20030180 Ver 7_Report_20030201

Prepared in cooperation with Macon County, North Carolina
Suspended Sediment and Bed Load in Three Tributaries
to Lake Emory in the Upper Little Tennessee River Basin,
North Carolina, 2000-02
U.S. Geological Survey
Water-Resources Investigations Report 03-4194
U.S. Geological Survey
U.S. Department of the Interior

Suspended Sediment and Bed Load in
Three Tributaries to Lake Emory in the
Upper Little Tennessee River Basin,
North Carolina, 2000-02
By Carolyn J. Oblinger
U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 03-4194
Prepared in cooperation with
Macon County, North Carolina
Raleigh, North Carolina
2003
U.S. DEPARTMENT OF THE INTERIOR
GALE A. NORTON, Secretary
U.S. GEOLOGICAL SURVEY
Charles G. Groat, Director
The use of firm, trade, and brand names in this report is for identification purposes
only and does not constitute endorsement by the U.S. Government.
Additional information about U.S. Geological Survey programs and products in
North Carolina can be obtained from the Web site: http://nc.water.usgs.gov
For additional information write to:
District Chief
U.S. Geological Survey
3916 Sunset Ridge Road
Raleigh, NC 27607
Copies of this report can be purchased
from:
U.S. Geological Survey
Branch of Information Services
Box 25286, Federal Center
Denver, CO 80225
[e-mail] 1-888-ASK-USGS
CONTENTS
Abstract ................................................................................................................................................................................
Introduction ..........................................................................................................................................................................
Purpose and scope ......................................................................................................................................................
Study area ...................................................................................................................................................................
Acknowledgments ......................................................................................................................................................
Data-collection methods .......................................................................................................................................................
Streamflow data ..........................................................................................................................................................
Suspended-sediment data ...........................................................................................................................................
Bed-load data .............................................................................................................................................................
Particle size ................................................................................................................................................................
Streamflow ...........................................................................................................................................................................
Estimation of streamflow in the Cullasaja River ........................................................................................................
Estimation of Porter's Bend dam releases ..................................................................................................................
Suspended sediment .............................................................................................................................................................
Load ............................................................................................................................................................................
Particle size ................................................................................................................................................................
Bed material .........................................................................................................................................................................
Bed load .....................................................................................................................................................................
Particle size ................................................................................................................................................................
Summary ..............................................................................................................................................................................
References ............................................................................................................................................................................
FIGURES
1-2. Maps showing:
1. Location of the upper Little Tennessee River basin, North Carolina ..............................................................
2. Locations of streamgages and sediment-sampling sites in the upper Little Tennessee
River basin, North Carolina ............................................................................................................................
3. Photograph of a Helley-Smith bed-load sampler ....................................................................................................
4-13. Graphs showing:
4. Total annual precipitation at the Franklin, North Carolina, Weather Station for
1990-2001, and the long-term average annual rainfall ..................................................................................
5. Long-term minimum and median daily-mean streamflow and daily-mean streamflow for
water year 2001 at (A) the Little Tennessee River near Prentiss and
(B) Cartoogechaye Creek near Franklin, North Carolina ...............................................................................
6. Departure from mean-monthly streamflow at (A) the Little Tennessee River near
Prentiss and (B) Cartoogechaye Creek near Franklin, North Carolina, and
(C) monthly rainfall at the Franklin Weather Station .....................................................................................
7. Distributions of sampled streamflows at (A) the Little Tennessee River and
(B) Cartoogechaye Creek in relation to long-term streamflow durations
from streamgages at the Little Tennessee River near Prentiss
and Cartoogechaye Creek near Franklin, North Carolina ...............................................................................
8. Relation of daily-mean streamflow in the Cullasaja River to daily-mean streamflows at
Cartoogechaye Creek near Franklin and the Little Tennessee River near
Prentiss, North Carolina, for water years 1970-71 .......................................................................................
1
1
3
3
3
4
5
6
6
6
6
9
13
13
13
19
21
21
23
23
24
2
4
6
7
7
8
9
10
Contents III
9. Relation of instantaneous and daily-mean streamflows at the Cullasaja River near
Franklin, North Carolina, to instantaneous (2001-02) and daily-mean (1970-71)
streamflows at the Little Tennessee River near Prentiss and
Cartoogechaye Creek near Franklin ................................................................................................................ 12
10. Distribution of suspended-sediment concentrations at the four Little Tennessee River
basin study sites in North Carolina .................................................................................................................. 16
11. Relation of daily sediment load to instantaneous streamflow at (A) the Cullasaja River
near Franklin, (B) Cartoogechaye Creek near Franklin, and (C) the Little Tennessee River
at Riverside, North Carolina ............................................................................................................................. 17
12. Relation of daily suspended-sediment load and instantaneous streamflow at
Cartoogechaye Creek near Franklin, North Carolina, for 1977-79 and 2001 ................................................ 19
13. Distribution of percentages of suspended-sediment particles finer than 0.062 millimeter
at the four Little Tennessee River basin study sites in North Carolina ........................................................... 21
TABLES
1. Selected U.S. Geological Survey streamgaging stations in the upper Little
Tennessee River basin, North Carolina ................................................................................................................... 5
2. Regression equations relating streamflow at the two Little Tennessee River basin index
sites to streamflow in the Cullasaja River, North Carolina ..................................................................................... 11
3. Relation of streamflow measured at the Cullasaja River to streamflow at Cartoogechaye
Creek near Franklin and the Little Tennessee River near Prentiss, North Carolina,
during water years 2001 and 2002 .......................................................................................................................... 11
4. Streamflow statistics for the Little Tennessee River basin, North Carolina, study sites
for the 2001 water year ........................................................................................................................................... 13
5. Suspended-sediment concentrations at the four Little Tennessee River basin
study sites in North Carolina and measured or estimated streamflow at
three of the study sites .............................................................................................................................................. 14
6. Results of regression analyses relating the natural log of instantaneous suspended-
sediment load to the natural log of instantaneous streamflow at three Little Tennessee
