Geomorphic Analysis of the Middle Rio Grande-Elephant Butte Reach

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

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.

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.

- iii - 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.

- iv - 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

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

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

- vii - 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

- viii - 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

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

- x -

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

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).

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).

Tiffany Plug 2005 1991, 1995, del Apache Bosque Plug, 2008 Sediment Plugs events Galisteo and Heron and Galisteo Elephant Butte Elephant and Vado El MRGCD Dams Diversion Platoro Jemez Canyon Control Flood Cochiti Nambe Falls Abiquiu Dams 9,200 cfs 7,600 cfs 50,000 cfs 50,000 cfs 25,000 cfs 47,000 cfs 30,000 cfs 30,000 7,600 cfs 7,600 12,300 cfs 12,300 cfs 12,400 100,000 cfs 100,000 9,2400 cfs 9,2400

Floods1 Elephant Butte Full Drought

Floodway clearing/mowing

Levees, channelization and jetty jacks2 LFCC Operation

1865 1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015 (1) Flood events listed are measured at various locations between Otowi and San Marcial. Year Figure 1.2 Historical Timeline of Middle Rio Grande (Modified After Makar 2011, Pers. Comm.)

Figure 1.3: Rio Grande Silvery Minnow and Southwestern Flycatcher

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

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.

Figure 1.4 Aerial View of Tiffany Plug in 2005

SECTION 2: SITE DESCRIPTION ANND BACKGROUND

2.1 Elephant Butte Reach

The section of the Middle Rio Grande examined in detail in this report will be referred to as the Elephant Butte Reach. This 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 (Riiver Mile 44.65). Figure 2.1 shows the location of the project area in New Mexico.

Figure 2.1: Location of the Elephant Butte Reach ffrom Google Maps

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. 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.

Figure 2.2 Profile of Elephant Butte Reach Widths and Thalweg at Agg/Deg Lines

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.

Figure 2.3 2008 Aerial Photo of Subreach 1

Tiffany Plug (1991, 1995, 2005)

Figure 2.4 2008 Aerial Photo of Subreach 2

Figure 2.5 2008 Aerial Photo of Subreach 3

Figure 2.6 2008 Aerial Photo of Subreach 4

Figure 2.7 2008 Aerial Photo of Subreach 5

Figure 2.8 2008 Aerial Photo of Subreach 6

Figure 2.9 2008 Aerial Photo of Elephant Butte Reservoir

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.

Agg/Deg 1637

Agg/Deg 1672 Agg/Deg 1696

Tiffany Plug Agg/Deg 1683 Agg/Deg 1728 (1991, 1995, 2005)

Agg/Deg 1751

Agg/Deg 1794

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

Tiffany Plug Agg/Deg 1728 Agg/Deg 1683 (1991 – 1995, 2005

Agg/Deg 1751

Agg/Deg 1794

Figure 2.11 Subreach Definitions and Range Line Locations (2008 GIS Elephant Butte Reach Delineation Shown)

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.

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,

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.

10000

9000 San Acacia San Marcial 8000

(cfs) 7000

6000

Discharge 5000

Peak 4000

3000 Annual 2000

1000

0 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 Year

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

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.

12000000

10000000

8000000

6000000

4000000

2000000

0 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 Year

San Marcial San Acacia

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 Oct. 1956 - July 1962 Sep. 1962 - Aug. 1966 RG at San Marcial Oct. 1966 - Sep. 1989 Oct. 1991 - Sep. 1995 Jan 1959 - Sep. 1959 Jan 1960 - Sep. 1961 July 1961 RG at San Acacia April 1962 - July 1962 Aug 1962 - Sep. 1962 March 1963 - Sep. 1996

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.

4450 DROUGHT DROUGHT

LFCC OPERATION

4400

4350 (ft)

WSE

4300

4250

4200 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Annual Mean WSE Annual Max WSE Annual Min WSE

Figure 3.1 Elephant Butte Reservoir Level Time Series

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.

MAX WSE

AVG. WSE

2010 AVG WSE

SR3 SR4 SR5 SR

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

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.).

Figure 4.1 Channel Planforms from Aerial Photography

Figure 4.2 Subreach 1 Channel Planforms from Aerial Photography

Figure 4.3 Subreach 2 Channel Planforms from Aerial Photography

Figure 4.4 Subreach 3 Channel Planforms from Aerial Photography

Figure 4.5 Subreach 4 Channel Planforms from Aerial Photography

Figure 4.6 Subreach 5 Channel Planforms from Aerial Photography

Figure 4.7 Subreach 6 Channel Planforms from Aerial Photography

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

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

2000

1800

1600

1400 (ft) 1200 Width

1000

800 y = 0.2353x2 ‐ 936.54x + 931904

Average R² = 0.9299 600

400

200

0 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Subreach 1 SubreachYear 2 Subreach 3 Subreach 4 Subreach 5 Subreach 6 Total (SR 1‐5) Total (SR 1‐6) Poly. (Total (SR 1‐6))

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,

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

decrease with a drop in base-level.

300

250 (ft) 200 Width

150

100 Average 50

0 1960 1970 1980 1990 2000 2010 Year

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

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:

Lc S  Lv

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

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.

40.00 35.00 30.00 (miles) 25.00 20.00 Length

15.00 10.00 Channel 5.00 0.00 1910 1930 1950 1970 1990 2010 Year Subreach 1 Subreach 2 Subreach 3 Subreach 4 Subreach 5 Subreach 6 Total Reach SB (1‐5) Total Reach SB (1‐6)

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

Table 4-1 Subreach Length and Total Length Values as Measured From GIS Data Measured Lengths (mi) Reach 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

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).

1.3 y = 6E‐05x2 ‐ 0.2196x + 219.57 R² = 0.8398 1.25

1.2

1.15 Sinuosity

1.1

1.05

1 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

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))

Figure 4.11 Temporal Sinuosity Trends

Table 4-2 Sinuosity Values Year Reach 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

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.

4500 SR1 SR2 SR3 SR4 SR5 SR6 1962 Thalweg Profile 1972 Thalweg Profile 1992 Thalweg Profile 4480 2002 Thalweg Profile

4460 (ft)

4440 Elevation

4420

4400

4380 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000160,000 Distance Downstream of South Boundary of Bosque del Apache NWR (ft)

Figure 4.12 Thalweg Elevation Profile From Agg/Deg Surveys

0.0009 0.0008 0.0007 0.0006 0.0005 Slope 0.0004 Subreach 1 Bed 0.0003 Subreach 2 Subreach 3 0.0002 Subreach 4 Subreach 5 0.0001 Subreach 6 Total Reach (1‐5) 0.0000 1960 1970 1980 1990 2000 2010 Year 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

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.

25 (ft)

20 Elevation 15

10 Thalweg

5 Channel

Change ‐5 1962 ‐ 1972 1972 ‐ 1992 1992 ‐ 2002 1962 ‐ 2002

SUBREACH 1 SUBREACH 2 SUBREACH 3 SUBREACH 4 SUBREACH 5 SUBREACH 6 TOTAL REACH

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

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.

