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THESIS
GEOMORPHIC ANALYSIS OF THE MIDDLE RIO GRANDE –
ELEPHANT BUTTE REACH, NEW MEXICO
Submitted by
Tracy Elizabeth Owen
Department of Civil and Environmental Engineering
In partial fulfillment of the requirements
For the Degree of Master of Science
Colorado State University
Fort Collins, Colorado
Spring 2012
Master’s Committee: Advisor: Pierre Julien Christopher Thornton Sara Rathburn
Copyright by Tracy Elizabeth Owen 2012
All Rights Reserved
ii
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.
- iii -
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.
- iv -
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.
v
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
vi
LIST OF FIGURES Figure 1.1 Map of the Rio Grande Watershed (MRGBI 2009) ......................................... 1 Figure 1.2 Historical Timeline of Middle Rio Grande (Modified After Makar 2011, Pers. Comm.) ............................................................................................................................... 4 Figure 1.3: Rio Grande Silvery Minnow and Southwestern Flycatcher ............................ 5 Figure 1.4 Aerial View of Tiffany Plug in 2005 ................................................................ 6 Figure 2.1: Location of the Elephant Butte Reach from Google Maps ............................. 7 Figure 2.2 Profile of Elephant Butte Reach Widths and Thalweg at Agg/Deg Lines ....... 9 Figure 2.3 2008 Aerial Photo of Subreach 1 .................................................................... 11 Figure 2.4 2008 Aerial Photo of Subreach 2 .................................................................... 12 Figure 2.5 2008 Aerial Photo of Subreach 3 .................................................................... 13 Figure 2.6 2008 Aerial Photo of Subreach 4 .................................................................... 14 Figure 2.7 2008 Aerial Photo of Subreach 5 .................................................................... 15 Figure 2.8 2008 Aerial Photo of Subreach 6 .................................................................... 16 Figure 2.9 2008 Aerial Photo of Elephant Butte Reservoir ............................................. 17 Figure 2.10 Subreach Definitions and Agg/Deg Line Locations (2008 GIS Elephant Butte Reach Delineation Shown) ...................................................................................... 19 Figure 2.11 Subreach Definitions and Range Line Locations (2008 GIS Elephant Butte Reach Delineation Shown) ............................................................................................... 20 Figure 2.12 Location of Gauges ....................................................................................... 22 Figure 2.13: Daily Discharge of the Rio Grande in 1999 ................................................. 23 Figure 2.14 Comparison of Annual Peak Flows at San Acacia and San Marcial Gauges24 Figure 2.15: Annual Suspended Sediment Yield at San Acacia and San Marcial Gauges25 Figure 3.1 Elephant Butte Reservoir Level Time Series ................................................. 27 Figure 3.2 Elephant Butte Reservoir Historical Sediment Survey Longitudinal Profile (Reclamation, 2008) .......................................................................................................... 29 Figure 4.1 Channel Planforms from Aerial Photography ................................................ 31 Figure 4.2 Subreach 1 Channel Planforms from Aerial Photography ............................. 32 Figure 4.3 Subreach 2 Channel Planforms from Aerial Photography ............................. 32 Figure 4.4 Subreach 3 Channel Planforms from Aerial Photography ............................. 33 Figure 4.5 Subreach 4 Channel Planforms from Aerial Photography ............................. 34 Figure 4.6 Subreach 5 Channel Planforms from Aerial Photography ............................. 35 Figure 4.7 Subreach 6 Channel Planforms from Aerial Photography ............................. 36 Figure 4.8 Channel Widths from GIS (1918 - 2010) ....................................................... 38 Figure 4.9 Channel Widths from GIS (1962 - 2010) ....................................................... 39 Figure 4.10 Subreach Lengths and Total Lengths as Measured From GIS Data ............ 40 Figure 4.11 Temporal Sinuosity Trends .......................................................................... 43 Figure 4.12 Thalweg Elevation Profile From Agg/Deg Surveys ..................................... 46 Figure 4.13 Bed Slope from Agg/Deg Surveys ............................................................... 47 Figure 4.14 Change in Channel Thalweg Elevation from Agg/Deg Surveys .................. 49 Figure 4.15 Change in Channel Thalweg Elevation (1962 – 1972) Based on Agg/Deg Surveys .............................................................................................................................. 50 Figure 4.16 Change in Channel Thalweg Elevation (1972 – 1992) Based on Agg/Deg Surveys .............................................................................................................................. 50
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Figure 4.17 Change in Channel Thalweg Elevation from 1992 – 2002 Based on Agg/Deg Surveys .............................................................................................................................. 51 Figure 4.18 Change in Channel Thalweg Elevation from 1962 – 2002 Based on Agg/Deg Surveys .............................................................................................................................. 51 Figure 4.19 Temporal Trend in Thalweg Elevation at Agg/Deg Lines ........................... 54 Figure 4.20 Rate of Channel Aggradation between 1972 and 1992 ................................ 55 Figure 4.21 Thalweg Elevation Profile From Range Line Survey Data .......................... 57 Figure 4.22 Subreach 1 Average Channel Thalweg Slope: Temporal Trend .................. 58 Figure 4.23 Subreach 2 Average Channel Thalweg Slope: Temporal Trend .................. 58 Figure 4.24 Subreach 3 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.25 Subreach 4 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.26 Subreach 5 Average Channel Thalweg Slope: Temporal Trend .................. 59 Figure 4.27 Subreach 6 Average Channel Thalweg Slope: Temporal Trend .................. 60 Figure 4.28 Subreach 1: SO-1641 Surveyed Cross-Sections ........................................... 62 Figure 4.29 Subreach 2: SO-1683 Surveyed Cross-Sections ........................................... 62 Figure 4.30 Subreach 3: EB-10 Surveyed Cross-Sections............................................... 63 Figure 4.31 Subreach 3: EB-10 (w/Floodplain) Surveyed Cross-Sections...................... 63 Figure 4.32 Subreach 4: EB-13 Surveyed Cross-Sections............................................... 64 Figure 4.33 Subreach 5: EB-20 Surveyed Cross-Sections............................................... 64 Figure 4.34 Subreach 6: EB-29 Surveyed Cross-Sections............................................... 65 Figure 4.35 Subreach 6: EB-29 (w/Floodplain) Surveyed Cross-Sections...................... 65 Figure 4.36 Subreach 6: EB-41 Surveyed Cross-Sections............................................... 66 Figure 4.37 Change in Thalweg Elevation at Range Lines (1980 – 2010) ...................... 67 Figure 4.38 Change in Average Channel Bed Elevation at Range Lines (1988-2010) ... 73 Figure 4.39 Change in Channel Thalweg Elevations at Range Lines (1988-2010) ......... 74 Figure 4.40 Magnitude of Aggradation and Degradation at Range Lines (2003-2004) .. 76 Figure 4.41 Magnitude of Aggradation and Degradation at River Miles (2003-2004) .... 76 Figure 4.42 Magnitude of Aggradation and Degradation at Range Lines (2004-2005) .. 77 Figure 4.43 Magnitude of Aggradation and Degradation at River Miles (2004 to 2005) 78 Figure 4.44 Change in Thalweg Elevation from 2004 to 2009........................................ 78 Figure 4.45 Magnitude of Degradation from 2004 to 2009 ............................................. 79 Figure 4.46 Magnitude of Aggradation from 2004-2009 ................................................ 80 Figure 4.47 Reservoir Water Surface Elevation Change from 2009-2010 Resulting in Wave 1 Channel Degradation ........................................................................................... 81 Figure 4.48 Rate of Wave 1 Propagation Upstream ........................................................ 81 Figure 4.49 Reservoir Water Surface Elevation Change from 2004-2009 Resulting in Wave 2 Channel Aggradation ........................................................................................... 82 Figure 4.50 Rate of Wave 2 Propagation Upstream ........................................................ 83 Figure 4.51 Reservoir Water Surface Elevation Change from 1997-2004 Resulting in Wave 3 Channel Degradation ........................................................................................... 84 Figure 4.52 Rate of Wave 3 Propagation Upstream ........................................................ 84 Figure 4.53 Reservoir Water Surface Elevation Change from 1990-1995 Resulting in Wave 4 Channel Aggradation ........................................................................................... 85 Figure 4.54 Rate of Wave 4 Propagation Upstream ........................................................ 86 Figure 4.55 EB-10 1992 Bed Material Grain Size Distributions ..................................... 88 Figure 4.56 San Acacia Gauge: Annual Bed Material Grain Size Distributions ............. 89
- viii -
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
ix
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
- x -
LIST OF APPENDICES
Appendix A: Range Line Survey Dates ......................................................................... 106 Appendix B: Daily Discharge Hydrographs……………………………………….…..117 Appendix C: Dates and Locations of Bed Material Samples………………………….125 Appendix D: Dates and Locations of USGS Gauge Bed Material Samples…………..127 Appendix E: Aerial Photograph Survey Dates and Information………………………129 Appendix F: Range Line Cross-Section Plots…………………………………………131 Appendix G: Change in Thalweg Elevation vs. River Mile Plots……………………..157 Appendix H: Bed Material Grain Size Distribution Plots……………………………..166
1
SECTION 1: INTRODUCTION
The Rio Grande is about 1890 miles long (3040 kilometers), making it one of the
longest rivers in the United States (Kammerer 1990). The headwaters of the Rio Grande
begin in southern Colorado near Camby Mountain. The river then flows south through
New Mexico, and then becomes a dividing border between Texas and Mexico. For
purposes of this report, the Middle Rio Grande is defined as the 180 mile stretch of the
Rio Grande River that extends from Cochiti Dam to the narrows of Elephant Butte
Reservoir. Figure 1.1 provides a map of the Rio Grande.
Figure 1.1 Map of the Rio Grande Watershed (MRGBI 2009)
Human activities have had an impact on the river for thousands of years. However,
it was not until the late 14th century when the Spanish settled near the Rio Grande that
humans began to dramatically influence the river (Finch 2004). Since then, the water
2
discharge, sediment discharge, and cross sectional geometry have changed as a result of
human colonization. Devastating floods were very common on the Rio Grande up until
the early 1900’s when large dams and reservoirs were constructed. In addition, large
stretches of the river were channelized. These projects helped regulate the water and
prevent extensive flooding. Mining, logging and grazing in the beginning of the 20th
century destroyed much of the vegetation, resulting in dramatic erosion and a subsequent
increase in the sediment load in the river (Scurlock 1998). The increased erosion and
sediment load caused a l3% loss of capacity within Elephant Butte Reservoir by the mid
1930’s (Clark 1987). The increased sediment and decreased flow also lead to severe
aggradation along the river. Between 1880 and 1924, the bed of the river rose 9 feet at
the San Marcial gauging station (Scurlock 1998).
1.1 Habitat and Endangered Species
Exotic plants like the Russian olive, Russian thistle, Siberian elm, tree-of-heaven,
and tamarisk, whose roots added extra shear strength to the sand near the river, were
introduced to try to keep the river more stable (Mussetter Engineering 2001). However,
due to the addition of these foreign plants, riparian vegetation, such as native cottonwood
trees and willow trees, have declined (Finch 2004, Earick 1999). New animals such as
the barbary sheep, ibex, and oryx were also introduced to the area (Finch 2004). Human
influences have caused several native species of animals that use the Rio Grande as their
habitat, such as the Rio Grande silvery minnow, Rio Grande cutthroat trout, southwestern
willow flycatcher, and whooping crane, to teeter on the brink of extinction. Human
impacts, coupled with natural events such as droughts, have also led to increased soil
erosion along much of the Middle Rio Grande (Scurlock 1998).
3
In order to resolve many problems regarding the Rio Grande, the Middle Rio
Grande Conservancy District (MRGCD) was formed in 1923. The purpose of the
MRGCD was to “provide flood protection from the Rio Grande, and make the
surrounding area hospitable for urbanization and agriculture” (MRGCD 2006). Between
1923 and 1935, one storage dam, four diversion dams, and 817 miles of drainage and
irrigation channels had been constructed by the MRGCD (MRGCD 2006). The work
completed by the MRGCD was successful in controlling the river’s floods, and the
Bureau of Reclamation and the Army Corps of Engineers continued to repair and update
the structures established by the MRGCD. Several new levees and Cochiti dam have
been constructed to combat flooding and sedimentation problems along the river
(MRGCD 2006). A historical timeline of the Middle Rio Grande is shown in Figure 1.2.
These dams and levees were able to control the flow of the river and altered the
seasonal flooding patterns that used to exist. The magnitude of the floods within the Rio
Grande was greatly reduced due to the construction of these structures. These floods
were essential for several species’ reproduction habitats. The Rio Grande silvery
minnow, shown in Figure 1.3, used the swampy flooded terrain as the ideal reproduction
habitat (Earick 1999; Borgan 2006). The Rio Grande silvery minnow used to flourish
within the river from Espanola, NM to the Gulf of Mexico, however, now it is present in
only 5% of its former range (Earick 1999; MRGESA 2006a). Today, about 95% of the
Rio Grande silvery minnow population is concentrated below the San Acacia diversion
dam in the San Acacia Reach of the Middle Rio Grande. It no longer exists below the
Elephant Butte Reservoir, and was placed on the endangered species list in 1994
(MRGCD 2002).
4
Figure 1.2 Historical Timeline of Middle Rio Grande (Modified After Makar 2011, Pers. Comm.)
1865 1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
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5
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
6
and prevents water from reaching Elephant Butte Reservoir due to increased infiltration
and evapotranspiration induced by the plugs. The current practice with sediment plugs
by the United States Bureau of Reclamation (Reclamation) is to excavate a pilot channel
through the plug to encourage water to flow again and re-channelize; this method is
expensive and time consuming. Sediment plugs occur at the location of a constriction or
channel aggradation (Burroughs 2011). As aggradation within the Elephant Butte Reach
is known to contribute to a decrease in channel capacity (Reclamation 2007), it is
important to understand the influences of Elephant Butte Reservoir levels on channel
aggradation/degradation in order to decrease the potential for future sediment plug
formation.
Figure 1.4 Aerial View of Tiffany Plug in 2005
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Apache Plug formed just upstream of the Elephant Butte Reach. Further understanding
of the influences of Elephant Butte Reservoir levels on channel aggradation/degradation
will provide insight into proper river management practices in order to decrease the
potential for sediment plug formation.
The objectives of this study include the following:
1. Quantify temporal changes in channel widths and sinuosity from 1935 to 2010.
2. Quantify change in channel slope temporally.
3. Quantify rate of aggradation/degradation in response to a change in base-level
(i.e., change in reservoir water surface elevation).
4. Quantify aggradation/degradation wave propagation upstream.
5. Quantify spatial and temporal trends in bed material grain size.
2.2 Subreach Definition
To thoroughly evaluate the significant changes in the study area, the reach was
divided into six subreaches. The subreach definitions were determined by initial
assessments of the channel widths and planforms from aerial photos and channel slope.
To determine the subreach divisions, the active channel widths, as measured from
edge of vegetation to edge of vegetation, were plotted for the entire Elephant Butte Reach
for years 1962, 1972, 1992, and 2002. The thalweg at each Agg/Deg-line was also
plotted for each set of years, as shown on Figure 2.2. The subreaches were chosen based
on the 2002 dataset because of the abundance of both GIS and Agg/Deg Cross-section
data during this year, but subreaches were confirmed using the 1962, 1972, and 1992
datasets.
Figurre 2.2 Profile off Elephant Butte
9
e Reach Widths and Thalweg att Agg/Deg Lines
10
There are no major slope distinctions along the Elephant Butte Reach in 2002;
therefore, subreaches were primarily selected based on width trends. Subreaches 1, 3,
and 5 tend to be wider than Subreaches 2, and 4 (based on 2002 data). Subreach 6 is a
transitional subreach, which is sometimes river, and sometimes reservoir, depending on
the level of Elephant Butte Reservoir. The first subreach begins at the south boundary of
the Bosque del Apache NWR, Agg/Deg 1637, and extends to Agg/Deg 1672. The
second subreach begins at Agg/Deg 1672 and ends at Agg/Deg 1696. The third subreach
begins at Agg/Deg 1696 and ends at Agg/Deg 1728. The fourth subreach begins at
Agg/Deg 1728 and ends at Agg/Deg 1751. The fifth subreach begins at Agg/Deg 1751
and ends at Agg/Deg 1794. The sixth, and last, subreach begins at Agg/Deg 1794 and
extends to Elephant Butte Reservoir.
Figure 2.3 through Figure 2.9 show the 2008 aerial photographs of the study area
and its subreaches. Notice the low-flow conveyance channel located on the west bank of
the river. The previous temporary outfall of the low-flow conveyance channel was at
Agg/Deg 1794, which marks the end of Subreach 5 and the beginning of Subreach 6.
The Black Mesa geologic feature is located east of Subreach 3. Levee construction along
the West side of the river has prevented the river from excessive meandering. The
Tiffany Plug location is shown on Figure 2.4; the Bosque del Apache Plug is located
about 7 miles upstream of the study reach and is, therefore, not shown.
11
Figure 2.3 2008 Aerial Photo of Subreach 1
12
Figure 2.4 2008 Aerial Photo of Subreach 2
Tiffany Plug (1991, 1995, 2005)
13
Figure 2.5 2008 Aerial Photo of Subreach 3
14
Figure 2.6 2008 Aerial Photo of Subreach 4
15
Figure 2.7 2008 Aerial Photo of Subreach 5
16
Figure 2.8 2008 Aerial Photo of Subreach 6
17
Figure 2.9 2008 Aerial Photo of Elephant Butte Reservoir
18
2.3 Available Data
The data used in this study was received from a number of different agencies:
United States Bureau of Reclamation (Reclamation), National Oceanic and Atmospheric
Administration (NOAA), the United States Geological Survey (USGS), and the Middle
Rio Grande database compiled at Colorado State University for Reclamation.
2.3.1 Survey Lines and Dates
Cross-sectional survey data was collected by Reclamation using both
Aggradation/Degradation line (Agg/Deg-line) surveys; Socorro range line (SO-line), and
Elephant Butte range line (EB-line) surveys. Agg/Deg-line elevations were derived using
photogrammetry. The Agg/Deg-lines are spaced about 500 feet apart and were surveyed
in 1962, 1972, 1992, and 2002. This information was used for the hydraulic and GIS
analyses to follow. Figure 2.10 shows the entire Elephant Butte Reach with each of the
six defined subreaches, and the Agg/Deg-lines with the 2008 GIS Elephant Butte Reach
delineation.
