1991 

1990‐1992 

1988‐1990 

1980‐1988 

EB‐32  0.02  0.53  ‐1.62  0.06  ‐0.17  ‐3.49  ‐2.74  ‐0.60  1.30  0.10  ‐0.30  0.60  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐33  ‐0.46  ‐1.21  1.07  ‐1.65  1.69  ‐2.27  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐35  ‐0.36  0.88  ‐1.91  0.09  ‐0.60  ‐1.71  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐36  ‐0.10  0.26  1.03  0.15  ‐2.28  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐37  1.80  ‐0.28  ‐0.71  ‐0.03  ‐1.86  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐37.5 

2.22  0.53  ‐0.49  ‐0.80  ‐0.89  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐38  1.54  1.27  0.20  ‐0.30  0.65  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐39  0.00  0.74  0.52  ‐0.36  ‐1.36  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐40  ‐0.98  2.31  0.25  2.32  0.85  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐40.5 

‐1.84  1.98  0.17  2.75  ‐0.30  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐41  ‐1.05  1.86  1.40  3.70  ‐1.29  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐42  1.42  0.05  ‐0.32  4.06  ‐0.83  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐43  1.04  2.06  0.60  5.24  ‐2.68  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐44  ‐1.54  4.22  ‐0.86  4.41  0.79  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐45  0.48  1.75  1.18  6.20  ‐2.02  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐46  0.13  2.93  0.46  6.83  ‐4.28  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐47  ‐1.02  2.23  ‐0.06  7.01  ‐3.80  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐48  3.79  ‐2.25  0.19  7.59  ‐3.62  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐49  0.82  0.12  ‐0.82  6.74  ‐2.17  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

EB‐50  ‐0.21  0.11  0.74  5.65  ‐3.55  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐  ‐‐‐‐ 

Res  ‐6.91  1.73  5.85  28.75  ‐9.07  ‐24.43  ‐51.95  ‐4.51  1.33  ‐7.17  0.12  3.23  1.41  10.64  1.29  11.94  ‐16.20  32.49 

72

The change in thalweg and mean channel bed elevation were evaluated using the

range line survey data. First, the minimum channel elevation (thalweg) was calculated

for each range line at different surveyed years. Then, the change in Thalweg elevation

was compared between years at each range line where data was available. A second,

similar analysis was done by calculating the change in the average channel bed elevations

for which a weighted average was used to calculate the mean bed elevation for each

range line at different surveyed years.

Because data was not available each year for every range line, different ranges of

years had to be used to calculate the change in elevation. This is indicated by the

different colors of bars in Figure 4.38 for the change in average bed elevation analysis,

and Figure 4.39 for the change in thalweg elevation analysis. The orange bars show a

change in elevation for range lines between 1988 and 1990; the turquoise bars show a

change in elevation between 1990 and 1995; the purple bars show a change in elevation

from 1995 to 2003; the green bars show a change in elevation between 2003 and 2004;

and the red bars show a change in elevation from 2004 to 2009; and blue bars show a

change in elevation from 2009 to 2010. Note that each set of bars has a different time

increment; this is because the selected years contain data for most of the range lines, and

the year sets represent an overall aggrading or degrading trend.

73

Figure 4.38 Change in Average Channel Bed Elevation at Range Lines (1988-2010)

‐20

‐15

‐10

‐5

0

5

10

15

SO‐1641

SO‐1652.7

SO‐1666

SO‐1673

SO‐1683

SO‐1692

SO‐1701.3

EB‐10

EB‐13

EB‐14

EB‐16

EB‐17

EB‐18

EB‐20

EB‐34

EB‐24

EB‐25

EB‐26

EB‐27

EB‐28

EB‐29

EB‐30

EB‐32

EB‐33

EB‐35

EB‐36

EB‐37

EB‐37.5

EB‐38

EB‐39

EB‐40

EB‐40.5

EB‐41

EB‐ 42

EB‐43

EB‐44

EB‐45

EB‐46

EB‐47

EB‐48

EB‐49

EB‐50

Chan

ge in

 Average

 Bed Elevation (ft)

Range Line ID

1988‐1990 1990‐1995 1995‐2003 2003‐2004 2004‐2009 2009‐2010

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

74

Figure 4.39 Change in Channel Thalweg Elevations at Range Lines (1988-2010)

‐20

‐15

‐10

‐5

0

5

10

15

SO‐1641

SO‐1652.7

SO‐1666

SO‐1673

SO‐1683

SO‐1692

SO‐1701.3

EB‐10

EB‐13

EB‐14

EB‐16

EB‐17

EB‐18

EB‐20

EB‐34

EB‐24

EB‐25

EB‐26

EB‐27

EB‐28

EB‐29

EB‐30

EB‐32

EB‐33

EB‐35

EB‐36

EB‐37

EB‐37.5

EB‐38

EB‐39

EB‐40

EB‐40.5

EB‐41

EB‐ 42

EB‐43

EB‐44

EB‐45

EB‐46

EB‐47

EB‐48

EB‐49

EB‐50

Thalweg Elevation Chan

ge (ft)

Range Line ID

1988‐1990 1990‐1995 1995‐2003 2003‐2004 2004‐2009 2009‐2010

SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

75

The following observations are based specifically on the change in thalweg

elevation; however, the general trends observed are similar for the change in average bed

elevation. From 1988 to 1990, primarily aggradation occurred, up to 3.2 ft. From 1990

to 1995, which includes the first instances in which the Tiffany Plug formed, there is

aggradation and degradation observed, depending on the range line; there does not appear

to be a hinge point spatially separating aggradation and degradation. From 1995 to 2003,

after the second Tiffany Plug, there is mostly aggradation between SO-1673 and EB-29,

up to 11.3 ft. From 2003 to 2004, there is degradation the majority of the reach, up to

10.7 ft. From 2004 to 2009, degradation is observed from SO-1652.7 to EB-37.5, at

which point aggradation is observed from EB-38 to EB-50. From 2009 to 2010, the

channel alternates between aggradation and degradation along the reach profile, with the

greatest magnitude of aggradation, 3.8 ft, occurring at EB-48.

4.3.3 Rate of Aggradation/Degradation from Range Line Surveys

From 2003 to 2004, shown in Figure 4.40 and Figure 4.41, degradation is

observed along the entire reach, except for at five range lines. The wave of degradation

between EB-13 and EB-50 (Wave 3) is in response to the drop in base-level (Reservoir

WSE) by about 100 ft between 1995 and 2004. Figure 4.41 shows the magnitude of

degradation from 2003 to 2004 at River Miles, which is represented by the following

second order polynomial equation:

y = -0.1601x2 + 16.209x - 410.5

Where, y is the magnitude of degradation and x is the longitudinal location along the

reach in River Miles (RM, as defined by Reclamation, where measurements begin at the

d

4

ownstream e

5.21 to RM

Figure 4.40

Figure 4.4

‐12

‐10

‐8

‐6

‐4

‐2

0

2

4Chan

ge in

 Thalweg Elevation (ft)

59

Ups

trea

m E

nd

Ut

Ed

end of the M

57.75.

0 Magnitude

1 Magnitude

557

Ups

trea

m E

nd

Middle Rio

e of Aggrada

e of Aggrada

y = ‐0.160R

535

76

Grande Riv

ation and De

ation and De

Range

1x2 + 16.209x ‐R² = 0.6064

51River Mile

ver); this equ

egradation at

egradation at

e Line

‐ 410.5

49

uation is app

t Range Line

t River Mile

47

propriate for

es (2003-200

es (2003-200

‐12

‐10

‐8

‐6

‐4

‐2

0

2

4

45

Dow

nstr

eam

End

r RM

04)

04)

Chan

ge in

 Thalweg (ft)

77

From 2004 to 2005, all of the thalweg elevations decreased between SO-line 1683

and EB-26; the decrease becomes more pronounced in the downstream direction between

these range lines, as seen in Figure 4.42 and Figure 4.43. From 2004 to 2005, SO-lines

1641, 1652.7, and 1683 increased. The wave of degradation between SO-1683 and EB-

26 (Wave 3) is in response to the drop in base-level (Reservoir WSE) by about 100 ft

between 1995 and 2004. Figure 4.42 shows the magnitude of degradation from 2004 to

2005 at River Miles, which is represented by the following linear equation:

y = 0.8233x – 58.29

Where, y is the magnitude of degradation and x is the longitudinal location along the

reach in River Miles; this equation is appropriate for RM 59.34 to RM 73.59.

Figure 4.42 Magnitude of Aggradation and Degradation at Range Lines (2004-2005)

‐12

‐10

‐8

‐6

‐4

‐2

0

2

4

6

SO‐1641

SO‐1652.7

SO‐1673

SO‐1692

SO‐1701.3

EB‐10

EB‐13

EB‐16

EB‐17

EB‐18

EB‐20

EB‐34

EB‐24

EB‐25

EB‐26

EB‐28

EB‐30

EB‐32

EB‐33

EB‐35

EB‐36

EB‐37

EB‐37.5

EB‐38Chan

ge in

 Thalweg Elevation (ft)

Range Line

Ups

trea

m E

nd

Dow

nstr

eam

E

nd

78

Figure 4.43 Magnitude of Aggradation and Degradation at River Miles (2004 to 2005)

From 2004 to 2009, shown in Figure 4.44, degradation is observed from SO-

1652.7 to EB-37.5, at which point aggradation is observed from EB-38 to EB-50. These

two trends represent two distinct waves of thalweg elevation changes in response to base-

level changes, Wave 3 and Wave 2, respectively.