1962 ‐ 1972 4 SR 1 SR 2 SR 3 SR 4 SR 5 SR 6 (ft) 3 2 1 Elevation 0

Invert ‐1

‐2 ‐3 Channel

in ‐4

‐5 ‐6 Change 1637 1645 1652 1662 1670 1678 1688 1695 1707 1733 1750 1777 1792 1804 1820 Agg/Deg #

Figure 4.15 Change in Channel Thalweg Elevation (1962 – 1972) Based on Agg/Deg Surveys 1972 ‐ 1992 25 SR 1 SR 2 SR 3 SR 4 SR 5 SR 6 (ft)

20 Elevation

15 Invert

10 Channel

Change 0 1637 1645 1652 1662 1670 1678 1688 1695 1707 1733 1750 1762 1786 1798 1809 Agg/Deg #

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

1992 ‐ 2002 9 SR 1 SR 2 SR 3 SR 4 SR 5 SR 6 (ft) 8 7

Elevation 6

5 Invert 4 3 Channel

in 2

Change 0 1637 1645 1652 1662 1670 1678 1688 1695 1703 1731 1747 1751 1777 1792 1804 Agg/Deg #

Figure 4.17 Change in Channel Thalweg Elevation from 1992 – 2002 Based on Agg/Deg Surveys 1962 ‐ 2002 30 SR 1 SR 2 SR 3 SR 4 SR 5 SR 6 (ft)

Elevation 20

Invert 15

10 Channel

in 5

Change 0 1637 1645 1652 1662 1670 1678 1688 1695 1703 1731 1747 1762 1786 1798 1809 1827 1848 1875 Agg/Deg #

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

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 Δ Δ Δ Agg/Deg Agg/Deg Agg/Deg Agg/Deg Thalweg Thalweg Thalweg Thalweg # # # # El (ft) El (ft) El (ft) El (ft) Max 1.30 1641 7.70 1652 3.14 1673.0 8.34 1662 Subreach 1 Min ‐3.10 1670 3.50 1645 0.84 1652.0 4.95 1645 Average ‐0.67 5.73 1.85 6.93 Max ‐1.30 1692 10.60 1695 4.35 1683.0 11.28 1692 Subreach 2 Min ‐4.30 1678 7.10 1678 2.58 1695.0 7.00 1678 Average ‐2.65 8.33 3.67 9.39 Max ‐2.40 1707 13.90 1731 4.99 1731.0 14.19 1731 Subreach 3 Min ‐4.70 1731 10.20 1707 3.68 1707.0 11.47 1707 Average ‐3.45 11.57 4.20 12.31 Max ‐1.70 1747 14.60 1751 6.36 1747.0 18.66 1747 Subreach 4 Min ‐5.50 1733 14.00 1747 5.53 1733.0 14.13 1733 Average ‐3.53 14.07 5.88 16.39 Max 2.60 1762 16.30 1777 7.92 1777.0 23.78 1762 Subreach 5 Min ‐1.20 1777 14.50 1762 6.68 1762.0 23.02 1777 Average 0.43 15.06 7.21 22.50 Max 1.40 1820 19.80 1798.00 7.80 1804.0 24.30 1809 Subreach 6 Min ‐0.90 1798 16.70 1804 5.20 1798.0 11.50 1875 Average 0.26 17.68 6.53 20.01 Max 2.60 1762 19.80 1798 7.92 1777.0 24.30 1809 Total Min ‐5.50 1733 3.50 1645 0.84 1652.0 4.95 1645 Reach Average ‐1.33 11.42 4.79 15.95

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.

4500 1625 1628 1633 1637 1641 4480 1645 1648 1652 1658 4460 1662 1666 1670 1673 1678 4440 1683 1688 1692 1695 4420 1703 1707 (ft)

1731 1733 1747 Elevation 4400 1750 1751 1762 1777 1786 4380 1792 1798 1804 1809 4360 1820 1827 1835 1848 1856 4340 1864 1875 1883 1887 4320 1894 1950 1960 1970 1980 1990 2000 2010 2020 1908 EB Res Year

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

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).

1.2 y = ‐0.0014x2 + 0.0649x + 0.1832 1 R² = 0.9334 (ft/yr) 0.8

0.6 Aggradation 0.4 of

Rate 0.2

0 0 5 10 15 20 Miles Downstream from Agg/Deg 1637

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

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.

4500 Tiffany Plug, 2005, 1988 SO-1683 (Agg/Deg 1683) 1991 1994 1995 4480 1999 2004 2005 2009 4460 Elephant Butte Reservoir Max WSE, El 4454 (Project Datum) (ft)

4440 Elevation

Thalweg 4420 SR 1 SR 2 SR 3 SR 4 SR 5 SR 6

4400 Agg/Deg 1751 Agg/Deg 1751 Agg/Deg 1794 Agg/Deg 1672 Agg/Deg 1672 Agg/Deg 1696 Agg/Deg 1696 4380 Agg/Deg 1637 Agg/Deg 1728 1600 1650 1700 1750 1800 1850 1900 1950 2000 Agg/Deg Line

Figure 4.21 Thalweg Elevation Profile From Range Line Survey Data

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.

8 7 (ft/mi)

6 5 Slope 4 3 2 Thalweg 1

Avg 0 1985 1990 1995 2000 2005 2010 Year

Figure 4.22 Subreach 1 Average Channel Thalweg Slope: Temporal Trend

8 7 (ft/mi)

6 5 Slope 4 3 2 Thalweg 1

Avg 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year

Figure 4.23 Subreach 2 Average Channel Thalweg Slope: Temporal Trend

6 5 (ft/mi) 4 Slope 3 2 Thalweg 1

Avg 0 1985 1990 1995 2000 2005 2010 Year

Figure 4.24 Subreach 3 Average Channel Thalweg Slope: Temporal Trend

6 5 (ft/mi) 4 Slope 3 2 Thalweg 1

Avg 0 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year

Figure 4.25 Subreach 4 Average Channel Thalweg Slope: Temporal Trend

6 5 (ft/mi) 4 Slope 3 2 Thalweg 1

Avg 0 1985 1990 1995 2000 2005 2010 2015 Year

Figure 4.26 Subreach 5 Average Channel Thalweg Slope: Temporal Trend

4 (ft/mi)

3 Slope 2

1 Thalweg

0 Avg 1985 1990 1995 2000 2005 2010 2015 Year

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 ‐‐‐‐ ‐‐‐‐

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.

SO‐1641 4500 2009

4498 2008 2007 4496 2006 2005 4494 2004 (ft)

2003 4492 2002 Elevation 4490 2001 1999 4488 1998 1997 4486 50 100 150 200 250 Station (ft) Figure 4.28 Subreach 1: SO-1641 Surveyed Cross-Sections

SO‐1683 4492 2009 4490 2008 2007 4488 2006 2005 4486 2004 (ft) 4484 2003 2002 4482 1999 Elevation 4480 1998 1997 4478 1995 1994 4476 1993 4474 1990 0 50 100 150 200 Station (ft)

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

EB‐10 2010 4482 2009 2008 4480 2007 2005 4478 2004 2003 4476 2002 2001 4474 (ft)

1999 1998 4472 1997 4470 1996 Elevation 1995 4468 1994 1993 4466 1992 1991 4464 1990 1988 4462 1987 500 600 700 800 900 1000 1986 1980 Station (ft)

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

EB‐10 (w/Floodplain) 4490 2010 2009 Active Channel 2008 4485 2007 2005 4480 2004 2003 2002 4475 2001 (ft) 1999 4470 1998 1997 1996 Elevation 4465 1995 1994 4460 1993 1992 1991 4455 1990 1988 4450 1987 0 500 1000 1500 2000 2500 1986 1980 Station (ft)