The range lines (SO-lines and EB-lines) were field surveyed by Reclamation
beginning in 1980. These surveys are more detailed than the channel cross-sections that
were developed from the aerial photographs (i.e., Agg/Deg lines). The spacing of these
surveys is greater than that of the Agg/Deg lines, but the field surveyed cross section
locations typically coincide with Agg/Deg line locations. Range line survey data was
available from 1980 to 2010 from Reclamation. 18 SO-lines and 102 EB-lines are
located within the reach. Figure 2.11 shows the location of the SO- and EB-lines and
Appendix A provides the dates of available survey data at each SO- and EB-line.
19
Figure 2.10 Subreach Definitions and Agg/Deg Line Locations (2008 GIS Elephant Butte Reach Delineation Shown)
Agg/Deg 1637
Agg/Deg 1672 Agg/Deg 1696
Agg/Deg 1728
Agg/Deg 1751
Agg/Deg 1794
Tiffany Plug Agg/Deg 1683 (1991, 1995, 2005)
20
Figure 2.11 Subreach Definitions and Range Line Locations (2008 GIS Elephant Butte
Reach Delineation Shown)
Agg/Deg 1637
Agg/Deg 1672 Agg/Deg 1696
Agg/Deg 1728
Agg/Deg 1751
Agg/Deg 1794
Tiffany Plug Agg/Deg 1683 (1991 – 1995, 2005
21
2.3.2 Discharge Data
Mean daily discharge data was primarily used from two USGS gauges: the San
Marcial gauge (08358400, primary gauge), located in the upstream end of the study
reach, and the San Acacia gauge (08354900, secondary gauge), located approximately 44
miles upstream of the study reach. The gauge numbers and their dates of available
discharge data are shown in Table 2-1.
Table 2-1: Available Daily Discharge Data USGS Gauging Station USGS Gauge Number Dates Available
RG at San Marcial 8358400 1949- current
RG at San Acacia 8354900 1958-current
The Elephant Butte Dam gauge (8361000), located approximately 34 miles
downstream of the Elephant Butte Reach, measures regulated reservoir releases, and was
therefore not useful in this study. The San Antonio gauge (8355490), located
approximately 25 miles upstream of the Elephant Butte reach, only contains discharge
data for recent years (2005 – Sep 2008), and therefore was not considered. An additional
gauge is located at the Escondida Bridge, approximately 16 miles upstream of the
Elephant Butte reach. However, this gauge only records real-time discharge and not the
historical data needed for this study. Figure 2.12 shows the locations of the nearby
gauges.
22
Figure 2.12 Location of Gauges
An example hydrograph for the San Acacia and San Marcial gauges for the year
1999 is shown in Figure 2.13. The hydrograph demonstrates that there are typically two
distinct peaks on the Middle Rio Grande. The first peak occurs between mid-May until
the end of June and the second peak occurs in August. As demonstrated in Figure 2.13,
23
significant evapotranspiration losses from the river largely contribute to the typically
lower discharge measurements at the San Marcial Gauge, compared to the San Acacia
Gauge (Baird, D., Pers. Comm.). Additional daily discharge graphs from the years 1990-
2010 are available in Appendix B.
Figure 2.13: Daily Discharge of the Rio Grande in 1999
The annual peak flow information for the San Acacia and San Marcial gauges was
obtained from the USGS website. Figure 2.14 displays a comparison of the peak flows at
the San Acacia Gauge and the San Marcial Gauge.
24
Figure 2.14 Comparison of Annual Peak Flows at San Acacia and San Marcial Gauges
2.3.3 Bed Material
Bed material data was collected by Reclamation from 1986-2007 at SO- and EB-
range lines. The dates and locations of the collected bed material data are provided in
Appendix C. Additional bed material data was also obtained from the USGS gauging
stations at San Acacia, located approximately 44 miles upstream of Elephant Butte
Reach, and San Marcial, located within the Elephant Butte Reach
(http://nwis.waterdata.usgs.gov). The dates and locations of the data recorded are
provided in Appendix D.
2.3.4 Suspended Sediment Data
As part of this study, the suspended sediment data was used from the Escondida
Reach Report (Larsen et al. 2007). This was used since no new sediment data is available
on the USGS website for the San Acacia and San Marcial guages. Daily suspended
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
1959
1961
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
Annual Peak Discharge
(cfs)
Year
San Acacia
San Marcial
25
sediment data was used for this analysis. Figure 2.15 shows the annual suspended
sediment load at each gauge. Continuous suspended sediment data was not always
available for all parameters at each gauge. A blank year indicates that complete sediment
data was not available for that year.
Figure 2.15: Annual Suspended Sediment Yield at San Acacia and San Marcial Gauges
Table 2-2 gives the dates of continuous, available data at each gauge.
Table 2-2: Available Suspended Sediment Data
USGS GAUGING STATION DATES
RG at San Marcial
Oct. 1956 - July 1962 Sep. 1962 - Aug. 1966 Oct. 1966 - Sep. 1989 Oct. 1991 - Sep. 1995
RG at San Acacia
Jan 1959 - Sep. 1959 Jan 1960 - Sep. 1961
July 1961 April 1962 - July 1962 Aug 1962 - Sep. 1962
March 1963 - Sep. 1996
0
2000000
4000000
6000000
8000000
10000000
12000000
1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994
Year
San Marcial San Acacia
26
SECTION 3: RESERVOIR LEVEL ANALYSIS
3.1.1 Reservoir Level Analysis
A reservoir level analysis was performed for the Elephant Butte Reservoir,
located at the downstream end of the Elephant Butte Reach. Figure 3.1 shows the
Elephant Butte Reservoir level time series. Elephant Butte Dam construction began in
1908 and was completed in 1916, with water storage operations beginning in January of
1915 (Reclamation, 2008). The maximum water surface elevation (WSE) of Elephant
Butte Reservoir is 4407.0 ft. Since its inception, the WSE behind Elephant Butte Dam
has varied more than 150 ft in elevation. The reservoir was not completely filled until
1942, at which point the reservoir level dropped about 150 ft between 1942 and 1954,
due to a drought which lasted from about 1942 to about 1974 (Figure 1.2). The low flow
conveyance channel (LFCC), which was built to hydraulically efficiently transport water
to Elephant Butte Reservoir and runs the entire length of Elephant Butte Reach, was in
operation by 1955 and operated until 1986. With the operation of the LFCC during the
drought, the reservoir WSE averaged between El 4331 and El 4404. By about 1977 the
reservoir began to fill again until it was full, or essentially full, from 1985 to 1999, at
which point another drought impacted the reservoir level, which decreased to an average
WSE of about 4340 ft in 2010.
27
Figure 3.1 Elephant Butte Reservoir Level Time Series
4200
4250
4300
4350
4400
4450
1915
1920
1925
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
WSE (ft)
Annual Mean WSE Annual Max WSE Annual Min WSE
DROUGHT DROUGHT
LFCC OPERATION
28
Figure 3.2 shows the historical sediment survey longitudinal profile with reservoir
sediment surveys completed in 1915, 1988, 1999, and 2007. Comparing the survey
between 1915 and 1988, up to 50 ft of aggradation has occurred within Elephant Butte
Reservoir. The decrease in longitudinal profile elevation from 1999 to 2007 can be
attributed to the consolidation of the deposited sediment during the low reservoir levels in
response to a second drought from 1999 to 2005.
In 1915, when the reservoir had just begun to fill, had the reservoir been at its
maximum WSE, then the upstream extent of the reservoir would have reached RL 10 (or
the upstream end of Subreach 3). By 2007, the upstream extent of the reservoir at its
maximum WSE would have been about RL 20 (or the upstream end of Subreach 6). This
means the maximum upstream extent of the reservoir would have shifted downstream
approximately 6 miles. The level of the reservoir impacts Elephant Butte Reach, due to
sediment deposition as a result of an increased base-level. The longitudinal profile of
Elephant Butte Reach is base-level controlled; with an increase in base-level, the channel
adjusts vertically by way of sediment deposition, resulting in channel aggradation.
29
Figure 3.2 Elephant Butte Reservoir Historical Sediment Survey Longitudinal Profile (Reclamation, 2008)
MAX WSE
AVG. WSE
2010 AVGWSE
SR3 SR4 SR5 SR
30
SECTION 4: CHANNEL ANALYSIS
4.1 Channel Planform Analysis from Aerial Photographs
Using ArcGIS and aerial photographs supplied by Reclamation, the study reach’s
active channel was delineated for 1918, 1935, 1949, 1962, 1972, 1985, 1992, 2001, 2002,
2003, 2004, 2005, 2006, 2008 and 2010. These active channel delineations will be
referred to as planforms for purposes of this report; the active channel corresponds to the
area bounded by established vegetation. Aerial photographs were not available during
1985, and a delineation provided by Reclamation was used; the 2010 active channel was
delineated using a Digital Elevation Model (DEM). See Appendix E for survey dates and
additional information about the aerial photographs.
The active channel width was measured at each Agg/Deg line using the delineated
planforms. A mean width value was then obtained for each subreach and for the overall
reach using a weighted average method. Finally, the sinuosity was computed.
4.1.1 Channel Delineation
Figure 4.1 shows the channel planforms that were delineated in ArcGIS. Figure 4.2
through Figure 4.7 show magnified versions of Figure 4.1. Based on visual observations,
the overall channel has narrowed and changed from a multithread channel to a primarily
single-thread channel. Subreaches 1, 2, 5, and 6 have straightened and narrowed
primarily between 1918 and 1962, and have remained relatively unchanged since then.
The multithread characteristics of the river observed from 1928 to 1949 are not repeated
after the recession of the reservoir from 2001 to 2003, because Reclamation regularly
excavated pilot channels within Subreach 6 (Baird, D., Pers. Comm.).
31
Figure 4.1 Channel Planforms from Aerial Photography
32
Figure 4.2 Subreach 1 Channel Planforms from Aerial Photography
Figure 4.3 Subreach 2 Channel Planforms from Aerial Photography
33
Figure 4.4 Subreach 3 Channel Planforms from Aerial Photography
34
Figure 4.5 Subreach 4 Channel Planforms from Aerial Photography
35
Figure 4.6 Subreach 5 Channel Planforms from Aerial Photography
36
Figure 4.7 Subreach 6 Channel Planforms from Aerial Photography
37
Note that the difference between the first set of delineations, 1918-1949, is 31
years, the second set of delineations, 1962-1985, is 23 years, the third set of delineations,
1992-2002 is 10 years, and the fourth set of delineations, 2003-2010 is only 7 years.
Based on a qualitative visual analysis, the first delineation comparison covers the longest
time period and shows the most change and the last delineation comparison shows the
shortest time period with the least change. Nevertheless, narrowing and straightening of
the reach is observed over time.
4.1.2 Channel Widths from GIS
The active channel width corresponds to the non-vegetated channel. The active
channel planforms were delineated from aerial photographs using this criterion, and
widths were measured at every Agg/Deg line and/or Range line for which the river
intersected. A distance-dependent, weighted average method was used to calculate the
average width at each subreach and for the total reach.
In general, Figure 4.8 illustrates a decreasing trend in the width over time for all
of the subreaches from 1935 to 1972. Subreaches 1 and 2 experienced an increase in
average width in 1949 due to the existence of a multithread channel; Subreach 1
increased from about 940 ft to about 1100 ft, and Subreach 2 increased from about 700 ft
to about 1700 ft. The decrease in channel width from 1935 to 1972 (on average, about
275 ft) may be attributed to lower than average discharges, a decrease in base-level, or a
combination of the two. The lower than average discharges and decrease in base-level
are both results of the drought, which lasted from 1942 to 1979. From 1935 to 2010, the
channel width decreased according to the following second order polynomial equation:
y = 0.2353x2 - 936.54x + 931904
38
Where, x is the year, and y is the average channel width (ft).
Figure 4.8 Channel Widths from GIS (1918 - 2010)
As seen in Figure 4.9, between 1972 and 1985, the average channel width
increased, on average, about 60 ft and the base-level increased by up to 125 ft. Between
1985 and 2000, the base-level remained relatively unchanged, changing no more than 27
ft, and the average channel width, on average, changed no more than 30 ft. Between
2000 and 2004, the base-level decreased by up to 100 ft, and the average channel width
increased 26 ft from 2001 to 2003 and decreased 45 ft from 2003 to 2004. The large
decrease in channel width between 2003 and 2004 was due to mechanical excavation of
narrow pilot channels by Reclamation (Baird, D. Pers. Comm.). The base-level increased
by about 50 ft between 2004 and 2010, and the average channel width increased about 55
ft between 2004 and 2006, and decreased about 55 ft between 2006 and 2010. In general,
y = 0.2353x2 ‐ 936.54x + 931904R² = 0.9299
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Average
Width (ft)
YearSubreach 1 Subreach 2 Subreach 3
Subreach 4 Subreach 5 Subreach 6
Total (SR 1‐5) Total (SR 1‐6) Poly. (Total (SR 1‐6))
39
based on this dataset, the channel width tends to increase with a rise in base-level, and
decrease with a drop in base-level.
Figure 4.9 Channel Widths from GIS (1962 - 2010)
4.1.3 Sinuosity
Sinuosity of the entire Elephant Butte Reach, as well as the six subreaches, was
computed using aerial photographs in ArcGIS. The sinuosity was determined by using
the following equation:
Where S is the sinuosity, Lc is the length of the channel, and Lv is the length of the
valley.
The length of the channel, and each of the six subreaches, was measured along the
river thalweg, an estimated delineation from aerial photographs and channel delineations.
The thalweg delineation was approximate and accuracy was, in some cases, further
0
50
100
150
200
250
300
1960 1970 1980 1990 2000 2010
Average
Width (ft)
Year
Subreach 1 Subreach 2 Subreach 3 Subreach 4
Subreach 5 Subreach 6 Total (SR 1‐5) Total (SR 1‐6)
Lv
LcS
40
limited by the clarity and quality of the aerial photographs. The 1985 and 1918
planforms delineated by Reclamation were used to estimate the length of the channel and
the length of the valley. For each year, the length of the valley was measured as the
straight-line distance between the upstream and downstream extents of the reach and
subreaches, as dictated by major geologic features, such as the Black Mesa. The channel
length measurements are plotted in Figure 4.10 and presented in Table 4-1. The channel
length decreased about 0.0126 miles/year between 1935 and 2010.
Figure 4.10 Subreach Lengths and Total Lengths as Measured From GIS Data
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
1910 1930 1950 1970 1990 2010
Chan
nel Length (miles)
YearSubreach 1 Subreach 2 Subreach 3Subreach 4 Subreach 5 Subreach 6Total Reach SB (1‐5) Total Reach SB (1‐6)
41
Table 4-1 Subreach Length and Total Length Values as Measured From GIS Data
Reach Measured Lengths (mi)
1918 1935 1949 1962 1972 1985 1992 2001 2002 2003 2004 2005 2006 2008 2010
Subreach 1 3.46 3.92 4.07 3.52 3.56 3.30 3.38 3.34 3.34 3.42 3.34 3.30 3.27 3.32
Subreach 2 1.51 1.54 1.59 2.39 2.21 2.25 2.27 2.26 2.28 2.31 2.28 2.27 2.31 2.27
Subreach 3 1.56 3.87 3.54 3.25 3.24 3.10 3.18 3.18 3.21 3.17 3.19 3.17 3.14 3.26 3.20
Subreach 4 2.04 2.12 2.14 2.13 2.13 2.13 2.13 2.13 2.13 2.15 2.15 2.13 2.14 2.11
Subreach 5 4.74 4.97 4.21 4.26 4.13 4.36 4.24 4.30 4.27 4.38 4.32 4.23 4.36 4.26
Subreach 6 17.39 16.11 18.12 16.14 5.56 2.04 2.03 7.67 16.73 16.93 16.48 16.48 17.11 0.79
Total Reach SR (1‐5) 6.52 16.10 16.29 15.52 15.41 14.92 15.33 15.15 15.26 9.57 15.45 15.25 15.07 15.35 15.16
Total Reach SR (1‐6) 6.52 33.48 32.40 33.64 31.55 20.48 17.37 17.18 22.93 26.31 32.38 31.73 31.55 32.46 15.96
Agg/Deg Start 1637 1637 1637 1637 1637 1637 1637 1637 1637 1692 1637 1637 1637 1637 1637
Agg/Deg End 1708 1962 1948 1962 1958 1849 1811 1811 1875 1962 1962 1960 1960 1962 1962
42
Figure 4.11 shows the sinuosity for the Elephant Butte Reach and each of the
subreaches, values are presented in Table 4-2. From 1918 to 1935 sinuosity increased for
the entire channel; though the overall sinuosity remains low, less than 1.3, Subreach 1 is
more sinuous than Subreach 2 by about 15 percent. There is not enough planform
delineated in Subreach 3 in 1918 to be considered representative of the entire subreach,
so this portion was disregarded. No planform data exists below Subreach 3 in 1918, so
sinuosity data is unavailable. From 1935 to 1949, the sinuosity for the entire channel,
and for each subreach, decreased by less than 6 percent, except Subreach 5, which
increased about by about 4 percent. Subreach 2 remained less sinuous, by about 15
percent on average and up to 20 percent, than the remaining Subreaches, which ranged in
sinuosity from 1.18 to 1.29. From 1949 to 1962, the sinuosity of Subreaches 1, 3, 4, and
5 decreased between 10 and 20 percent, while Subreaches 2 and 6 increased between 5
and 10 percent. From 1962 to 2010 sinuosity tends to increase and decrease repetitively
between a range of 1.0 and 1.15 for Subreaches 1 through 5, while Subreach 6 tends to
have a higher sinuosity than the other subreaches from 1962 to 2010 and ranges from
1.12 to 1.24. The higher sinuosities observed in Subreach 6 in the mid-2000s is because
Reclamation mechanically introduced a sinuous channel to Subreach 6 by excavating a
pilot channel after the lowering of Elephant Butte Reservoir (Baird, D., Pers. Comm.). In
general, it can be said that this channel has experienced relatively low sinuosity (less than
1.25) since 1962. From 1935 to 2010, the channel sinuosity can be described using the
following second order polynomial:
y = 6E-05x2 - 0.2196x + 219.57
Where, x is year, and y is channel sinuosity (ft/ft).