Figure 4.44 Change in Thalweg Elevation from 2004 to 2009

The wave of degradation between SO-1701.3 and EB-26 (Wave 3) is in response

to the decrease in base-level by about 100 ft between 1995 and 2004. Figure 4.45 shows

y = 0.8233x ‐ 58.285R² = 0.821

‐12

‐10

‐8

‐6

‐4

‐2

0

2

4

6

5560657075

Chan

ge in

 Thalweg Elevation (ft)

River Mile

‐15

‐10

‐5

0

5

10

15

SO‐1641

SO‐1666

SO‐1683

SO‐1701.3

EB‐13

EB‐16

EB‐18

EB‐34

EB‐25

EB‐27

EB‐29

EB‐32

EB‐35

EB‐37

EB‐38

EB‐40

EB‐41

EB‐43

EB‐45

EB‐47

EB‐49

Thalweg Elevation Chan

ge (ft)

Range Line ID

Dow

nstr

eam

End

Ups

trea

m E

nd

79

the magnitude of degradation from 2004 to 2009, which is represented by the following

second order polynomial equation:

y = -0.0226x2 + 4.0x – 171.53

Where, y is the magnitude of degradation and x is the longitudinal location along the

reach in River Miles; this equation is appropriate for RM 45.21 to RM 52.03.

The wave of aggradation between EB-38 and EB-50 (Wave 2) is in response to

the reservoir WSE increase of about 35 ft between 2004 and 2009. Figure 4.46 shows the

magnitude of aggradation from 2004 to 2009, which is represented by the following

second order polynomial equation between RM 59.34 and RM 73.59:

y = -0.4355x2 + 41.11x – 962.27

Where, y is the magnitude of degradation and x is the longitudinal location along the

reach in River Miles.

Figure 4.45 Magnitude of Degradation from 2004 to 2009

y = ‐0.0226x2 + 4.0052x ‐ 171.53R² = 0.9302

‐16

‐14

‐12

‐10

‐8

‐6

‐4

‐2

0

2

5560657075

Chan

ge in

 Thalweg Elevation (ft)

River Mile

Dow

nstr

eam

End

Ups

trea

m E

nd

80

Figure 4.46 Magnitude of Aggradation from 2004-2009

Appendix G presents plots of the change in thalweg elevation between selected

year sets versus river mile, along with trendlines associated with “waves” of aggradation

and “waves” of degradation.

4.3.4 Rate of Wave Propagation Upstream from Range Line Surveys

Wave 1, resulting from the decrease in base-level from 2009 to 2010, is

represented by range line EB-50. EB-50 decreased approximately 0.2 ft between 2009

and 2010. The rate of wave propagation upstream was determined by first plotting the

river mile of the upstream extent of the reservoir during the first year of the wave. Then,

the river mile of the upstream-most affected range line cross-section was determined and

plotted versus the latter year of the year set. If a wave continued beyond one year set,

then this step was repeated for each year set that the wave propagated and for which data

existed. The upstream extent of the reservoir was determined by interpolating (or

extrapolating) the average channel thalweg slope during the first year of the wave to the

average elevation of the reservoir; where the channel slope and reservoir elevation

intersected, the river mile was calculated. Figure 4.47 shows the reservoir water surface

y = ‐0.4355x2 + 41.112x ‐ 962.27R² = 0.8399

‐4

‐2

0

2

4

6

8

10

12

454749515355

Chan

ge in

 Thalweg Elevation 

(ft)

River Mile

Dow

nstr

eam

E

nd

Ups

trea

m E

nd

81

elevation change from 2009 to 2010, which induces Wave 1 degradation. Figure 4.48

shows the rate of Wave 1 propagation upstream as a result of the decrease in WSE (base-

level) from 2009 to 2010. The wave propagated upstream at a rate of 1.46 miles/year

with a decrease in base-level of 6.9 ft/year, and the upstream extent of the reservoir

receded 2.71 miles/year.

Figure 4.47 Reservoir Water Surface Elevation Change from 2009-2010 Resulting in

Wave 1 Channel Degradation

Figure 4.48 Rate of Wave 1 Propagation Upstream

Wave 2 resulted from an increase in base-level from 2004 to 2009. Figure 4.49

shows the reservoir water surface elevation change from 2004 to 2009, which induced

y = ‐6.9072x + 18267

4383

4384

4385

4386

4387

4388

4389

4390

4391

4392

2008 2009 2010 2011

Reservoir W

SE (ft)

Year

y = 1.4607x ‐ 2890.8

y = ‐2.7127x + 5493.5

30

32

34

36

38

40

42

44

46

2008 2009 2010 2011

River Mile

 (mi)

Year

Chnl Bed Wave 2Res U/S ExtentLinear (Chnl Bed Wave 2)Linear (Res U/S Extent)

82

Wave 2 aggradation. Figure 4.50 shows the rate of Wave 2 propagation upstream as a

result of the increase in WSE (base-level) from 2004 to 2009. With an increase in base-

level of 6.8 ft/year, Wave 2 propagated upstream according to the following second order

polynomial:

y = -0.5522x2 + 2219.1x - 2E+06

Where, y is the upstream-most River Mile at which aggradation occurs as a result of an

increase in base-level of 6.8 ft/year, and x is the year at which River Mile y begins to

aggrade. The upstream extent of the reservoir progressed upstream at a rate of 1.36

miles/year.

Figure 4.49 Reservoir Water Surface Elevation Change from 2004-2009 Resulting in Wave 2 Channel Aggradation

y = 6.7963x ‐ 9259.3

4350

4355

4360

4365

4370

4375

4380

4385

4390

4395

4400

2003 2004 2005 2006 2007 2008 2009 2010

Reservoir W

SE (ft)

Year

83

Figure 4.50 Rate of Wave 2 Propagation Upstream

Wave 3 resulted from a decrease in base-level from 1997 to 2004. Figure 4.51

shows the reservoir water surface elevation change from 1997 to 2004, which induced

Wave 3 degradation. Figure 4.52 shows the rate of Wave 3 propagation upstream as a

result of the decrease in WSE (base-level) from 1997 to 2004. With a decrease in base-

level of 14.2 ft/year, Wave 3 propagated upstream according to the following second

order polynomial:

y = 0.0692x2 - 276.2x + 275686

Where, y is the upstream-most River Mile at which degradation occurs as a result of a

decrease in base-level of 14.2 ft/year, and x is the year at which River Mile y begins to

degrade. The upstream extent of the reservoir receded at a rate of 2.9 miles/year.

y = ‐0.5522x2 + 2219.1x ‐ 2E+06R² = 0.9969

y = 1.3609x ‐ 2689.6R² = 0.9633

30

35

40

45

50

55

2003 2004 2005 2006 2007 2008 2009 2010 2011

River Mile

 (mi)

Year

Chnl Bed Wave 2

Res U/S Extent

Poly. (Chnl Bed Wave 2)

Linear (Res U/S Extent)

84

Figure 4.51 Reservoir Water Surface Elevation Change from 1997-2004 Resulting in Wave 3 Channel Degradation

Figure 4.52 Rate of Wave 3 Propagation Upstream

Wave 4 resulted from an increase in base-level from 1990 to 1995. Figure 4.53

shows the reservoir water surface elevation change from 1990 to 1995, which induced

Wave 4 aggradation. Figure 4.54 shows the rate of Wave 4 propagation upstream as a

y = ‐14.243x + 32904

4340

4360

4380

4400

4420

4440

4460

4480

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Reservoir W

SE (ft)

Year

y = 0.0692x2 ‐ 276.2x + 275686R² = 0.8863

y = ‐2.9297x + 5909.5R² = 0.9068

30

35

40

45

50

55

60

65

70

75

80

1990 1995 2000 2005 2010

River Mile

 (mi)

Year

Chnl Bed Wave 3Res U/S ExtentPoly. (Chnl Bed Wave 3)Linear (Res U/S Extent)

85

result of the increase in WSE (base-level) from 1990 to 1995. With an increase in base-

level of 3.7 ft/year, Wave 4 propagated upstream according to the following second order

polynomial:

y = -0.1222x2 + 489.03x – 489299

Where, y is the upstream-most River Mile at which aggradation occurs as a result of an

increase in base-level of 3.7 ft/year, and x is the year at which River Mile y begins to

aggrade. The upstream extent of the reservoir progressed upstream at a rate of 1.07

miles/year.

Figure 4.53 Reservoir Water Surface Elevation Change from 1990-1995 Resulting in Wave 4 Channel Aggradation

y = 3.7339x ‐ 2996.4

4430

4435

4440

4445

4450

4455

1989 1990 1991 1992 1993 1994 1995 1996

Reservoir W

SE (ft)

Year

Reservoir WSE

Linear (Reservoir WSE)

86

Figure 4.54 Rate of Wave 4 Propagation Upstream

4.4 Bed Material Analysis

4.4.1 Grain Size Distributions

Bed material surveys taken at SO- and EB- range lines by Reclamation were used

to create grain size distribution curves for each subreach. Also, San Acacia and San

Marcial gauges’ bed material grain size distributions were plotted to study the trend of

the bed material grain size about 44 miles upstream of the study reach and within the

study reach.