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

EB‐13 4476 2009 4474 2008

4472 2007 2005 4470

(ft) 2004

4468 2002 2000

Elevation 4466 1998 4464 1992 1988 4462 1987 4460 1986 1950 2000 2050 2100 2150 2200 2250 2300 Station (ft)

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

4465 EB‐20 2009 2008 2007 4460 2005 2004 2002 4455 2000 1999 (ft) 1998 4450 1997 1995

Elevation 1994 4445 1993 1992 1991 4440 1990 1988 1980 4435 150 200 250 300 350 400 450 Station (ft)

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

EB‐29 4450 2009 2008 4445 2007 2005

(ft) 4440 2004

2002 4435 2000 Elevation 1999

4430 1997 1995

4425 1993 5000 5100 5200 5300 5400 5500 5600 1989 Station (ft)

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

EB‐29 (w/Floodplain) 2009 4455 2008 Active Channel 2007 4450 2005 4445 2004 (ft) 2002 4440 2000 1999 Elevation 4435 1997 1995 4430 1993

4425 1989 3750 4250 4750 5250 5750 6250 6750 Station (ft)

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

EB‐41 4416

4414

4412

4410 2009

(ft) 2008 4408 2007 4406 2004 Elevation 4404

4402

4400

4398 0 50 100 150 200 250 300 Station (ft)

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.

4500 4600 SO‐1641 SO‐1652.7 SO‐1666 4490 SO‐1673 S0‐1683 4480 SO‐1692 SO‐1701.3 EB‐10 4470 4550 EB‐13 EB‐14 EB‐16 4460 EB‐17 EB‐18 4450 EB‐20 EB‐34 EB‐24 (ft) 4440 4500 EB‐25 EB‐26 (ft) EB‐27 4430 Elevation EB‐28 WSE

EB‐29 4420 EB‐30 Thalweg EB‐32 Reservoir EB‐33 4410 4450 EB‐35 Channel EB‐36 4400 EB‐37 EB‐37.5 EB‐38 4390 EB‐39 EB‐40 EB‐40.5 4380 4400 EB‐41 EB‐42 4370 EB‐43 EB‐44 EB‐45 4360 EB‐46 EB‐47 EB‐48 4350 4350 EB‐49 1980 1985 1990 1995 2000 2005 2010 EB‐50 Year Reservoir Level

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

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

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.

Table 4-7 Change in Thalweg Elevation Between Select Year Sets 2009‐ 2008‐ 2007‐ 2004‐ 2003‐ 2002‐ 1999‐ 1998‐ 1997‐ 1995‐ 1994‐ 1993‐ 1992‐ 1991‐ 1990‐ 1990‐ 1988‐ 1980‐ 2010 2009 2008 2007 2004 2003 2002 1999 1998 1997 1995 1994 1993 1992 1991 1992 1990 1988 SO‐ ‐‐‐‐ 0.73 ‐1.35 1.65 ‐0.17 1.26 ‐1.52 ‐0.12 1.81 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 1641 SO‐ ‐‐‐‐ ‐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 ‐‐‐‐ ‐‐‐‐ 1652.7 SO‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐0.16 1.43 ‐1.84 1.40 ‐0.40 ‐1.02 1.22 0.70 ‐1.00 ‐0.30 ‐‐‐‐ ‐‐‐‐ 1666 SO‐ ‐‐‐‐ ‐0.55 ‐1.22 0.26 ‐1.32 2.02 0.15 1.37 ‐2.22 3.70 0.50 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 1673 SO‐ ‐‐‐‐ 0.51 ‐0.52 ‐1.04 ‐2.21 2.61 1.36 0.67 ‐1.73 0.00 1.80 0.20 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 1683 SO‐ ‐‐‐‐ 0.66 ‐1.35 1.02 ‐1.84 1.16 ‐0.03 1.16 ‐‐‐‐ ‐‐‐‐ ‐7.60 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 1692 SO‐ ‐‐‐‐ ‐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 ‐‐‐‐ ‐‐‐‐ 1701.3 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 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐

Table 4-7 Change in Thalweg Elevation Between Select Years (Part 2) 2009‐ 2008‐ 2007‐ 2004‐ 2003‐ 2002‐ 1999‐ 1998‐ 1997‐ 1995‐ 1994‐ 1993‐ 1992‐ 1991‐ 1990‐ 1990‐ 1988‐ 1980‐ 2010 2009 2008 2007 2004 2003 2002 1999 1998 1997 1995 1994 1993 1992 1991 1992 1990 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‐ 2.22 0.53 ‐0.49 ‐0.80 ‐0.89 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 37.5 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‐ ‐1.84 1.98 0.17 2.75 ‐0.30 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 40.5 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

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.

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

5 (ft)

Elevation

0 Bed

‐5 Average in

Change ‐10

‐15

‐20 10 13 14 16 17 18 20 34 24 25 26 27 28 29 30 32 33 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ 37.5 40.5 1692 1683 1673 1666 1641 ‐ ‐ ‐ ‐ ‐ ‐ ‐ EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB 1701.3 1652.7 ‐ ‐ EB EB SO SO SO SO SO SO SO Range Line ID

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

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

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

5 (ft)

0 Change

Elevation

‐5 Thalweg ‐10

‐15

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

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

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

downstream end of the Middle Rio Grande River); this equation is appropriate for RM

45.21 to RM 57.75.

(ft) 2

0 ‐2 Elevation

‐4 d n Thalweg ‐6 E

in ‐8 ream ‐10 t ps Change ‐12 U Ut Ed

Range Line

Figure 4.40 Magnitude of Aggradation and Degradation at Range Lines (2003-2004)

0 (ft) ‐2

‐4 Thalweg

2 y = ‐0.1601x + 16.209x ‐ 410.5 ‐6 R² = 0.6064 Change ‐8

‐10

Upstream End Upstream End Downstream End ‐12 59 57 55 53 51 49 47 45 River Mile

Figure 4.41 Magnitude of Aggradation and Degradation at River Miles (2003-2004)

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.

6 (ft)

4 2 0 Elevation ‐2 ‐4 ‐6 Thalweg

in ‐8

‐10 ‐12 Upstream End Downstream End Change 10 13 16 17 18 20 34 24 25 26 28 30 32 33 35 36 37 38 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ 37.5 1692 1673 1641 ‐ ‐ ‐ ‐ EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB 1701.3 1652.7 ‐ ‐ EB SO SO SO SO SO Range Line

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

6 y = 0.8233x ‐ 58.285 (ft)

4 R² = 0.821 2 0 Elevation ‐2 ‐4 ‐6 Thalweg

‐8 in

‐10 Downstream End Upstream End Upstream End ‐12 Change 75 70 65 60 55 River Mile

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.

15 (ft) 10

5 Change

‐5 Elevation

‐10

Thalweg ‐15 13 16 18 34 25 27 29 32 35 37 38 40 41 43 45 47 49 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ 1683 1666 1641 ‐ ‐ ‐ EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB EB 1701.3 ‐ SO SO SO SO Range Line ID

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

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.

2 2

y = ‐0.0226x + 4.0052x ‐ 171.53 (ft) 0 R² = 0.9302 ‐2 ‐4 Elevation ‐6 ‐8 ‐10 Thalweg

‐12 ‐14 Upstream End Upstream End Downstream End

‐16 Change 75 70 65 60 55 River Mile

Figure 4.45 Magnitude of Degradation from 2004 to 2009

2 y = ‐0.4355x + 41.112x ‐ 962.27 10 R² = 0.8399 8 Elevation 6 4 (ft) Thalweg 2 in

0 ‐2 Change Upstream End Upstream End Downstream End ‐4 55 53 51 49 47 45 River Mile 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

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.