43
Figure 4.11 Temporal Sinuosity Trends
y = 6E‐05x2 ‐ 0.2196x + 219.57R² = 0.8398
1
1.05
1.1
1.15
1.2
1.25
1.3
1915
1920
1925
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
Sinuosity
Year
Subreach 1 Subreach 2 Subreach 3
Subreach 4 Subreach 5 Subreach 6
Total Reach (SR 1‐5) Total Reach (SR 1‐6) Poly. (Total Reach (SR 1‐5))
44
Table 4-2 Sinuosity Values
Reach Year
1918 1935 1949 1962 1972 1985 1992 2001 2002 2003 2004 2005 2006 2008 2010
Subreach 1 1.118 1.222 1.180 1.039 1.110 1.027 1.052 1.017 1.037 1.062 1.039 1.003 1.050 1.067
Subreach 2 1.032 1.054 1.014 1.106 1.013 1.013 1.075 1.024 1.010 1.002 1.025 1.055 1.091 1.073
Subreach 3 1.049 1.259 1.182 1.054 1.004 1.016 1.052 1.017 1.134 1.035 1.008 1.061 1.013 1.086 1.066
Subreach 4 ‐‐ 1.293 1.280 1.026 1.034 1.033 1.031 1.010 1.047 1.018 1.012 1.057 1.019 1.100 1.084
Subreach 5 ‐‐ 1.233 1.280 1.062 1.069 1.028 1.124 1.087 1.113 1.104 1.145 1.109 1.076 1.128 1.101
Subreach 6 ‐‐ 1.194 1.181 1.246 1.137 1.225 1.158 1.182 1.121 1.149 1.162 1.145 1.145 1.176
Total Reach (SR 1‐5) ‐‐ 1.213 1.200 1.078 1.081 1.037 1.079 1.063 1.080 1.095 1.068 1.083 1.077 1.064
Total Reach (SR 1‐6) 1.108 1.210 1.202 1.176 1.121 1.098 1.093 1.089 1.098 1.140 1.135 1.119 1.117 1.146 1.064
Agg/Deg Start 1637 1637 1637 1637 1637 1637 1637 1637 1637 1692 1637 1637 1637 1637 1637
Agg/Deg End 1708 1962 1948 1962 1958 1849 1811 1811 1875 1962 1962 1960 1960 1962 1794
45
4.2 Aggradation and Degradation from Agg/Deg Surveys
4.2.1 Channel Thalweg Profile from Agg/Deg Surveys
The channel thalweg profile from the Agg/Deg survey data was utilized to
demonstrate how the minimum elevation and slope of the reach has changed over time, as
shown in Figure 4.12. The average bed slope for each subreach and for the entire reach
was determined by first plotting the thalweg profile versus downstream distance, as
measured along the estimated thalweg in GIS, and fitting a linear regression trendline to
each subreach. The slope of the linear regression line was considered the average bed
slope of the respective subreach. A linear regression trendline was also fit to the total
reach thalweg profile, from which the slope of the regression trendline was considered
the average bed slope of the total reach. This method was used for 1962, 1972, 1992, and
2002. The average bed slope for each subreach and for the entire reach is shown in
Figure 4.13.
438
440
442
444
446
448
450
Elevation (ft)
80
00
20
40
60
80
00
0
SR1
Figure 4
20,000 4
D
SR2
4.12 Thalweg E
40,000 60
Distance Downstre
SR3 SR4
46
Elevation Profil
0,000 80,
eam of South Boun
SR5 4
e From Agg/De
,000 100,
ndary of Bosque d
SR6
eg Surveys
000 120,0
del Apache NWR (ft
000 140,00
t)
1962 Th
1972 Th
1992 Th
2002 Th
00 160,00
alweg Profile
alweg Profile
alweg Profile
alweg Profile
0
47
Figure 4.13 Bed Slope from Agg/Deg Surveys
Between the years 1962 and 1972, the bed slope increased between 15 and 30
percent for Subreaches 1, 2, and 3; bed slope decreased 40 and 20 percent for Subreaches
4 and 5, respectively. From 1972 to 1992, bed slope decreased between 10 and 45
percent for all subreaches. From 1992 to 2002, Subreach 2 increased 10 percent and
Subreach 6 increased fourfold; all other subreaches decrease between 3 and 15 percent.
The overall decrease in bed slope along the entire reach suggests aggradation has
occurred between 1962 and 2002. The decrease in bed slope from 1972 to 1992 in
Subreach 6 could be caused by the increased Elephant Butte Reservoir level (base-level),
which increased by about 130 ft. The fourfold increase in bed slope from 1992 to 2002 in
Subreach 6 could be due to the drop base-level, which dropped about 85 feet between
1992 and 2002. The longitudinal profile of Elephant Butte Reach is base-level
controlled; with an increase in base-level, the channel adjusts vertically by way of
sediment deposition, resulting in channel aggradation and a decrease in channel slope. It
is important to note, however, that these trends could also be due to the lack of data in
Subreach 6, especially in 1972 and 1992, which could skew the calculated bed slope
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
0.0009
1960 1970 1980 1990 2000 2010
Bed Slope
Year
Subreach 1Subreach 2Subreach 3Subreach 4Subreach 5Subreach 6Total Reach (1‐5)
48
value to be inaccurate. Table 4-3 shows the average values of the channel slope for each
subreach and the overall reach.
Table 4-3 Average Bed Slope from Agg/Deg Surveys Subreach Agg/Deg Lines 1962 1972 1992 2002
1 1637 ‐ 1672 0.000509 0.000675 0.000523 0.000441
2 1672 ‐ 1696 0.000823 0.000830 0.000480 0.000532
3 1696 ‐ 1728 0.000699 0.000797 0.000564 0.000538
4 1728 ‐ 1751 0.000855 0.000537 0.000498 0.000417
5 1751 ‐ 1794 0.000730 0.000600 0.000550 0.000532
6 1794 ‐ 1875 0.000370 0.000370 0.000205 0.000819
Total (1‐6) 1637 ‐ 1875 0.000594 0.000684 0.000535 0.000495
Total (1‐5) 1637 ‐ 1794 0.000710 0.000720 0.000562 0.000481
4.2.2 Change in Channel Thalweg Elevation from Agg/Deg Surveys
A weighted average of the change in thalweg elevation was computed for the
entire reach, as well as each subreach, for each year of available Agg/Deg survey data.
The average change in thalweg elevation was then compared between years to determine
the change in elevation over time. Figure 4.14 shows the average change in thalweg
elevation for each subreach, and the overall reach over time; the tabulated values are
displayed in Table 4-4. The results show that the average change in the channel thalweg
elevation decreased between 0.7 and 3.5 ft from 1962 to 1972 for all subreaches except
Subreaches 5 and 6; Subreaches 5 and 6 increased in elevation by about 0.2 to 0.4 ft. The
average change in channel thalweg elevation has been increasing since 1972. An
increase in channel thalweg elevation indicates aggradation, whereas a decrease indicates
degradation. The entire reach has been aggrading since 1972.
49
Figure 4.14 Change in Channel Thalweg Elevation from Agg/Deg Surveys
Table 4-4 Change in Channel Thalweg Elevation Values from Agg/Deg Surveys
Δ Channel Thalweg Elevation (ft)
Weighted Average 1962 ‐ 1972 1972 ‐ 1992 1992 ‐ 2002 1962 ‐ 2002
U/S OF EB REACH 0.79 3.36 1.76 5.91
SUBREACH 1 ‐0.67 5.73 1.85 6.93
SUBREACH 2 ‐2.65 8.33 3.67 9.39
SUBREACH 3 ‐3.45 11.57 4.20 12.31
SUBREACH 4 ‐3.53 14.07 5.88 16.39
SUBREACH 5 0.43 15.06 7.21 22.50
SUBREACH 6 0.26 17.68 6.53 20.01
TOTAL REACH ‐1.33 11.42 4.79 15.95
Analyses were done using the Agg/Deg data to show the change in thalweg
elevation at each Agg/Deg line (see Figure 4.15 to view the changes from 1962-1972,
Figure 4.16 for 1972-1992, Figure 4.17 for 1992-2002, and Figure 4.18 for 1962-2002).
Recall that Agg/Deg data does not have surveys available at every Agg/Deg line during
the years 1962, 1972, and 1992, therefore the plots only show the Agg/Deg lines for
‐5
0
5
10
15
20
25
1962 ‐ 1972 1972 ‐ 1992 1992 ‐ 2002 1962 ‐ 2002
Chan
ge in
Chan
nel Thalweg Elevation (ft)
SUBREACH 1 SUBREACH 2 SUBREACH 3 SUBREACH 4
SUBREACH 5 SUBREACH 6 TOTAL REACH
50
which data exists. Table 4-5 shows the average, maximum and minimum changes in
channel thalweg elevation with their respective Agg/Deg line for each group of years.
Figure 4.15 Change in Channel Thalweg Elevation (1962 – 1972) Based on Agg/Deg
Surveys
Figure 4.16 Change in Channel Thalweg Elevation (1972 – 1992) Based on Agg/Deg
Surveys
‐6
‐5
‐4
‐3
‐2
‐1
0
1
2
3
4
1637
1645
1652
1662
1670
1678
1688
1695
1707
1733
1750
1777
1792
1804
1820
Chan
ge in
Chan
nel Invert Elevation (ft)
Agg/Deg #
1962 ‐ 1972
0
5
10
15
20
25
1637
1645
1652
1662
1670
1678
1688
1695
1707
1733
1750
1762
1786
1798
1809
Chan
ge in
Chan
nel Invert Elevation (ft)
Agg/Deg #
1972 ‐ 1992
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
51
Figure 4.17 Change in Channel Thalweg Elevation from 1992 – 2002 Based on Agg/Deg
Surveys
Figure 4.18 Change in Channel Thalweg Elevation from 1962 – 2002 Based on Agg/Deg
Surveys
0
1
2
3
4
5
6
7
8
9
1637
1645
1652
1662
1670
1678
1688
1695
1703
1731
1747
1751
1777
1792
1804
Chan
ge in
Chan
nel Invert Elevation (ft)
Agg/Deg #
1992 ‐ 2002
0
5
10
15
20
25
30
1637
1645
1652
1662
1670
1678
1688
1695
1703
1731
1747
1762
1786
1798
1809
1827
1848
1875
Chan
ge in
Chan
nel Invert Elevation (ft)
Agg/Deg #
1962 ‐ 2002
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
52
Table 4-5 Average, Maximum and Minimum Change in Channel Thalweg Elevation Based on Agg/Deg Surveys
Year: 1962 ‐ 1972 1972 ‐ 1992 1992 ‐ 2002 1962 ‐ 2002
Δ Thalweg El (ft)
Agg/Deg #
Δ Thalweg El (ft)
Agg/Deg #
Δ Thalweg El (ft)
Agg/Deg #
Δ Thalweg El (ft)
Agg/Deg #
Subreach 1
Max 1.30 1641 7.70 1652 3.14 1673.0 8.34 1662
Min ‐3.10 1670 3.50 1645 0.84 1652.0 4.95 1645
Average ‐0.67 5.73 1.85 6.93
Subreach 2
Max ‐1.30 1692 10.60 1695 4.35 1683.0 11.28 1692
Min ‐4.30 1678 7.10 1678 2.58 1695.0 7.00 1678
Average ‐2.65 8.33 3.67 9.39
Subreach 3
Max ‐2.40 1707 13.90 1731 4.99 1731.0 14.19 1731
Min ‐4.70 1731 10.20 1707 3.68 1707.0 11.47 1707
Average ‐3.45 11.57 4.20 12.31
Subreach 4
Max ‐1.70 1747 14.60 1751 6.36 1747.0 18.66 1747
Min ‐5.50 1733 14.00 1747 5.53 1733.0 14.13 1733
Average ‐3.53 14.07 5.88 16.39
Subreach 5
Max 2.60 1762 16.30 1777 7.92 1777.0 23.78 1762
Min ‐1.20 1777 14.50 1762 6.68 1762.0 23.02 1777
Average 0.43 15.06 7.21 22.50
Subreach 6
Max 1.40 1820 19.80 1798.00 7.80 1804.0 24.30 1809
Min ‐0.90 1798 16.70 1804 5.20 1798.0 11.50 1875
Average 0.26 17.68 6.53 20.01
Total Reach
Max 2.60 1762 19.80 1798 7.92 1777.0 24.30 1809
Min ‐5.50 1733 3.50 1645 0.84 1652.0 4.95 1645
Average ‐1.33 11.42 4.79 15.95
53
From 1962 to 1972 degradation occurred in all subreaches. The upstream half of
Subreach 1 aggraded from 1962 to 1972, along with five sections in Subreach 5 and
Subreach 6. Since 1972, the channel has been aggrading along all subreaches. From
1962 to 2002, a maximum aggradation of 24.30 feet has occurred at Agg/Deg 1809, at the
downstream end of the reach, with a minimum aggradation of 4.95 ft at Agg/Deg 1645, at
the upstream end of the reach. From Figure 4.18, it is clear that aggradation increases in
the downstream direction. Within Subreach 6, however, there tends to be a decrease in
aggradation in the downstream direction. The overall aggradation of the reach is due to
the increase in base-level between 1972 and 1985, at which point the base-level changed
less than 30 ft between 1985 and 2000. Between 1992 and 2002, aggradation continued
in the upstream portions of the reach, still in response to the increase in base-level
between 1972 and 1985. However, the downstream portion of Subreach 6 (Agg/Deg
1827 to Agg/Deg 1875) did not aggrade as much as the upstream portion of Subreach 6,
because of the drop in base-level of about 80 ft between 2000 and 2002.
Figure 4.19 shows the change in the thalweg elevation at selected Agg/Deg lines
from 1962 – 1992. Only Agg/Deg lines with sufficient years of sample data were plotted.
It can be inferred from this plot that as the reservoir level increases, the channel thalweg
elevation increases at each Agg/Deg line, and that the increase in channel thalweg
elevation is more pronounced in the downstream direction, closer to the reservoir.
54
Figure 4.19 Temporal Trend in Thalweg Elevation at Agg/Deg Lines
4320
4340
4360
4380
4400
4420
4440
4460
4480
4500
1950 1960 1970 1980 1990 2000 2010 2020
Elevation (ft)
Year
1625
1628
1633
1637
1641
1645
1648
1652
1658
1662
1666
1670
1673
1678
1683
1688
1692
1695
1703
1707
1731
1733
1747
1750
1751
1762
1777
1786
1792
1798
1804
1809
1820
1827
1835
1848
1856
1864
1875
1883
1887
1894
1908
EB Res
55
Figure 4.20 shows the rate of aggradation between 1972 and 1992 at each
Agg/Deg line for which there is data. A second order polynomial trendline was fit to the
data. For an increase in base-level (Reservoir WSE) of up to 13.4 ft/yr, the following
second order polynomial describes the rate of aggradation from 1972 to 1992 for the
Elephant Butte Reach:
Rate of Aggradation = -0.0014x2 + 0.0649x + 0.1832
Where, x is the distance in miles downstream of Agg/Deg 1637 (or the upstream end of
Elephant Butte Reach).
Figure 4.20 Rate of Channel Aggradation between 1972 and 1992
4.3 Aggradation and Degradation from Range Line Surveys
4.3.1 Channel Thalweg Profile from Range Line Surveys
Figure 4.21 shows the thalweg elevation profile of the entire reach. Only years
with enough range line survey data were plotted. Not all years are presented, because the
lines on the plot would be too dense to see trends if all the years were plotted, so certain
years were chosen to represent changes. The thalweg elevation profile shows a general
y = ‐0.0014x2 + 0.0649x + 0.1832R² = 0.9334
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20
Rate of Aggradation (ft/yr)
Miles Downstream from Agg/Deg 1637
56
trend of varying aggradation and degradation over time. One of the most notable trends
from this plot is the flattening of the channel slope from 2004 to 2009 in the downstream
half of the reach, which is due to the aggradation induced by a rise in base-level from
2004 to 2009. Also noteworthy is the significant aggradation in 2005 upstream of EB-10
(Agg/Deg 1707). The Tiffany Plug formed in 2005 at SO-1683 (Agg/Deg 1683), just
upstream of EB-10, which can be seen in the profile. In 1995, severe degradation can be
seen downstream of SO-1683 (Agg/Deg 1683), and virtually no change at SO-1683, even
though a sediment plug had formed upstream of SO-1683 in 1995. This is likely
explained by the timing of the survey, which seems to have occurred after the sediment
plug was mechanically removed by Reclamation.
57
Figure 4.21 Thalweg Elevation Profile From Range Line Survey Data
4380
4400
4420
4440
4460
4480
4500
1600 1650 1700 1750 1800 1850 1900 1950 2000
Thalweg Elevation (ft)
Agg/Deg Line
1988
1991
1994
1995
1999
2004
2005
2009
Tiffany Plug, 2005, SO-1683 (Agg/Deg 1683)
Elephant Butte Reservoir Max WSE, El 4454 (Project Datum)
SR 2SR 1 SR 3 SR 4 SR 5 SR 6
Agg
/Deg
163
7
Agg
/Deg
167
2
Agg
/Deg
169
6
Agg
/Deg
172
8
Agg
/Deg
175
1
Agg
/Deg
179
4
58
The channel thalweg profile from the range line survey data was utilized to
demonstrate how the minimum elevation and slope of the reach has changed over time.
The average bed slope for each subreach was determined by first plotting the thalweg
profile versus river mile, and then fitting a linear regression trendline to each subreach.
The slope of the linear regression line was considered the average bed slope of the
respective subreach. This method was used for all years for which range line survey data
was available. The average channel thalweg slopes for each Subreach 1 through
Subreach 6 are presented in Figure 4.22 through Figure 4.27, respectively. Table 4-6
presents the values of the average channel thalweg slopes for each subreach.