Since complete temporal sequences of data related to each range line were not

available, those with the most complete set of data were chosen to represent each

subreach (see Table 4-8).

y = ‐0.1222x2 + 489.03x ‐ 489299R² = 0.892

y = 1.0734x ‐ 2079.6R² = 0.8114

30

35

40

45

50

55

60

65

70

75

80

1985 1990 1995 2000 2005

River Mile

 (mi)

Year

Chnl Bed Wave 4

Res U/S Extent

Poly. (Chnl Bed Wave 4)

Linear (Res U/S Extent)

87

Table 4-8 Representative Range Lines for Each Subreach Subreach Range Line 

1  SO‐1641 

2  SO‐1683 

3  EB‐10 

4  EB‐13 

5  EB‐18 

6  EB‐24 

Multiple samples were collected at a given range line and for a given year. In

many cases, stations along the range line cross-section at which samples were collected

were provided. Where stations were provided, the sample locations were compared to

the surveyed range line cross-sections, which were presented in Section 4.3. If the

samples collected were from the floodplain within the cross-section, then the sample was

not included in this analysis, as bed material only is of interest. If sample locations were

not provided, then it was assumed that the sample was a bed material sample, because the

data provided was defined by Reclamation as bed material sample data. The grain size

distributions of all the collected bed material samples at a given station and in a given

year were plotted. A representative grain size distribution was selected for each range

line and for each year, from which the average mean grain size was computed. This same

procedure was applied to the San Acacia and San Marcial gauge data. For example,

Figure 4.55 shows different grain size distributions for range line EB-10 in 1992. The

most representative distribution chosen for that year is highlighted in yellow.

88

Figure 4.55 EB-10 1992 Bed Material Grain Size Distributions

Figure 4.56 through Figure 4.63 show the compilation of representative grain size

distributions for each year at the San Acacia gauge, at the San Marcial gauge, and at each

subreach. Select bed material grain size distribution plots are provided in Appendix H.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

89

Figure 4.56 San Acacia Gauge: Annual Bed Material Grain Size Distributions

Figure 4.57 San Marcial Gauge: Annual Bed Material Grain Size Distributions

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100

% Finer by Weight

Grain Size Distribution (mm)

1966 19681969 19731975 19761978 19791980 19811982 19831984 19851986 19871988 19891990 19911992 19931994 19951996 19971998 19992000 20012002 20032004 2005

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size Distribution (mm)

1968 19691972 19731974 19751976 19771978 19791980 19811982 19831984 19851986 19871988 19891990 19911992 19931994 19951996 19971998 19992000 20012002 20032004 20052006 20072008 20092010

90

Figure 4.58 Subreach 1 (SO-1641): Annual Bed Material Grain Size Distributions

Figure 4.59 Subreach 2 (SO-1683): Annual Bed Material Grain Size Distributions

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size Distribution (mm)

2001200220042005

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1

% Finer by Weight

Grain Size Distribution (mm)

1999

91

Figure 4.60 Subreach 3 (EB-10): Annual Bed Material Grain Size Distributions

Figure 4.61 Subreach 4 (EB-13): Annual Bed Material Grain Size Distributions

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100

% Finer by Weight

Grain Size Distribution (mm)

1986 19871988 19901992 19931994 19971998 19992002

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size Distribution (mm)

198619871988199019992002

92

Figure 4.62 Subreach 5 (EB-18): Annual Bed Material Grain Size Distributions

Figure 4.63 Subreach 6 (EB-24): Annual Bed Material Grain Size Distributions

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size Distribution (mm)

198619871988199019931994199719992002

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size Distribution (mm)

1986

1992

1999

2002

93

The San Acacia and San Marcial grain size distribution plots show that the bed

material has become slightly coarser over time as indicated by the grain size distribution

curves moving to the right with time. Note that the San Acacia gauge is 44 miles

upstream of this study reach and is not representative of this study reach, while the San

Marcial gauge is located at the upstream end of this study reach, and therefore represents

this study reach very well. The grain size distributions of each subreach have

experienced minimal changes throughout the years. It should be noted that in the case of

San Acacia and San Marcial gauges, the sequences of data ranges from 1967 to 2008,

while Subreaches 3, 4, 5, and 6 data range from 1986 to 2002; Subreach 1 only ranges

from 2001 to 2005; and Subreach 2 only has data from 1999.

4.4.2 Median Grain Size

Figure 4.64 shows the change over time of the average median bed material grain

size in each subreach and at the San Acacia and San Marcial gauges, located 44 miles

upstream of the study reach and within the study reach, respectively. Figure 4.65 shows

the average median bed material grain size trends for each subreach from 1986 to 2005.

94

Figure 4.64 Average Median Bed Material Grain Size Temporal Trends

Figure 4.65 Average Median Bed Material Grain Size: Subreach Temporal Trends

Overall, mean grain sizes of the study reach range between 0.11 and 0.26 mm,

corresponding to very fine to medium sand (Julien 2002). In general, the bed material at

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1965 1975 1985 1995 2005 2015

Average

 Median Grain Size (mm)

Year

San Acacia Gauge San Marcial Gauge

Subreach 1 (SO‐1641) Subreach 2 (SO‐1683)

Subreach 3 (EB‐10) Subreach 4 (EB‐13)

Subreach 5 (EB‐18) Subreach 6 (EB‐24)

0

0.05

0.1

0.15

0.2

0.25

0.3

1985 1990 1995 2000 2005 2010

Average

 Median Grain Size (mm)

Year

Subreach 1 (SO‐1641)

Subreach 2 (SO‐1683)

Subreach 3 (EB‐10)

Subreach 4 (EB‐13)

Subreach 5 (EB‐18)

Subreach 6 (EB‐24)

Linear (Subreach 1 (SO‐1641))

Linear (Subreach 3 (EB‐10))

Linear (Subreach 4 (EB‐13))

Linear (Subreach 5 (EB‐18))

Linear (Subreach 6 (EB‐24))

95

the San Marcial gauge has become coarser since the 1960s by about 0.002 mm/year

(from a minimum of 0.08 mm in 1991 to a maximum of 0.24 mm in 2004). The bed

material at the San Acacia gauge has become coarser by about 0.009 mm/year (from a

minimum of 0.04 mm in 1980 to a maximum of 0.85 mm in 2009), which is about five

times faster than the bed material coarsening rate at the San Marcial gauge. Note that the

rates of bed material coarsening were determined using the entire datasets for each

respective gauge that are presented in Figure 4.64.

Figure 4.65 shows that the average median grain size in Subreach 1 has become

finer at a rate of 0.0046 mm/year between 2001 and 2005; Subreach 2 has no temporal

trend, because the only data available for Subreach 2 is from 1999; the average median

grain size within Subreach 3 coarsened at a rate of 0.0027 mm/year between 1986 and

2002; the average median grain size within Subreach 4 coarsened at a rate of 0.0031

mm/year between 1986 and 2002; the average median grain size within Subreach 5

coarsened at a rate of 0.0031 mm/year between 1986 and 2002; the average median grain

size within Subreach 6 became finer at a rate of 0.0005 mm/year between 1986 and 2002.

All average median grain sizes are within the very fine to fine sand range, except

for the averages in Subreach 1 in 2001 and in Subreach 3 in 1994, which are in the low

end of the medium sand classification (0.26 mm). So, though there has been overall

coarsening of the bed material within this study reach, it is less than 0.003 mm/year, and

is still generally classified as very fine to fine sand. Figure 4.65 also shows that while the

median bed material size has coarsened with time, it tends to get finer in the downstream

direction.

96

4.5 Suspended Sediment Data

Suspended sediment data was used from the Escondida Reach Report (Larsen et

al. 2007). Single and double mass curves developed in the Escondida Reach Report

(Larsen et al. 2007) are presented below. Trends in water discharge, suspended sediment

discharge, and suspended sediment concentration are shown in Figure 4.66, Figure 4.67,

and Figure 4.68, respectively.

The single mass curve for water discharge, Figure 4.66, shows similar trends at

the San Marcial and San Acacia gauges. Both curves show breaks around 1979 and

2000. In about 1979, the discharge increased from about 600 cfs to over 2000 cfs. Table

4-9, also from the Escondida Reach Report (Larsen et al. 2007), is presented below and

shows the average discharge for each period displayed on the graph.

Figure 4.66 Water Discharge Single Mass Curve (Larsen et al. 2007)

0.0E+00

5.0E+06

1.0E+07

1.5E+07

2.0E+07

2.5E+07

3.0E+07

10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999

Cu

mu

lati

ve D

isch

arg

e (a

cre-

ft)

DateSA: 1958-1979 SA: 1980-1999SA: 2000-2005 SM: 1949-1978SM: 1979-2000 SM: 2001-2005Linear (SA: 1958-1979) Linear (SA: 1980-1999)Linear (SA: 2000-2005) Linear (SM: 1949-1978)

97

Table 4-9 Water Discharge (Larsen et al. 2007) Gauge Years acre-ft/day R2 value

San Acacia

1958-1979 522 0.98 1980-1999 2856 0.99 2000-2005 1055 0.93

San Marcial

1949-1978 621 0.94 1979-2000 2263 0.99

2001-2005 740 0.84

Figure 4.67 shows the single mass curve for suspended sediment discharge at the

San Acacia and San Marcial Gauges. The San Marcial gauge has a much higher

suspended sediment discharge than the San Acacia gauge from 1956 until about 1968.

From 1968 to 1991, the two gauges both have a suspended sediment discharge of about

10,000 tons/day. From 1991 to 1996, the San Marcial gauge again shows a much higher

suspended sediment discharge. Table 4-10 shows the average suspended sediment

discharge for the periods shown on the graph.

Figure 4.67 Suspended Sediment Discharge Single Mass Curve (Larsen et al. 2007)

0.0E+00

2.0E+07

4.0E+07

6.0E+07

8.0E+07

1.0E+08

1.2E+08

1.4E+08

1.6E+08

1.8E+08

10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999

Cu

mu

lati

ve S

usp

end

ed S

edim

ent

(to

ns)

DateSA: 1959-1967 SA: 1968-1975 SA: 1976-1996

SM: 1956-1959 SM: 1960-1989 SM: 1991-1995

Linear (SA: 1959-1967) Linear (SA: 1968-1975) Linear (SA: 1976-1996)

Linear (SM: 1956-1959) Linear (SM: 1960-1989) Linear (SM: 1991-1995)

98

Table 4-10 Suspended Sediment Discharge (Larsen et al. 2007)

Gauge Years tons/day R2 value

San Acacia

1959-1967 6062 0.94 1968-1975 9172 0.92 1976-1996 10066 0.99

San Marcial

1956-1959 35276 0.88 1960-1989 10232 0.98

1991-1995 16707 0.98 Double mass curves were developed at each gauge to show the changes in

suspended sediment concentration over time, as seen in Figure 4.68.