River basin study sites in North Carolina ................................................................................................................ 18
7. Estimated suspended-sediment loads and yields at the three study sites and at
sites sampled in 1970-79 in the Little Tennessee River basin, North Carolina ..................................................... 18
8. Streamflow and suspended-sediment concentration and particle-size distributions
in samples from the four Little Tennessee River basin study sites in North Carolina ............................................ 20
9. Bed load and suspended-sediment load during three runoff events at three sites in
the Little Tennessee River basin in North Carolina ................................................................................................ 22
10. Particle-size distribution in bed-load samples from three sites in the Little Tennessee
River basin in North Carolina ................................................................................................................................. 23
IV Contents
CONVERSION FACTORS, ABBREVIATIONS, and ACRONYMS
Multiply By To obtain
Length
millimeter (mm) 0.03937 inch
centimeter (cm) 0.3937 inch
meter (m) 3.281 foot
1.094 yard
kilometer (km) 0.6214 mile
Area
hectare (ha) 2.471 acre
square kilometer (km2) 0.3861 square mile
Volume
cubic meter (m3) 35.31 cubic foot
1.308 cubic yard
Flow
meter per second (m/s) 3.281 foot per second
cubic meter per second (m3/s) 35.31 cubic foot per second
cubic meter per second per square kilometer [(m3/s)/km2] 91.49 cubic foot per second per square mile
Mass
kilogram (kg) 2.205 pound
metric ton (t) 1.102 short ton (2,000 pounds)
metric ton per day (t/d) 1.102 short ton (2,000 pounds)
metric ton per square kilometer (t/km2) 2.855 short ton (2,000 pounds) per square mile
Abbreviated water-quality units: mg/L, milligram per liter
L, liter (a unit of volume equal to approximately 1.056 quarts)
EWI equal-width integrated
FISP Federal Interagency Sedimentation Project
MEWI multiple equal-width increment
NOAA National Oceanic and Atmospheric Administration
NWIS National Water Information System
USGS U.S. Geological Survey
VA visual accumulation
GLOSSARY
Daily-mean streamflow-The mean streamflow for any one day. For example, the daily-mean streamflow
for October 10, 2002.
Annual-mean streamflow-The arithmetic mean of the daily-mean streamflows for the year noted or for
the designated period. For example, the annual-mean streamflow for 1944 to 2001 is the arithmetic mean of
all daily-mean streamflow for that period.
Mean-monthly streamflow-The arithmetic mean of the means of record for a specific month during a
specific period of years. For example, the mean-monthly streamflow for October is the arithmetic mean of all
October means during 1944 to 2001.
Contents V
Suspended Sediment and Bed Load in Three Tributaries
to Lake Emory in the Upper Little Tennessee River Basin,
North Carolina, 2000-02
By Carolyn J. Oblinger
ABSTRACT
A study was conducted in the upper Little
Tennessee River basin to characterize suspended-
sediment and bed-load sediment transport into Lake
Emory from the main stem and two major
tributaries -Cartoogechaye Creek and the Cullasaja
River. Suspended-sediment concentrations in the
discharge from Lake Emory also were measured.
Weekly samples for suspended-sediment concentration
were collected between November 2000 and November
2001, and periodic samples were collected during
targeted high-flow events. Suspended-sediment
samples were collected during stormwater runoff
conditions for analysis of particle-size distribution.
Three bed-load samples were collected at each stream
site.
The greatest annual load (5,700 metric tons) and
yield (18 metric tons per square kilometer) of
suspended sediment during the study period were in the
Little Tennessee River near Riverside, North Carolina.
Much smaller annual yields were calculated for Lake
Emory, the Cullasaja River, and Cartoogechaye Creek
(5, 5, and 7 metric tons per square kilometer,
respectively). Drought conditions during the study
period appear to have been a factor in the small loads
compared to loads measured in the same area in the
1970's. The annual-mean streamflow at the Little
Tennessee River at Prentiss during 2001 was about
50 percent of the long-term annual-mean streamflow
(1944-2001). High-flow events carry most of the
annual sediment load.
INTRODUCTION
The upper Little Tennessee River basin in
western North Carolina is part of the Little Tennessee
River basin upstream from Fontana Lake (fig. 1). The
upper basin is mountainous and rural-less than
5 percent of the land use in the basin is classified as
urban and 89 percent is forested. Parts of the basin lie
within the Great Smoky Mountains National Park and
Nantahala National Forest. Because the Little
Tennessee River is a mountain river, its tributaries
typically have relatively steep gradients and riffle
habitats capable of supporting trout populations (North
Carolina Division of Water Quality, 2000). The Little
Tennessee River also supports a large variety of other
aquatic species, including three rare species on the
Federal endangered species list-the Appalachian
elktoe mussel (Alasmidonta raveneliana), the little-
wing pearly mussel (Pegias fabula), and the Spotfin
chub (Cyprinella monacha). The Little Tennessee
River basin is the only basin in North Carolina where
the slippershell mussel (Alasmidonta viridis) and
Tennessee pigtoe mussel (Fusconaia barnesiana) can
be found.
A major water-quality issue in the rural setting of
the Little Tennessee River basin is sedimentation-
both historic and recent (North Carolina Division of
Water Quality, 2002). Sedimentation is the primary
factor affecting ecological communities in the basin
(Harding and others, 1998), resulting in loss of in-
stream microhabitats and aquatic-habitat degradation.
Sedimentation is caused primarily by land-clearing
Abstract 1
84'
35°42'
83°42'
83°24'
83°O6'
EXPLANATION
? GREAT SMOKY MOUNTAINS NATIONAL PARK
® NANTAHALA NATIONAL FOREST
• • BASIN BOUNDARY
03503000. ACTIVE STREAMGAGING STATIONS
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Base from digital files of
U.S. Department of Commerce, Bureau of Census,
1990 Precensus TIGER/Line Files-Political boundaries, 1991
Environmental Protection Agency, River File 3
U.S. Geological Survey, 1:100,000 scale
figure 1. Location of the upper Little Tennessee River basin, North Carolina.
2 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
LOCATION OF LITTLE TENNESSEE RIVER BASIN AND BLUE RIDGE PHYSIOGRAPHIC
PROVINCE IN NORTH CAROLINA
activities, rural roads, loss of riparian vegetation to
agriculture and silviculture, and urban runoff. In
addition, landscape features, such as high stream-
channel gradients, are important factors contributing to
sedimentation rates (Scott and others, 2002). Harding
and others (1998) reported that the conditions of
current aquatic communities are related more to past
land use than to current land use.
Historically, sediment has clogged the channel of
the upper Little Tennessee River and has deposited
sediment in Lake Emory (fig. 1; North Carolina
Department of Environment, Health, and Natural
Resources, 1992, p. 155). Riparian agricultural
practices, such as stock watering and growing specialty
vegetable crops, and more recently, increasing
urbanization in the upper portion of the watershed in
the towns of Highlands and Franklin have increased the
river's suspended-sediment load and bed load. Thus, by
trapping sediments, Lake Emory has protected
important natural resources downstream, particularly
in respect to several federally listed species of
freshwater mussel.
Suspended-sediment data are available from the
1970's for the Little Tennessee River at Needmore and
Cartoogechaye Creek near Franklin (Simmons, 1993).
Average annual suspended-sediment loads were
calculated to be 100,000 metric tons (t) for the Little
Tennessee River at Needmore and 10,000 t for
Cartoogechaye Creek near Franklin for the 1970's.
Average annual suspended-sediment yields at these
sites were 110 and 81 metric tons per square kilometer
(t/km2), respectively. By comparison, an average yield
of 68 t/km2 was calculated for rural, agricultural sites in
the upper Tennessee River basin (Simmons, 1993).
Federal, State, and local agencies and
organizations are working to restore degraded aquatic
resources in the upper Little Tennessee River and some
of its tributaries, including protection and enhancement
of threatened and endangered species populations and
wetland restoration. Key to developing restoration
strategies is a better understanding of the amount of
sediment that is transported in the upper Little
Tennessee River, the sediment sources and particle-size
characteristics, and the amount of sediment that is
transported past Porter's Bend dam at Lake Emory. The
data collected during this investigation begin to address
these issues.
Purpose and Scope
This report describes the results of a study to
characterize suspended-sediment and bed-load
sediment transport into Lake Emory from the main
stem of the Little Tennessee River and two major
tributaries -Cartoogechaye Creek and the Cullasaja
River. Suspended-sediment concentration in discharge
from Lake Emory also was measured. Sediment
samples were collected weekly over a 12-month period
from November 2000 to November 2001. In addition,
three bed-load measurements were made between
October 2001 and September 2002.
Study Area
The Little Tennessee River basin is in the Blue
Ridge Physiographic Province. The river rises in
Georgia near the North Carolina border and flows north
through North Carolina into Tennessee (fig. 1) where it
joins the Tennessee River. The upper Little Tennessee
River basin is the area of the Little Tennessee River
basin that is upstream from Fontana Lake. The study
area includes the portion of the upper Tennessee River
basin upstream from Porter's Bend dam at Lake Emory
(fig. 2). The study area is drained by the Little
Tennessee River, the Cullasaja River, and
Cartoogechaye Creek. The Cullasaja River and