Figure 4.22 Subreach 1 Average Channel Thalweg Slope: Temporal Trend
Figure 4.23 Subreach 2 Average Channel Thalweg Slope: Temporal Trend
0
1
2
3
4
5
6
7
8
1985 1990 1995 2000 2005 2010
Avg Thalweg Slope (ft/m
i)
Year
0
1
2
3
4
5
6
7
8
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
Avg Thalweg Slope (ft/m
i)
Year
59
Figure 4.24 Subreach 3 Average Channel Thalweg Slope: Temporal Trend
Figure 4.25 Subreach 4 Average Channel Thalweg Slope: Temporal Trend
Figure 4.26 Subreach 5 Average Channel Thalweg Slope: Temporal Trend
0
1
2
3
4
5
6
1985 1990 1995 2000 2005 2010
Avg Thalweg Slope (ft/m
i)
Year
0
1
2
3
4
5
6
1975 1980 1985 1990 1995 2000 2005 2010 2015
Avg Thalweg Slope (ft/m
i)
Year
0
1
2
3
4
5
6
1985 1990 1995 2000 2005 2010 2015
Avg Thalweg Slope (ft/m
i)
Year
60
Figure 4.27 Subreach 6 Average Channel Thalweg Slope: Temporal Trend
Table 4-6 Average Channel Thalweg Slopes for Subreaches 1 through 6
Channel Thalweg Slope (ft/mi)
Year SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
2010 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 3.3058 3.9285 2.7865
2009 3.819 2.5421 14.345 3.191 4.7156 2.8378
2008 2.3551 3.2975 2.1491 3.6395 4.2458 2.9771
2007 1.5905 3.215 3.4676 3.6845 4.1554 3.1211
2006 3.3542 3.0568 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 3.4361
2005 0.1714 5.4088 0.2545 3.7804 4.8768 3.4627
2004 2.1619 3.6974 4.9293 3.7213 3.1183 4.1643
2003 0.7829 3.3695 2.9158 3.6717 2.9102 4.2159
2002 2.7047 2.8284 1.9506 3.99 2.5376 4.2891
2001 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 2.3077
2000 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 5.0078 2.9984 2.7499
1999 3.3741 2.7141 1.147 5.0078 2.9984 3.2324
1998 4.1195 2.5813 4.1364 3.7546 3.2622 3.567
1997 2.3206 4.9367 4.3273 4.2125 1.6368 3.4796
1996 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 2.5278 2.1193 4.2534
1995 6.8687 7.3103 ‐6 4.3334 1.949 4.2116
1994 4.3434 2.2019 3.0909 4.3229 3.9316 3.5435
1993 2.303 ‐‐‐‐ 4.7273 4.0989 2.6817 3.6434
1992 4.1414 ‐‐‐‐ 3.6364 3.053 2.5 4.6557
1991 6.4848 ‐‐‐‐ 2.5273 4.4329 5.5 ‐‐‐‐
1990 3.6869 ‐‐‐‐ 2.9455 3.3211 2.8516 4.1049
1989 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 3.9154
1988 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 4.4677 3.0734 1.7771
1987 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 5.1043 ‐‐‐‐ ‐‐‐‐
1986 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 5.1482 ‐‐‐‐ ‐‐‐‐
1980 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 3.8767 ‐‐‐‐ ‐‐‐‐
0
1
2
3
4
5
1985 1990 1995 2000 2005 2010 2015
Avg Thalweg Slope (ft/m
i)
Year
61
Subreaches 1 through 5 don’t appear to have a trend relating average channel
thalweg slope to time. Subreach 6, however, has a decreasing trend from 1995 to 2001
and again from 2002 to 2010. From 1995 to 2001, the channel slope decreases at a rate
of 0.32 ft/mi/yr; from 2002 to 2010, the channel slope decreases at a rate of 0.21 ft/mi/yr.
From 1995 to 2001, the base-level drops about 35 ft, while Subreach 6’s slope decreases.
From 2001-2004, the base-level drops another 60 ft, and from 2004 to 2009, the base-
level increases about 35 ft, all while the channel slope decreases. Therefore, the channel
slope is not dependent on the base-level changes within the same time-frame. Rather, the
channel slope decrease from 1995 to 2001 is due to the increase in base-level from 1982
to 1986, or from the increase in base-level from 1990 to 1995. And, the channel slope
decrease from 2001 to 2010 is due to the increase in base-level from 2004 to 2009. The
sudden jump in channel slope from 2.3 ft/mile, in 2001, to 4.3 ft/mile, in 2002, is likely a
result of the decrease in base-level between 1995 and 2004, during which the base-level
dropped by about 100 ft.
Cross-sections were plotted at select range lines for all years of available data and
are presented in Appendix F. Figure 4.28 through Figure 4.36 show representative cross-
sections of Elephant Butte Reach. SO-1683, Figure 4.29, is located in Subreach 2. From
2004 to 2005 the channel aggraded by about 8 ft and then degraded by about 8 ft from
2005 to 2006. This is the location of the Tiffany Sediment Plug in 2005. The sediment
plug was removed by excavating a pilot channel, which accounts for the decrease in bed
elevation from 2005 to 2006. EB-41, Figure 4.36, is located in Subreach 6. When the
reservoir was full from 1985 to 2000, this range line was inundated by the reservoir,
which is why there is only data available beginning in 2004.
62
Figure 4.28 Subreach 1: SO-1641 Surveyed Cross-Sections
Figure 4.29 Subreach 2: SO-1683 Surveyed Cross-Sections
4486
4488
4490
4492
4494
4496
4498
4500
50 100 150 200 250
Elevation (ft)
Station (ft)
SO‐16412009
2008
2007
2006
2005
2004
2003
2002
2001
1999
1998
1997
4474
4476
4478
4480
4482
4484
4486
4488
4490
4492
0 50 100 150 200
Elevation (ft)
Station (ft)
SO‐16832009
2008
2007
2006
2005
2004
2003
2002
1999
1998
1997
1995
1994
1993
1990
63
Figure 4.30 Subreach 3: EB-10 Surveyed Cross-Sections
Figure 4.31 Subreach 3: EB-10 (w/Floodplain) Surveyed Cross-Sections
4462
4464
4466
4468
4470
4472
4474
4476
4478
4480
4482
500 600 700 800 900 1000
Elevation (ft)
Station (ft)
EB‐1020102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980
4450
4455
4460
4465
4470
4475
4480
4485
4490
0 500 1000 1500 2000 2500
Elevation (ft)
Station (ft)
EB‐10 (w/Floodplain)20102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980
Active Channel
64
Figure 4.32 Subreach 4: EB-13 Surveyed Cross-Sections
Figure 4.33 Subreach 5: EB-20 Surveyed Cross-Sections
4460
4462
4464
4466
4468
4470
4472
4474
4476
1950 2000 2050 2100 2150 2200 2250 2300
Elevation (ft)
Station (ft)
EB‐132009
2008
2007
2005
2004
2002
2000
1998
1992
1988
1987
1986
4435
4440
4445
4450
4455
4460
4465
150 200 250 300 350 400 450
Elevation (ft)
Station (ft)
EB‐20200920082007200520042002200019991998199719951994199319921991199019881980
65
Figure 4.34 Subreach 6: EB-29 Surveyed Cross-Sections
Figure 4.35 Subreach 6: EB-29 (w/Floodplain) Surveyed Cross-Sections
4425
4430
4435
4440
4445
4450
5000 5100 5200 5300 5400 5500 5600
Elevation (ft)
Station (ft)
EB‐292009
2008
2007
2005
2004
2002
2000
1999
1997
1995
1993
1989
4425
4430
4435
4440
4445
4450
4455
3750 4250 4750 5250 5750 6250 6750
Elevation (ft)
Station (ft)
EB‐29 (w/Floodplain) 2009
2008
2007
2005
2004
2002
2000
1999
1997
1995
1993
1989
Active Channel
66
Figure 4.36 Subreach 6: EB-41 Surveyed Cross-Sections
4.3.2 Change in Thalweg and Average Bed Elevation from Range Line Surveys
As seen in Figure 4.28 through Figure 4.36 aggradation and degradation occur
across the entire channel bed, not just the thalweg. Therefore, the following analyses
focus on the change in thalweg elevation temporally and spatially. Figure 4.37 shows the
change in the thalweg elevation at selected range lines from 1980-2010. Only range lines
with sufficient years of sample data were plotted.
4398
4400
4402
4404
4406
4408
4410
4412
4414
4416
0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
EB‐41
2009
2008
2007
2004
67
Figure 4.37 Change in Thalweg Elevation at Range Lines (1980 – 2010)
4350
4400
4450
4500
4550
4600
4350
4360
4370
4380
4390
4400
4410
4420
4430
4440
4450
4460
4470
4480
4490
4500
1980 1985 1990 1995 2000 2005 2010
Reservoir W
SE (ft)
Chan
nel Thalweg Elevation (ft)
Year
SO‐1641
SO‐1652.7
SO‐1666
SO‐1673
S0‐1683
SO‐1692
SO‐1701.3
EB‐10
EB‐13
EB‐14
EB‐16
EB‐17
EB‐18
EB‐20
EB‐34
EB‐24
EB‐25
EB‐26
EB‐27
EB‐28
EB‐29
EB‐30
EB‐32
EB‐33
EB‐35
EB‐36
EB‐37
EB‐37.5
EB‐38
EB‐39
EB‐40
EB‐40.5
EB‐41
EB‐42
EB‐43
EB‐44
EB‐45
EB‐46
EB‐47
EB‐48
EB‐49
EB‐50
Reservoir Level
68
From 1980 to 1988, aggradation occurred at all range lines for which there is data.
From 1988 to 1994, the thalweg elevation alternated between increasing and decreasing
elevation, typically changing no more than 3 ft in either direction. From 1994 to 1995,
mostly aggradation occurs, up to 6.2 ft, near the upstream reservoir extent; degradation
occurs just downstream of the 1995 Tiffany Sediment Plug at SO-1692 and SO-1701.3,
7.6 ft and 3.6 ft, respectively. From 1995 to 2002, the change in channel thalweg
elevation varies between aggradation and degradation. From 2002 to 2003, aggradation
occurs from SO-1641 to EB-29, ranging between 1 ft and 4 ft; degradation occurs
downstream of EB-29, up to 3.5 ft. From 2003 to 2004, the channel degraded from SO-
1641 to SO-1692, and from EB-20 to EB-50 by up to 10.7 ft; the channel aggraded from
SO-1701.3 to EB-18 by up to 1 ft. From 2004 to 2007, aggradation occurred from SO-
1641 to SO-1692, up to 2.3 ft, and from EB-40 to EB-50, up to 7.6 ft; degradation
occurred from SO-1701.3 to EB-39, up to 11 ft. From 2007 to 2008, degradation
occurred from SO-1641 to EB-37.5, up to 2.7 ft; aggradation occurred from EB-38 to
EB-50, up to 1.4 ft. From 2008 to 2009, the channel degraded from SO-1641 to EB-37,
up to 2.6 ft; the channel aggraded from EB-37.5 to EB-50, up to 4.2 ft. From 2009 to
2010, the channel varied between aggradation and degradation, ranging between -1.8 ft
and 2.2 ft in elevation change.
A few notable changes occurred at EB-24. From 1990 to 1992 the thalweg
elevation decreased by about 12 ft, from 1992 to 1993 the thalweg elevation increased by
about 7.8 ft, and from 1994 to 1995, the thalweg elevation increased another 6.2 ft.
These changes are in direct response to the change in reservoir WSE, as the shape of the
69
thalweg elevation over time mimics the shape of the change in WSE over time, as seen in
Figure 4.37.
Table 4-7 shows the calculated values of change in thalweg elevation between
selected year sets at each range line for which there is data. The table is color-coded such
that cells highlighted with light red fill indicate degradation between the year set, while
cells highlighted with light green fill indicate aggradation, or in the case of the reservoir
level change, the colors indicate a drop in level and rise in level, respectively. A Cell
highlighted with blue fill and white text, or a cell under the area of the pink outline,
indicates the cross-section was inundated by the reservoir during the latter of the two
years associated with the year set. If the text within a cell reads “----”, then data was not
available at that range line during at least one of the two years associated with the year
set. A cell within the area of a red outline indicates the cell is associated with a “wave”
of degradation, while a cell within the area of a green outline indicates the cell is
associated with a “wave” of aggradation. If a cell is between the area of a red and green
outline, then the cell is considered a transitional area.
Four “waves” were analyzed from this dataset. The first wave is a wave of
degradation and is the result of a decrease in average reservoir level (base-level) from
2009 to 2010 of about 7 ft. The second wave is a wave of aggradation and is the result of
an increase in average base-level from 2004 to 2009 of about 35 ft. The third wave is a
wave of degradation and is the result of a decrease in average base-level from 1995 to
2004 of about 105 ft. The fourth and final wave analyzed, is a wave of aggradation and is
the result of an increase in average base-level from 1990 to 1995. No other waves were
analyzed in detail, due to the lack of available data between 1980 and 1990.
70
Table 4-7 Change in Thalweg Elevation Between Select Year Sets
2009‐2010
2008‐2009
2007‐2008
2004‐2007
2003‐2004
2002‐2003
1999‐2002
1998‐1999
1997‐1998
1995‐1997
1994‐1995
1993‐1994
1992‐1993
1991‐1992
1990‐1991
1990‐1992
1988‐1990
1980‐1988
SO‐1641
‐‐‐‐ 0.73 ‐1.35 1.65 ‐0.17 1.26 ‐1.52 ‐0.12 1.81 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
SO‐1652.7
‐‐‐‐ ‐0.81 ‐2.15 2.25 ‐1.62 1.92 ‐0.30 ‐0.57 ‐1.33 0.30 2.10 1.00 ‐0.60 ‐1.62 1.77 0.15 ‐‐‐‐ ‐‐‐‐
SO‐1666
‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐0.16 1.43 ‐1.84 1.40 ‐0.40 ‐1.02 1.22 0.70 ‐1.00 ‐0.30 ‐‐‐‐ ‐‐‐‐
SO‐1673
‐‐‐‐ ‐0.55 ‐1.22 0.26 ‐1.32 2.02 0.15 1.37 ‐2.22 3.70 0.50 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
SO‐1683
‐‐‐‐ 0.51 ‐0.52 ‐1.04 ‐2.21 2.61 1.36 0.67 ‐1.73 0.00 1.80 0.20 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
SO‐1692
‐‐‐‐ 0.66 ‐1.35 1.02 ‐1.84 1.16 ‐0.03 1.16 ‐‐‐‐ ‐‐‐‐ ‐7.60 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
SO‐1701.3
‐‐‐‐ ‐0.15 ‐1.72 ‐2.74 1.22 2.38 ‐0.33 ‐0.58 1.80 3.50 ‐3.60 1.40 ‐0.60 ‐1.37 0.00 ‐1.37 ‐‐‐‐ ‐‐‐‐
EB‐10 1.27 ‐1.56 ‐0.99 ‐1.94 0.12 1.85 ‐0.77 1.06 1.91 ‐2.18 1.40 2.30 ‐1.20 ‐1.98 0.23 ‐1.75 1.25 8.10
EB‐13 ‐0.18 ‐0.78 ‐0.70 ‐4.92 0.20 2.09 1.46 ‐0.61 ‐1.87 2.43 0.90 1.20 0.40 ‐2.19 ‐0.18 ‐2.37 1.47 12.10
EB‐14 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 2.68 4.54 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 12.80
EB‐16 ‐0.75 ‐0.39 ‐0.76 ‐5.89 0.49 2.17 0.34 0.40 2.28 ‐2.28 2.00 0.20 0.70 ‐‐‐‐ ‐‐‐‐ ‐1.88 3.18 11.00
EB‐17 ‐0.15 0.06 ‐0.56 ‐4.33 ‐0.06 2.79 1.96 ‐1.90 1.01 1.49 0.30 1.20 ‐2.20 ‐0.22 ‐1.78 ‐2.00 2.70 11.90
EB‐18 ‐0.79 0.25 ‐2.39 ‐6.27 0.02 3.35 ‐1.15 ‐0.67 4.37 ‐1.70 ‐1.80 3.40 ‐‐‐‐ ‐‐‐‐ ‐0.27 ‐‐‐‐ ‐0.36 2.80
EB‐20 1.35 ‐2.58 ‐1.77 ‐7.37 ‐0.52 2.65 ‐0.71 2.90 ‐1.63 0.43 0.90 1.60 0.60 0.86 ‐2.91 ‐2.05 ‐‐‐‐ ‐‐‐‐
EB‐34 0.80 ‐0.53 ‐2.66 ‐8.56 ‐0.40 2.56 ‐0.13 ‐0.45 1.26 ‐1.21 2.50 0.70 0.90 ‐‐‐‐ ‐‐‐‐ ‐2.50 0.20 ‐‐‐‐
EB‐24 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐8.62 ‐2.11 2.38 2.23 ‐2.30 2.84 ‐2.74 6.20 ‐0.80 7.80 ‐6.36 ‐5.68 ‐12.04 ‐1.56 20.40
EB‐25 0.05 ‐0.83 ‐1.20 ‐10.40 ‐0.62 2.26 ‐0.76 0.40 0.30 ‐0.10 0.60 ‐0.80 2.40 ‐‐‐‐ ‐‐‐‐ ‐0.86 0.86 ‐‐‐‐
EB‐26 ‐0.47 ‐0.29 ‐1.48 ‐11.13 0.44 1.01 0.45 ‐1.40 1.70 ‐3.80 1.20 ‐0.17 1.87 ‐‐‐‐ ‐‐‐‐ 2.43 2.27 ‐‐‐‐
EB‐27 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐0.86 ‐1.30 ‐‐‐‐ ‐‐‐‐ 1.10 2.30 ‐2.10 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ 5.20
EB‐28 ‐0.06 ‐0.27 ‐1.07 ‐1.86 ‐8.15 2.72 ‐1.51 ‐0.26 0.05 0.75 1.50 ‐0.70 3.30 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐29 ‐0.83 0.43 ‐2.15 ‐1.06 ‐10.69 4.12 ‐0.60 ‐2.47 3.04 0.80 0.30 ‐0.50 1.20 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐30 0.32 ‐0.66 0.85 ‐0.75 ‐4.24 ‐1.03 ‐4.53 2.47 1.03 2.00 0.90 ‐0.70 0.10 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
71
Table 4-7 Change in Thalweg Elevation Between Select Years (Part 2)
2009‐2010
2008‐2009
2007‐2008
2004‐2007
2003‐2004
2002‐2003
1999‐2002
1998‐1999
1997‐1998
1995‐1997
1994‐1995
1993‐1994
1992‐1993
1991‐1992
1990‐1991
1990‐1992
1988‐1990
1980‐1988
EB‐32 0.02 0.53 ‐1.62 0.06 ‐0.17 ‐3.49 ‐2.74 ‐0.60 1.30 0.10 ‐0.30 0.60 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐33 ‐0.46 ‐1.21 1.07 ‐1.65 1.69 ‐2.27 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐35 ‐0.36 0.88 ‐1.91 0.09 ‐0.60 ‐1.71 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐36 ‐0.10 0.26 1.03 0.15 ‐2.28 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐37 1.80 ‐0.28 ‐0.71 ‐0.03 ‐1.86 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐37.5
2.22 0.53 ‐0.49 ‐0.80 ‐0.89 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐38 1.54 1.27 0.20 ‐0.30 0.65 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐39 0.00 0.74 0.52 ‐0.36 ‐1.36 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐40 ‐0.98 2.31 0.25 2.32 0.85 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐40.5
‐1.84 1.98 0.17 2.75 ‐0.30 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐41 ‐1.05 1.86 1.40 3.70 ‐1.29 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐42 1.42 0.05 ‐0.32 4.06 ‐0.83 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐43 1.04 2.06 0.60 5.24 ‐2.68 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐44 ‐1.54 4.22 ‐0.86 4.41 0.79 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐45 0.48 1.75 1.18 6.20 ‐2.02 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐46 0.13 2.93 0.46 6.83 ‐4.28 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐47 ‐1.02 2.23 ‐0.06 7.01 ‐3.80 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐48 3.79 ‐2.25 0.19 7.59 ‐3.62 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐49 0.82 0.12 ‐0.82 6.74 ‐2.17 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
EB‐50 ‐0.21 0.11 0.74 5.65 ‐3.55 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐
Res ‐6.91 1.73 5.85 28.75 ‐9.07 ‐24.43 ‐51.95 ‐4.51 1.33 ‐7.17 0.12 3.23 1.41 10.64 1.29 11.94 ‐16.20 32.49
72
The change in thalweg and mean channel bed elevation were evaluated using the
range line survey data. First, the minimum channel elevation (thalweg) was calculated
for each range line at different surveyed years. Then, the change in Thalweg elevation
was compared between years at each range line where data was available. A second,
similar analysis was done by calculating the change in the average channel bed elevations
for which a weighted average was used to calculate the mean bed elevation for each
range line at different surveyed years.