Figure 4.68 Suspended Sediment Concentration Double Mass Curves (Larsen et al. 2007)

From 1959 to 1978, the two curves are very similar, with an average suspended

sediment concentration of about 13,000 mg/L. Around 1978, both curves break, and the

0.0E+00

2.0E+07

4.0E+07

6.0E+07

8.0E+07

1.0E+08

1.2E+08

1.4E+08

1.6E+08

1.8E+08

0.0E+00 5.0E+06 1.0E+07 1.5E+07 2.0E+07 2.5E+07

Cu

mu

lati

ve S

usp

end

ed S

edim

ent

(to

ns)

Cumulative Water Discharge (acre-ft)

SA: 1959-1978 SA: 1979-1996 SM: 1956-1977

SM: 1978-1989 SM: 1990-1995 Linear (SA: 1959-1978)

Linear (SA: 1979-1996) Linear (SM: 1956-1977) Linear (SM: 1978-1989)

Linear (SM: 1990-1995)

99

suspended sediment concentration drops to about 3,000 mg/L. The concentration at the

San Acacia gauge remains at about 3,000 mg/L through the end of the available data.

The San Marcial gauge, however, shows an increase in suspended sediment concentration

from 3,000 mg/L to 4,500 mg/L around 1990. Table 4-11 shows the average

concentration as well as the R2 values for each segment of the graph.

Table 4-11 Suspended Sediment Concentration (Larsen et al. 2007) Gauge Years tons/acre-ft mg/L R2 value

San Acacia

1959-1978 17.9 13165 0.97 1979-1996 3.58 2633 0.98

San Marcial

1956-1977 17.21 12657 0.97 1978-1989 4.16 3060 0.92

1990-1995 6.2 4560 0.98

From 1960 to 1989 at the San Marcial gauge, and from 1959 to 1996 at the San

Acacia gauge, the suspended sediment discharge consistently averaged between about

9,000 and 10,000 tons/day, as seen in Figure 4.67. Around 1980, the water discharge at

the San Acacia and San Marcial gauges increased four to five times the average water

discharge from 1949 to 1980. From 1942 to 1979, New Mexico experienced a state-wide

drought (Paulson et al 1988). The decrease in suspended sediment concentration in 1979

was due to the increase in water discharge following the nearly 40 year drought, and was

not due to a change in suspended sediment discharge.

100

SECTION 5: SUMMARY AND CONCLUSIONS

The Elephant Butte Reach spans about 30 miles, beginning from the South Boundary

of the Bosque del Apache National Wildlife Refuge (River Mile 73.9) to the “narrows” of

the Elephant Butte Reservoir (River Mile 44.65), in central New Mexico. Further

understanding of the historical and spatial changes within Elephant Butte Reach, along

with a better understanding of the influences of Elephant Butte Reservoir levels on

channel aggradation/degradation is essential for improvement in future river management

practices along the Middle Rio Grande. The objectives addressed in this study included

the following:

6. Quantified temporal changes in channel widths and sinuosity from 1935 to 2010.

7. Quantified change in channel slope temporally.

8. Quantified rate of aggradation/degradation in response to a change in base-level

(i.e., change in reservoir water surface elevation).

9. Quantified aggradation/degradation wave propagation upstream.

10. Quantified spatial and temporal trends in bed material grain size.

The average channel width and channel sinuosity for Elephant Butte Reach have

decreased since 1918. From 1935 to 2010, the average channel width decreased

according to the following equation:

Avg. Chnl Width = 0.2353x2 – 936.54x + 931904

Where, x is the year. Since 1962, the average channel width has ranged between 50 ft

and 300 ft. From 1935 to 2010, channel sinuosity has decreased according to the

following equation:

101

Channel Sinuosity = 6E-05x2 – 0.2196x + 219.57

Where, x is the year. Since 1962, channel sinuosity has remained lower than 1.25.

The channel slope since 1962 has primarily decreased. From 1962 to 2002, based

on Agg/Deg-line survey data, the average channel slope (Subreaches 1 through 5)

decreased about 0.03 ft/mile/year. Within Subreach 6, based on range line survey data,

the channel slope decreased 0.32 ft/mile/year from 1995 to 2001 as a result of an increase

in base-level of about 20 ft from 1990 to 1995; from 2002 to 2010, the channel slope

decreased 0.21 ft/mile/year as a result of an increase in base-level of about 35 ft from

2004 to 2009; from 2001 to 2002, the channel slope increased from 2.3 ft/ft to 4.3 ft/ft in

one year as a result of a decrease in base-level of about 100 ft from 1995 to 2004.

The rate of aggradation/degradation along the reach varied between different year

sets. Based on Agg/Deg-line survey data, from 1972 to 1992, the base-level increased

13.4 ft/year, and the channel aggraded in response as described by the following

equation:

Rate of Aggradation = -0.0014x2 + 0.0649x + 0.1832

Where, x is the distance (in miles) downstream of Agg/Deg 1637 (or the upstream end of

Elephant Butte Reach).

Between 1995 and 2004, the base-level dropped 100 ft (11.1 ft/year). The following

equations describe the rate of degradation for year sets 2003-2004, 2004-2005, and 2004-

2009, respectively:

(2003-2004) Rate of Degradation = -0.1601x2+16.209x – 410.5

(2004-2005) Rate of Degradation = 0.8233x – 58.29

(2004-2009) Rate of Degradation = -0.0226x2 + 4.0x – 171.53

102

Where, x is the River Mile (as defined by Reclamation). From 2004 to 2009, the channel

aggraded in response to an increase in base-level of about 35 ft between 2004 and 2009

(7 ft/yr), as follows (where x is the River Mile):

(2004-2009) Rate of Aggradation = -0.4355x2 + 41.11x – 962.27

Wave 1 propagated upstream at a rate of 1.46 miles/year with a decrease in base-

level of 6.9 ft/year. Wave 2 propagated upstream following a rise in base-level of 6.8

ft/year between 2004 and 2009, as follows:

y = -0.5522x2 + 2219.1x – 2*106

Wave 3 propagated upstream following a drop in base-level of 14.2 ft/year between 1997

and 2004, as follows:

y = 0.0692x2 – 276.2x + 275686

Wave 4 propagated upstream following a rise in base-level of 3.7 ft/year between 1990

and 1995, as follows:

y = -0.1222x2 + 489.03x – 489299

Where, x is year and y is river mile.

The average median grain size in Subreach 1 has become finer at a rate of 0.0046

mm/year between 2001 and 2005; Subreach 2 only has data available in 1999; between

1986 and 2002, the average median grain size within Subreach 3, 4, and 5 coarsened at a

rate of 0.0027 mm/year, 0.0031 mm/year, and 0.0031 mm/year respectively; the average

median grain size within Subreach 6 became finer at a rate of 0.0005 mm/year between

1986 and 2002. There has been overall coarsening of the bed material within this study

reach at a rate of less than 0.003 mm/year. Lastly, the median bed material size gets finer

in the downstream direction, and is generally classified as very fine to fine sand.

103

REFERENCES

Bender, T.R. (2011). Bosque Reach. Arroyo de las Canas to South Boundary Bosque del Apache National Wildlife Refuge. Overbank Flow Analysis. 1962 - 2002. Middle Rio Grande, New Mexico. Prepared for the U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, New Mexico. Colorado State university, Fort Collins, CO. 63 p. Borgan, M.A., Allen, C.D., Muldavin, E.H., Platania, S.P., Stuart, J.N., Farely, G.H., Melhop, P., and Belnap, J. (1998). "Southwest." In: Mac, M.J., Opler, P.A., Puckett Haecker, C.E., and Doran, P.D. (eds.). Status and Trends of the Nation's Biological Resources. Vol. 2. U.S. Department of the Interior, U.S. Geological Survey, Reston, VA. pp. 543 - 592. Bullard, K. L., and Lane, W.L. (1993). Middle Rio Grande Peak Flow Frequency Study. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 36 p. Burroughs, C. B. (2011). Criteria for the Formation of Sediment Plugs in Alluvial Rivers. Journal of Hydraulic Engineering. American Society of Civil Engineers. pp. 569 - 576. Clark, I. G. (1987). Water in New Mexico: A History of its Management and Use. Albuquerque, NM: University of New Mexico Press. 839 p. Earick, D. (1999). "The History and Development of the Rio Grande River in the Albuquerque Region," from http://www.unm.edu/~abqteach/EnvirCUs/99-03-04.htm. Finch, D. M., and Tainter, J.A. (2004). Ecology, Diversity and Sustainability of the Middle Rio Grande Basin. Darby, PA: Diane Publishing Co. 186 p. Julien, P. Y. (2010). Erosion and Sedimentation. 2nd ed. New York: Cambridge University Press. 371 p. Kammerer, J. C. (1990). "Water Fact Sheet - Largest Rivers in the United States." U.S. Department of the Interior, U.S. Geological Survey, Reston, VA. 2 p. Larsen, A.K., Shah-Fairbank, S. C., and Julien, P.Y. (2007). Escondida Reach. Escondida to San Antonio. Hydraulic Modeling Analysis. 1962-2006. Middle Rio Grande, New Mexico. Prepared for the U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, New Mexico. Colorado State University, Fort Collins, CO. 179 p. MRGBI (2009). Middle Rio Grande Bosque Initiative. Dams and Diversions Along the Rio Grande, from www.fws.gov/southwest/mrgbi/Resources/Dams/index.html MRGCD (2002). Middle Rio Grande Conservancy District v. Norton. Nos. 01-2057 and 01-2145. United States Court of Appeals, Tenth Circuit. 21 June 2002. 15 p.