Cartoogechaye Creek join the Little Tennessee River
near Franklin, N.C. (fig. 2).
Lake Emory is a 76-hectare (ha) reservoir built
in the 1920's as a source of hydropower. Nantahala
Power and Light Company has owned and operated the
lake since 1933 (North Carolina Department of
Environment, Health, and Natural Resources, 1992).
Based on lake samples collected in July 1988, the lake
has been described as eutrophic and shallow and having
a short retention time (North Carolina Department of
Environment, Health, and Natural Resources, 1992).
Suspended-solids concentrations at each of three sites
sampled in the lake were at least 18 milligrams per liter
(mg/L)
Acknowledgments
This investigation was cooperatively funded by
the U.S. Geological Survey (USGS) and Macon
County, N.C. The author wishes to thank Eugene
Gonzales of Macon County for collecting weekly
Introduction 3
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03500000
rr
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River
1
Prentiss
I
Riverside
0349998425 1 0I I0.5 I 1I 2 KILOMETERS
i f f ?f?
0 1 5 MILES
EXPLANATION
SITES AND USGS SITE NUMBER
03501000 Q DISCONTINUED STREAMGAGE
03500000 . STREAMGAGE ONLY
0349998425 V SEDIMENTONLY
03500240 / STREAMGAGE AND SEDIMENT
Figure 2. Locations of streamgages and sediment-sampling sites in the upper Little Tennessee River
basin, North Carolina.
suspended-sediment samples regardless of weather
conditions. The author also wishes to acknowledge the
assistance of Gene Barker and his staff from the USGS
Field Office in Asheville, N.C. Leadership in bringing
together the partners who supported this investigation
was provided by Linda Adcock of the U.S. Army Corps
of Engineers in Nashville, Tenn.
DATA-COLLECTION METHODS
The data-collection methods used during this
investigation are consistent with published USGS
protocols (Rantz and others, 1982; U.S. Geological
Survey, 1997-present; Edwards and Glysson, 1999).
Results of all sediment analyses are stored in the USGS
4 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
National Water Information System (NWIS) water-
quality database.
Streamflow Data
Streamflow in the upper Little Tennessee River
basin was determined from measurements from
available streamgage records (Rantz and others, 1982)
or from estimates based on record from a nearby
streamgage. The streamgages in the study area are
operated and maintained by the USGS in cooperation
with the North Carolina Department of Environment
and Natural Resources.
Of the four study sites (table 1), streamflow is
recorded continuously only at Cartoogechaye Creek
near Franklin. Streamflow at the Little Tennessee River
at Riverside was estimated from streamflow record at
the Little Tennessee River near Prentiss, about
4.8 kilometers (km) downstream. Streamflow near
Prentiss was reduced by multiplying by a factor
determined by the ratio of the drainage areas
(311 km2 / 363 km2 = 0.857) to obtain an estimate of
the streamflow at Riverside.
Estimating the streamflow at Cullasaja River
near Franklin was more complex, however, because no
streamgage was in operation on the Cullasaja River
during the study period. A location just upstream from
the Cullasaja study site was operated from 1921 to
197 1 -Cullasaja River at Cullasaja, N.C. (03501000).
Although the difference in the drainage areas of the two
sites is only 12 km 2, a stage-streamflow relation from
this gage was too dated to be useful. In addition, a
60-ha drinking-water reservoir, Lake Sequoyah,
impounds the upper 23 km2 of the watershed and
potentially affects streamflow downstream (fig. 1).
As a result, two nearby streamgages were
selected as potential index sites for estimating
streamflow at the Cullasaja River near Franklin-the
Little Tennessee River near Prentiss (03500000) and
Cartoogechaye Creek near Franklin (03500240).
Historic streamflow records were retrieved from the
NWIS surface-water database and analyzed to
determine which of the two sites was the better index
site.
Discharge below the dam at Lake Emory also
had to be estimated. Although water is released through
the turbines at the Porter's Bend dam for power
generation, no records of the releases are maintained by
Nantahala Power and Light Company (Richard Conley,
Duke Power Lake Management, oral commun.,
December 20, 2001). In addition, leakage occurs
through the dam structure, and when lake levels are
high, water also may be released over the spillway. An
annual-mean streamflow was estimated for 2001 based
Table 1. Selected U.S. Geological Survey streamgaging stations in the upper Little Tennessee River basin, North Carolina
[USGS, U.S. Geological Survey; km2, square kilometer; m3/s, cubic meter per second; t, metric ton; t/km2, metric ton per square kilometer; bold/shaded
station numbers and names identify sites sampled for this study; -, no data]
USGS station Period of Drainage Annual-mean streamflow Annual suspended
number' Station name streamflow area (m /s) sediment
(fig 2) record (km2) Period of 2001 water Load Yield
b
(water years ? record year (t) it/kin2)
0349998425 Little Tennessee River at Riverside - 311 - - - -
03500000 Little Tennessee River near Prentiss 1943-present 363 11 5.44 - -
03500240 Cartoogechaye Creek near Franklin 1944, 1947, 148 4.1 2.09 10,000 81
1953-55,
1958, 1960,
1961-present
0350116510 Cullasaja River near Franklin - 236 - - - -
03501000 Cullasaja River at Cullasaja 1907-09, 224 - - - -
1921-71
03501564 Lake Emory at the dam near Franklin - 804 - - - -
03503000 Little Tennessee River at Needmore 1943-81, 1,130 29.9 15.2 100,000 110
1983-present
a Station number is assigned by the U.S. Geological Survey on the basis of geographic location. The downstream order number system is used for
surface-water sites.
b Water year is the period October 1 through September 30 and is identified by the year in which the period ends.
Data-Collection Methods 5
on record from the streamgage at the Little Tennessee
River at Needmore about 32 km below the dam (fig. 1).
Suspended-Sediment Data
Stream samples for analysis of suspended-
sediment concentration were collected once per week at
each of the four study sites. In addition, several samples
were collected during targeted high-flow events. At
each data-collection stream site, a box enclosure
containing a US-D-74 suspended-sediment sampler
was mounted to a bridge rail at the approximate center
of streamflow (Edwards and Glysson, 1999). Macon
County staff used this equipment to collect single,
vertical, suspended-sediment samples (box samples)
once per week. The US-D-74 sampler is one of a
number of samplers designed by the Federal
Interagency Sedimentation Project (FISP) for use in
collecting a depth-integrated suspended-sediment
sample. USGS staff used a US-DH-81 or US-DH-59
sampler periodically to collect equal-width integrated
(EWI) suspended-sediment samples that could be used
to validate the single, vertical samples as being
representative of the average suspended-sediment
concentration in the stream cross section. Suspended-
sediment concentrations in samples collected using the
EWI method were compared to concentrations
measured in the box samples. The samples were
shipped to the USGS sediment laboratory in Louisville,
Ky., and analyzed for suspended-sediment
concentration. Samples were analyzed by using the
filtration method described by Guy (1977).
Bed-Load Data
A Helley-Smith type sampler was used to sample
bed load (fig. 3). The sampler is designed to collect
particles less than 76 millimeters (mm) at mean
velocities up to 3.0 meters per second (m/s). The
sampler has a 76-mm by 76-mm opening to a 0.25-mm
mesh sampling bag that is supported by a metal frame.
The sampler weighs 29.9 kilograms (kg). The nozzle-
expansion ratio is 3.1.
Bed-load samples were analyzed for total weight
by the USGS sediment laboratory in Iowa City, Iowa,
using methods described by Guy (1977). Two samples
were collected from each stream site using the multiple
equal-width-increment (MEWI) method (Edwards and
Glysson, 1999, p. 75). Each stream cross section was
sampled at five equally spaced locations. The sampler
was positioned on the streambed at each location for
20 minutes in October 2001 when streamflow was low,
and for 5 minutes in January and September 2002 when
streamflow was much greater. Two transects were
collected for a total of 10 subsamples for each sample.
Subsamples were combined into one composite sample
that was analyzed for total weight and particle-size
distribution. The number of subsections, width of each
subsection, time the sampler rested on the streambed,
number of transects, and average streamflow during the
sampling period were recorded.
Particle Size
Selected suspended-sediment samples were
analyzed for the distribution of particle sizes. The
quantity of material collected was, for most samples,
insufficient for a full particle-size analysis. Therefore,
samples were sieved according to Guy (1977) to
determine the percentage of particles finer than
sand-less than (<) 0.062 mm. However, at least one
suspended-sediment sample from each stream site was
analyzed for a more complete range of particle sizes by
using the visual accumulation (VA) tube method (Guy,
1977). Each bed-load sample was analyzed for particle-
size distribution by the USGS sediment laboratory in
Iowa City using methods described by Guy (1977).
STREAMFLOW
A severe drought was occurring in western North
Carolina during the study period. Rainfall at the
National Oceanic and Atmospheric Administration's
6 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
Figure 3. Helley-Smith bed-load sampler.
(NOAA) Franklin, N.C., weather station 180
typically averages 134 centimeters (cm) per
year based on data collected from 1949 through
2000 (Southeast Regional Climate Center,
2003). Rainfall amounts at the Franklin weather w 160
station are seasonally variable but declined
steadily overall from about July 1998 (fig. 4). w
Ninety percent of the daily-mean streamflows Z
in 2001 were less than the median daily-mean a
?
140 Average annual