4392 4391 4390 y = ‐6.9072x + 18267 (ft)

4389

WSE 4388

4387 4386 Reservoir 4385 4384 4383 2008 2009 2010 2011 Year

Figure 4.47 Reservoir Water Surface Elevation Change from 2009-2010 Resulting in Wave 1 Channel Degradation

46 44 y = 1.4607x ‐ 2890.8 42 (mi)

40 y = ‐2.7127x + 5493.5 38 Mile

36 Chnl Bed Wave 2

River 34 Res U/S Extent Linear (Chnl Bed Wave 2) 32 Linear (Res U/S Extent) 30 2008 2009 2010 2011 Year 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

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.

4400 4395 4390 (ft)

4385 y = 6.7963x ‐ 9259.3 4380 WSE 4375 4370 4365 Reservoir 4360 4355 4350 2003 2004 2005 2006 2007 2008 2009 2010 Year

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

55 y = ‐0.5522x2 + 2219.1x ‐ 2E+06 R² = 0.9969 50

(mi) 45

Mile y = 1.3609x ‐ 2689.6 40 R² = 0.9633 River Chnl Bed Wave 2 35 Res U/S Extent Poly. (Chnl Bed Wave 2) Linear (Res U/S Extent) 30 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

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.

4480

4460

4440 (ft)

4420 WSE

4400 y = ‐14.243x + 32904

Reservoir 4380

4360

4340 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year

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

80 y = 0.0692x2 ‐ 276.2x + 275686 75 R² = 0.8863 70 65

(mi) 60

55 Mile

River y = ‐2.9297x + 5909.5 45 Chnl Bed Wave 3 R² = 0.9068 40 Res U/S Extent Poly. (Chnl Bed Wave 3) 35 Linear (Res U/S Extent) 30 1990 1995 2000 2005 2010 Year

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

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.

4455 y = 3.7339x ‐ 2996.4 4450 (ft)

4445 WSE

4440

Reservoir Reservoir WSE 4435 Linear (Reservoir WSE)

4430 1989 1990 1991 1992 1993 1994 1995 1996 Year

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

80 y = ‐0.1222x2 + 489.03x ‐ 489299 75 R² = 0.892 70 65

(mi) 60 y = 1.0734x ‐ 2079.6 55 Mile

R² = 0.8114 50

River Chnl Bed Wave 4 45 Res U/S Extent 40 Poly. (Chnl Bed Wave 4) 35 Linear (Res U/S Extent) 30 1985 1990 1995 2000 2005 Year

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).

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.

100.0

90.0

80.0

70.0

60.0 Weight

by 50.0

40.0 Finer

% 30.0

20.0

10.0

0.0 0.01 0.1 1 10 Grain Size (mm)

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.

100 90 80 70 1966 1968 1969 1973 60 1975 1976 Weight

1978 1979 1980 1981 by 50 1982 1983 1984 1985 40 1986 1987 Finer

1988 1989

% 30 1990 1991 1992 1993 1994 1995 20 1996 1997 1998 1999 10 2000 2001 2002 2003 0 2004 2005 0.001 0.01 0.1 1 10 100 Grain Size Distribution (mm) Figure 4.56 San Acacia Gauge: Annual Bed Material Grain Size Distributions 100

90 1968 1969 1972 1973 80 1974 1975 1976 1977 70 1978 1979 1980 1981 1982 1983 60 1984 1985

Weight 1986 1987 1988 1989

by 50 1990 1991 1992 1993 40 Finer 1994 1995

% 1996 1997 30 1998 1999 2000 2001 2002 2003 20 2004 2005 2006 2007 10 2008 2009 2010 0 0.01 0.1 1 10 Grain Size Distribution (mm) Figure 4.57 San Marcial Gauge: Annual Bed Material Grain Size Distributions

100 2001 90 2002 2004 80 2005 70

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size Distribution (mm)

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

100

80 1999 70

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 Grain Size Distribution (mm)

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

100 1986 1987 90 1988 1990 80 1992 1993 1994 1997 70 1998 1999 2002 60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 100 Grain Size Distribution (mm)

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

100 1986 90 1987 1988 80 1990 1999 70 2002

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 100 1000 Grain Size Distribution (mm)

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

100 1986 90 1987 1988 80 1990 1993 70 1994 1997 60 1999 Weight

2002

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 100 1000 Grain Size Distribution (mm)

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

100 1986 90 1992 80 1999 2002 70

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 Grain Size Distribution (mm)

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

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.

0.9 San Acacia Gauge San Marcial Gauge 0.8 Subreach 1 (SO‐1641) Subreach 2 (SO‐1683) Subreach 3 (EB‐10) Subreach 4 (EB‐13) 0.7 Subreach 5 (EB‐18) Subreach 6 (EB‐24) (mm) 0.6 Size

0.5 Grain

0.4 Median

0.3

Average 0.2

0.1

0 1965 1975 1985 1995 2005 2015 Year Figure 4.64 Average Median Bed Material Grain Size Temporal Trends

0.3

0.25 Subreach 1 (SO‐1641) (mm) Subreach 2 (SO‐1683) 0.2

Size Subreach 3 (EB‐10)

Subreach 4 (EB‐13)

Grain Subreach 5 (EB‐18) 0.15 Subreach 6 (EB‐24) Linear (Subreach 1 (SO‐1641)) Median 0.1 Linear (Subreach 3 (EB‐10)) Linear (Subreach 4 (EB‐13)) Linear (Subreach 5 (EB‐18)) Average 0.05 Linear (Subreach 6 (EB‐24))

0 1985 1990 1995 2000 2005 2010 Year 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

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.

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.

3.0E+07

2.5E+07

2.0E+07

1.5E+07

1.0E+07

Cumulative Discharge (acre-ft) Discharge Cumulative 5.0E+06

0.0E+00 10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999 Date SA: 1958-1979 SA: 1980-1999 SA: 2000-2005 SM: 1949-1978 SM: 1979-2000 SM: 2001-2005 Linear (SA: 1958-1979) Linear (SA: 1980-1999) Linear (SA: 2000-2005) Linear (SM: 1949-1978)

Figure 4.66 Water Discharge Single Mass Curve (Larsen et al. 2007)

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.

1.8E+08

1.6E+08

1.4E+08

1.2E+08

1.0E+08

8.0E+07

6.0E+07

4.0E+07

2.0E+07

0.0E+00 10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999

Cumulative Suspended Sediment (tons) Sediment Suspended Cumulative SA: 1959-1967 SA: 1968-1975Date 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)

Figure 4.67 Suspended Sediment Discharge Single Mass Curve (Larsen et al. 2007)

Table 4-10 Suspended Sediment Discharge (Larsen et al. 2007) Gauge Years tons/dayR2 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.

1.8E+08

1.6E+08

1.4E+08

1.2E+08

1.0E+08

8.0E+07

6.0E+07

4.0E+07

Cumulative Suspended Sediment (tons) Sediment Suspended Cumulative 2.0E+07

0.0E+00 0.0E+00 5.0E+06 1.0E+07 1.5E+07 2.0E+07 2.5E+07 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)

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

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.

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:

100

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

101

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.

102

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.

103

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.