104

MRGCD (2006). Middle Rio Grande Conservancy District. About the District, from http://www.mrgcd.com. MRGESA (2006a). Middle Rio Grande Endangered Species Act Collaborative Program. The Rio Grande Silvery Minnow, from http://www.mrgesa.com. MRGESA (2006b). Middle Rio Grande Endangered Species Act Collaborative Program. The Southwestern Willow Flycatcher, from http://www.mrgesa.com. Mussetter Engineering, I. (2001). The Middle Rio Grande Geomorphology Final Report. 195 p. NOAA (2004). NOAA National Weather Service. The North American Monsoon. Reports to the Nation on our Changing Planet, from http://www.cpc.noaa.gov/products/outreach/Report-to-the-Nation-Monsoon_aug04.pdf Paulson, R.W., Chase, E.B., Roberts, R.S., and Moody, D.W., Compilers (1989). National Water Summary 1988-89. Hydrologic Events and Floods and Droughts. U.S. Geological Survey. Water-Supply Paper 2375. 591 p. Reclamation (2007). Middle Rio Grande River Maintenance Plan Summary - Part 1 Report. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 39 p. Reclamation (2003). Geomorphologic Assessment of the Rio Grande, San Acacia Reach. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 75 p. Reclamation (2008). Elephant Butte Reservoir 2007 Sedimentation Survey. U.S. Department of the Interior, Bureau of Reclamation, Denver, CO, 154 p. Scurlock, D. (1998). From the Rio to the Sierra: An Environmental History of the Middle Rio Grande Basin. General Technical Report RMRS-GTR-5. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 440 p.

105

APPENDICES

106

Appendix A: Range Line Survey Dates

107

Table A.1 Range Line Survey Dates Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

SO‐1638.8                        x

SO‐1641                   x x x     x x x x x x x x x

SO‐1643.1                        x

SO‐1644.8                        x

SO‐1645                 x x x x x x     x x x

SO‐1646.9                        x

SO‐1649.1                        x

SO‐1650                   x x x     x x

SO‐1650.7                        x

SO‐1652.7                 x x x x x x x     x x x x x x x

SO‐1656.1                        x

SO‐1657.7                        x

SO‐1660                   x x x     x x x x x x x

SO‐1662                   x x x x     x x x x

SO‐1663                   x x x x     x x x x x x x x

SO‐1664                   x x x x     x x x

SO‐1665                   x x x x     x x x x x x x

SO‐1666                 x x x x x x x x x     x x x

SO‐1667                   x x x     x x x

SO‐1668                   x x x x     x x x

SO‐1668.4                        x

SO‐1670                   x x x x     x x x x x x x x

SO‐1671.5                        x

SO‐1673                   x x x x x     x x x x x x x x

SO‐1674.8                        x

SO‐1676.4                        x

SO‐1679.4                        x

SO‐1680.8                        x

SO‐1683                 x x x x x x x x     x x x x x x x x

108

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

SO‐1684.7                        x

SO‐1686.4                        x

SO‐1689.9                        x

SO‐1692                   x x x x     x x x x x x x x

SO‐1694.9                        x

SO‐1696.7                        x

SO‐1698.9                        x

SO‐1701.3                 x x x x x x x x     x x x x x x x x

EB‐5     x  x  x  x        

EB‐9  x        x       x  x 

EB‐9.2                   x x    

EB‐9.4                        x x x

EB‐9.5                        x x x

EB‐10  x  x  x  x     x x x x x x x x x x  x  x x x x x x x x x

EB‐10.1                        x x x

EB‐10.2                        x x x

EB‐10.3                        x x x

EB‐10.45                        x x x

EB‐10.5                   x x    

EB‐10.7                        x x x

EB‐10.9                        x x x

EB‐11           x       x  x 

EB‐11.1                        x x x

EB‐11.5                        x x x

EB‐11.9                        x x x

EB‐12           x       x x  x  x x

EB‐12X                   x x x      x

EB‐12.4                        x x x

EB‐12.7                        x x x

 

109

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐13  x  x  x  x     x x x x x x x x x  x  x x x x x x x x x

EB‐13.9                        x x x

EB‐14  x  x  x  x       x x x  x  x x

EB‐14.3                        x x x

EB‐14.5                        x x x

EB‐14.7                        x x x

EB‐15           x       x x  x  x x

EB‐15.1                        x x x

EB‐15.4                        x x x

EB‐15.7                        x x x

EB‐15X                   x x x      x

EB‐16  x  x  x  x     x x x x x x x x  x  x x x x x x x x

EB‐16.5                        x x x

EB‐17  x  x  x  x     x x x x x x x x x  x  x x x x x x x x x

EB‐17.1                        x

EB‐17.2                        x

EB‐17.3                        x

EB‐17.35                        x x x

EB‐17.4                        x

EB‐17.5                        x

EB‐17.6                        x

EB‐17.7                        x x x x

EB‐17.8                        x x x

EB‐17.85                        x x x

EB‐17.9                        x x x

FC‐1754                   x    

EB‐18  x  x  x  x     x x x x x x x x x x  x  x x x x x x x x x

EB‐18.5                        x x x

EB‐18.9                        x x x

 

110

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐19           x       x x  x  x x

EB‐19.1                        x x x

EB‐19.3                        x x x

EB‐19.5                        x x x

EB‐19.7                        x x x

EB‐19.8                        x x x

EB‐20  x  x  x  x     x x x x x x x x x x  x  x x x x x x x x x

EB‐20.3                        x x x

EB‐20.7                        x x x

EB‐21           x       x  x  x x x

EB‐22           x       x  x  x x x

EB‐22.2                        x x x

EB‐22.6                        x x x

EB‐23           x       x  x  x

EB‐23.05                        x x x

EB‐23.1                       

EB‐23.2                        x x x

EB‐23.3                       

EB‐23.4                        x x x x

EB‐23.5A                       

EB‐23.5B                        x

EB‐23.6A                        x x x

EB‐23.6B                        x

EB‐23.8                        x x x

EB‐23.9                        x

EB‐23.9A                        x

EB‐24  x        x  x  x x x x x x x x x x  x  x x x x x x x

EB‐24‐A                   x x x x x x x      x x x x

EB‐24.3                        x x x

 

111

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐24.4                       

EB‐24.5                        x

EB‐24.6                        x x x

EB‐24.8                       

EB‐24.9                        x x x

EB‐24B                       

EB‐25  x        x  x  x x x x x x x x x  x  x x x x x x x x x x

EB‐25.2                       

EB‐25.3                        x x x

EB‐25.4                       

EB‐25.5                        x x

EB‐25.6                        x

EB‐25.8                       

EB‐25.9                       

EB‐26           x     x x x x x x x x x     x x x x x x x x

EB‐26.3                   x     

EB‐26.6                   x     

EB‐26.7                       

EB‐26A                       

EB‐26B                       

EB‐26C                       

EB‐26D                        x x x

EB‐26E                       

EB‐26F                        x x x

EB‐26G                       

EB‐26H                       

EB‐26I                        x x x

EB‐26J                       

EB‐26K                       

 

112

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐27  x        x  x    x x x x x x x  x  x x x

EB‐27.3                        x x x

EB‐27.6                        x x x

EB‐27A                       

EB‐27B                       

EB‐27C                       

EB‐27D                       

EB‐27E                       

EB‐28                   x x x x x x x  x  x x x x x x x x x

EB‐28 TCH                       

EB‐28.3                        x x x

EB‐28.5                        x x x

EB‐28.7                        x x x

EB‐28A                       

EB‐29              x    x x x x x x x  x  x x x x x x x x x

EB‐29 TCH                       

EB‐29.1                        x x x

EB‐29.2                        x

EB‐29.3                        x x x

EB‐29.5                        x x x x x x x x

EB‐29.7                        x x x

EB‐29.8                        x x x x

EB‐30                   x x x x x x x  x  x x x x x x x x x x

EB‐30.3                        x x x

EB‐30.5                        x

EB‐30.6                        x x x

EB‐31                        x x x x x x x x x

EB‐32              x    x x x x x x     x x x x x x x x x

EB‐32.1                        x x x

 

113

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐32.3                        x x x x x x x x x

EB‐32.5                        x x x

EB‐32.7                        x x x x x x x x x

EB‐33                        x x x x x x x x x x

EB‐33.3                        x x x x

EB‐33.6                        x x x

EB‐33.65                        x x x

EB‐33.7                        x x x x

EB‐33.8                        x x

EB‐34           x     x x x x x x x x  x  x x x x x x x x

EB‐34.5                        x x x

EB‐34.8                        x

EB‐35                        x x x x x x x x

EB‐35.2                        x x x

EB‐35.5                        x x x

EB‐35.8                        x x x

EB‐36                        x x x x x x x

EB‐36.3                        x x x

EB‐36.6                        x x x

EB‐37                        x x x x x x x

EB‐37.2                        x x x

EB‐37.5                        x x x x x x x x

EB‐37.7                        x x x

EB‐38                        x x x x x x x x

EB‐38.1                        x x x x x

EB‐38.15                        x

EB‐38.2                        x x x x x

EB‐38.3                        x x x x x

EB‐38.4                        x

 

114

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐38.6                        x x x x