Because data was not available each year for every range line, different ranges of
years had to be used to calculate the change in elevation. This is indicated by the
different colors of bars in Figure 4.38 for the change in average bed elevation analysis,
and Figure 4.39 for the change in thalweg elevation analysis. The orange bars show a
change in elevation for range lines between 1988 and 1990; the turquoise bars show a
change in elevation between 1990 and 1995; the purple bars show a change in elevation
from 1995 to 2003; the green bars show a change in elevation between 2003 and 2004;
and the red bars show a change in elevation from 2004 to 2009; and blue bars show a
change in elevation from 2009 to 2010. Note that each set of bars has a different time
increment; this is because the selected years contain data for most of the range lines, and
the year sets represent an overall aggrading or degrading trend.
73
Figure 4.38 Change in Average Channel Bed Elevation at Range Lines (1988-2010)
‐20
‐15
‐10
‐5
0
5
10
15
SO‐1641
SO‐1652.7
SO‐1666
SO‐1673
SO‐1683
SO‐1692
SO‐1701.3
EB‐10
EB‐13
EB‐14
EB‐16
EB‐17
EB‐18
EB‐20
EB‐34
EB‐24
EB‐25
EB‐26
EB‐27
EB‐28
EB‐29
EB‐30
EB‐32
EB‐33
EB‐35
EB‐36
EB‐37
EB‐37.5
EB‐38
EB‐39
EB‐40
EB‐40.5
EB‐41
EB‐ 42
EB‐43
EB‐44
EB‐45
EB‐46
EB‐47
EB‐48
EB‐49
EB‐50
Chan
ge in
Average
Bed Elevation (ft)
Range Line ID
1988‐1990 1990‐1995 1995‐2003 2003‐2004 2004‐2009 2009‐2010
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
74
Figure 4.39 Change in Channel Thalweg Elevations at Range Lines (1988-2010)
‐20
‐15
‐10
‐5
0
5
10
15
SO‐1641
SO‐1652.7
SO‐1666
SO‐1673
SO‐1683
SO‐1692
SO‐1701.3
EB‐10
EB‐13
EB‐14
EB‐16
EB‐17
EB‐18
EB‐20
EB‐34
EB‐24
EB‐25
EB‐26
EB‐27
EB‐28
EB‐29
EB‐30
EB‐32
EB‐33
EB‐35
EB‐36
EB‐37
EB‐37.5
EB‐38
EB‐39
EB‐40
EB‐40.5
EB‐41
EB‐ 42
EB‐43
EB‐44
EB‐45
EB‐46
EB‐47
EB‐48
EB‐49
EB‐50
Thalweg Elevation Chan
ge (ft)
Range Line ID
1988‐1990 1990‐1995 1995‐2003 2003‐2004 2004‐2009 2009‐2010
SR 1 SR 2 SR 3 SR 4 SR 5 SR 6
75
The following observations are based specifically on the change in thalweg
elevation; however, the general trends observed are similar for the change in average bed
elevation. From 1988 to 1990, primarily aggradation occurred, up to 3.2 ft. From 1990
to 1995, which includes the first instances in which the Tiffany Plug formed, there is
aggradation and degradation observed, depending on the range line; there does not appear
to be a hinge point spatially separating aggradation and degradation. From 1995 to 2003,
after the second Tiffany Plug, there is mostly aggradation between SO-1673 and EB-29,
up to 11.3 ft. From 2003 to 2004, there is degradation the majority of the reach, up to
10.7 ft. From 2004 to 2009, degradation is observed from SO-1652.7 to EB-37.5, at
which point aggradation is observed from EB-38 to EB-50. From 2009 to 2010, the
channel alternates between aggradation and degradation along the reach profile, with the
greatest magnitude of aggradation, 3.8 ft, occurring at EB-48.
4.3.3 Rate of Aggradation/Degradation from Range Line Surveys
From 2003 to 2004, shown in Figure 4.40 and Figure 4.41, degradation is
observed along the entire reach, except for at five range lines. The wave of degradation
between EB-13 and EB-50 (Wave 3) is in response to the drop in base-level (Reservoir
WSE) by about 100 ft between 1995 and 2004. Figure 4.41 shows the magnitude of
degradation from 2003 to 2004 at River Miles, which is represented by the following
second order polynomial equation:
y = -0.1601x2 + 16.209x - 410.5
Where, y is the magnitude of degradation and x is the longitudinal location along the
reach in River Miles (RM, as defined by Reclamation, where measurements begin at the
d
4
ownstream e
5.21 to RM
Figure 4.40
Figure 4.4
‐12
‐10
‐8
‐6
‐4
‐2
0
2
4Chan
ge in
Thalweg Elevation (ft)
59
Ups
trea
m E
nd
Ut
Ed
end of the M
57.75.
0 Magnitude
1 Magnitude
557
Ups
trea
m E
nd
Middle Rio
e of Aggrada
e of Aggrada
y = ‐0.160R
535
76
Grande Riv
ation and De
ation and De
Range
1x2 + 16.209x ‐R² = 0.6064
51River Mile
ver); this equ
egradation at
egradation at
e Line
‐ 410.5
49
uation is app
t Range Line
t River Mile
47
propriate for
es (2003-200
es (2003-200
‐12
‐10
‐8
‐6
‐4
‐2
0
2
4
45
Dow
nstr
eam
End
r RM
04)
04)
Chan
ge in
Thalweg (ft)
77
From 2004 to 2005, all of the thalweg elevations decreased between SO-line 1683
and EB-26; the decrease becomes more pronounced in the downstream direction between
these range lines, as seen in Figure 4.42 and Figure 4.43. From 2004 to 2005, SO-lines
1641, 1652.7, and 1683 increased. The wave of degradation between SO-1683 and EB-
26 (Wave 3) is in response to the drop in base-level (Reservoir WSE) by about 100 ft
between 1995 and 2004. Figure 4.42 shows the magnitude of degradation from 2004 to
2005 at River Miles, which is represented by the following linear equation:
y = 0.8233x – 58.29
Where, y is the magnitude of degradation and x is the longitudinal location along the
reach in River Miles; this equation is appropriate for RM 59.34 to RM 73.59.
Figure 4.42 Magnitude of Aggradation and Degradation at Range Lines (2004-2005)
‐12
‐10
‐8
‐6
‐4
‐2
0
2
4
6
SO‐1641
SO‐1652.7
SO‐1673
SO‐1692
SO‐1701.3
EB‐10
EB‐13
EB‐16
EB‐17
EB‐18
EB‐20
EB‐34
EB‐24
EB‐25
EB‐26
EB‐28
EB‐30
EB‐32
EB‐33
EB‐35
EB‐36
EB‐37
EB‐37.5
EB‐38Chan
ge in
Thalweg Elevation (ft)
Range Line
Ups
trea
m E
nd
Dow
nstr
eam
E
nd
78
Figure 4.43 Magnitude of Aggradation and Degradation at River Miles (2004 to 2005)
From 2004 to 2009, shown in Figure 4.44, degradation is observed from SO-
1652.7 to EB-37.5, at which point aggradation is observed from EB-38 to EB-50. These
two trends represent two distinct waves of thalweg elevation changes in response to base-
level changes, Wave 3 and Wave 2, respectively.
Figure 4.44 Change in Thalweg Elevation from 2004 to 2009
The wave of degradation between SO-1701.3 and EB-26 (Wave 3) is in response
to the decrease in base-level by about 100 ft between 1995 and 2004. Figure 4.45 shows
y = 0.8233x ‐ 58.285R² = 0.821
‐12
‐10
‐8
‐6
‐4
‐2
0
2
4
6
5560657075
Chan
ge in
Thalweg Elevation (ft)
River Mile
‐15
‐10
‐5
0
5
10
15
SO‐1641
SO‐1666
SO‐1683
SO‐1701.3
EB‐13
EB‐16
EB‐18
EB‐34
EB‐25
EB‐27
EB‐29
EB‐32
EB‐35
EB‐37
EB‐38
EB‐40
EB‐41
EB‐43
EB‐45
EB‐47
EB‐49
Thalweg Elevation Chan
ge (ft)
Range Line ID
Dow
nstr
eam
End
Ups
trea
m E
nd
79
the magnitude of degradation from 2004 to 2009, which is represented by the following
second order polynomial equation:
y = -0.0226x2 + 4.0x – 171.53
Where, y is the magnitude of degradation and x is the longitudinal location along the
reach in River Miles; this equation is appropriate for RM 45.21 to RM 52.03.
The wave of aggradation between EB-38 and EB-50 (Wave 2) is in response to
the reservoir WSE increase of about 35 ft between 2004 and 2009. Figure 4.46 shows the
magnitude of aggradation from 2004 to 2009, which is represented by the following
second order polynomial equation between RM 59.34 and RM 73.59:
y = -0.4355x2 + 41.11x – 962.27
Where, y is the magnitude of degradation and x is the longitudinal location along the
reach in River Miles.
Figure 4.45 Magnitude of Degradation from 2004 to 2009
y = ‐0.0226x2 + 4.0052x ‐ 171.53R² = 0.9302
‐16
‐14
‐12
‐10
‐8
‐6
‐4
‐2
0
2
5560657075
Chan
ge in
Thalweg Elevation (ft)
River Mile
Dow
nstr
eam
End
Ups
trea
m E
nd
80
Figure 4.46 Magnitude of Aggradation from 2004-2009
Appendix G presents plots of the change in thalweg elevation between selected
year sets versus river mile, along with trendlines associated with “waves” of aggradation
and “waves” of degradation.
4.3.4 Rate of Wave Propagation Upstream from Range Line Surveys
Wave 1, resulting from the decrease in base-level from 2009 to 2010, is
represented by range line EB-50. EB-50 decreased approximately 0.2 ft between 2009
and 2010. The rate of wave propagation upstream was determined by first plotting the
river mile of the upstream extent of the reservoir during the first year of the wave. Then,
the river mile of the upstream-most affected range line cross-section was determined and
plotted versus the latter year of the year set. If a wave continued beyond one year set,
then this step was repeated for each year set that the wave propagated and for which data
existed. The upstream extent of the reservoir was determined by interpolating (or
extrapolating) the average channel thalweg slope during the first year of the wave to the
average elevation of the reservoir; where the channel slope and reservoir elevation
intersected, the river mile was calculated. Figure 4.47 shows the reservoir water surface
y = ‐0.4355x2 + 41.112x ‐ 962.27R² = 0.8399
‐4
‐2
0
2
4
6
8
10
12
454749515355
Chan
ge in
Thalweg Elevation
(ft)
River Mile
Dow
nstr
eam
E
nd
Ups
trea
m E
nd
81
elevation change from 2009 to 2010, which induces Wave 1 degradation. Figure 4.48
shows the rate of Wave 1 propagation upstream as a result of the decrease in WSE (base-
level) from 2009 to 2010. The wave propagated upstream at a rate of 1.46 miles/year
with a decrease in base-level of 6.9 ft/year, and the upstream extent of the reservoir
receded 2.71 miles/year.
Figure 4.47 Reservoir Water Surface Elevation Change from 2009-2010 Resulting in
Wave 1 Channel Degradation
Figure 4.48 Rate of Wave 1 Propagation Upstream
Wave 2 resulted from an increase in base-level from 2004 to 2009. Figure 4.49
shows the reservoir water surface elevation change from 2004 to 2009, which induced
y = ‐6.9072x + 18267
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
2008 2009 2010 2011
Reservoir W
SE (ft)
Year
y = 1.4607x ‐ 2890.8
y = ‐2.7127x + 5493.5
30
32
34
36
38
40
42
44
46
2008 2009 2010 2011
River Mile
(mi)
Year
Chnl Bed Wave 2Res U/S ExtentLinear (Chnl Bed Wave 2)Linear (Res U/S Extent)
82
Wave 2 aggradation. Figure 4.50 shows the rate of Wave 2 propagation upstream as a
result of the increase in WSE (base-level) from 2004 to 2009. With an increase in base-
level of 6.8 ft/year, Wave 2 propagated upstream according to the following second order
polynomial:
y = -0.5522x2 + 2219.1x - 2E+06
Where, y is the upstream-most River Mile at which aggradation occurs as a result of an
increase in base-level of 6.8 ft/year, and x is the year at which River Mile y begins to
aggrade. The upstream extent of the reservoir progressed upstream at a rate of 1.36
miles/year.
Figure 4.49 Reservoir Water Surface Elevation Change from 2004-2009 Resulting in Wave 2 Channel Aggradation
y = 6.7963x ‐ 9259.3
4350
4355
4360
4365
4370
4375
4380
4385
4390
4395
4400
2003 2004 2005 2006 2007 2008 2009 2010
Reservoir W
SE (ft)
Year
83
Figure 4.50 Rate of Wave 2 Propagation Upstream
Wave 3 resulted from a decrease in base-level from 1997 to 2004. Figure 4.51
shows the reservoir water surface elevation change from 1997 to 2004, which induced
Wave 3 degradation. Figure 4.52 shows the rate of Wave 3 propagation upstream as a
result of the decrease in WSE (base-level) from 1997 to 2004. With a decrease in base-
level of 14.2 ft/year, Wave 3 propagated upstream according to the following second
order polynomial:
y = 0.0692x2 - 276.2x + 275686
Where, y is the upstream-most River Mile at which degradation occurs as a result of a
decrease in base-level of 14.2 ft/year, and x is the year at which River Mile y begins to
degrade. The upstream extent of the reservoir receded at a rate of 2.9 miles/year.
y = ‐0.5522x2 + 2219.1x ‐ 2E+06R² = 0.9969
y = 1.3609x ‐ 2689.6R² = 0.9633
30
35
40
45
50
55
2003 2004 2005 2006 2007 2008 2009 2010 2011
River Mile
(mi)
Year
Chnl Bed Wave 2
Res U/S Extent
Poly. (Chnl Bed Wave 2)
Linear (Res U/S Extent)
84
Figure 4.51 Reservoir Water Surface Elevation Change from 1997-2004 Resulting in Wave 3 Channel Degradation
Figure 4.52 Rate of Wave 3 Propagation Upstream
Wave 4 resulted from an increase in base-level from 1990 to 1995. Figure 4.53
shows the reservoir water surface elevation change from 1990 to 1995, which induced
Wave 4 aggradation. Figure 4.54 shows the rate of Wave 4 propagation upstream as a
y = ‐14.243x + 32904
4340
4360
4380
4400
4420
4440
4460
4480
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Reservoir W
SE (ft)
Year
y = 0.0692x2 ‐ 276.2x + 275686R² = 0.8863
y = ‐2.9297x + 5909.5R² = 0.9068
30
35
40
45
50
55
60
65
70
75
80
1990 1995 2000 2005 2010
River Mile
(mi)
Year
Chnl Bed Wave 3Res U/S ExtentPoly. (Chnl Bed Wave 3)Linear (Res U/S Extent)
85
result of the increase in WSE (base-level) from 1990 to 1995. With an increase in base-
level of 3.7 ft/year, Wave 4 propagated upstream according to the following second order
polynomial:
y = -0.1222x2 + 489.03x – 489299
Where, y is the upstream-most River Mile at which aggradation occurs as a result of an
increase in base-level of 3.7 ft/year, and x is the year at which River Mile y begins to
aggrade. The upstream extent of the reservoir progressed upstream at a rate of 1.07
miles/year.
Figure 4.53 Reservoir Water Surface Elevation Change from 1990-1995 Resulting in Wave 4 Channel Aggradation
y = 3.7339x ‐ 2996.4
4430
4435
4440
4445
4450
4455
1989 1990 1991 1992 1993 1994 1995 1996
Reservoir W
SE (ft)
Year
Reservoir WSE
Linear (Reservoir WSE)
86
Figure 4.54 Rate of Wave 4 Propagation Upstream
4.4 Bed Material Analysis
4.4.1 Grain Size Distributions
Bed material surveys taken at SO- and EB- range lines by Reclamation were used
to create grain size distribution curves for each subreach. Also, San Acacia and San
Marcial gauges’ bed material grain size distributions were plotted to study the trend of
the bed material grain size about 44 miles upstream of the study reach and within the
study reach.
Since complete temporal sequences of data related to each range line were not
available, those with the most complete set of data were chosen to represent each
subreach (see Table 4-8).
y = ‐0.1222x2 + 489.03x ‐ 489299R² = 0.892
y = 1.0734x ‐ 2079.6R² = 0.8114
30
35
40
45
50
55
60
65
70
75
80
1985 1990 1995 2000 2005
River Mile
(mi)
Year
Chnl Bed Wave 4
Res U/S Extent
Poly. (Chnl Bed Wave 4)
Linear (Res U/S Extent)
87
Table 4-8 Representative Range Lines for Each Subreach Subreach Range Line
1 SO‐1641
2 SO‐1683
3 EB‐10
4 EB‐13
5 EB‐18
6 EB‐24
Multiple samples were collected at a given range line and for a given year. In
many cases, stations along the range line cross-section at which samples were collected
were provided. Where stations were provided, the sample locations were compared to
the surveyed range line cross-sections, which were presented in Section 4.3. If the
samples collected were from the floodplain within the cross-section, then the sample was
not included in this analysis, as bed material only is of interest. If sample locations were
not provided, then it was assumed that the sample was a bed material sample, because the
data provided was defined by Reclamation as bed material sample data. The grain size
distributions of all the collected bed material samples at a given station and in a given
year were plotted. A representative grain size distribution was selected for each range
line and for each year, from which the average mean grain size was computed. This same
procedure was applied to the San Acacia and San Marcial gauge data. For example,
Figure 4.55 shows different grain size distributions for range line EB-10 in 1992. The
most representative distribution chosen for that year is highlighted in yellow.