104

APPENDICES

105

Appendix A: Range Line Survey Dates

106 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

107

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

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 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

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‐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

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‐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

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‐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

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‐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

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‐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

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‐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

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‐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

116

Appendix B: Daily Discharge Hydrographs

117

3000

2500

2000

1500

1000 Discharge (cfs) 500

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.1 1990 Daily Discharge Data

8000 7000 6000 5000 4000 3000

Discharge (cfs) 2000 1000 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.2 1991 Daily Discharge Data

7000

6000

5000

4000

3000

Discharge (cfs) 2000

1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.3 1992 Daily Discharge Data

118

7000 6000 5000 4000 3000

Discharge (cfs) 2000 1000 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia

Figure B.4 1993 Daily Discharge Data

8000

6000

4000

Discharge (cfs) 2000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.5 1994 Daily Discharge Data

7000

6000

5000

4000

3000

Discharge (cfs) 2000

1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.6 1995 Daily Discharge Data

119

6000

5000

4000

3000

2000 Discharge (cfs) 1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.7 1996 Daily Discharge Data

6000

5000

4000

3000

2000 Discharge (cfs) 1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.8 1997 Daily Discharge Data

4000 3500 3000 2500 2000 1500 Discharge (cfs) 1000 500 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.9 1998 Daily Discharge Data

120

6000

5000

4000

3000

2000 Discharge (cfs) 1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.10 1999 Daily Discharge Data

1600 1400 1200 1000 800 600

Discharge (cfs) 400 200 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.11 2000 Daily Discharge Data

3500 3000

2500 2000 1500

Discharge (cfs) 1000 500 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.12 2001 Daily Discharge Data

121

2500

2000

1500

1000 Discharge (cfs) 500

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.13 2002 Daily Discharge Data

2500

2000

1500

1000 Discharge (cfs) 500

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.14 2003 Daily Discharge Data

3500 3000 2500 2000 1500

Discharge (cfs) 1000 500 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B. 15 2004 Daily Discharge Data

122

7000

6000

5000

4000

3000

Discharge (cfs) 2000

1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May San Marcial San Acacia Month Figure B.16 2005 Daily Discharge Data

6000 5000 4000 3000 2000 Discharge (cfs) 1000 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.17 2006 Daily Discharge Data

4000 3500 3000 2500 2000 1500

Discharge (cfs) 1000 500 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.18 2007 Daily Discharge Data

123

6000

5000

4000

3000

2000 Discharge (cfs) 1000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Marcial San Acacia Figure B.19 2008 Daily Discharge Data

4,000

3,000

2,000

Discharge (cfs) 1,000

0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Acacia San Marcial Figure B.20 2009 Daily Discharge Data

4,000 3,500 3,000 2,500 2,000 1,500

Discharge (cfs) 1,000 500 0 Jul Jan Jun Oct Apr Feb Sep Dec Aug Nov Mar May Month San Acacia San Marcial Figure B.21 2010 Daily Discharge Data

124

Appendix C: Dates and Locations of Bed Material Samples

125

Table C.1 Available Bed Material Data at Range Lines Year Range Line 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

126

Appendix D: Dates and Locations of USGS Gauge Bed Material Samples

127

Table D.1: Available Bed Material Data at USGS gauging stations: San Acacia and San Marcial Gauging station Gauging station Year San San Year San San Acacia Marcial Acacia 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

128

Appendix E: Aerial Photograph Survey Dates and Information

129

Table E.1 Aerial Photo Survey Dates and Information

Mean Daily Discharge Notes Date San Acacia San Marcial Scale (1918-2002:from Novak 2006 2005: from ArcGIS metadata) Hand-drafted linens (39 sheets). 1918 No Data No Data 1:12,000 USBR Albuquerque Area Office. Surveyed in 1918. Published in 1922. Black and white photography. USBR 1935 No Data No Data 1:8,00 Albuquerque Area Office. Flown in 1935. Published in 1936. Photo-mosaic. J-Ammann Photogrammetric Engineers, San No Data No Data 1:5,000 1949 Antonio, TX. USBR Albuquerque Area Office. Photo-mosaic. Abram Aerial Survey March 25 cfs 0 cfs 1:4,800 Corp, Lansing, MI. USBR 1962 Albuquerque Area Office. Photo-mosaic. Limbaugh Engineers, April 1972 4 cfs 0 cfs 1:4,800 Inc., Albuquerque, NM. USBR Albuquerque Area Office. Orthophoto. M&I Consulting Engineers, Fort Collins, CO. Aero- March 1900 cfs 1320 cfs 1:4,800 1985 Metric Engineering, Sheboygan, MN. USBR Albuquerque Area Office. Ratio-rectified photo-mosaic. Koogle and Poules Engineering, February 1020 cfs 630 cfs 1:4,800 1992 Albuquerque, NM. USBR Albuquerque Area Office. Ratio-rectified photo-mosaic. Pacific Western Technologies, Ltd., February 770 cfs 560 cfs 1:4,800 2001 Albuquerque, NM. USBR Albuquerque Area Office. Digital ortho-imagery. Pacific Western Technologies, Ltd., March 310 cfs 150 cfs 1:4,800 2002 Albuquerque, NM. USBR Albuquerque Area Office. Digital ortho-imagery. USBR December 628 cfs 439 cfs 1:28,800 2003 Albuquerque Area Office. Date Date Digital ortho-rectified imagery. USBR Winter 1:4,800 2004 Unknown Unknown Albuquerque Area Office. Digital ortho-rectified imagery. Aero- April 2005 2270 cfs 1680 cfs 1:4,800 Metric, Inc., Fort Collins, CO. USBR Albuquerque Area Office. Digital ortho-rectified imagery. Aero- Date Date January 1:4,800 Metric, Inc., Fort Collins, CO. USBR Unknown Unknown 2006 Albuquerque Area Office. Digital ortho-rectified imagery. USBR June 3990 cfs 3460 1:45,720 2008 Albuquerque Area Office. LiDAR Optec 3100 EA LiDAR 3m. Date Date Aero-Metric, Inc., Fort Collins, CO. 2010 Unknown Unknown USBR Albuquerque Area Office.

130

Appendix F: Range Line Cross-Section Plots

131

4500 2009 2008 4498 2007 4496 2006 2005 4494 2004 (ft)

4492 2003 2002 Elevation 4490 2001 1999 4488 1998 4486 1997 0 50 100 150 200 250 300

Station (ft) Figure F.1 SO‐1641 Cross‐Section

4496 2009 2008 4494 2007 2006 2005 4492 2004

(ft) 2003

4490 2002 1999

Elevation 1998 4488 1997 1995 1994 4486 1993 1991 4484 1990 50 150 250 350 450 Station (ft)

Figure F.2 SO‐1652.7 Cross‐Section

132

4492

2006 4490 2002 1999 4488 1998 (ft) 1997 4486 1995

Elevation 1994 4484 1992

4482 1991 1990

4480 750 800 850 900 950 1000 Station (ft) Figure F.3 SO‐1666 Cross‐Section

4492 2009

4490 2008 2007 4488 2005 4486 2004 (ft) 2002 4484 1999

Elevation 4482 1998 1997 4480 1995 4478 1994

4476 600 650 700 750 800 850 900 Station (ft) Figure F.4 SO‐1673 Cross‐Section

133

4492 2009 2008 4490 2007 4488 2006

4486 2004 2003 (ft) 4484 2002 4482 1999

Elevation 1998 4480 1997 4478 1994 1993 4476 1990 4474 0 50 100 150 200 Station (ft) Figure F.5 SO‐1683 Cross‐Section