- rainfall
1949-2000
streamflow at the Little Tennessee River near a ,
Prentiss and Cartoogechaye Creek near a
Franklin (fig. 5), and the annual-mean stream- Z
flow for 2001 was 50 percent of the long-term a
annual-mean streamflow (table 1). Moreover, o 120
new minimum values for daily-mean stream-
I
flow were established for 12 and 18 percent of
the days in 2001 at the Little Tennessee River
NN
near Prentiss and Cartoogechaye Creek near 100
Franklin, respectively. Monthly departures 1990 1991 1992 1993 1994 1995 1996 1997 1999 1999 2000 2001
from the long-term mean-monthly streamflows
were almost entirely negative at these two sites Figure 4. Total annual precipitation atthe Franklin, North Carolina, Weather
beginning in July 1998 (fig. 6). Station for 1990-2001, and the long-term average annual rainfall.
30
25
20
- A. Little Tennesse River near Prentiss
II I?V1

Daily mean, 2001
- - - Minimum daily mean, 1944-2001
Median daily mean, 1944-2001
I • I I I
15
0
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Z
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W
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it 15
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10 I-
5

OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AU G. SEPT.
Figure 5. Long-term minimum and median daily-mean streamflow and daily-mean streamflow for water year 2001 at
(A) the Little Tennessee River near Prentiss and (B) Cartoogechaye Creek near Franklin, North Carolina.
0
Daily mean, 2001
Minimum daily mean, 1944-2001
Median daily mean, 1944.2001
Streamflow 7
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w ?
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a-
Z
w
J U
Z 10
Z
O
2
0. Little Tennessee River near Prentiss
.In.l? I lull II II ul,l III II II I III. IIII „ II,LI
...... I I
. ,.?lln' ? nl?lp„ l ?I„ . l ?llll?l???."III III I) ?IIIIII??IIIII
B. Cartoogechaye Creek near Franklin
I li ?IIII?I II II II. I .I I nlll I I I I III II ? ., III,
C. Franklin Weather Station
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Figure 6. Departure from mean-monthly streamflow at (A) the Little Tennessee River near
Prentiss and (8) Cartoogechaye Creek near Franklin, North Carolina, and (C) monthly rainfall at
the Franklin Weather Station.
Because streamflows generally were very low
during the period of study, few of the sampled
streamflows represent high-flow conditions. This is
important to note because most suspended sediment is
transported under high-flow conditions. In figure 7, the
distributions of sampled streamflows at Cartoogechaye
Creek and the Little Tennessee River are shown in
relation to long-term streamflow durations from
streamgages at Cartoogechaye Creek near Franklin and
the Little Tennessee River near Prentiss. At both sites,
75 percent of the suspended-sediment samples were
collected at streamflows that were approximately equal
to the long-term 701 to 751 percentile streamflow
duration. That is, most of the samples were collected at
streamflows that, when compared to long-term
streamflow record, are equaled or exceeded 70 to
75 percent of the time. However, the maximum
streamflow sampled at Cartoogechaye Creek was quite
high-near the long-term 1St percentile streamflow
duration (fig. 7B). Likewise, the maximum streamflow
sampled at the Little Tennessee River was between the
long-term 151i and 201' percentile streamflow duration
(fig. 7A). Suspended-sediment concentrations
collected during these high streamflow events are
crucial to adequately define the relation between
streamflow and sediment concentration.
8 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
100
60
40
30
20
10
6
4
3
0
z 2
0
w 1
C/)
0.6
a 0.4
N 0.3
w 0.2
W
g 01
A. Little Tennessee River
N=60
U 0 5 10 15 20 30 40 50 60 70 80 85 90 95
100
z 60
30
° 20
LL
10
W
6
y 4
3
2
1
0.6
0.4
0.3
0.2
01
100
B.Cartoogechaye Creek
N=60
0 5 10 15 20 30 40 50 60 70 80 85 90 95
PERCENTAGE OF TIME STREAM FLOW WAS EQUALED OR EXCEEDED
EXPLANATION
--0- LONG-TERM STREAMFLOW DURATION
BOXPLOT OF SAMPLED STREAMFLOWS
- OUTLIER
-75th PERCENTILE
- MEDIAN
-25th PERCENTILE
Figure 7. Distributions of sampled streamflows at (A) the Little Tennessee River and
(B) Cartoogechaye Creek in relation to long-term streamflow durations from streamgages at
the Little Tennessee River near Prentiss and Cartoogechaye Creek near Franklin, North
Carolina.
Estimation of Streamflow in the Cullasaja River
Record from a discontinued streamgage at
Cullasaja River at Cullasaja, which has a drainage area
12 km2 less than the drainage area near Franklin
(table 1), provided daily-mean streamflow that was
compared to coincidental daily-mean streamflow at
streamgages at Cartoogechaye Creek near Franklin and
the Little Tennessee River near Prentiss to assess
whether either of these streamgages could be used as an
index gage. An index gage was needed to estimate
streamflow during the study period for the Cullasaja
River near Franklin. The most recent year for which
100
coincident daily-mean streamflow data were available
for these three sites was water year' 1971. Streamflow
was compared for water years 1970-71 (fig. 8).
Equations relating daily-mean streamflow at the index
sites to daily-mean streamflow at the Cullasaja River at
Cullasaja were determined by means of ordinary least-
squares linear regression (table 2). The greater scatter
about the regression line and the lower coefficient of
determination (R2) for Cartoogechaye Creek near
1 Water year is the period October I through September 30 and is
identified by the year in which the period ends.
Streamflow 9
100
90
80
70
60
50
i
i 40
30
20
10
9
8
7
6
5
4
3
2
Little Tennessee River near Prentiss index gage
-- Cartoogechaye Creek near Franklin index gage
A
0
11 2 3 4 5 6 7 8 9 10 20 30 40 50
DAILY-MEAN STREAMFLOW AT INDEX GAGES, IN CUBIC METERS PER SECOND
Figure S. Relation of daily-mean streamflow in the Cullasaia River to daily-mean streamflows at
Cartoogechaye Creek near Franklin and the Little Tennessee River near Prentiss, North Carolina, for
water years 1970-71.
A
4
A ?
a5
d A
4 ?; A a1LL f '.
,ESA A. ` A A°' .aw
A AA
4?k A A v
AA AAA A A? SB
A AhPA A A 4b
AA -e M A *
M. A y, w I
A AA A A
A At Ofd
A A A
AAA. A. A
A A A ?'
A .. i ? FK•S6 r: ?'
a ? A Yr Pa.l a
10 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
Table 2. Regression equations relating streamflow at the two Little Tennessee River basin index
sites to streamflow in the Cullasaja River, North Carolina
[N, number of observations; R 2, coefficient of determination; P value, probability that the slope is equal to zero;
Q,c, streamflow, in meters per second, at the Cullasaja River at Cullasaja; Qcr, streamflow, in meters per second,
at the Cullasaja River near Franklin; InQi, natural log of streamflow, in meters per second, at the index gage]
Type of streamflow record N Regression equation R2 Pvalue for
the slope
Little Tennessee River near Prentiss'
Daily mean, 1970-71 730 Qcc = e0.98(1nQi)-0.46 0.9242 0.0000
Instantaneous, 2001-02 7 Qcr= e1014(hQi)-0.45 0.9886 0.0000
Cartoogechaye Crook near Franklin
Daily mean, 1970-71 730 QCC = e0.85(1nQi)4.70 0.8159 0.0000
Instantaneous, 2001-02 7 Q?f = eo.83(1nQi)-0.75 0.8834 0.0016
Franklin indicate that Cartoogechaye Creek is a poorer
index gage for the Cullasaja River than is the Little
Tennessee River near Prentiss.
During the study, instantaneous streamflow was
measured seven times at the Cullasaja River near
Franklin at streamflows ranging from 1.77 to 21.0
cubic meters per second (m 3/S; table 3). These
instantaneous streamflow measurements were
compared to simultaneous instantaneous streamflow
determined from the streamgage record at the potential
index sites (table 3; fig. 9). Instantaneous streamflows
at the index sites were related to instantaneous
streamflow at the Cullasaja River near Franklin using
ordinary least-squares linear regression (table 2).
As in the 1970-71 relations (fig. 8; table 2), the
greater scatter about the regression line and the lower
R2 value for Cartoogechaye Creek near Franklin
indicate that Cartoogechaye Creek is a poorer index
gage for the Cullasaja River than is the Little Tennessee
River near Prentiss. The slope and intercept of the
2001-02 relation for the Little Tennessee River near
Prentiss are very similar to the slope and intercept of
the 1970-71 relation. The slight offset of the 2001-02
regression relation compared with the 1970-71
relation is due, in part, to the difference in the drainage
areas of the Cullasaja River at Cullasaja (1970-71
relation) and the Cullasaja River near Franklin
(2001-02 relation; table 1). For example, when
Table 3. Relation of streamflow measured at the Cullasaja River to streamflow at Cartoogechaye Creek
near Franklin and the Little Tennessee River near Prentiss, North Carolina, during water years 2001 and 2002
[Water year is the period October 1 through September 30 and is identified by the year in which the period ends; %, percent]
Predicted streamflow at Cullasaja River
Instantaneous streamflow, based on comparison of data for the study
in cubic meters per second period with data from the index gage
Date Time
(percent error)
Little