88
Figure 4.55 EB-10 1992 Bed Material Grain Size Distributions
Figure 4.56 through Figure 4.63 show the compilation of representative grain size
distributions for each year at the San Acacia gauge, at the San Marcial gauge, and at each
subreach. Select bed material grain size distribution plots are provided in Appendix H.
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
89
Figure 4.56 San Acacia Gauge: Annual Bed Material Grain Size Distributions
Figure 4.57 San Marcial Gauge: Annual Bed Material Grain Size Distributions
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100
% Finer by Weight
Grain Size Distribution (mm)
1966 19681969 19731975 19761978 19791980 19811982 19831984 19851986 19871988 19891990 19911992 19931994 19951996 19971998 19992000 20012002 20032004 2005
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size Distribution (mm)
1968 19691972 19731974 19751976 19771978 19791980 19811982 19831984 19851986 19871988 19891990 19911992 19931994 19951996 19971998 19992000 20012002 20032004 20052006 20072008 20092010
90
Figure 4.58 Subreach 1 (SO-1641): Annual Bed Material Grain Size Distributions
Figure 4.59 Subreach 2 (SO-1683): Annual Bed Material Grain Size Distributions
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size Distribution (mm)
2001200220042005
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1
% Finer by Weight
Grain Size Distribution (mm)
1999
91
Figure 4.60 Subreach 3 (EB-10): Annual Bed Material Grain Size Distributions
Figure 4.61 Subreach 4 (EB-13): Annual Bed Material Grain Size Distributions
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100
% Finer by Weight
Grain Size Distribution (mm)
1986 19871988 19901992 19931994 19971998 19992002
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size Distribution (mm)
198619871988199019992002
92
Figure 4.62 Subreach 5 (EB-18): Annual Bed Material Grain Size Distributions
Figure 4.63 Subreach 6 (EB-24): Annual Bed Material Grain Size Distributions
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size Distribution (mm)
198619871988199019931994199719992002
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size Distribution (mm)
1986
1992
1999
2002
93
The San Acacia and San Marcial grain size distribution plots show that the bed
material has become slightly coarser over time as indicated by the grain size distribution
curves moving to the right with time. Note that the San Acacia gauge is 44 miles
upstream of this study reach and is not representative of this study reach, while the San
Marcial gauge is located at the upstream end of this study reach, and therefore represents
this study reach very well. The grain size distributions of each subreach have
experienced minimal changes throughout the years. It should be noted that in the case of
San Acacia and San Marcial gauges, the sequences of data ranges from 1967 to 2008,
while Subreaches 3, 4, 5, and 6 data range from 1986 to 2002; Subreach 1 only ranges
from 2001 to 2005; and Subreach 2 only has data from 1999.
4.4.2 Median Grain Size
Figure 4.64 shows the change over time of the average median bed material grain
size in each subreach and at the San Acacia and San Marcial gauges, located 44 miles
upstream of the study reach and within the study reach, respectively. Figure 4.65 shows
the average median bed material grain size trends for each subreach from 1986 to 2005.
94
Figure 4.64 Average Median Bed Material Grain Size Temporal Trends
Figure 4.65 Average Median Bed Material Grain Size: Subreach Temporal Trends
Overall, mean grain sizes of the study reach range between 0.11 and 0.26 mm,
corresponding to very fine to medium sand (Julien 2002). In general, the bed material at
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1965 1975 1985 1995 2005 2015
Average
Median Grain Size (mm)
Year
San Acacia Gauge San Marcial Gauge
Subreach 1 (SO‐1641) Subreach 2 (SO‐1683)
Subreach 3 (EB‐10) Subreach 4 (EB‐13)
Subreach 5 (EB‐18) Subreach 6 (EB‐24)
0
0.05
0.1
0.15
0.2
0.25
0.3
1985 1990 1995 2000 2005 2010
Average
Median Grain Size (mm)
Year
Subreach 1 (SO‐1641)
Subreach 2 (SO‐1683)
Subreach 3 (EB‐10)
Subreach 4 (EB‐13)
Subreach 5 (EB‐18)
Subreach 6 (EB‐24)
Linear (Subreach 1 (SO‐1641))
Linear (Subreach 3 (EB‐10))
Linear (Subreach 4 (EB‐13))
Linear (Subreach 5 (EB‐18))
Linear (Subreach 6 (EB‐24))
95
the San Marcial gauge has become coarser since the 1960s by about 0.002 mm/year
(from a minimum of 0.08 mm in 1991 to a maximum of 0.24 mm in 2004). The bed
material at the San Acacia gauge has become coarser by about 0.009 mm/year (from a
minimum of 0.04 mm in 1980 to a maximum of 0.85 mm in 2009), which is about five
times faster than the bed material coarsening rate at the San Marcial gauge. Note that the
rates of bed material coarsening were determined using the entire datasets for each
respective gauge that are presented in Figure 4.64.
Figure 4.65 shows that the average median grain size in Subreach 1 has become
finer at a rate of 0.0046 mm/year between 2001 and 2005; Subreach 2 has no temporal
trend, because the only data available for Subreach 2 is from 1999; the average median
grain size within Subreach 3 coarsened at a rate of 0.0027 mm/year between 1986 and
2002; the average median grain size within Subreach 4 coarsened at a rate of 0.0031
mm/year between 1986 and 2002; the average median grain size within Subreach 5
coarsened at a rate of 0.0031 mm/year between 1986 and 2002; the average median grain
size within Subreach 6 became finer at a rate of 0.0005 mm/year between 1986 and 2002.
All average median grain sizes are within the very fine to fine sand range, except
for the averages in Subreach 1 in 2001 and in Subreach 3 in 1994, which are in the low
end of the medium sand classification (0.26 mm). So, though there has been overall
coarsening of the bed material within this study reach, it is less than 0.003 mm/year, and
is still generally classified as very fine to fine sand. Figure 4.65 also shows that while the
median bed material size has coarsened with time, it tends to get finer in the downstream
direction.
96
4.5 Suspended Sediment Data
Suspended sediment data was used from the Escondida Reach Report (Larsen et
al. 2007). Single and double mass curves developed in the Escondida Reach Report
(Larsen et al. 2007) are presented below. Trends in water discharge, suspended sediment
discharge, and suspended sediment concentration are shown in Figure 4.66, Figure 4.67,
and Figure 4.68, respectively.
The single mass curve for water discharge, Figure 4.66, shows similar trends at
the San Marcial and San Acacia gauges. Both curves show breaks around 1979 and
2000. In about 1979, the discharge increased from about 600 cfs to over 2000 cfs. Table
4-9, also from the Escondida Reach Report (Larsen et al. 2007), is presented below and
shows the average discharge for each period displayed on the graph.
Figure 4.66 Water Discharge Single Mass Curve (Larsen et al. 2007)
0.0E+00
5.0E+06
1.0E+07
1.5E+07
2.0E+07
2.5E+07
3.0E+07
10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999
Cu
mu
lati
ve D
isch
arg
e (a
cre-
ft)
DateSA: 1958-1979 SA: 1980-1999SA: 2000-2005 SM: 1949-1978SM: 1979-2000 SM: 2001-2005Linear (SA: 1958-1979) Linear (SA: 1980-1999)Linear (SA: 2000-2005) Linear (SM: 1949-1978)
97
Table 4-9 Water Discharge (Larsen et al. 2007) Gauge Years acre-ft/day R2 value
San Acacia
1958-1979 522 0.98 1980-1999 2856 0.99 2000-2005 1055 0.93
San Marcial
1949-1978 621 0.94 1979-2000 2263 0.99
2001-2005 740 0.84
Figure 4.67 shows the single mass curve for suspended sediment discharge at the
San Acacia and San Marcial Gauges. The San Marcial gauge has a much higher
suspended sediment discharge than the San Acacia gauge from 1956 until about 1968.
From 1968 to 1991, the two gauges both have a suspended sediment discharge of about
10,000 tons/day. From 1991 to 1996, the San Marcial gauge again shows a much higher
suspended sediment discharge. Table 4-10 shows the average suspended sediment
discharge for the periods shown on the graph.
Figure 4.67 Suspended Sediment Discharge Single Mass Curve (Larsen et al. 2007)
0.0E+00
2.0E+07
4.0E+07
6.0E+07
8.0E+07
1.0E+08
1.2E+08
1.4E+08
1.6E+08
1.8E+08
10/1/1949 9/29/1959 9/26/1969 9/24/1979 9/21/1989 9/19/1999
Cu
mu
lati
ve S
usp
end
ed S
edim
ent
(to
ns)
DateSA: 1959-1967 SA: 1968-1975 SA: 1976-1996
SM: 1956-1959 SM: 1960-1989 SM: 1991-1995
Linear (SA: 1959-1967) Linear (SA: 1968-1975) Linear (SA: 1976-1996)
Linear (SM: 1956-1959) Linear (SM: 1960-1989) Linear (SM: 1991-1995)
98
Table 4-10 Suspended Sediment Discharge (Larsen et al. 2007)
Gauge Years tons/day R2 value
San Acacia
1959-1967 6062 0.94 1968-1975 9172 0.92 1976-1996 10066 0.99
San Marcial
1956-1959 35276 0.88 1960-1989 10232 0.98
1991-1995 16707 0.98 Double mass curves were developed at each gauge to show the changes in
suspended sediment concentration over time, as seen in Figure 4.68.
Figure 4.68 Suspended Sediment Concentration Double Mass Curves (Larsen et al. 2007)
From 1959 to 1978, the two curves are very similar, with an average suspended
sediment concentration of about 13,000 mg/L. Around 1978, both curves break, and the
0.0E+00
2.0E+07
4.0E+07
6.0E+07
8.0E+07
1.0E+08
1.2E+08
1.4E+08
1.6E+08
1.8E+08
0.0E+00 5.0E+06 1.0E+07 1.5E+07 2.0E+07 2.5E+07
Cu
mu
lati
ve S
usp
end
ed S
edim
ent
(to
ns)
Cumulative Water Discharge (acre-ft)
SA: 1959-1978 SA: 1979-1996 SM: 1956-1977
SM: 1978-1989 SM: 1990-1995 Linear (SA: 1959-1978)
Linear (SA: 1979-1996) Linear (SM: 1956-1977) Linear (SM: 1978-1989)
Linear (SM: 1990-1995)
99
suspended sediment concentration drops to about 3,000 mg/L. The concentration at the
San Acacia gauge remains at about 3,000 mg/L through the end of the available data.
The San Marcial gauge, however, shows an increase in suspended sediment concentration
from 3,000 mg/L to 4,500 mg/L around 1990. Table 4-11 shows the average
concentration as well as the R2 values for each segment of the graph.
Table 4-11 Suspended Sediment Concentration (Larsen et al. 2007) Gauge Years tons/acre-ft mg/L R2 value
San Acacia
1959-1978 17.9 13165 0.97 1979-1996 3.58 2633 0.98
San Marcial
1956-1977 17.21 12657 0.97 1978-1989 4.16 3060 0.92
1990-1995 6.2 4560 0.98
From 1960 to 1989 at the San Marcial gauge, and from 1959 to 1996 at the San
Acacia gauge, the suspended sediment discharge consistently averaged between about
9,000 and 10,000 tons/day, as seen in Figure 4.67. Around 1980, the water discharge at
the San Acacia and San Marcial gauges increased four to five times the average water
discharge from 1949 to 1980. From 1942 to 1979, New Mexico experienced a state-wide
drought (Paulson et al 1988). The decrease in suspended sediment concentration in 1979
was due to the increase in water discharge following the nearly 40 year drought, and was
not due to a change in suspended sediment discharge.
100
SECTION 5: SUMMARY AND CONCLUSIONS
The Elephant Butte Reach spans about 30 miles, beginning from the South Boundary
of the Bosque del Apache National Wildlife Refuge (River Mile 73.9) to the “narrows” of
the Elephant Butte Reservoir (River Mile 44.65), in central New Mexico. Further
understanding of the historical and spatial changes within Elephant Butte Reach, along
with a better understanding of the influences of Elephant Butte Reservoir levels on
channel aggradation/degradation is essential for improvement in future river management
practices along the Middle Rio Grande. The objectives addressed in this study included
the following:
6. Quantified temporal changes in channel widths and sinuosity from 1935 to 2010.
7. Quantified change in channel slope temporally.
8. Quantified rate of aggradation/degradation in response to a change in base-level
(i.e., change in reservoir water surface elevation).
9. Quantified aggradation/degradation wave propagation upstream.
10. Quantified spatial and temporal trends in bed material grain size.
The average channel width and channel sinuosity for Elephant Butte Reach have
decreased since 1918. From 1935 to 2010, the average channel width decreased
according to the following equation:
Avg. Chnl Width = 0.2353x2 – 936.54x + 931904
Where, x is the year. Since 1962, the average channel width has ranged between 50 ft
and 300 ft. From 1935 to 2010, channel sinuosity has decreased according to the
following equation:
101
Channel Sinuosity = 6E-05x2 – 0.2196x + 219.57
Where, x is the year. Since 1962, channel sinuosity has remained lower than 1.25.
The channel slope since 1962 has primarily decreased. From 1962 to 2002, based
on Agg/Deg-line survey data, the average channel slope (Subreaches 1 through 5)
decreased about 0.03 ft/mile/year. Within Subreach 6, based on range line survey data,
the channel slope decreased 0.32 ft/mile/year from 1995 to 2001 as a result of an increase
in base-level of about 20 ft from 1990 to 1995; from 2002 to 2010, the channel slope
decreased 0.21 ft/mile/year as a result of an increase in base-level of about 35 ft from
2004 to 2009; from 2001 to 2002, the channel slope increased from 2.3 ft/ft to 4.3 ft/ft in
one year as a result of a decrease in base-level of about 100 ft from 1995 to 2004.
The rate of aggradation/degradation along the reach varied between different year
sets. Based on Agg/Deg-line survey data, from 1972 to 1992, the base-level increased
13.4 ft/year, and the channel aggraded in response as described by the following
equation:
Rate of Aggradation = -0.0014x2 + 0.0649x + 0.1832
Where, x is the distance (in miles) downstream of Agg/Deg 1637 (or the upstream end of
Elephant Butte Reach).
Between 1995 and 2004, the base-level dropped 100 ft (11.1 ft/year). The following
equations describe the rate of degradation for year sets 2003-2004, 2004-2005, and 2004-
2009, respectively:
(2003-2004) Rate of Degradation = -0.1601x2+16.209x – 410.5
(2004-2005) Rate of Degradation = 0.8233x – 58.29
(2004-2009) Rate of Degradation = -0.0226x2 + 4.0x – 171.53
102
Where, x is the River Mile (as defined by Reclamation). From 2004 to 2009, the channel
aggraded in response to an increase in base-level of about 35 ft between 2004 and 2009
(7 ft/yr), as follows (where x is the River Mile):
(2004-2009) Rate of Aggradation = -0.4355x2 + 41.11x – 962.27
Wave 1 propagated upstream at a rate of 1.46 miles/year with a decrease in base-
level of 6.9 ft/year. Wave 2 propagated upstream following a rise in base-level of 6.8
ft/year between 2004 and 2009, as follows:
y = -0.5522x2 + 2219.1x – 2*106
Wave 3 propagated upstream following a drop in base-level of 14.2 ft/year between 1997
and 2004, as follows:
y = 0.0692x2 – 276.2x + 275686
Wave 4 propagated upstream following a rise in base-level of 3.7 ft/year between 1990
and 1995, as follows:
y = -0.1222x2 + 489.03x – 489299
Where, x is year and y is river mile.
The average median grain size in Subreach 1 has become finer at a rate of 0.0046
mm/year between 2001 and 2005; Subreach 2 only has data available in 1999; between
1986 and 2002, the average median grain size within Subreach 3, 4, and 5 coarsened at a
rate of 0.0027 mm/year, 0.0031 mm/year, and 0.0031 mm/year respectively; the average
median grain size within Subreach 6 became finer at a rate of 0.0005 mm/year between
1986 and 2002. There has been overall coarsening of the bed material within this study
reach at a rate of less than 0.003 mm/year. Lastly, the median bed material size gets finer
in the downstream direction, and is generally classified as very fine to fine sand.
103
REFERENCES
Bender, T.R. (2011). Bosque Reach. Arroyo de las Canas to South Boundary Bosque del Apache National Wildlife Refuge. Overbank Flow Analysis. 1962 - 2002. Middle Rio Grande, New Mexico. Prepared for the U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, New Mexico. Colorado State university, Fort Collins, CO. 63 p. Borgan, M.A., Allen, C.D., Muldavin, E.H., Platania, S.P., Stuart, J.N., Farely, G.H., Melhop, P., and Belnap, J. (1998). "Southwest." In: Mac, M.J., Opler, P.A., Puckett Haecker, C.E., and Doran, P.D. (eds.). Status and Trends of the Nation's Biological Resources. Vol. 2. U.S. Department of the Interior, U.S. Geological Survey, Reston, VA. pp. 543 - 592. Bullard, K. L., and Lane, W.L. (1993). Middle Rio Grande Peak Flow Frequency Study. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 36 p. Burroughs, C. B. (2011). Criteria for the Formation of Sediment Plugs in Alluvial Rivers. Journal of Hydraulic Engineering. American Society of Civil Engineers. pp. 569 - 576. Clark, I. G. (1987). Water in New Mexico: A History of its Management and Use. Albuquerque, NM: University of New Mexico Press. 839 p. Earick, D. (1999). "The History and Development of the Rio Grande River in the Albuquerque Region," from http://www.unm.edu/~abqteach/EnvirCUs/99-03-04.htm. Finch, D. M., and Tainter, J.A. (2004). Ecology, Diversity and Sustainability of the Middle Rio Grande Basin. Darby, PA: Diane Publishing Co. 186 p. Julien, P. Y. (2010). Erosion and Sedimentation. 2nd ed. New York: Cambridge University Press. 371 p. Kammerer, J. C. (1990). "Water Fact Sheet - Largest Rivers in the United States." U.S. Department of the Interior, U.S. Geological Survey, Reston, VA. 2 p. Larsen, A.K., Shah-Fairbank, S. C., and Julien, P.Y. (2007). Escondida Reach. Escondida to San Antonio. Hydraulic Modeling Analysis. 1962-2006. Middle Rio Grande, New Mexico. Prepared for the U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, New Mexico. Colorado State University, Fort Collins, CO. 179 p. MRGBI (2009). Middle Rio Grande Bosque Initiative. Dams and Diversions Along the Rio Grande, from www.fws.gov/southwest/mrgbi/Resources/Dams/index.html MRGCD (2002). Middle Rio Grande Conservancy District v. Norton. Nos. 01-2057 and 01-2145. United States Court of Appeals, Tenth Circuit. 21 June 2002. 15 p.
