Surface-water quality and flow Modeling Interest Group
Visualization of Drifting Buoy Deployments on St. Clair River near
Public Water Intakes-October 3-5, 2000
byDavid J. Holtschlag
and Steve S. Aichele
U.S. Geological Survey
6520 Mercantile Way, Suite 5
Lansing, MI 48911-5991
Internet: dholtschlag@usgs.gov,
saichele@usgs.gov
Phone: (517) 887-8910, (517) 887-8918
FAX: (517) 887-8937
Editor's note:
This paper is U.S. Geological Survey (USGS) Open-File Report 01-17; its
primary publication outlet is the Internet. This work was performed in
cooperation with the Michigan Department of Environmental Quality
Source Water Assessment Program.
In this report, water levels are referenced to the International Great Lakes
Datum of 1985. The animations in this paper rely on the ShockwaveFlash
plug-in, which may be downloaded for free from
Macromedia.
Use of product or firm names in this report is for identification only and
does not constitute endorsement by the USGS or the US Federal Government.
This version of the paper has all of the figures inline. A version
with all of the figures converted to thumbnails,
with links to the larger images, is also available; the download time for
the thumbnail version will be shorter, but the thumbnail figures may be
less convenient for viewing and printing.
Citation:
Holtschlag, D.J. and Aichele, S.S., 2001, Visualization of drifting buoy
deployments on St. Clair River near public water intakes--October 3-5, 2000:
U.S. Geological Survey Open File Report 01-17
<http://smig.usgs.gov/features_0301/drifters.html>.
St. Clair River is a connecting channel of the Great Lakes between Lake Huron
and Lake St. Clair. The river forms part of the international boundary
between the United States and Canada in the eastern Lower Peninsula of
Michigan and southern Ontario. Drifting buoys were deployed to help
investigate flow characteristics near public water intakes in ten reaches
of St. Clair River from October 3-5, 2000. In eight deployments, buoys
were released at uniform intervals in a transect across the river to better
understand flow patterns. In the remaining six deployments, buoys were
released in a cluster near the middle of the channel to study turbulent
dispersion characteristics. The eight spherical and seven cylindrical
buoys used in the study were equipped with drogues and had similar drift
characteristics. Each buoy contained a geographical positioning system
(GPS) to monitor its movement. Computer animations were developed
that integrated these GPS data with data shown on navigational charts.
These computer animations, which can be viewed through the Internet,
provide a scientific visualization tool to study the deployments.
Michigan Department of Environmental Quality (MDEQ) Source Water Assessment
Program (SWAP), in cooperation the U.S. Geological Survey (USGS), is assessing
the vulnerability of 13 public water supplies along the St. Clair-Detroit
River Waterway. Intakes in this area provide water to about one third of
the residents of Michigan. The assessment will identify likely sources of
water to public supply intakes and provide a basis for planning emergency
responses to contaminant spills. Drifting buoy deployments described in
this report were conducted as part of this assessment to better understand
flow patterns and turbulent dispersion characteristics in St. Clair River.
St. Clair River is a connecting channel between Lake Huron and Lake St. Clair
that forms part of the international boundary between the United States and
Canada (fig. 1). In addition to being a major commercial navigation route
through the Great Lakes, the river provides a water supply for adjacent
communities. Port Huron, Marysville, St. Clair, Marine City, and Algonac,
Michigan, in addition to communities in the Canadian province of Ontario,
have water intakes on St. Clair River.
Figure 1. Location of St. Clair River between the United States and
Canada.
St. Clair River extends about 39 miles from its head at the outlet of Lake
Huron to its mouth on Lake St. Clair. The river discharges an average
of 182,000 ft3/s (cubic feet per second) from a drainage area
of about 222,400 mi2 (square miles). Within the river, water
surface elevations fall about 5 ft (feet), much of which occurs in the
upper reaches of the river. Model simulations show that average flow
velocities range from about 5.76 ft/s (feet per second) near Port Huron,
Michigan during high flow conditions to about 1.84 ft/s near Algonac,
Michigan during low-flow conditions (Coordinating Committee on Great Lakes
Hydraulic and Hydrologic Data, 1986).
Drifting buoys, which carried geographical positioning systems (GPS),
were deployed to help describe flow patterns and turbulent dispersion
characteristics within selected reaches of St. Clair River. Computer
animations showing the generalized buoy movements during these deployments
were developed to aid visualization of the results. Flow and stage data are
provided as supporting information. Further analysis and interpretation
of these data is needed to quantify hydraulic properties of the river for
the vulnerability analysis.
The Detroit District of the U.S. Army Corps of Engineers (1983) conducted
a drifting buoy study of St. Clair River in May and June of 1982. In this
study, drifting buoy movements were monitored from the air. Detailed plots
provide quantitative surface-current velocity data throughout the river
and graphs of wind velocity. The study enhances emergency preparedness by
providing detailed information on local flow patterns, thus facilitating
the prediction of constituent transport.
The study was made possible by funding from the Michigan Department of
Environmental Quality (MDEQ), Source Water Assessment Program (SWAP).
Brad Brogren of MDEQ assisted with the field deployment and recovery of
the buoys. Environment Canada provided the use of their research vessel,
The Pelican, and the assistance of Brian Magee and Aaron Thompson to help
deploy, track, and recover the buoys. Staff from the Detroit District
of the U.S. Army Corps of Engineers (USACE), John Koschik, Paul Taylor,
Marty Kuhn, and Phil Ross measured streamflow in St. Clair River and major
tributaries during the deployments. Rick Hooper, Office of Water Quality
of the USGS provided the spherical buoys, and John Costa, USGS Office of
Surface Water, provided enhanced equipment for recording buoy positions.