4484 2009 4482 2008 2007 4480 2006 (ft) 2005 4478 2004

Elevation 2002 4476 1999

4474 1998 1994 4472 50 100 150 200 250 Station (ft)

Figure F.6 SO‐1692 Cross‐Section

134

2009 4484 2008 4482 2007 2006 4480 2005 2004 4478 2002 (ft) 1999 4476 1998 1997 Elevation 4474 1995 1994 4472 1993 1992 4470 1991 1990 4468 0 100 200 300 400 500 Station (ft)

Figure F.7 SO‐1701.3 Cross‐Section

135

4482

4480 2010 2009 4478 2008 2007 4476 2005 2004 4474 2003 (ft) 2002 4472 2001 1999

Elevation 4470 1998 1997 4468 1996 1995 4466 1994 1993 4464 1992 1991 4462 1990 500 600 700 800 900 1000 1988 Station (ft) 1987

Figure F.8 EB‐10 Cross‐Section

4490 2010 2009 2008 4485 2007 2005 4480 2004 2003 4475 2002 2001 (ft) 4470 1999 1998 4465 1997 1996 Elevation 4460 1995 1994 1993 4455 1992 1991 4450 1990 1988 4445 1987 0 500 1000 1500 2000 2500 1986 1980 Station (ft)

Figure F.9 EB‐10 (w/Floodplain) Cross‐Section

136

4476 2009

4474 2008 2007 4472 2005 4470 2004 (ft)

2002 4468 2000

Elevation 4466 1998

4464 1992 1988 4462 1987 4460 1986 1950 2000 2050 2100 2150 2200 2250 2300 Station (ft)

Figure F.10 EB‐13 Cross‐Section

4475

1999/2001 4470 1998

4465 1997 1996 (ft)

4460 1988 1980 Elevation 4455

4450

4445 150 200 250 300 350 400 Station (ft) Figure F.11 EB‐14 Cross‐Section

137

4472

2009 4470 2008 4468 2007 2005 4466

(ft) 2004

4464 2002 2000 Elevation 4462 1999

4460 1998 1997 4458 1994

4456 1993 100 150 200 250 300 350 1992 Station (ft)

Figure F.12 EB‐16 Cross‐Section

4474 2009 2008 4472 2007 4470 2005 4468 2002 2001 4466 1999 (ft) 4464 1998 4462 1997 1996 Elevation 4460 1995 4458 1994 4456 1993 1992 4454 1991 4452 1988 50 100 150 200 250 1980 Station (ft)

Figure F.13 EB‐17 Cross‐Section

138

4468 2009 4466 2008 4464 2007

4462 2003 2004 (ft) 4460 2002 4458 2000 Elevation 4456 1999 1998 4454 1997 4452 1996 4450 600 650 700 750 800 850 900 950 1000 Station (ft) Figure F.14 EB‐18 Cross‐Section

2009 4465 2008 2007 4460 2005 2004 2002 4455 2000 1999 (ft) 1998 4450 1997 1995

Elevation 1994 4445 1993 1992 4440 1991 1990 1988 4435 1980 150 200 250 300 350 400 450 Station (ft)

Figure F.15 EB‐20 Cross‐Section

139

4462 4460 2009 4458 2008 4456 2007 4454 2005 (ft) 2004 4452 2002 4450 2000 Elevation 4448 1999 4446 1998 4444 1997 4442 1996 4440 250 300 350 400 450 500 550 600 Station (ft) Figure F.16 EB‐34 Cross‐Section

4460.00 2007 4455.00 2005 2004 4450.00 2002 2000 4445.00 (ft)

1999 4440.00 1998 1997 Elevation 4435.00 1989 1980 4430.00

4425.00 5800 6000 6200 6400 6600 6800 7000 Station (ft) Figure F.17 EB‐24 Cross‐Section

140

4460 2009 2008 4455 2007 2005 2004 4450 2002 (ft)

2000 1998 4445 1999 Elevation 1996 1995 4440 1994 1993 1989 4435 4750 4800 4850 4900 4950 5000 5050 5100 5150 5200 Station (ft) Figure F.18 EB‐25 Cross‐Section

4455 2009 2008 2007 4450 2005 2004 4445 2002 (ft) 1999 1998 1997

Elevation 4440 1996 1995 4435 1994 1993 1980 4430 4800 4900 5000 5100 5200 5300 Station (ft) Figure F.19 EB‐26 Cross‐Section

141

4452 2002

4450 2000 1999 4448 1998 (ft) 4446 1995 1993 4444

Elevation 1992 4442 1989 1988 4440 1980 4438 4700 4800 4900 5000 5100 5200 5300 Station (ft)

Figure F.20 EB‐27 Cross‐Section

4460 2002 4455 2000

4450 1999 1998 4445 1995 (ft)

1994 4440 1993

Elevation 4435 1992 1989 4430 1988

4425 1980

4420 0 2000 4000 6000 8000 10000 Station (ft)

Figure F.21 EB‐27 (w/Floodplain) Cross‐Section

142

4448 2009 4446 2008 4444 2007 4442 2005

(ft) 4440 2002 4438 2000 4436 Elevation 1999 4434 1998 4432 1995 4430 1992 4428 4980 5030 5080 5130 5180 5230 Station (ft)

Figure F.22 EB‐28 Cross‐Section

4450 2009 4448 2008 4446 2007 4444 2005 4442

(ft) 2002 4440 2000 4438 1999 Elevation 4436 1998 4434 1995 4432 1993 4430 1992 4428 4000 5000 6000 7000 8000 9000 10000 Station (ft)

Figure F.23 EB‐28 (w/Floodplain) Cross‐Section

143

4450 2009 2008 2007 4445 2005 2004 4440 (ft)

2002 2000 4435 1999 Elevation 1997

4430 1995 1993 1989 4425 5000 5100 5200 5300 5400 5500 5600 Station (ft)

Figure F.24 EB‐29 Cross‐Section

2009 4455 2008 2007 4450 2005

4445 2004 (ft)

2002 4440 2000 1999 Elevation 4435 1997 1995 4430 1993

4425 1989 3750 4250 4750 5250 5750 6250 6750 7250 Station (ft)

Figure F.25 EB‐29 (w/Floodplain) Cross‐Section

144

4440 2009 4438 2008 2007 4436 2006 4434 2005 (ft)

4432 2004 2002

Elevation 4430 2000 4428 1997 1995 4426 1993 4424 1992 3590 3690 3790 3890 3990 Station (ft)

Figure F.26 EB‐30 Cross‐Section

4442 2009 2008 4440 2007 4438 2006

4436 2005 2004 (ft) 4434 2002 4432 2000 Elevation 4430 1999 1997 4428 1995 4426 1993 4424 1992 2000 3000 4000 5000 6000 7000 8000 9000 10000 Station (ft)

Figure F.27 EB‐30 (w/Floodplain) Cross‐Section

145

4436 2009

4434 2007 2006 4432 2005 4430 2004 (ft) 2002 4428 1999

Elevation 4426 1997 1995 4424 1993 4422 1989

4420 5200 5300 5400 5500 5600 5700 5800 Station (ft)