EB‐39                        x x x x x x x

EB‐39.1                        x

EB‐39.3                        x x x x

EB‐39.6                        x x x x

EB‐40                        x x x x x x

EB‐40.2                        x x x x

EB‐40.4                        x x x x

EB‐40.5                        x x x x x x

EB‐40.7                        x x x x

EB‐40.9                        x x x x

EB‐41                        x x x x x x

EB‐41.4                        x x x x

EB‐41.8                        x x x x

EB‐42                        x x x x x x

EB‐42.3                        x x x x

EB‐42.5                        x x x x

EB‐42.8                        x x x x

EB‐43                        x x x x x x

EB‐43.6                        x x x x

EB‐44                        x x x x x x

EB‐44.6                        x x x x

EB‐45                        x x x x x x

EB‐45.6                        x x x x

EB‐46                        x x x x x x

EB‐46.4                        x x x x

EB‐47                        x x x x x x

EB‐47.3                        x x x x

EB‐47.7                        x x x x

 

115

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐48                        x x x x x x

EB‐48.3                        x x x x

EB‐48.5                        x x x x

EB‐48.7                        x x x x

EB‐49                        x x x x x x

EB‐49.5                        x x x x

EB‐49.7                        x x x x

EB‐50                        x x x x x x

EB‐50.3                        x x

EB‐50.7                        x x

EB‐51                        x x

EB‐51.3                        x x

EB‐51.7                        x x

EB‐52                        x x

EB‐52.4                        x x

EB‐52.7                        x x

EB‐53                        x x

EB‐53.3                        x x

EB‐53.7                        x x

EB‐54                        x x

EB‐54.4                        x x

EB‐54.7                        x x

EB‐55                        x x

EB‐55.3                        x x

EB‐55.7                        x x

EB‐56                        x x

EB‐56.4                        x x

EB‐56.7                        x x

EB‐57                        x x

 

116

Range Line Survey Dates (Continued) 

Range  Year

Line  80  86  87  88  89  90 91 92 93 94 95 96 97 98 99  00  01 02 03 04 05 06 07 08 09 10

EB‐57.3                        x x

EB‐57.5                        x x

EB‐57.8                        x x

EB‐58                        x x

EB‐58.4                        x x

EB‐58.6                        x x

EB‐59                        x x

EB‐59.5                        x x

EB‐60                        x x

 

117

Appendix B: Daily Discharge Hydrographs

118

Figure B.1 1990 Daily Discharge Data

Figure B.2 1991 Daily Discharge Data

Figure B.3 1992 Daily Discharge Data

0

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119

Figure B.4 1993 Daily Discharge Data

Figure B.5 1994 Daily Discharge Data

Figure B.6 1995 Daily Discharge Data

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120

Figure B.7 1996 Daily Discharge Data

Figure B.8 1997 Daily Discharge Data

Figure B.9 1998 Daily Discharge Data

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121

Figure B.10 1999 Daily Discharge Data

Figure B.11 2000 Daily Discharge Data

Figure B.12 2001 Daily Discharge Data

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Figure B.13 2002 Daily Discharge Data

Figure B.14 2003 Daily Discharge Data

Figure B. 15 2004 Daily Discharge Data

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2500

3000

3500

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Marcial San Acacia

123

Figure B.16 2005 Daily Discharge Data

Figure B.17 2006 Daily Discharge Data

Figure B.18 2007 Daily Discharge Data

0

1000

2000

3000

4000

5000

6000

7000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Marcial San Acacia

0

1000

2000

3000

4000

5000

6000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Marcial San Acacia

0

500

1000

1500

2000

2500

3000

3500

4000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Marcial San Acacia

124

Figure B.19 2008 Daily Discharge Data

Figure B.20 2009 Daily Discharge Data

Figure B.21 2010 Daily Discharge Data

0

1000

2000

3000

4000

5000

6000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Marcial San Acacia

0

1,000

2,000

3,000

4,000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Acacia San Marcial

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Jan

Fe

b

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Dis

cha

rge

(cf

s)

Month San Acacia San Marcial

125

Appendix C: Dates and Locations of Bed Material Samples

126

Table C.1 Available Bed Material Data at Range Lines

Range Line

Year

86 87 88 90 92 93 94 96 97 98 99 01 02 04 05 07

SO-1641 X X X X

SO-1652.7 X X

SO-1660 X

SO-1665 X

SO-1666 X X X

SO-1670 X

SO-1683 X

SO-1701.3 X X X

EB-5 X X X

EB-10 X X X X X X X X X X X

EB-13 X X X X X X

EB-14 X X X

EB-16 X X X X

EB-17 X X

FC-1754 X

EB-18 X X X X X X X X X

EB-20 X X X X X X X X X

EB-34 X X X

EB-24 X X X X

EB-24A X X X X X

EB-25 X X

EB-26 X

EB-26.6 X

EB-27 X

EB-28 X

EB-29 X

EB-29.5 X

EB-30 X

EB-36 X

127

Appendix D: Dates and Locations of USGS Gauge Bed Material Samples

128

Table D.1: Available Bed Material Data at USGS gauging stations: San Acacia and San

Marcial

Year

Gauging station

Year

Gauging station

San Acacia

San Marcial

San Acacia

San Marcial

1966 x 1988 x x

1967 1989 x x

1968 x x 1990 x x

1969 x x 1991 x x

1970 1992 x x

1971 1993 x x

1972 x 1994 x x

1973 x x 1995 x x

1974 x 1996 x x

1975 x x 1997 x x

1976 x x 1998 x x

1977 x 1999 x x

1978 x x 2001 x x

1979 x x 2002 x x

1980 x x 2003 x x

1981 x x 2004 x x

1982 x x 2005 x x

1983 x x 2006 x x

1984 x x 2007 x x

1985 x x 2008 x x

1986 x x 2009 x x

1987 x x 2010 x x

129

Appendix E: Aerial Photograph Survey Dates and Information

130

Table E.1 Aerial Photo Survey Dates and Information

Mean Daily Discharge

Date San Acacia San Marcial Scale Notes

(1918-2002:from Novak 2006 2005: from ArcGIS metadata)

1918 No Data No Data 1:12,000

Hand-drafted linens (39 sheets).

USBR Albuquerque Area Office.

Surveyed in 1918. Published in 1922.

1935 No Data No Data 1:8,00

Black and white photography. USBR

Albuquerque Area Office. Flown in

1935. Published in 1936.

1949 No Data No Data 1:5,000

Photo-mosaic. J-Ammann

Photogrammetric Engineers, San

Antonio, TX. USBR Albuquerque

Area Office.

March 1962

25 cfs 0 cfs 1:4,800

Photo-mosaic. Abram Aerial Survey

Corp, Lansing, MI. USBR

Albuquerque Area Office.

April 1972 4 cfs 0 cfs 1:4,800

Photo-mosaic. Limbaugh Engineers,

Inc., Albuquerque, NM. USBR

Albuquerque Area Office.

March 1985

1900 cfs 1320 cfs 1:4,800

Orthophoto. M&I Consulting

Engineers, Fort Collins, CO. Aero-

Metric Engineering, Sheboygan, MN.

USBR Albuquerque Area Office.

February 1992

1020 cfs 630 cfs 1:4,800

Ratio-rectified photo-mosaic. Koogle

and Poules Engineering,

Albuquerque, NM. USBR

Albuquerque Area Office.

February 2001

770 cfs 560 cfs 1:4,800

Ratio-rectified photo-mosaic. Pacific

Western Technologies, Ltd.,

Albuquerque, NM. USBR

Albuquerque Area Office.

March 2002

310 cfs 150 cfs 1:4,800

Digital ortho-imagery. Pacific

Western Technologies, Ltd.,

Albuquerque, NM. USBR

Albuquerque Area Office.

December 2003

628 cfs 439 cfs 1:28,800 Digital ortho-imagery. USBR

Albuquerque Area Office.

Winter 2004

Date

Unknown

Date

Unknown 1:4,800

Digital ortho-rectified imagery. USBR

Albuquerque Area Office.

April 2005 2270 cfs 1680 cfs 1:4,800

Digital ortho-rectified imagery. Aero-

Metric, Inc., Fort Collins, CO. USBR

Albuquerque Area Office.

January 2006

Date

Unknown

Date

Unknown 1:4,800

Digital ortho-rectified imagery. Aero-

Metric, Inc., Fort Collins, CO. USBR

Albuquerque Area Office.

June 2008

3990 cfs 3460 1:45,720 Digital ortho-rectified imagery. USBR

Albuquerque Area Office.

2010 Date

Unknown

Date

Unknown

LiDAR Optec 3100 EA LiDAR 3m.

Aero-Metric, Inc., Fort Collins, CO.

USBR Albuquerque Area Office.