Cartoogechaye Tennessee Cullasaja Little Tennessee
Cartoogechaye

Creek River near River River near
Creek

Prentiss Prentiss
03-14-2001 1030 3.20 9.03 6.00 5.56(7%) 5.48(9%)
05-02-2001 1050 1.90 5.12 3.88 3.60(7%) 3.73(4%)
06-22-2001 1220 1.13 3.06 1.77 2.35(-33%) 1.97(-11%)
08-31-2001 1030 1.05 3.06 1.86 2.20(-18%) 2.19(-18%)
09-25-2001 1130 2.32 12.32 7.70 4.26(45%) 8.05(-5%)
10-25-2001 1055 2.07 4.62 3.31 3.65(-10%) 3.03(9%)
01-23-2002 1523 19.7 32.0 21.0 25.1 (-20%) 21.1(-1%)
Streamflow 11
40
30
- --- Little Tennessee River, daily mean, 1970 - 71
_F Little Tennessee River, instantaneous, 2001 - 02
------ Cartoogechaye Creek, daily mean, 1970-71
-0-- Cartoogechaye Creek, instantaneous, 2001 - 02
20
10
9
8

7
6
4
7 6.03
/
/
/
/
/
/
/
/
/
/
/
1
/
/
/
/
/
/
/
/
/
/
/
/

6.52
40
N
0
30
°o
N
0
z
0
U
w
20
w
LL
W
cc
w
w
U
Co
U
Z
10 Z
9 Y
8 FF
LL
7 =
2 3 4 5 6 7 8 9 10 20 30 40 50
STREAMFLOW AT THE INDEX GAGE, IN CUBIC METERS PER SECOND
Figure 9. Relation of instantaneous and daily-mean streamflows at the Cullasaia River near Franklin,
North Carolina, to instantaneous (2001-02) and daily-mean (1970-71) streamflows at the Little
Tennessee River near Prentiss and Cartoogechaye Creek near Franklin.
streamflow at the Little Tennessee River near Prentiss
is 10 m3/S, the calculated streamflow using the relation
for 2001-02 data from the Cullasaja River near
Franklin is 6.52 m3/S, whereas the calculated
streamflow using the relation for 1970-71 data from
the Cullasaja River at Cullasaja is 6.03 m3/s (fig. 9).
When divided by the drainage area, the resulting runoff
values are nearly the same-0.028 and 0.027 cubic
meter per second per square kilometer [(m3/S)/km2]
near Franklin and at Cullasaja, respectively.
The Little Tennessee River near Prentiss was
selected as the best index site for estimating streamflow
at the Cullasaja River near Franklin based on the better
closeness of fit (table 3) and higher coefficient of
determination (92 to 98 percent, table 2) for the
regression equation compared with the equation for the
other potential index site. The equation based on
2001-02 data was selected even though it was based on
only seven measurements, because the data were more
current and the relation was verified by the large
amount of data collected during 1970-71.
12 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
Estimation of Porter's Bend Dam Releases
No records exist of releases through the Porter's
Bend dam at Lake Emory, so the quantity of water
discharged from the lake had to be estimated in order to
estimate sediment load from the lake. Two methods
were used to estimate an annual-mean water discharge
from the dam. In the first method, streamflows in the
Little Tennessee River near Prentiss, Cartoogechaye
Creek near Franklin, and the Cullasaja River near
Franklin were measured or estimated at 15-minute
intervals for the study period, and the values were
summed. The result was 396,800,000 m3 of streamflow
for the study period (1.25 years), or an annual-mean
streamflow of 10.0 m3/s, which was the assumed
discharge through the dam. In the second method, the
measured annual-mean streamflow at the Little
Tennessee River at Needmore for 2001 (15.3 m3/s,
table 4) was reduced by multiplying by a factor
determined by the ratio of drainage areas
(804 / 1,130 = 0.71) to estimate an annual-mean
streamflow of 11 m3/s, which was the assumed
discharge through Porter's Bend dam.
Using the two estimated values, the annual
runoff, in centimeters, was calculated and compared
with annual runoff at the other sites (table 4). The
estimated annual runoff for the dam obtained by using
Table 4. Streamflow statistics for the Little Tennessee River
basin, North Carolina, study sites for the 2001 water year
[Water year is the period October 1 through September 30 and is identified
by the year in which the period ends; km2, square kilometer; m3/s, cubic
meter per second; cm, centimeter]
Drainage Annual-mean