Figure F.28 EB‐32 Cross‐Section

4438 2009 4436 2007

4434 2006 2005 4432 2004 (ft) 4430 2002 4428 1999

Elevation 1997 4426 1995 4424 1993 4422 1989 4420 3750 4250 4750 5250 5750 6250 Station (ft)

Figure F.29 EB‐32 (w/Floodplain) Cross‐Section

146

4434

4432

4430 2009

4428 2008 (ft) 2007 4426 2005

Elevation 4424 2004

4422

4420

4418 5100 5200 5300 5400 5500 5600 5700 5800 Station (ft)

Figure F.30 EB‐33 Cross‐Section

4432

4430

4428

4426 2009 (ft)

2008 4424 2007 4422 2005 Elevation 4420 2004 4418

4416

4414 3500 3600 3700 3800 3900 4000 4100 Station (ft) Figure F.31 EB‐35 Cross‐Section

147

4430

4428

4426

4424 2010

(ft) 2009 4422 2008 4420 2007 Elevation 4418 2005

4416 2004 2003 4414

4412 5400 5500 5600 5700 5800 Station (ft)

Figure F.32 EB‐36 Cross‐Section

EB‐37 4430

4428

4426

4424 2010 4422

(ft) 2009

4420 2008

4418 2007 Elevation 2005 4416 2004 4414 2003 4412

4410 3000 3100 3200 3300 3400 3500 3600 3700 3800 Station (ft)

Figure F.33 EB‐37 Cross‐Section

148

4428

4426

4424 2010 2009 4422 2008 (ft)

4420 2007 4418 2006

Elevation 2005 4416 2004 4414 2003 4412

4410 0 100 200 300 400 500 Station (ft)

Figure F.34 EB‐37.5 Cross‐Section

4428 4426 4424 4422 2009 2008

(ft) 4420

4418 2007 4416 2006 Elevation 4414 2005 4412 4410 4408 2800 2900 3000 3100 3200 3300 3400 Station (ft)

Figure F.35 EB‐38 Cross‐Section

149

4428 4426 4424 2010 4422 2009 4420 2008 (ft) 4418 2007 4416 2006 Elevation 4414 Perpindicular 4412 2004 4410 2003 4408 4406 ‐100 0 100 200 300 400 Station (ft)

Figure F.36 EB‐39 Cross‐Section

4425

4420 2010

4415 2009 (ft)

2008 2007 4410 Elevation 2004 2003 4405

4400 4550 4600 4650 4700 4750 4800 4850 4900 Station (ft)

Figure F.37 EB‐40 Cross‐Section

150

4430

4425

2010 4420 2009 (ft)

2008 4415 2007

Elevation 2004 4410 2003

4405

4400 ‐50 0 50 100 150 200 250 300 350 Station (ft)

Figure F.38 EB‐40.5 Cross‐Section

4416

4414

4412

4410 2009 2008 (ft) 4408 2007 4406 2004 Elevation 4404

4402

4400

4398 0 50 100 150 200 250 300 Station (ft)

Figure F.39 EB‐41 Cross‐Section

151

4416

4414

4412 2010 4410 2009 (ft)

4408 2008 4406 2007

Elevation 2004 4404 2003 4402

4400

4398 ‐100 ‐50 0 50 100 150 200 250 300 350 Station (ft)

Figure F.40 EB‐42 Cross‐Section

4420

4415

2010 4410 2009 (ft) 2008 4405 2007 Elevation 4400 2004 2003 4395

4390 ‐100 0 100 200 300 400 Station (ft)

Figure F.41 EB‐43 Cross‐Section

152

4414

4412

4410

4408 2010

4406 2009 (ft)

2008 4404 2007 4402 Elevation 2004 4400 2003 4398

4396

4394 ‐100 ‐50 0 50 100 150 200 250 300 Station (ft)

Figure F.42 EB‐44 Cross‐Section

4420

4415

2010 4410 2009 (ft)

2008 4405 2007 Elevation 4400 2004 2003

4395

4390 ‐100 0 100 200 300 400 Station (ft)

Figure F.43 EB‐45 Cross‐Section

153

4416

4414

4412

4410 (ft)

2009 4408 2008 4406 2007 Elevation 4404

4402

4400

4398 0 50 100 150 200 250 300 Station (ft)

Figure F.44 EB‐46 Cross‐Section

4420

4415

2010 4410 2009 (ft)

2008 4405 2007

Elevation 2004 4400 2003

4395

4390 0 50 100 150 200 250 300 Station (ft)

Figure F.45 EB‐47 Cross‐Section

154

4410

4405 2010

4400 2009 (ft)

2008 2007 4395 Elevation 2004 2003 4390

4385 ‐100 0 100 200 300 400 Station (ft)

Figure F.46 EB‐48 Cross‐Section

4420

4415

4410 2010 2009 (ft) 4405 2008

4400 2007 Elevation 2004 4395 2003

4390

4385 0 100 200 300 400 500 600 Station (ft)

Figure F.47 EB‐49 Cross‐Section

155

4410

4405

4400 2009 (ft)

2008 2007

Elevation 4395 2006

4390

4385 0 50 100 150 200 250 300 350 400 450 Station (ft)

Figure F.48 EB‐50 Cross‐Section

156

Appendix G: Change in Thalweg Elevation vs. River Mile Plots

157

3.0

2.5 (ft) 2.0

1.5 Thalweg

1.0 Change

0.5

0.0 61 59 57 55 53 51 49 47 45 River Mile

Wave 4 1990‐1992

Figure G.1 1990‐1992 Thalweg Change

y = 4.1023x ‐ 253.93 1 R² = 1 0 (ft)

‐1

‐2 Thalweg

‐3

‐4 Change ‐5

‐6

‐7 63 62.5 62 61.5 61 60.5 60 River Mile

Wave 4 1991‐1992 Linear (Wave 4 1991‐1992)

Figure G.2 1991‐1992 Thalweg Change

158

6 (ft) y = ‐0.0992x2 + 11.97x ‐ 358.74 R² = 0.1623 4 Thalweg

in 2

0 Change

‐2

‐4 70 65 60 55 50 45 River Mile

Wave 4 1992‐1993 Poly. (Wave 4 1992‐1993)

Figure G.3 1992‐1993 Thalweg Change

4.0 3.5 3.0 2.5 (ft)

2.0 1.5 Thalweg 2

y = 0.0008x + 0.0616x ‐ 6.2002 1.0 in

R² = 0.285 0.5

0.0 Change ‐0.5 ‐1.0 ‐1.5 70 65 60 55 50 45 River Mile

Wave 4 1993‐1994 Poly. (Wave 4 1993‐1994)

Figure G.4 1993‐1994 Thalweg Change

159

7 6 5

y = ‐0.0179x + 2.1771x ‐ 64.765 (ft)

4 R² = 0.0227 3

2 Thalweg

in 1 0 Change ‐1 ‐2 ‐3 70 65 60 55 50 45 River Mile

Wave 4 1994‐1995 Poly. (Wave 4 1994‐1995)

Figure G.5 1994‐1995 Thalweg Change

2 (ft) 1

0 Thalweg

‐1

‐2 Change y = 0.0683x2 ‐ 8.6959x + 276.42 ‐3 R² = 0.0933 ‐4

‐5 70 65 60 55 50 45 River Mile

Wave 4 1995‐1997 Wave 3/4 Transition 1995‐1997 Poly. (Wave 4 1995‐1997)

Figure G.6 1995‐1997 Thalweg Change

160

3 (ft)