104
MRGCD (2006). Middle Rio Grande Conservancy District. About the District, from http://www.mrgcd.com. MRGESA (2006a). Middle Rio Grande Endangered Species Act Collaborative Program. The Rio Grande Silvery Minnow, from http://www.mrgesa.com. MRGESA (2006b). Middle Rio Grande Endangered Species Act Collaborative Program. The Southwestern Willow Flycatcher, from http://www.mrgesa.com. Mussetter Engineering, I. (2001). The Middle Rio Grande Geomorphology Final Report. 195 p. NOAA (2004). NOAA National Weather Service. The North American Monsoon. Reports to the Nation on our Changing Planet, from http://www.cpc.noaa.gov/products/outreach/Report-to-the-Nation-Monsoon_aug04.pdf Paulson, R.W., Chase, E.B., Roberts, R.S., and Moody, D.W., Compilers (1989). National Water Summary 1988-89. Hydrologic Events and Floods and Droughts. U.S. Geological Survey. Water-Supply Paper 2375. 591 p. Reclamation (2007). Middle Rio Grande River Maintenance Plan Summary - Part 1 Report. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 39 p. Reclamation (2003). Geomorphologic Assessment of the Rio Grande, San Acacia Reach. U.S. Department of the Interior, Bureau of Reclamation, Albuquerque, NM. 75 p. Reclamation (2008). Elephant Butte Reservoir 2007 Sedimentation Survey. U.S. Department of the Interior, Bureau of Reclamation, Denver, CO, 154 p. Scurlock, D. (1998). From the Rio to the Sierra: An Environmental History of the Middle Rio Grande Basin. General Technical Report RMRS-GTR-5. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 440 p.
105
APPENDICES
106
Appendix A: Range Line Survey Dates
107
Table A.1 Range Line Survey Dates Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
SO‐1638.8 x
SO‐1641 x x x x x x x x x x x x
SO‐1643.1 x
SO‐1644.8 x
SO‐1645 x x x x x x x x x
SO‐1646.9 x
SO‐1649.1 x
SO‐1650 x x x x x
SO‐1650.7 x
SO‐1652.7 x x x x x x x x x x x x x x
SO‐1656.1 x
SO‐1657.7 x
SO‐1660 x x x x x x x x x x
SO‐1662 x x x x x x x x
SO‐1663 x x x x x x x x x x x x
SO‐1664 x x x x x x x
SO‐1665 x x x x x x x x x x x
SO‐1666 x x x x x x x x x x x x
SO‐1667 x x x x x x
SO‐1668 x x x x x x x
SO‐1668.4 x
SO‐1670 x x x x x x x x x x x x
SO‐1671.5 x
SO‐1673 x x x x x x x x x x x x x
SO‐1674.8 x
SO‐1676.4 x
SO‐1679.4 x
SO‐1680.8 x
SO‐1683 x x x x x x x x x x x x x x x x
108
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
SO‐1684.7 x
SO‐1686.4 x
SO‐1689.9 x
SO‐1692 x x x x x x x x x x x x
SO‐1694.9 x
SO‐1696.7 x
SO‐1698.9 x
SO‐1701.3 x x x x x x x x x x x x x x x x
EB‐5 x x x x
EB‐9 x x x x
EB‐9.2 x x
EB‐9.4 x x x
EB‐9.5 x x x
EB‐10 x x x x x x x x x x x x x x x x x x x x x x x x
EB‐10.1 x x x
EB‐10.2 x x x
EB‐10.3 x x x
EB‐10.45 x x x
EB‐10.5 x x
EB‐10.7 x x x
EB‐10.9 x x x
EB‐11 x x x
EB‐11.1 x x x
EB‐11.5 x x x
EB‐11.9 x x x
EB‐12 x x x x x x
EB‐12X x x x x
EB‐12.4 x x x
EB‐12.7 x x x
109
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐13 x x x x x x x x x x x x x x x x x x x x x x x
EB‐13.9 x x x
EB‐14 x x x x x x x x x x
EB‐14.3 x x x
EB‐14.5 x x x
EB‐14.7 x x x
EB‐15 x x x x x x
EB‐15.1 x x x
EB‐15.4 x x x
EB‐15.7 x x x
EB‐15X x x x x
EB‐16 x x x x x x x x x x x x x x x x x x x x x
EB‐16.5 x x x
EB‐17 x x x x x x x x x x x x x x x x x x x x x x x
EB‐17.1 x
EB‐17.2 x
EB‐17.3 x
EB‐17.35 x x x
EB‐17.4 x
EB‐17.5 x
EB‐17.6 x
EB‐17.7 x x x x
EB‐17.8 x x x
EB‐17.85 x x x
EB‐17.9 x x x
FC‐1754 x
EB‐18 x x x x x x x x x x x x x x x x x x x x x x x x
EB‐18.5 x x x
EB‐18.9 x x x
110
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐19 x x x x x x
EB‐19.1 x x x
EB‐19.3 x x x
EB‐19.5 x x x
EB‐19.7 x x x
EB‐19.8 x x x
EB‐20 x x x x x x x x x x x x x x x x x x x x x x x x
EB‐20.3 x x x
EB‐20.7 x x x
EB‐21 x x x x x x
EB‐22 x x x x x x
EB‐22.2 x x x
EB‐22.6 x x x
EB‐23 x x x x
EB‐23.05 x x x
EB‐23.1
EB‐23.2 x x x
EB‐23.3
EB‐23.4 x x x x
EB‐23.5A
EB‐23.5B x
EB‐23.6A x x x
EB‐23.6B x
EB‐23.8 x x x
EB‐23.9 x
EB‐23.9A x
EB‐24 x x x x x x x x x x x x x x x x x x x x x
EB‐24‐A x x x x x x x x x x x
EB‐24.3 x x x
111
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐24.4
EB‐24.5 x
EB‐24.6 x x x
EB‐24.8
EB‐24.9 x x x
EB‐24B
EB‐25 x x x x x x x x x x x x x x x x x x x x x x x
EB‐25.2
EB‐25.3 x x x
EB‐25.4
EB‐25.5 x x
EB‐25.6 x
EB‐25.8
EB‐25.9
EB‐26 x x x x x x x x x x x x x x x x x x
EB‐26.3 x
EB‐26.6 x
EB‐26.7
EB‐26A
EB‐26B
EB‐26C
EB‐26D x x x
EB‐26E
EB‐26F x x x
EB‐26G
EB‐26H
EB‐26I x x x
EB‐26J
EB‐26K
112
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐27 x x x x x x x x x x x x x x
EB‐27.3 x x x
EB‐27.6 x x x
EB‐27A
EB‐27B
EB‐27C
EB‐27D
EB‐27E
EB‐28 x x x x x x x x x x x x x x x x x
EB‐28 TCH
EB‐28.3 x x x
EB‐28.5 x x x
EB‐28.7 x x x
EB‐28A
EB‐29 x x x x x x x x x x x x x x x x x x
EB‐29 TCH
EB‐29.1 x x x
EB‐29.2 x
EB‐29.3 x x x
EB‐29.5 x x x x x x x x
EB‐29.7 x x x
EB‐29.8 x x x x
EB‐30 x x x x x x x x x x x x x x x x x x
EB‐30.3 x x x
EB‐30.5 x
EB‐30.6 x x x
EB‐31 x x x x x x x x x
EB‐32 x x x x x x x x x x x x x x x x
EB‐32.1 x x x
113
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐32.3 x x x x x x x x x
EB‐32.5 x x x
EB‐32.7 x x x x x x x x x
EB‐33 x x x x x x x x x x
EB‐33.3 x x x x
EB‐33.6 x x x
EB‐33.65 x x x
EB‐33.7 x x x x
EB‐33.8 x x
EB‐34 x x x x x x x x x x x x x x x x x x
EB‐34.5 x x x
EB‐34.8 x
EB‐35 x x x x x x x x
EB‐35.2 x x x
EB‐35.5 x x x
EB‐35.8 x x x
EB‐36 x x x x x x x
EB‐36.3 x x x
EB‐36.6 x x x
EB‐37 x x x x x x x
EB‐37.2 x x x
EB‐37.5 x x x x x x x x
EB‐37.7 x x x
EB‐38 x x x x x x x x
EB‐38.1 x x x x x
EB‐38.15 x
EB‐38.2 x x x x x
EB‐38.3 x x x x x
EB‐38.4 x
114
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐38.6 x x x x
EB‐39 x x x x x x x
EB‐39.1 x
EB‐39.3 x x x x
EB‐39.6 x x x x
EB‐40 x x x x x x
EB‐40.2 x x x x
EB‐40.4 x x x x
EB‐40.5 x x x x x x
EB‐40.7 x x x x
EB‐40.9 x x x x
EB‐41 x x x x x x
EB‐41.4 x x x x
EB‐41.8 x x x x
EB‐42 x x x x x x
EB‐42.3 x x x x
EB‐42.5 x x x x
EB‐42.8 x x x x
EB‐43 x x x x x x
EB‐43.6 x x x x
EB‐44 x x x x x x
EB‐44.6 x x x x
EB‐45 x x x x x x
EB‐45.6 x x x x
EB‐46 x x x x x x
EB‐46.4 x x x x
EB‐47 x x x x x x
EB‐47.3 x x x x
EB‐47.7 x x x x
115
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐48 x x x x x x
EB‐48.3 x x x x
EB‐48.5 x x x x
EB‐48.7 x x x x
EB‐49 x x x x x x
EB‐49.5 x x x x
EB‐49.7 x x x x
EB‐50 x x x x x x
EB‐50.3 x x
EB‐50.7 x x
EB‐51 x x
EB‐51.3 x x
EB‐51.7 x x
EB‐52 x x
EB‐52.4 x x
EB‐52.7 x x
EB‐53 x x
EB‐53.3 x x
EB‐53.7 x x
EB‐54 x x
EB‐54.4 x x
EB‐54.7 x x
EB‐55 x x
EB‐55.3 x x
EB‐55.7 x x
EB‐56 x x
EB‐56.4 x x
EB‐56.7 x x
EB‐57 x x
116
Range Line Survey Dates (Continued)
Range Year
Line 80 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10
EB‐57.3 x x
EB‐57.5 x x
EB‐57.8 x x
EB‐58 x x
EB‐58.4 x x
EB‐58.6 x x
EB‐59 x x
EB‐59.5 x x
EB‐60 x x
117
Appendix B: Daily Discharge Hydrographs
118
Figure B.1 1990 Daily Discharge Data
Figure B.2 1991 Daily Discharge Data
Figure B.3 1992 Daily Discharge Data
0
500
1000
1500
2000
2500
3000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1000
2000
3000
4000
5000
6000
7000
8000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1000
2000
3000
4000
5000
6000
7000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
119
Figure B.4 1993 Daily Discharge Data
Figure B.5 1994 Daily Discharge Data
Figure B.6 1995 Daily Discharge Data
0
1000
2000
3000
4000
5000
6000
7000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
2000
4000
6000
8000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1000
2000
3000
4000
5000
6000
7000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
MonthSan Marcial San Acacia
120
Figure B.7 1996 Daily Discharge Data
Figure B.8 1997 Daily Discharge Data
Figure B.9 1998 Daily Discharge Data
0
1000
2000
3000
4000
5000
6000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1000
2000
3000
4000
5000
6000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
500
1000
1500
2000
2500
3000
3500
4000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
MonthSan Marcial San Acacia
121
Figure B.10 1999 Daily Discharge Data
Figure B.11 2000 Daily Discharge Data
Figure B.12 2001 Daily Discharge Data
0
1000
2000
3000
4000
5000
6000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
200
400
600
800
1000
1200
1400
1600
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
500
1000
1500
2000
2500
3000
3500
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
MonthSan Marcial San Acacia
122
Figure B.13 2002 Daily Discharge Data
Figure B.14 2003 Daily Discharge Data
Figure B. 15 2004 Daily Discharge Data
0
500
1000
1500
2000
2500
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
500
1000
1500
2000
2500
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
500
1000
1500
2000
2500
3000
3500
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
123
Figure B.16 2005 Daily Discharge Data
Figure B.17 2006 Daily Discharge Data
Figure B.18 2007 Daily Discharge Data
0
1000
2000
3000
4000
5000
6000
7000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1000
2000
3000
4000
5000
6000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
500
1000
1500
2000
2500
3000
3500
4000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
124
Figure B.19 2008 Daily Discharge Data
Figure B.20 2009 Daily Discharge Data
Figure B.21 2010 Daily Discharge Data
0
1000
2000
3000
4000
5000
6000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Marcial San Acacia
0
1,000
2,000
3,000
4,000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Acacia San Marcial
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
Jan
Fe
b
Ma
r
Ap
r
Ma
y
Jun
Jul
Au
g
Se
p
Oct
No
v
De
c
Dis
cha
rge
(cf
s)
Month San Acacia San Marcial
125
Appendix C: Dates and Locations of Bed Material Samples
126
Table C.1 Available Bed Material Data at Range Lines
Range Line
Year
86 87 88 90 92 93 94 96 97 98 99 01 02 04 05 07
SO-1641 X X X X
SO-1652.7 X X
SO-1660 X
SO-1665 X
SO-1666 X X X
SO-1670 X
SO-1683 X
SO-1701.3 X X X
EB-5 X X X
EB-10 X X X X X X X X X X X
EB-13 X X X X X X
EB-14 X X X
EB-16 X X X X
EB-17 X X
FC-1754 X
EB-18 X X X X X X X X X
EB-20 X X X X X X X X X
EB-34 X X X
EB-24 X X X X
EB-24A X X X X X
EB-25 X X
EB-26 X
EB-26.6 X
EB-27 X
EB-28 X
EB-29 X
EB-29.5 X
EB-30 X
EB-36 X
127
Appendix D: Dates and Locations of USGS Gauge Bed Material Samples
128
Table D.1: Available Bed Material Data at USGS gauging stations: San Acacia and San
Marcial
Year
Gauging station
Year
Gauging station
San Acacia
San Marcial
San Acacia
San Marcial
1966 x 1988 x x
1967 1989 x x
1968 x x 1990 x x
1969 x x 1991 x x
1970 1992 x x
1971 1993 x x
1972 x 1994 x x
1973 x x 1995 x x
1974 x 1996 x x
1975 x x 1997 x x
1976 x x 1998 x x
1977 x 1999 x x
1978 x x 2001 x x
1979 x x 2002 x x
1980 x x 2003 x x
1981 x x 2004 x x
1982 x x 2005 x x
1983 x x 2006 x x
1984 x x 2007 x x
1985 x x 2008 x x
1986 x x 2009 x x
1987 x x 2010 x x
129
Appendix E: Aerial Photograph Survey Dates and Information
130
Table E.1 Aerial Photo Survey Dates and Information
Mean Daily Discharge
Date San Acacia San Marcial Scale Notes
(1918-2002:from Novak 2006 2005: from ArcGIS metadata)
1918 No Data No Data 1:12,000
Hand-drafted linens (39 sheets).
USBR Albuquerque Area Office.
Surveyed in 1918. Published in 1922.
1935 No Data No Data 1:8,00
Black and white photography. USBR
Albuquerque Area Office. Flown in
1935. Published in 1936.
1949 No Data No Data 1:5,000
Photo-mosaic. J-Ammann
Photogrammetric Engineers, San
Antonio, TX. USBR Albuquerque
Area Office.
March 1962
25 cfs 0 cfs 1:4,800
Photo-mosaic. Abram Aerial Survey
Corp, Lansing, MI. USBR
Albuquerque Area Office.
April 1972 4 cfs 0 cfs 1:4,800
Photo-mosaic. Limbaugh Engineers,
Inc., Albuquerque, NM. USBR
Albuquerque Area Office.
March 1985
1900 cfs 1320 cfs 1:4,800
Orthophoto. M&I Consulting
Engineers, Fort Collins, CO. Aero-
Metric Engineering, Sheboygan, MN.
USBR Albuquerque Area Office.
February 1992
1020 cfs 630 cfs 1:4,800
Ratio-rectified photo-mosaic. Koogle
and Poules Engineering,
Albuquerque, NM. USBR
Albuquerque Area Office.
February 2001
770 cfs 560 cfs 1:4,800
Ratio-rectified photo-mosaic. Pacific
Western Technologies, Ltd.,
Albuquerque, NM. USBR
Albuquerque Area Office.
March 2002
310 cfs 150 cfs 1:4,800
Digital ortho-imagery. Pacific
Western Technologies, Ltd.,
Albuquerque, NM. USBR
Albuquerque Area Office.
December 2003
628 cfs 439 cfs 1:28,800 Digital ortho-imagery. USBR
Albuquerque Area Office.
Winter 2004
Date
Unknown
Date
Unknown 1:4,800
Digital ortho-rectified imagery. USBR
Albuquerque Area Office.
April 2005 2270 cfs 1680 cfs 1:4,800
Digital ortho-rectified imagery. Aero-
Metric, Inc., Fort Collins, CO. USBR
Albuquerque Area Office.
January 2006
Date
Unknown
Date
Unknown 1:4,800
Digital ortho-rectified imagery. Aero-
Metric, Inc., Fort Collins, CO. USBR
Albuquerque Area Office.
June 2008
3990 cfs 3460 1:45,720 Digital ortho-rectified imagery. USBR
Albuquerque Area Office.
2010 Date
Unknown
Date
Unknown
LiDAR Optec 3100 EA LiDAR 3m.
Aero-Metric, Inc., Fort Collins, CO.
USBR Albuquerque Area Office.