Site
area,
streamflow, Runoff,
in km2 in m3/s in cm
Little Tennessee River at 311 4.58 46.4
Riverside
Little Tennessee River at 1,130 15.3 42.7
Needmore
Cartoogechaye Creek 148 2.09 44.5
near Franklin
Cullasaja River near 236 3.4 45.4
Franklin
Porter's Bend dam at 804 a10/b, l c39/d43
Lake Emory
a Estimated annual-mean streamflow by using method one.
b Estimated annual-mean streamflow by using method two.
Calculated runoff by using estimated annual-mean streamflow from
method one.
d Calculated runoff by using estimated annual-mean streamflow from
method two,
the second method was reasonably close to runoff at
other sites in the study area, so the annual-mean
streamflow of 11 m3/s was judged to be a reasonable
estimate for calculating suspended-sediment load.
SUSPENDED SEDIMENT
Samples for analysis of suspended-sediment
concentration were collected once per week at each site
from November 2000 to November 2001 (table 5). In
addition, several samples were collected during
targeted high-flow events. The distribution of measured
concentrations at each site is shown in figure 10. The
greatest median suspended-sediment concentration was
measured at Porter's Bend dam at Lake Emory
(12 mg/L). Lowest median concentrations were
measured at the Cullasaja and Cartoogechaye sites
(5 and 4.9 mg/L, respectively), although the range of
concentrations was large.
Load
Instantaneous suspended-sediment loads, in
metric tons per day, were calculated from instantaneous
streamflow and measured suspended-sediment
concentration. A regression equation was developed for
each site-the Little Tennessee River at Riverside,
Cartoogechaye Creek, and the Cullasaja River-
relating the natural log of streamflow to the natural log
of suspended-sediment load at each site (fig. 11;
table 6). The regression equations were used to
calculate suspended-sediment loads for each 15-minute
(unit value) interval at each site by using continuous
streamflow record (Cartoogechaye Creek and the Little
Tennessee River at Riverside) or estimates of
streamflow (Cullasaja River). These unit-value load
data were summed for each site. Each sum was adjusted
by multiplying by the mean of the antilog of the
regression residuals (Duan's smearing estimator) to
account for retransformation bias (Duan, 1983; Koltun
and others, 1994) to determine the total load for the
study period (1.25 years). The total load for the period
of study, annual load, and annual yield are shown in
table 7.
As noted previously, suspended-sediment load
could not be calculated for water discharged from Lake
Emory because there was no record of streamflow out
of the dam. Instead, suspended-sediment load was
estimated by using the 11-m3/s estimate for average
Suspended Sediment 13
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14 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
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Suspended Sediment 15
1,000
700
600
500
400
300
200
! 100
70
60
50
40
30
20
10
7
6
5
4
3
2

•
•
•

i
•

•
LITTLE CARTOOGECHAYE CREEK CULLASAJA RIVER LAKE EMORY
TENNESSEE RIVER NEAR FRANKLIN NEAR FRANKLIN NEAR FRANKLIN
AT RIVERSIDE
EXPLANATION
• - OUTLIER
T 1.5 (ICR)
-75th PERCENTILE
-MEDIAN
- 251h PERCENTILE
1.5 (ICR)
ICR INTEROUARTILE RANGE
Figure 10. Distribution of suspended-sediment concentrations at the four Little Tennessee River basin study sites in North
Carolina.
16 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
A. Cullasaja River near Franklin m
10
0'
i
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100
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INSTANTANEOUS STREAMFLOW (%w , IN CUBIC METERS PER SECOND
a 0
1,000
100
10
1.0
0
B. Cartoogechaye Creek near Franklin G
- L e1.98(lnOwj-1.44
s'
1 2 3 4 5 6 7 8 9 10 20
INSTANTANEOUS STREAMFLOW (Ow), IN CUBIC METERS PER SECOND
1 2 3 4 5 6 7 8 9 10 20 30 40 50
INSTANTANEOUS STREAMFLOW (QW), IN CUBIC METERS PER SECOND
Figure 11. Relation of daily sediment load to instantaneous streamflow at (A) the Cullasaja
River near Franklin, (B) Cartoogechaye Creek near Franklin, and (C) the Little Tennessee
River at Riverside, North Carolina.
Suspended Sediment 17
Table 6. Results of regression analyses relating the natural log of
instantaneous suspended-sediment load to the natural log of instantaneous
streamflow at three Little Tennessee River basin study sites in North Carolina
[R 2, coefficient of determination; P value, probability that the slope is equal to zero]
Mae
Slope 2 of th
Site Intercept coefficient R Pvalue antil
of th
resid
Cartoogechaye -1.44 1.98 0.72 0.00 1.5
Creek
Cullasaja River -2.23 2.09 .62 .00
Little Tennessee -2.38 2.62 .80 .00
River at Riverside
basins in the Blue Ridge Province of North
Carolina.
In order to assess the significance of
drought conditions during the study period on
n suspended-sediment loads, the 2001 data were
uals streamflows at Cartoogechaye Creek near
9 compared with estimates of suspended-
0 sediment load and yield, and the annual-mean
7 Franklin and the Little Tennessee River at
Needmore between 1970 and 1979 (Simmons,
4 1993; table 7). Annual load and yield were an
4 order of magnitude less during the study period
- compared to estimates from the 1970's. This
may be, in part, due to the higher streamflows
during the period 1970-79 when annual-mean
streamflows were more than twice as high as those
during the study period (table 7).
The decrease in suspended-sediment load
compared to the 1970's also may be a result of long-
term change in the relation between suspended-
sediment load and streamflow as a result of changes in
land-use conditions in the basin. Annual suspended-
sediment loads are highly variable and difficult to
assess with only 1 year of recent data. The relation of
suspended-sediment load to instantaneous streamflow
for the period 1977-79 (when streamflow and
suspended-sediment data are available) was compared
to the relation of suspended-sediment load to
instantaneous streamflow for the study period at
Cartoogechaye Creek (fig. 12). During 1977-79, more
1.4
1.2
daily discharge from the dam (table 4) and a median
measured suspended-sediment concentration of
12 mg/L (fig. 10). This resulted in an estimated annual
suspended-sediment load of 4,200 t and yield of
5 dkm2 (table 7).
The greatest annual load and yield in 2001
(5,700 t and 18 dkm2, respectively) was in the Little
Tennessee River at Riverside (table 7). The yield at
Riverside far exceeded the yields at Cartoogechaye
Creek, the Cullasaja River, and out of Lake Emory. By
comparison, Simmons (1993) calculated mean-annual
suspended-sediment yields, based on data from the
1970's, of 20 t/km2 for the Nantahala River near
Rainbow Springs and 15 dkm2 for Cataloochee Creek
near Cataloochee-two relatively pristine, forested
Table 7. Estimated suspended-sediment loads and yields at the three study sites and at sites sampled in 1970-79 in the Little
Tennessee River basin, North Carolina
[m3/ s, cubic meter per second; t, metric ton; t/kml, metric ton per square kilometer; -, no data]
Suspended sediment,
2000-01
Suspended sediment,
1970-79°
Annual-mean Load, in t Annual load, Annual Annual-mean Annual load Annual
,
Site streamflow, 10-01-00 to yield, streamflow, yield,
in m3/s 12-31-01 in t in t/km2 in m3/s in t in t/kM2
Little Tennessee River at 4.58 7,200 5,700 18 - - -
Riverside
Cartoogechaye Creek near 2.09 1,300 1,000 7 4.39 10,000 81
Franklin
Cullasaja River near c 3.4 1,500 1,200 5 - - -
Franklin
Porter's Bend dam at Lake c 11 - 4,200 5 - - -
Emory
Little Tennessee River at 15.3 - - - 33.7 100,000 110
Needmore
a From Simmons (1993).
b Streamflow at the Prentiss, North Carolina, streamgage
Estimated.
18 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
10,000
-0- 1977 - 79
-+- 2001
? eh0 0,40
1,000
0
Zz
0
U
2
W
Z
O
Q
O
Z
w
0
w
v?
0
w
Zz
N
J
a
0
100
I
® I/
/
/
I
/
? ? I ? i
4
10
0.1