1 Thalweg

in y = 0.274x2 ‐ 36.539x + 1219.1 R² = 0.2054 0 Change ‐1

‐2

‐3 70 65 60 55 50 45 River Mile

Wave 4 1997‐1998 Wave 3/4 Transition 1997‐1998 Poly. (Wave 4 1997‐1998)

Figure G.7 1997‐1998 Thalweg Change

2 (ft)

1 Thalweg

in 0

‐1 y = 0.0553x2 ‐ 7.4734x + 252.98 Change R² = 0.08 ‐2

‐3 75 70 65 60 55 50 45 River Mile

Wave 3 1998‐1999 Wave 4 1998‐1999 Wave 3/4 Transition 1998‐1999 Poly. (Wave 4 1998‐1999)

Figure G.8 1998‐1999 Thalweg Change

161

1 (ft)

‐1 Thalweg

in y = 0.0309x2 ‐ 4.2878x + 148.76 ‐2 R² = 0.0832

‐3 Change

y = ‐2.2408x + 120.61 ‐4 R² = 1 ‐5 75 70 65 60 55 50 45 River Mile Wave 3 1999‐2002 Wave 4 1999‐2002 Wave 3/4 Transition 1999‐2002 Linear (Wave 3 1999‐2002) Poly. (Wave 4 1999‐2002)

Figure G.9 1999‐2002 Thalweg Change

5 y = ‐0.0127x2 + 1.6943x ‐ 54.451 R² = 0.1822 4 3 (ft) 2

1 Thalweg

‐1 Change y = 0.885x2 ‐ 96.405x + 2622.5 ‐2 R² = 0.6265 ‐3

‐4 80 75 70 65 60 55 50 45 River Mile Wave 3 2003‐2004 Wave 4 2003‐2004 Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004)

Figure G.10 2002‐2003 Thalweg Change

162

0 (ft)

‐2 y = 0.0402x2 ‐ 5.7666x + 205.93

‐4 Thalweg R² = 0.3261 in

y = ‐0.009x2 + 0.963x ‐ 27.412 ‐6 R² = 0.0059 ‐8 Change

‐10

‐12 80 75 70 65 60 55 50 45 River Mile Wave 3 2003‐2004 Wave 4 2003‐2004 Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004) Poly. (Wave 4 2003‐2004)

Figure G.11 2003‐2004 Thalweg Change

5 y = 0.1767x2 ‐ 21.993x + 676.35 (ft) R² = 0.5992 825.83

741.44 0 +

‐ Thalweg

0.4563 23.548x ‐5 32.295x 0.8947

‐ =

+ 2 =

2 R² R² Change ‐10 0.1679x

0.3485x =

‐ y =

y ‐15 80 75 70 65 60 55 50 45 Wave 2 2004‐2007 River Mile 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)

Figure G. 12 2004‐2007 Thalweg Change

163

2.0 y = ‐0.0069x2 + 0.7283x ‐ 18.716 R² = 0.0311 1.5 1.0

0.5 (ft) y = ‐0.0064x2 + 0.864x ‐ 30.281 R² = 0.1006 0.0

‐0.5 Thalweg

in ‐1.0 ‐1.5 Change ‐2.0 ‐2.5 ‐3.0 80 75 70 65 60 55 50 45 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)

Figure G.13 2007‐2008 Thalweg Change

4 y = ‐0.2133x2 + 20.808x ‐ 505.26 R² = 0.3004 3 (ft)

y = 0.0078x2 ‐ 0.9912x + 30.863 2 R² = 0.0929

1 Thalweg

‐1 Change

‐2

‐3 80 75 70 65 60 55 50 45 River Mile Wave 2 2008‐2009 Wave 2/3 Transitional 2008‐2009 Wave 3 2008‐2009 Poly. (Wave 2 2008‐2009) Poly. (Wave 3 2008‐2009)

Figure G.14 2008‐2009 Thalweg Change

164

3 (ft) 2 y = 0.0363x2 ‐ 4.054x + 112.8 R² = 0.5874

1 Elevation

0 Thalweg

y = 0.074x2 ‐ 9.3306x + 293.35 ‐1 R² = 0.8984 Change

‐2

‐3 70 65 60 55 50 45 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)

Figure G.15 2009‐2010 Thalweg Change

165

Appendix H: Bed Material Grain Size Distribution Plots

166

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.1 SO‐1641 2001 Grain Size Distribution

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 Grain Size (mm)

Figure H.2 SO‐1641 2002 Grain Size Distribution

167

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.3 SO‐1641 2004 Grain Size Distribution

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 Grain Size (mm)

Figure H.4 SO‐1641 2005 Grain Size Distribution

168

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.5 SO‐1683 1999 Grain Size Distribution

169

100

60 Weight

by 50

Finer

40 % 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.6 EB‐10 1986 Grain Size Distribution

170

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 100 Grain Size (mm)

Figure H.7 EB‐10 1987 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.8 EB‐10 1988 Grain Size Distribution

171

100

60 Weight

by 50

Finer 40

% 30

0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.9 EB‐10 1990 Grain Size Distribution

172

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.10 EB‐10 1992 Grain Size Distribution

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.11 EB‐10 1993 Grain Size Distribution

173

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 100 Grain Size (mm)

Figure H.12 EB‐10 1994 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H. 13 EB‐10 1997 Grain Size Distribution

174

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.14 EB‐10 1998 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.15 EB‐10 1999 Grain Size Distribution

175

100

60 Weight

by 50

Finer

40 %

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.16 EB‐10 2002 Grain Size Distribution

176

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.17 EB‐13 1986 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.18 EB‐13 1987 Grain Size Distribution

177

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.19 EB‐13 1988 Grain Size Distribution

100 90 80 70 60 Weight

by 50

40 Finer

% 30 20 10 0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.20 EB‐13 1990 Grain Size Distribution

178

100

90 80 70

60 Weight

by 50

40 Finer

% 30 20

10 0 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.21 EB‐13 1999 Grain Size Distribution

100

60 Weight

by 50

Finer

40 % 30

0 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.22 EB‐13 2002 Grain Size Distribution

179

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.23 EB‐18 1986 Grain Size Distribution

100

60 Weight

by 50

Finer 40

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.24 EB‐18 1987 Grain Size Distribution

180

100

90 80 70

60 Weight

by 50

40 Finer

% 30 20

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.25 EB‐18 1988 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.26 EB‐18 1990 Grain Size Distribution

181

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.27 EB‐18 1993 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.28 EB‐18 1994 Grain Size Distribution

182

100

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.29 EB‐18 1997 Grain Size Distribution

100

60 Weight

by 50

Finer

40 % 30

0 0.001 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.30 EB‐18 1999 Grain Size Distribution

183

100

60 Weight

by 50

Finer

40 % 30

0 0.01 0.1 1 10 100 1000 Grain Size (mm)

Figure H.31 EB‐18 2002 Grain Size Distribution

184

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.32 EB‐24 1986 Grain Size Distribution

100 90

80 70 60 Weight

by 50

40 Finer

% 30 20 10 0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.33 EB‐24 1992 Grain Size Distribution

185

100

60 Weight

by 50

40 Finer

% 30

0 0.001 0.01 0.1 1 10 Grain Size (mm)

Figure H.34 EB‐24 1999 Grain Size Distribution

100

60 Weight

by 50

40 Finer

% 30

0 0.01 0.1 1 10 Grain Size (mm)

Figure H.35 EB‐24 2002 Grain Size Distribution

186