131

Appendix F: Range Line Cross-Section Plots

132  

 

Figure F.2  SO‐1652.7 Cross‐Section 

4484

4486

4488

4490

4492

4494

4496

50 150 250 350 450

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2003

2002

1999

1998

1997

1995

1994

1993

1991

1990

4486

4488

4490

4492

4494

4496

4498

4500

0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2003

2002

2001

1999

1998

1997

Figure F.1  SO‐1641 Cross‐Section

133  

 

Figure F.3  SO‐1666 Cross‐Section 

 

Figure F.4  SO‐1673 Cross‐Section 

4480

4482

4484

4486

4488

4490

4492

750 800 850 900 950 1000

Elevation (ft)

Station (ft)

2006

2002

1999

1998

1997

1995

1994

1992

1991

1990

4476

4478

4480

4482

4484

4486

4488

4490

4492

600 650 700 750 800 850 900

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

1999

1998

1997

1995

1994

134  

 

Figure F.5  SO‐1683 Cross‐Section 

 

Figure F.6  SO‐1692 Cross‐Section 

4474

4476

4478

4480

4482

4484

4486

4488

4490

4492

0 50 100 150 200

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2004

2003

2002

1999

1998

1997

1994

1993

1990

4472

4474

4476

4478

4480

4482

4484

50 100 150 200 250

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2002

1999

1998

1994

135  

 

Figure F.7  SO‐1701.3 Cross‐Section 

 

4468

4470

4472

4474

4476

4478

4480

4482

4484

0 100 200 300 400 500

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2002

1999

1998

1997

1995

1994

1993

1992

1991

1990

136  

 

Figure F.8  EB‐10 Cross‐Section 

 

Figure F.9  EB‐10 (w/Floodplain) Cross‐Section 

4462

4464

4466

4468

4470

4472

4474

4476

4478

4480

4482

500 600 700 800 900 1000

Elevation (ft)

Station (ft)

201020092008200720052004200320022001199919981997199619951994199319921991199019881987

4445

4450

4455

4460

4465

4470

4475

4480

4485

4490

0 500 1000 1500 2000 2500

Elevation (ft)

Station (ft)

20102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980

137  

 

Figure F.10  EB‐13 Cross‐Section 

 

Figure F.11  EB‐14 Cross‐Section 

4460

4462

4464

4466

4468

4470

4472

4474

4476

1950 2000 2050 2100 2150 2200 2250 2300

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1998

1992

1988

1987

1986

4445

4450

4455

4460

4465

4470

4475

150 200 250 300 350 400

Elevation (ft)

Station (ft)

1999/2001

1998

1997

1996

1988

1980

138  

 

Figure F.12  EB‐16 Cross‐Section 

 

Figure F.13  EB‐17 Cross‐Section 

4456

4458

4460

4462

4464

4466

4468

4470

4472

100 150 200 250 300 350

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1999

1998

1997

1994

1993

1992

4452

4454

4456

4458

4460

4462

4464

4466

4468

4470

4472

4474

50 100 150 200 250

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2002

2001

1999

1998

1997

1996

1995

1994

1993

1992

1991

1988

1980

139  

 

Figure F.14  EB‐18 Cross‐Section 

 

 

Figure F.15  EB‐20 Cross‐Section 

4450

4452

4454

4456

4458

4460

4462

4464

4466

4468

600 650 700 750 800 850 900 950 1000

Elevation (ft)

Station (ft)

2009

2008

2007

2003

2004

2002

2000

1999

1998

1997

1996

4435

4440

4445

4450

4455

4460

4465

150 200 250 300 350 400 450

Elevation (ft)

Station (ft)

200920082007200520042002200019991998199719951994199319921991199019881980

140  

 

 

Figure F.16  EB‐34 Cross‐Section 

 

Figure F.17  EB‐24 Cross‐Section 

4440

4442

4444

4446

4448

4450

4452

4454

4456

4458

4460

4462

250 300 350 400 450 500 550 600

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1999

1998

1997

1996

4425.00

4430.00

4435.00

4440.00

4445.00

4450.00

4455.00

4460.00

5800 6000 6200 6400 6600 6800 7000

Elevation (ft)

Station (ft)

2007

2005

2004

2002

2000

1999

1998

1997

1989

1980

141  

 

 

Figure F.18  EB‐25 Cross‐Section 

 

Figure F.19  EB‐26 Cross‐Section 

4435

4440

4445

4450

4455

4460

4750 4800 4850 4900 4950 5000 5050 5100 5150 5200

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1998

1999

1996

1995

1994

1993

1989

4430

4435

4440

4445

4450

4455

4800 4900 5000 5100 5200 5300

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

1999

1998

1997

1996

1995

1994

1993

1980

142  

 

Figure F.20  EB‐27 Cross‐Section 

 

 

Figure F.21  EB‐27 (w/Floodplain) Cross‐Section 

4438

4440

4442

4444

4446

4448

4450

4452

4700 4800 4900 5000 5100 5200 5300

Elevation (ft)

Station (ft)

2002

2000

1999

1998

1995

1993

1992

1989

1988

1980

4420

4425

4430

4435

4440

4445

4450

4455

4460

0 2000 4000 6000 8000 10000

Elevation (ft)

Station (ft) 

2002

2000

1999

1998

1995

1994

1993

1992

1989

1988

1980

143  

 

Figure F.22  EB‐28 Cross‐Section 

 

Figure F.23  EB‐28 (w/Floodplain) Cross‐Section 

4428

4430

4432

4434

4436

4438

4440

4442

4444

4446

4448

4980 5030 5080 5130 5180 5230

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2002

2000

1999

1998

1995

1992

4428

4430

4432

4434

4436

4438

4440

4442

4444

4446

4448

4450

4000 5000 6000 7000 8000 9000 10000

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2002

2000

1999

1998

1995

1993

1992

144  

 

Figure F.24  EB‐29 Cross‐Section 

 

Figure F.25  EB‐29 (w/Floodplain) Cross‐Section 

4425

4430

4435

4440

4445

4450

5000 5100 5200 5300 5400 5500 5600

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1999

1997

1995

1993

1989

4425

4430

4435

4440

4445

4450

4455

3750 4250 4750 5250 5750 6250 6750 7250

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

2002

2000

1999

1997

1995

1993

1989

145  

 

Figure F.26  EB‐30 Cross‐Section 

 

Figure F.27  EB‐30 (w/Floodplain) Cross‐Section 

4424

4426

4428

4430

4432

4434

4436

4438

4440

3590 3690 3790 3890 3990

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2002

2000

1997

1995

1993

1992

4424

4426

4428

4430

4432

4434

4436

4438

4440

4442

2000 3000 4000 5000 6000 7000 8000 9000 10000

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

2004

2002

2000

1999

1997

1995

1993

1992

146  

 

Figure F.28  EB‐32 Cross‐Section 

 

Figure F.29  EB‐32 (w/Floodplain) Cross‐Section 

4420

4422

4424

4426

4428

4430

4432

4434

4436

5200 5300 5400 5500 5600 5700 5800

Elevation (ft)

Station (ft)

2009

2007

2006

2005

2004

2002

1999

1997

1995

1993

1989

4420

4422

4424

4426

4428

4430

4432

4434

4436

4438

3750 4250 4750 5250 5750 6250

Elevation (ft)

Station (ft)

2009

2007

2006

2005

2004

2002

1999

1997

1995

1993

1989

147  

 

Figure F.30  EB‐33 Cross‐Section 

 

Figure F.31  EB‐35 Cross‐Section 

4418

4420

4422

4424

4426

4428

4430

4432

4434

5100 5200 5300 5400 5500 5600 5700 5800

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

4414

4416

4418

4420

4422

4424

4426

4428

4430

4432

3500 3600 3700 3800 3900 4000 4100

Elevation (ft)

Station (ft)

2009

2008

2007

2005

2004

148  

 

Figure F.32  EB‐36 Cross‐Section 

 

Figure F.33  EB‐37 Cross‐Section 

4412

4414

4416

4418

4420

4422

4424

4426

4428

4430

5400 5500 5600 5700 5800

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2005

2004

2003

4410

4412

4414

4416

4418

4420

4422

4424

4426

4428

4430

3000 3100 3200 3300 3400 3500 3600 3700 3800

Elevation (ft)

Station (ft)

EB‐37

2010

2009

2008

2007

2005

2004

2003

149  

 

Figure F.34  EB‐37.5 Cross‐Section 

 

Figure F.35  EB‐38 Cross‐Section 

4410

4412

4414

4416

4418

4420

4422

4424

4426

4428

0 100 200 300 400 500

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2006

2005

2004

2003

4408

4410

4412

4414

4416

4418

4420

4422

4424

4426

4428

2800 2900 3000 3100 3200 3300 3400

Elevation (ft)

Station (ft)

2009

2008

2007

2006

2005

150  

 

Figure F.36  EB‐39 Cross‐Section 

 

Figure F.37  EB‐40 Cross‐Section 

4406

4408

4410

4412

4414

4416

4418

4420

4422

4424

4426

4428

‐100 0 100 200 300 400

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2006Perpindicular2004

2003

4400

4405

4410

4415

4420

4425

4550 4600 4650 4700 4750 4800 4850 4900

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

151  

 

Figure F.38  EB‐40.5 Cross‐Section 

 

Figure F.39  EB‐41 Cross‐Section 

4400

4405

4410

4415

4420

4425

4430

‐50 0 50 100 150 200 250 300 350

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

4398

4400

4402

4404

4406

4408

4410

4412

4414

4416

0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

2009

2008

2007

2004

152  

 

Figure F.40  EB‐42 Cross‐Section

 

Figure F.41  EB‐43 Cross‐Section 

4398

4400

4402

4404

4406

4408

4410

4412

4414

4416

‐100 ‐50 0 50 100 150 200 250 300 350

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

4390

4395

4400

4405

4410

4415

4420

‐100 0 100 200 300 400

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

153  

 

Figure F.42  EB‐44 Cross‐Section 

 

Figure F.43  EB‐45 Cross‐Section 

4394

4396

4398

4400

4402

4404

4406

4408

4410

4412

4414

‐100 ‐50 0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

4390

4395

4400

4405

4410

4415

4420

‐100 0 100 200 300 400

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

154  

 

Figure F.44  EB‐46 Cross‐Section 

 

Figure F.45  EB‐47 Cross‐Section 

4398

4400

4402

4404

4406

4408

4410

4412

4414

4416

0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

2009

2008

2007

4390

4395

4400

4405

4410

4415

4420

0 50 100 150 200 250 300

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

155  

 

Figure F.46  EB‐48 Cross‐Section 

 

Figure F.47  EB‐49 Cross‐Section 

4385

4390

4395

4400

4405

4410

‐100 0 100 200 300 400

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

4385

4390

4395

4400

4405

4410

4415

4420

0 100 200 300 400 500 600

Elevation (ft)

Station (ft)

2010

2009

2008

2007

2004

2003

156  

 

Figure F.48  EB‐50 Cross‐Section 

 