2
0.8 1 2 3 4 5 6 7 8 910 20 30 40
INSTANTANEOUS STREAMFLOW AT CARTOOGECHAYE CREEK, IN CUBIC METERS PER SECOND
Figure 12. Relation of daily suspended-sediment load and instantaneous streamflow
at Cartoogechaye Creek near Franklin, North Carolina, for 1977-79 and 2001.
samples were collected at high streamflow than during
the study period when nearly 75 percent of the samples
were collected at streamflows less than 2 m3/s because
of drought conditions (fig. 12). Figure 12 indicates a
decrease in the slope and intercept of the line
determined by regressing streamflow on instantaneous
load in 2001 compared with 1977-79. However, more
samples are needed at streamflows greater than 10 m3/s
to adequately define the suspended-sediment load and
streamflow relation for the 2001 water year.
Particle Size
Selected suspended-sediment samples were
analyzed for particle size (table 8). Based on the small
number of samples collected during this study, particle
sizes were predominately finer than sand (finer than
0.062 mm) at all of the sites (fig. 13). This, too,
probably is an effect of low streamflows during the
study. There was little variation in the median
percentage of particles finer than 0.062 mm among the
sites; however, as would be expected, the median
Suspended Sediment 19
Table 8. Streamflow and suspended-sediment concentration and particle-size distributions in samples from the four Little Tennessee River
basin study sites in North Carolina
[m3/ s, cubic meter per second; mg/L, milligram per liter; mm, millimeter; -, no data]
Percentage of suspended-sediment particles finer
than the indicated size
Instantaneous Suspended-
Site Date rime discharge, sediment 0.062 0.125 0250 0.500 1.00
in m3/s concentration, mm mm mm mm mm
in mg/L
04-24-01 1000 4.7 11 70 - - - -
05-08-01 1000 3.9 8 81 - - - -
05-22-01 0900 3.6 24 85 - - - -
aLittle Tennessee River at
Riverside 07-31-01 1240 11.1 441 86 92 97 100 100
09-26-01 1055 7.6 19 85 88 100 100 100
01-20-02 1130 13.4 87 64 68 100 100 100
01-23-02 1325 35.7 369 64 72 82 100 100
04-24-01 1100 2.2 8 75 - - - -
05-08-01 1100 1.6 6 64 - - - -
05-22-01 1000 1.4 8 81 - - - -
Cartoogechaye Creek near 07
31
01 1120 b

Franklin -
- 1.3 3 95 - - - -
09-26-01 1151 1.6 b 2 100 - - - -
01-20-02 0952 8.6 79 70 70 89 100 100
01-23-02 1110 21.7 324 80 87 97 100 100
04-24-01 1200 3.8 6 71 - - - -
05-08-01 1000 3.1 5 70 - - - -
05-22-01 1100 2.6 9 60 - - - -
aCullasaja River near

Franklin 07-31-01 1350 8.5 5 90 - - - -
09-26-01 1351 4.9 b 3 100 - - - -
01-20-02 1040 - b 15 100 - - - -
01-23-02 1215 22.4 114 79 85 100 100 100
04-24-01 1300 - 8 93 - - - -
05-08-01 1300 - 9 93 - - - -
Lake Emory at Porter's 05-22-01 1200 - 35 77 - - - -
Bend dam near Franklin
07-31-01 1020 - b 10 100 - - - -
09-26-01 1325 - b 9 100 - - - -
a Streamflows are estimated for the Little Tennessee River at Riverside and Cullasaja River near Frankllin
b Concentration was too low for full particle-size analysis.
20 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
100
90
80
•
50
70
60
LITTLE CARTOOGECHAYE CULLASAJA LAKE EMORY
TENNESSEE RIVER CREEK RIVER NEAR FRANKLIN
AT RIVERSIDE NEAR FRANKLIN NEAR FRANKLIN
EXPLANATION
• - OUTLIER
1.5 (ICR)
-751h PERCENTILE
MEDIAN
-25th PERCENTILE
1.5 (ICR)
ICR I NTERQUARTI LE RANGE
Figure 13. Distribution of percentages of suspended-sediment particles finer than 0.062 millimeter at the four
Little Tennessee River basin study sites in North Carolina.
percentage of fine suspended-sediment particles
(<0.062 mm) was greatest at Porter's Bend dam.
BED MATERIAL
Sediment that is deposited on the streambed is
bed material. Small particles can be resuspended during
periods of elevated streamflow to produce suspended-
sediment load (discussed previously). Larger particles
that are too heavy to be suspended in the water column
during elevated streamflows may move along the
streambed as bed load.
Bed Load
Bed load is sediment that moves by sliding,
rolling, or bouncing along on or near the streambed
(Edwards and Glysson, 1999). Bed load is difficult to
accurately measure because (1) any sampling device
placed on the bed may disturb bed-load flow and rate of
movement and (2) bed load is highly temporally and
spatially variable. The material collected with the bed-
load sampler generally consists of material that is not
collected by suspended-sediment sampling equipment.
Drought conditions during the study period
limited opportunities for collecting bed-load samples
because most bed load is carried during high-
streamflow events. Three bed-load samples were
collected at each stream site to estimate the amount of
material that was being transported near the streambed
and that was unaccounted for by the suspended-
sediment sampler (tables 9, 10). Bed load was added to
the suspended-sediment load calculated for a particular
day to determine a total load.
Bed Material 21
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C C
y C r M CN
E 10 E m C o 00
6 t` t`
> 0 7 O
d N N I O 0 I O M
o " E
,c
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W ?`Wr

pN
S

=

p

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S

_O

N
O
v Q E O O O
to
° C O O O O
9 d m - V V
d ? 6 'Y
C
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"
C
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c1 V1 M --? O V1 M
D
•y O ?
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? O M In O N v'i

C W
y
q d

N
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9 Q E o

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0 °

d - I I I
0.
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M
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E o
g 0
oo
? 0
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0