131
Appendix F: Range Line Cross-Section Plots
132
Figure F.2 SO‐1652.7 Cross‐Section
4484
4486
4488
4490
4492
4494
4496
50 150 250 350 450
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2003
2002
1999
1998
1997
1995
1994
1993
1991
1990
4486
4488
4490
4492
4494
4496
4498
4500
0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2003
2002
2001
1999
1998
1997
Figure F.1 SO‐1641 Cross‐Section
133
Figure F.3 SO‐1666 Cross‐Section
Figure F.4 SO‐1673 Cross‐Section
4480
4482
4484
4486
4488
4490
4492
750 800 850 900 950 1000
Elevation (ft)
Station (ft)
2006
2002
1999
1998
1997
1995
1994
1992
1991
1990
4476
4478
4480
4482
4484
4486
4488
4490
4492
600 650 700 750 800 850 900
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
1999
1998
1997
1995
1994
134
Figure F.5 SO‐1683 Cross‐Section
Figure F.6 SO‐1692 Cross‐Section
4474
4476
4478
4480
4482
4484
4486
4488
4490
4492
0 50 100 150 200
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2004
2003
2002
1999
1998
1997
1994
1993
1990
4472
4474
4476
4478
4480
4482
4484
50 100 150 200 250
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2002
1999
1998
1994
135
Figure F.7 SO‐1701.3 Cross‐Section
4468
4470
4472
4474
4476
4478
4480
4482
4484
0 100 200 300 400 500
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2002
1999
1998
1997
1995
1994
1993
1992
1991
1990
136
Figure F.8 EB‐10 Cross‐Section
Figure F.9 EB‐10 (w/Floodplain) Cross‐Section
4462
4464
4466
4468
4470
4472
4474
4476
4478
4480
4482
500 600 700 800 900 1000
Elevation (ft)
Station (ft)
201020092008200720052004200320022001199919981997199619951994199319921991199019881987
4445
4450
4455
4460
4465
4470
4475
4480
4485
4490
0 500 1000 1500 2000 2500
Elevation (ft)
Station (ft)
20102009200820072005200420032002200119991998199719961995199419931992199119901988198719861980
137
Figure F.10 EB‐13 Cross‐Section
Figure F.11 EB‐14 Cross‐Section
4460
4462
4464
4466
4468
4470
4472
4474
4476
1950 2000 2050 2100 2150 2200 2250 2300
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1998
1992
1988
1987
1986
4445
4450
4455
4460
4465
4470
4475
150 200 250 300 350 400
Elevation (ft)
Station (ft)
1999/2001
1998
1997
1996
1988
1980
138
Figure F.12 EB‐16 Cross‐Section
Figure F.13 EB‐17 Cross‐Section
4456
4458
4460
4462
4464
4466
4468
4470
4472
100 150 200 250 300 350
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1999
1998
1997
1994
1993
1992
4452
4454
4456
4458
4460
4462
4464
4466
4468
4470
4472
4474
50 100 150 200 250
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2002
2001
1999
1998
1997
1996
1995
1994
1993
1992
1991
1988
1980
139
Figure F.14 EB‐18 Cross‐Section
Figure F.15 EB‐20 Cross‐Section
4450
4452
4454
4456
4458
4460
4462
4464
4466
4468
600 650 700 750 800 850 900 950 1000
Elevation (ft)
Station (ft)
2009
2008
2007
2003
2004
2002
2000
1999
1998
1997
1996
4435
4440
4445
4450
4455
4460
4465
150 200 250 300 350 400 450
Elevation (ft)
Station (ft)
200920082007200520042002200019991998199719951994199319921991199019881980
140
Figure F.16 EB‐34 Cross‐Section
Figure F.17 EB‐24 Cross‐Section
4440
4442
4444
4446
4448
4450
4452
4454
4456
4458
4460
4462
250 300 350 400 450 500 550 600
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1999
1998
1997
1996
4425.00
4430.00
4435.00
4440.00
4445.00
4450.00
4455.00
4460.00
5800 6000 6200 6400 6600 6800 7000
Elevation (ft)
Station (ft)
2007
2005
2004
2002
2000
1999
1998
1997
1989
1980
141
Figure F.18 EB‐25 Cross‐Section
Figure F.19 EB‐26 Cross‐Section
4435
4440
4445
4450
4455
4460
4750 4800 4850 4900 4950 5000 5050 5100 5150 5200
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1998
1999
1996
1995
1994
1993
1989
4430
4435
4440
4445
4450
4455
4800 4900 5000 5100 5200 5300
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
1999
1998
1997
1996
1995
1994
1993
1980
142
Figure F.20 EB‐27 Cross‐Section
Figure F.21 EB‐27 (w/Floodplain) Cross‐Section
4438
4440
4442
4444
4446
4448
4450
4452
4700 4800 4900 5000 5100 5200 5300
Elevation (ft)
Station (ft)
2002
2000
1999
1998
1995
1993
1992
1989
1988
1980
4420
4425
4430
4435
4440
4445
4450
4455
4460
0 2000 4000 6000 8000 10000
Elevation (ft)
Station (ft)
2002
2000
1999
1998
1995
1994
1993
1992
1989
1988
1980
143
Figure F.22 EB‐28 Cross‐Section
Figure F.23 EB‐28 (w/Floodplain) Cross‐Section
4428
4430
4432
4434
4436
4438
4440
4442
4444
4446
4448
4980 5030 5080 5130 5180 5230
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2002
2000
1999
1998
1995
1992
4428
4430
4432
4434
4436
4438
4440
4442
4444
4446
4448
4450
4000 5000 6000 7000 8000 9000 10000
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2002
2000
1999
1998
1995
1993
1992
144
Figure F.24 EB‐29 Cross‐Section
Figure F.25 EB‐29 (w/Floodplain) Cross‐Section
4425
4430
4435
4440
4445
4450
5000 5100 5200 5300 5400 5500 5600
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1999
1997
1995
1993
1989
4425
4430
4435
4440
4445
4450
4455
3750 4250 4750 5250 5750 6250 6750 7250
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
2002
2000
1999
1997
1995
1993
1989
145
Figure F.26 EB‐30 Cross‐Section
Figure F.27 EB‐30 (w/Floodplain) Cross‐Section
4424
4426
4428
4430
4432
4434
4436
4438
4440
3590 3690 3790 3890 3990
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2002
2000
1997
1995
1993
1992
4424
4426
4428
4430
4432
4434
4436
4438
4440
4442
2000 3000 4000 5000 6000 7000 8000 9000 10000
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
2004
2002
2000
1999
1997
1995
1993
1992
146
Figure F.28 EB‐32 Cross‐Section
Figure F.29 EB‐32 (w/Floodplain) Cross‐Section
4420
4422
4424
4426
4428
4430
4432
4434
4436
5200 5300 5400 5500 5600 5700 5800
Elevation (ft)
Station (ft)
2009
2007
2006
2005
2004
2002
1999
1997
1995
1993
1989
4420
4422
4424
4426
4428
4430
4432
4434
4436
4438
3750 4250 4750 5250 5750 6250
Elevation (ft)
Station (ft)
2009
2007
2006
2005
2004
2002
1999
1997
1995
1993
1989
147
Figure F.30 EB‐33 Cross‐Section
Figure F.31 EB‐35 Cross‐Section
4418
4420
4422
4424
4426
4428
4430
4432
4434
5100 5200 5300 5400 5500 5600 5700 5800
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
4414
4416
4418
4420
4422
4424
4426
4428
4430
4432
3500 3600 3700 3800 3900 4000 4100
Elevation (ft)
Station (ft)
2009
2008
2007
2005
2004
148
Figure F.32 EB‐36 Cross‐Section
Figure F.33 EB‐37 Cross‐Section
4412
4414
4416
4418
4420
4422
4424
4426
4428
4430
5400 5500 5600 5700 5800
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2005
2004
2003
4410
4412
4414
4416
4418
4420
4422
4424
4426
4428
4430
3000 3100 3200 3300 3400 3500 3600 3700 3800
Elevation (ft)
Station (ft)
EB‐37
2010
2009
2008
2007
2005
2004
2003
149
Figure F.34 EB‐37.5 Cross‐Section
Figure F.35 EB‐38 Cross‐Section
4410
4412
4414
4416
4418
4420
4422
4424
4426
4428
0 100 200 300 400 500
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2006
2005
2004
2003
4408
4410
4412
4414
4416
4418
4420
4422
4424
4426
4428
2800 2900 3000 3100 3200 3300 3400
Elevation (ft)
Station (ft)
2009
2008
2007
2006
2005
150
Figure F.36 EB‐39 Cross‐Section
Figure F.37 EB‐40 Cross‐Section
4406
4408
4410
4412
4414
4416
4418
4420
4422
4424
4426
4428
‐100 0 100 200 300 400
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2006Perpindicular2004
2003
4400
4405
4410
4415
4420
4425
4550 4600 4650 4700 4750 4800 4850 4900
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
151
Figure F.38 EB‐40.5 Cross‐Section
Figure F.39 EB‐41 Cross‐Section
4400
4405
4410
4415
4420
4425
4430
‐50 0 50 100 150 200 250 300 350
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
4398
4400
4402
4404
4406
4408
4410
4412
4414
4416
0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
2009
2008
2007
2004
152
Figure F.40 EB‐42 Cross‐Section
Figure F.41 EB‐43 Cross‐Section
4398
4400
4402
4404
4406
4408
4410
4412
4414
4416
‐100 ‐50 0 50 100 150 200 250 300 350
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
4390
4395
4400
4405
4410
4415
4420
‐100 0 100 200 300 400
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
153
Figure F.42 EB‐44 Cross‐Section
Figure F.43 EB‐45 Cross‐Section
4394
4396
4398
4400
4402
4404
4406
4408
4410
4412
4414
‐100 ‐50 0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
4390
4395
4400
4405
4410
4415
4420
‐100 0 100 200 300 400
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
154
Figure F.44 EB‐46 Cross‐Section
Figure F.45 EB‐47 Cross‐Section
4398
4400
4402
4404
4406
4408
4410
4412
4414
4416
0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
2009
2008
2007
4390
4395
4400
4405
4410
4415
4420
0 50 100 150 200 250 300
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
155
Figure F.46 EB‐48 Cross‐Section
Figure F.47 EB‐49 Cross‐Section
4385
4390
4395
4400
4405
4410
‐100 0 100 200 300 400
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
4385
4390
4395
4400
4405
4410
4415
4420
0 100 200 300 400 500 600
Elevation (ft)
Station (ft)
2010
2009
2008
2007
2004
2003
156
Figure F.48 EB‐50 Cross‐Section
4385
4390
4395
4400
4405
4410
0 50 100 150 200 250 300 350 400 450
Elevation (ft)
Station (ft)
2009
2008
2007
2006
157
Appendix G: Change in Thalweg Elevation vs. River Mile Plots
158
Figure G.1 1990‐1992 Thalweg Change
Figure G.2 1991‐1992 Thalweg Change
0.0
0.5
1.0
1.5
2.0
2.5
3.0
454749515355575961
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1990‐1992
y = 4.1023x ‐ 253.93R² = 1
‐7
‐6
‐5
‐4
‐3
‐2
‐1
0
1
2
6060.56161.56262.563
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1991‐1992 Linear (Wave 4 1991‐1992)
159
Figure G.3 1992‐1993 Thalweg Change
Figure G.4 1993‐1994 Thalweg Change
y = ‐0.0992x2 + 11.97x ‐ 358.74R² = 0.1623
‐4
‐2
0
2
4
6
8
10
455055606570
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1992‐1993 Poly. (Wave 4 1992‐1993)
y = 0.0008x2 + 0.0616x ‐ 6.2002R² = 0.285
‐1.5
‐1.0
‐0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
455055606570
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1993‐1994 Poly. (Wave 4 1993‐1994)
160
Figure G.5 1994‐1995 Thalweg Change
Figure G.6 1995‐1997 Thalweg Change
y = ‐0.0179x2 + 2.1771x ‐ 64.765R² = 0.0227
‐3
‐2
‐1
0
1
2
3
4
5
6
7
455055606570
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1994‐1995 Poly. (Wave 4 1994‐1995)
y = 0.0683x2 ‐ 8.6959x + 276.42R² = 0.0933
‐5
‐4
‐3
‐2
‐1
0
1
2
3
4
455055606570
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1995‐1997 Wave 3/4 Transition 1995‐1997 Poly. (Wave 4 1995‐1997)
161
Figure G.7 1997‐1998 Thalweg Change
Figure G.8 1998‐1999 Thalweg Change
y = 0.274x2 ‐ 36.539x + 1219.1R² = 0.2054
‐3
‐2
‐1
0
1
2
3
4
5
455055606570
Chan
ge in
Thalweg (ft)
River Mile
Wave 4 1997‐1998 Wave 3/4 Transition 1997‐1998 Poly. (Wave 4 1997‐1998)
y = 0.0553x2 ‐ 7.4734x + 252.98R² = 0.08
‐3
‐2
‐1
0
1
2
3
4
45505560657075
Chan
ge in
Thalweg (ft)
River Mile
Wave 3 1998‐1999 Wave 4 1998‐1999
Wave 3/4 Transition 1998‐1999 Poly. (Wave 4 1998‐1999)
162
Figure G.9 1999‐2002 Thalweg Change
Figure G.10 2002‐2003 Thalweg Change
y = ‐2.2408x + 120.61R² = 1
y = 0.0309x2 ‐ 4.2878x + 148.76R² = 0.0832
‐5
‐4
‐3
‐2
‐1
0
1
2
3
45505560657075
Chan
ge in
Thalweg (ft)
River Mile
Wave 3 1999‐2002 Wave 4 1999‐2002Wave 3/4 Transition 1999‐2002 Linear (Wave 3 1999‐2002)Poly. (Wave 4 1999‐2002)
y = 0.885x2 ‐ 96.405x + 2622.5R² = 0.6265
y = ‐0.0127x2 + 1.6943x ‐ 54.451R² = 0.1822
‐4
‐3
‐2
‐1
0
1
2
3
4
5
4550556065707580
Chan
ge in
Thalweg (ft)
River Mile
Wave 3 2003‐2004 Wave 4 2003‐2004
Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004)
163
Figure G.11 2003‐2004 Thalweg Change
Figure G. 12 2004‐2007 Thalweg Change
y = ‐0.009x2 + 0.963x ‐ 27.412R² = 0.0059
y = 0.0402x2 ‐ 5.7666x + 205.93R² = 0.3261
‐12
‐10
‐8
‐6
‐4
‐2
0
2
4
4550556065707580
Chan
ge in
Thalweg (ft)
River Mile
Wave 3 2003‐2004 Wave 4 2003‐2004Wave 3/4 Transition 2003‐2004 Poly. (Wave 3 2003‐2004)Poly. (Wave 4 2003‐2004)
y = ‐0.3485x2+ 32.295x ‐741.44
R² = 0.8947
y = 0.1767x2 ‐ 21.993x + 676.35R² = 0.5992
y = 0.1679x2
‐23.548x + 825.83
R² = 0.4563
‐15
‐10
‐5
0
5
10
4550556065707580
Chan
ge in
Thalweg (ft)
River MileWave 2 2004‐2007 Wave 2/3 Transitional 2004‐2007
Wave 3 2007‐2008 Wave 4 2004 ‐ 2007
Poly. (Wave 2 2004‐2007) Poly. (Wave 3 2007‐2008)
Poly. (Wave 4 2004 ‐ 2007)
164
Figure G.13 2007‐2008 Thalweg Change
Figure G.14 2008‐2009 Thalweg Change
y = ‐0.0069x2 + 0.7283x ‐ 18.716R² = 0.0311
y = ‐0.0064x2 + 0.864x ‐ 30.281R² = 0.1006
‐3.0
‐2.5
‐2.0
‐1.5
‐1.0
‐0.5
0.0
0.5
1.0
1.5
2.0
4550556065707580
Chan
ge in
Thalweg (ft)
River Mile
Wave 2 2007‐2008 Wave 2/3 Transitional 2007‐2008
Wave 3 2007‐2008 Poly. (Wave 2 2007‐2008)
Poly. (Wave 3 2007‐2008)
y = ‐0.2133x2 + 20.808x ‐ 505.26R² = 0.3004
y = 0.0078x2 ‐ 0.9912x + 30.863R² = 0.0929
‐3
‐2
‐1
0
1
2
3
4
5
4550556065707580
Chan
ge in
Thalweg (ft)
River MileWave 2 2008‐2009 Wave 2/3 Transitional 2008‐2009
Wave 3 2008‐2009 Poly. (Wave 2 2008‐2009)
Poly. (Wave 3 2008‐2009)
165
Figure G.15 2009‐2010 Thalweg Change
y = 0.0363x2 ‐ 4.054x + 112.8R² = 0.5874
y = 0.074x2 ‐ 9.3306x + 293.35R² = 0.8984
‐3
‐2
‐1
0
1
2
3
4
455055606570
Chan
ge in
Thalweg Elevation (ft)
River Mile
Wave 1 2009‐2010 Wave 2 2009‐2010
Wave 2/3 Transition 2009‐2010 Wave 3 2009‐2010
Poly. (Wave 2/3 Transition 2009‐2010) Poly. (Wave 3 2009‐2010)
166
Appendix H: Bed Material Grain Size Distribution Plots
167
Figure H.1 SO‐1641 2001 Grain Size Distribution
Figure H.2 SO‐1641 2002 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1
% Finer by Weight
Grain Size (mm)
168
Figure H.3 SO‐1641 2004 Grain Size Distribution
Figure H.4 SO‐1641 2005 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1
% Finer by Weight
Grain Size (mm)
169
Figure H.5 SO‐1683 1999 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
170
Figure H.6 EB‐10 1986 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
171
Figure H.7 EB‐10 1987 Grain Size Distribution
Figure H.8 EB‐10 1988 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
172
Figure H.9 EB‐10 1990 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
173
Figure H.10 EB‐10 1992 Grain Size Distribution
Figure H.11 EB‐10 1993 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
174
Figure H.12 EB‐10 1994 Grain Size Distribution
Figure H. 13 EB‐10 1997 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
175
Figure H.14 EB‐10 1998 Grain Size Distribution
Figure H.15 EB‐10 1999 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
176
Figure H.16 EB‐10 2002 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
177
Figure H.17 EB‐13 1986 Grain Size Distribution
Figure H.18 EB‐13 1987 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
178
Figure H.19 EB‐13 1988 Grain Size Distribution
Figure H.20 EB‐13 1990 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
179
Figure H.21 EB‐13 1999 Grain Size Distribution
Figure H.22 EB‐13 2002 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
180
Figure H.23 EB‐18 1986 Grain Size Distribution
Figure H.24 EB‐18 1987 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
181
Figure H.25 EB‐18 1988 Grain Size Distribution
Figure H.26 EB‐18 1990 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
182
Figure H.27 EB‐18 1993 Grain Size Distribution
Figure H.28 EB‐18 1994 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
183
Figure H.29 EB‐18 1997 Grain Size Distribution
Figure H.30 EB‐18 1999 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
184
Figure H.31 EB‐18 2002 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
% Finer by Weight
Grain Size (mm)
185
Figure H.32 EB‐24 1986 Grain Size Distribution
Figure H.33 EB‐24 1992 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
186
Figure H.34 EB‐24 1999 Grain Size Distribution
Figure H.35 EB‐24 2002 Grain Size Distribution
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10
% Finer by Weight
Grain Size (mm)
Recommended