 

4385

4390

4395

4400

4405

4410

0 50 100 150 200 250 300 350 400 450

Elevation (ft)

Station (ft)

2009

2008

2007

2006

157

Appendix G: Change in Thalweg Elevation vs. River Mile Plots

158  

 

Figure G.1  1990‐1992 Thalweg Change 

 

Figure G.2  1991‐1992 Thalweg Change 

0.0

0.5

1.0

1.5

2.0

2.5

3.0

454749515355575961

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1990‐1992

y = 4.1023x ‐ 253.93R² = 1

‐7

‐6

‐5

‐4

‐3

‐2

‐1

0

1

2

6060.56161.56262.563

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1991‐1992 Linear (Wave 4 1991‐1992)

159  

 

Figure G.3  1992‐1993 Thalweg Change 

 

Figure G.4  1993‐1994 Thalweg Change 

y = ‐0.0992x2 + 11.97x ‐ 358.74R² = 0.1623

‐4

‐2

0

2

4

6

8

10

455055606570

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1992‐1993 Poly. (Wave 4 1992‐1993)

y = 0.0008x2 + 0.0616x ‐ 6.2002R² = 0.285

‐1.5

‐1.0

‐0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

455055606570

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1993‐1994 Poly. (Wave 4 1993‐1994)

160  

 

Figure G.5  1994‐1995 Thalweg Change 

 

Figure G.6  1995‐1997 Thalweg Change 

y = ‐0.0179x2 + 2.1771x ‐ 64.765R² = 0.0227

‐3

‐2

‐1

0

1

2

3

4

5

6

7

455055606570

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1994‐1995 Poly. (Wave 4 1994‐1995)

y = 0.0683x2 ‐ 8.6959x + 276.42R² = 0.0933

‐5

‐4

‐3

‐2

‐1

0

1

2

3

4

455055606570

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1995‐1997 Wave 3/4 Transition 1995‐1997 Poly. (Wave 4 1995‐1997)

161  

 

Figure G.7  1997‐1998 Thalweg Change 

 

Figure G.8  1998‐1999 Thalweg Change 

y = 0.274x2 ‐ 36.539x + 1219.1R² = 0.2054

‐3

‐2

‐1

0

1

2

3

4

5

455055606570

Chan

ge in

 Thalweg (ft)

River Mile

Wave 4 1997‐1998 Wave 3/4 Transition 1997‐1998 Poly. (Wave 4 1997‐1998)

y = 0.0553x2 ‐ 7.4734x + 252.98R² = 0.08

‐3

‐2

‐1

0

1

2

3

4

45505560657075

Chan

ge in

 Thalweg (ft)

River Mile

Wave 3 1998‐1999 Wave 4 1998‐1999

Wave 3/4 Transition 1998‐1999 Poly. (Wave 4 1998‐1999)

162  

 

Figure G.9  1999‐2002 Thalweg Change 

 

Figure G.10  2002‐2003 Thalweg Change 

y = ‐2.2408x + 120.61R² = 1

y = 0.0309x2 ‐ 4.2878x + 148.76R² = 0.0832

‐5

‐4

‐3

‐2

‐1

0

1

2

3

45505560657075

Chan

ge in

 Thalweg (ft)

River Mile

Wave 3 1999‐2002 Wave 4 1999‐2002Wave 3/4 Transition 1999‐2002 Linear (Wave 3 1999‐2002)Poly. (Wave 4 1999‐2002)

y = 0.885x2 ‐ 96.405x + 2622.5R² = 0.6265

y = ‐0.0127x2 + 1.6943x ‐ 54.451R² = 0.1822

‐4

‐3

‐2

‐1

0

1

2

3

4

5

4550556065707580

Chan

ge in

 Thalweg (ft)

River Mile

Wave 3 2003‐2004 Wave 4 2003‐2004

Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004)

163  

 

Figure G.11  2003‐2004 Thalweg Change 

 

Figure G. 12  2004‐2007 Thalweg Change 

y = ‐0.009x2 + 0.963x ‐ 27.412R² = 0.0059

y = 0.0402x2 ‐ 5.7666x + 205.93R² = 0.3261

‐12

‐10

‐8

‐6

‐4

‐2

0

2

4

4550556065707580

Chan

ge in

 Thalweg (ft)

River Mile

Wave 3 2003‐2004 Wave 4 2003‐2004Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004)Poly. (Wave 4 2003‐2004)

y = ‐0.3485x2+ 32.295x ‐741.44

R² = 0.8947

y = 0.1767x2 ‐ 21.993x + 676.35R² = 0.5992

y = 0.1679x2

‐23.548x + 825.83

R² = 0.4563

‐15

‐10

‐5

0

5

10

4550556065707580

Chan

ge in

 Thalweg (ft)

River MileWave 2 2004‐2007 Wave 2/3 Transitional 2004‐2007

Wave 3 2007‐2008 Wave 4 2004 ‐ 2007

Poly. (Wave 2 2004‐2007) Poly. (Wave 3 2007‐2008)

Poly. (Wave 4 2004 ‐ 2007)

164  

 

Figure G.13  2007‐2008 Thalweg Change 

 

Figure G.14  2008‐2009 Thalweg Change 

y = ‐0.0069x2 + 0.7283x ‐ 18.716R² = 0.0311

y = ‐0.0064x2 + 0.864x ‐ 30.281R² = 0.1006

‐3.0

‐2.5

‐2.0

‐1.5

‐1.0

‐0.5

0.0

0.5

1.0

1.5

2.0

4550556065707580

Chan

ge in

 Thalweg (ft)

River Mile

Wave 2 2007‐2008 Wave 2/3 Transitional 2007‐2008

Wave 3 2007‐2008 Poly. (Wave 2 2007‐2008)

Poly. (Wave 3 2007‐2008)

y = ‐0.2133x2 + 20.808x ‐ 505.26R² = 0.3004

y = 0.0078x2 ‐ 0.9912x + 30.863R² = 0.0929

‐3

‐2

‐1

0

1

2

3

4

5

4550556065707580

Chan

ge in

 Thalweg (ft)

River MileWave 2 2008‐2009 Wave 2/3 Transitional 2008‐2009

Wave 3 2008‐2009 Poly. (Wave 2 2008‐2009)

Poly. (Wave 3 2008‐2009)

165  

 

Figure G.15  2009‐2010 Thalweg Change 

y = 0.0363x2 ‐ 4.054x + 112.8R² = 0.5874

y = 0.074x2 ‐ 9.3306x + 293.35R² = 0.8984

‐3

‐2

‐1

0

1

2

3

4

455055606570

Chan

ge in

 Thalweg Elevation (ft)

River Mile

Wave 1 2009‐2010 Wave 2 2009‐2010

Wave 2/3 Transition 2009‐2010 Wave 3 2009‐2010

Poly. (Wave 2/3 Transition 2009‐2010) Poly. (Wave 3 2009‐2010)

166

Appendix H: Bed Material Grain Size Distribution Plots

167  

 

Figure H.1  SO‐1641 2001 Grain Size Distribution 

 

Figure H.2  SO‐1641 2002 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1

% Finer by Weight

Grain Size (mm)

168  

 

Figure H.3  SO‐1641 2004 Grain Size Distribution 

 

Figure H.4  SO‐1641 2005 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1

% Finer by Weight

Grain Size (mm)

169  

 

Figure H.5  SO‐1683 1999 Grain Size Distribution 

 

 

 

 

 

 

 

 

 

 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

170  

 

Figure H.6  EB‐10 1986 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

171  

 

Figure H.7  EB‐10 1987 Grain Size Distribution 

 

Figure H.8  EB‐10 1988 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

172  

 

Figure H.9  EB‐10 1990 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

173  

 

Figure H.10  EB‐10 1992 Grain Size Distribution 

 

Figure H.11 EB‐10 1993 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

174  

 

Figure H.12  EB‐10 1994 Grain Size Distribution 

 

Figure H. 13  EB‐10 1997 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

175  

 

Figure H.14  EB‐10 1998 Grain Size Distribution 

 

Figure H.15  EB‐10 1999 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

176  

 

Figure H.16  EB‐10 2002 Grain Size Distribution 

 

 

 

 

 

 

 

 

 

 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

177  

 

 

Figure H.17  EB‐13 1986 Grain Size Distribution 

 

Figure H.18  EB‐13 1987 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

178  

 

 

Figure H.19  EB‐13 1988 Grain Size Distribution 

 

Figure H.20  EB‐13 1990 Grain Size Distribution 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

179  

 

Figure H.21  EB‐13 1999 Grain Size Distribution 

 

Figure H.22  EB‐13 2002 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

180  

 

Figure H.23  EB‐18 1986 Grain Size Distribution 

 

Figure H.24  EB‐18 1987 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

181  

 

 

Figure H.25  EB‐18 1988 Grain Size Distribution 

 

Figure H.26  EB‐18 1990 Grain Size Distribution 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

182  

 

Figure H.27  EB‐18 1993 Grain Size Distribution 

 

Figure H.28  EB‐18 1994 Grain Size Distribution 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

183  

 

Figure H.29  EB‐18 1997 Grain Size Distribution 

 

Figure H.30  EB‐18 1999 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

184  

 

Figure H.31  EB‐18 2002 Grain Size Distribution 

 

 

 

 

 

 

 

 

 

 

 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100 1000

% Finer by Weight

Grain Size (mm)

185  

 

 

Figure H.32  EB‐24 1986 Grain Size Distribution 

 

Figure H.33  EB‐24 1992 Grain Size Distribution 

 

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

186  

 

Figure H.34  EB‐24 1999 Grain Size Distribution 

 

Figure H.35  EB‐24 2002 Grain Size Distribution 

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

% Finer by Weight

Grain Size (mm)