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N
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N O d d' •-'- ?O O, 00 00 ?O V
O 'r d M 00 00 00 D1 V
r E M o N O M
•
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gm r, 00
v1 N
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kr; 00 0o
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d d d
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22 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02
Table 10. Particle-size distribution in bed-load samples from three sites in the Little Tennessee River basin in North Carolina
[m3/s, cubic meter per second; mm, millimeter]
Percentage of bed-load particles finer than size indicated
Date Discharge, 0.062 mm 0.125 mm
inm/s 0.250 mm 0.500 mm 1.00 mm 2.00 mm 4.00 mm 8.00 mm 16.0 mm
Little Tennessee River at Riverside 0349998425
10-24-01 4.3 0.2 0.4 8.5 59 90 97 99 100 100
01-24-02 19.4 0 0 4 29 74 96 99 100 100
09-26-02 29.4 .3 .7 4.6 38 91 100 100 100 100
Cartoogechaye Creek near Franklin (03500240)
10-24-01 1.05 2.2 2.2 16 58 71 76 78 84 100
01-24-02 10.6 0 1 12 70 92 97 99 100 100
09-26-02 15.5 .5 1.5 17 80 93 95 96 97 100
Cullasaja River near Franklin (0350116510)
10-24-01 3.3 .2 .8 13 66 79 85 90 93 100
01-24-02 12.4 0 0 10 73 94 98 99 100 100
09-26-02 18.4 .6 1.7 17 60 86 97 99 100 100
Not surprisingly, total load was significantly less
during low flow than during high flow. Bed load was
negligible at all three sites during low-flow conditions.
Greatest daily bed load, in metric tons, and bed-load
yield, in metric tons per square kilometer, was in the
Little Tennessee River at Riverside during runoff
events. Bed loads in Cartoogechaye Creek and the
Cullasaja River were not substantially different from
each other and were less than one-fifth the bed load and
yield in the Little Tennessee River on the same day. Bed
load accounted for 25 to 44 percent of the total
sediment load in January 2002 when both bed and
suspended-sediment loads were measured (table 9).
Particle Size
The bed-sediment particle-size distributions
were similar at the two tributary sites for the dates
sampled (table 10). The Little Tennessee River at
Riverside transports slightly greater particle sizes than
the tributaries. For the high-flow samples in January
2002 and September 2002, more than 60 percent of the
particles were finer than 0.5 mm in the tributaries,
whereas less than 38 percent of the particles were finer
than 0.5 mm in the Little Tennessee River at Riverside.
SUMMARY
A study of sediment transport in the upper Little
Tennessee River basin was begun in June 2000 in
cooperation with Macon County. The purpose of the
study was to characterize bed and suspended-sediment
loads into Lake Emory from the main stem and major
tributaries -Cartoogechaye Creek and the Cullasaja
River. The study was designed to be completed in
1 year; however, because of extreme drought
conditions in western North Carolina, some sampling
continued into September 2002 in order to collect
samples during high-flow conditions.
Weekly samples for suspended-sediment
concentration were collected at the Little Tennessee
River near Riverside, Cartoogechaye Creek near
Franklin, the Cullasaja River near Franklin, and Lake
Emory at the Porter's Bend dam between November
2000 and November 2001. In addition, some samples
were collected during targeted high-flow events and
analyzed for particle-size distribution of suspended
sediment. Three bed-load samples were collected at
each stream site and analyzed to determine mass and
particle-size distribution.
Annual suspended-sediment load was calculated
based, in part, on continuous record of discharge for
Cartoogechaye Creek near Franklin. Streamflow data
Summary 23
for the Little Tennessee River at Prentiss were used to
estimate instantaneous streamflow record and
suspended-sediment load at the Little Tennessee River
at Riverside and Cullasaja River near Franklin.
Streamflow at the Little Tennessee River at Needmore
was used to estimate an annual-mean discharge for
2001 for releases from Lake Emory. Equations relating
estimated streamflow to suspended-sediment
concentration were developed and used to compute
estimates of annual suspended-sediment loads.
Bed-load samples were collected in October
2001 during low-flow conditions and in January and
September 2002 during stormwater-runoff conditions.
Bed-load samples were analyzed for weight and
particle-size distribution. Selected suspended-sediment
samples were analyzed for particle-size distribution.
For the study period, the greatest annual load and
yield of suspended sediment (5,700 t and 18 t/km2,
respectively) was at the Little Tennessee River near
Riverside. Much smaller annual yields were calculated
for Lake Emory, the Cullasaja River, and
Cartoogechaye Creek-5, 5, and 7 t/km2, respectively.
In an earlier study in the 1970's, the mean-annual
suspended-sediment yield at Cartoogechaye Creek was
81 t/km2 and 110 t/km2 at the Little Tennessee River at
Needmore, which indicates a decline in sediment loads.
The mean-annual suspended-sediment yield for
relatively pristine, forested sites in the North Carolina
Blue Ridge Province was 20 t/km2 for the Nantahala
River near Rainbow Springs and 15 t/km2 for
Cataloochee Creek near Cataloochee. Drought
conditions during the more recent study period
probably were a factor in the small loads at these sites
in 2001 compared to those in the 1970's and to forested
reference sites. The annual-mean streamflow for the
2001 water year was about 50 percent of the long-term
annual-mean streamflow (1944-2001), and high-flow
events carry most of the annual sediment load.
REFERENCES
Duan, N., 1983, Smearing estimate-a nonparametric
retransformation method: Journal of the American
Statistical Association, v. 78, no. 383, p. 605-610.
Edwards, T.K., and Glysson, G.D., 1999, Field methods for
measurement of fluvial sediment: U.S. Geological
Survey Techniques of Water-Resources Investigations,
book 3, chap. C2, 89 p.
Guy, H.P., 1977, Laboratory theory and methods for
sediment analysis: U.S. Geological Survey Techniques
of Water-Resources Investigations, book 5, chap. C1,
58 p.
Harding, J.S., Benfield, E.F., Bolstad, P.V., Helfman, G.S.,
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computation of suspended-sediment discharge: U.S.
Geological Survey Open-File Report 94-459, 46 p.
North Carolina Department of Environment, Health, and
Natural Resources, Division of Environmental
Management, 1992, North Carolina lake assessment
report: Raleigh, N.C., North Carolina Department of
Environment, Health, and Natural Resources, Report
92-02, 353 p.
North Carolina Division of Water Quality, 2000, Basinwide
assessment report-Little Tennessee River: Raleigh,
N.C., North Carolina Department of Environment and
Natural Resources, 83 p.
2002, Little Tennessee River basinwide water quality
plan: Raleigh, N.C., North Carolina Department of
Environment and Natural Resources, 129 p.
Rantz, S.E., and others, 1982, Measurement and
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Scott, M.C., Helfman, G.S., McTammany, M.E., Benfield,
E.F., and Bolstad, P.V., 2002, Multiscale influences on
physical and chemical stream conditions across Blue
Ridge landscapes: Journal of the American Water
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Simmons, C.E., 1993, Sediment characteristics of North
Carolina streams, 1970-79: U.S. Geological Survey
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Southeast Regional Climate Center, 2003, Historical climate
summaries for North Carolina: accessed on Jan. 16,
2003, at http://cirrus.dnr.state.sc.us/cgi-
bin/sercc/cliMAIN.pl?nc3228
U.S. Geological Survey, 1997 to present, National field
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paged].
24 Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in the Upper Little Tennessee River Basin, North Carolina, 2000-02