Stewart Rounds, USGS Oregon District, integrated the report text and
animations to create the web version of the report.
Eight spherical and seven cylindrical buoys were deployed in St. Clair River.
The spherical buoys are surface drifters that were originally designed
for extended deployments in ocean environments by Clearwater Oceanographic
Instrumentation. These buoys are about 16 inches in diameter and weigh
about 45 pounds (fig. 2). They are equipped with telemetry to transmit
positional information to satellite or hand-held receivers. For St. Clair
River deployments, the electronics of these buoys were enhanced to decrease
the sampling interval from 30 minutes to about 90 seconds and to increase
the precision of positional information from about 700 ft to about 70 ft.
Local interferences, however, often reduced the average sampling intervals
to more than 180 seconds. One of the spherical buoys was enhanced to
internally record data at one-second intervals.
Figure 2. Spherical buoy and plastic bucket drogue used in the
drifting buoy deployments on St. Clair River.
The cylindrical buoys were constructed by joining a 9-inch length of
3-inch diameter PVC (polyvinyl chloride) pipe with a 36-inch length
of 4-inch diameter PVC pipe (fig 3). The 3-inch diameter pipe floated
above the waterline (fig. 4) and contained a Garmin GPS 12 unit that was
set to internally record positional information at 45-second intervals.
The specified positional accuracy of the Garmin GPS units, during the
period of the Selective Availability Program, was 49 ft (Garmin Corporation,
1999). The 4-inch diameter part of the cylindrical buoys provided buoyancy.
The lower end of the buoy was weighted to help provide a vertical orientation
when deployed.
Figure 3. Cylindrical buoy used in deployments on St. Clair River.
Figure 4. Spherical and cylindrical buoys drifting in St. Clair
River.
The U.S. Department of Defense Selective Availability Program had been
discontinued before these buoy deployments. Thus, the accuracy of the
positional information is considered constant throughout the deployments.
In some deployments, positional data was not transmitted or recorded from
one or more buoys with sufficient frequency to include in the animations.
All buoys were equipped with drogues to reduce the effects of wind on
buoy movements. Drogues were made from 5-gallon plastic buckets that were
suspended about 3 feet below the bottom of the buoys. Holes were cut in
the bottom of the buckets to allow drainage and facilitate buoy recovery.
The drogues were weighted so that they remained suspended below the buoys.
Floats were attached to the buoys to facilitate recovery.
Fourteen buoy deployments were used to investigate flow characteristics in
ten reaches of St. Clair River. Deployments generally lasted about 1 hour.
During all deployments, winds were generally light to calm (under 10 miles
per hour) and wave heights were generally less than one foot. Thus,
winds and waves are not thought to significantly impact buoy movements
during these deployments.
In eight of the deployments, buoys were distributed at about equal distances
in a transect across the river. In these transect deployments, spherical
and cylindrical buoys were generally released alternately. The transect
deployments were used to investigate flow patterns and relative velocities
within the reach.
In the remaining six deployments, buoys were released in a tightly grouped
cluster near the center of the channel. The cluster deployments were used
to investigate the turbulent dispersion characteristics of the reach.
Streamflow. Staff from the Detroit District
of the U.S. Army Corps of Engineers measured streamflow on St. Clair River
and selected tributaries by use of an acoustic Doppler current profiler
(Table 1). Streamflow during the buoy deployments was generally lower
than average.
Table 1. Streamflow measurements during buoy deployments on St. Clair
River. [Measurements were taken by the Detroit District of the U.S. Army
Corps of Engineers.]
Stage. Water surface elevation (stage) is
recorded at 6-minute intervals at six National Oceanic and Atmospheric
Administration (NOAA) gauges on St. Clair River. During the buoy
deployments, average water levels remained fairly constant (fig. 5).
Greater variation in water levels, however, was detected at upstream
gauges than downstream gauges. Specifically, the standard deviation of
water levels ranged from 0.12 foot at the Fort Gratiot gauge compared to
a standard deviation of 0.05 foot at the Algonac gauge.
Figure 5. Water level fluctuations along St. Clair River during
buoy deployments.
Buoy animations were developed by use of LiveMotion®, a software
product of Adobe Corporation. All animations represent one minute of actual
deployment time as one second of animation time. Background maps for the
animations were scanned from 1:15,000 scale maps (National Oceanic and
Atmospheric Administration, 1999), which show contour and point depths
of flow in feet below low-water datum. The pixel coordinates of the
scanned images were registered with positional information on the maps
to facilitate plotting of measured buoy locations. Buoy locations were
generally included at about 90-second intervals, when GPS data was available.
Between measured locations, buoy positions were automatically interpolated
by use of a Bezier curve. Pairs of Macromedia Flash file format (SWF)
and hypertext markup language (html) files were created to display the
animations through the Internet. A Flash file reader plug in for standard
Internet browsers is available without charge from
Macromedia.
Data on buoy deployments were animated to help visualize the flow pattern
and turbulent dispersion characteristics near public water intakes on
St. Clair River. Figure 6 shows the locations of the drifter studies,
with links to the animations.
Figure 6. Location of drifter studies on St. Clair River near Port
Huron, Michigan.
The drifter animations also may be accessed from the following list:
These animations are controlled through the use of a standard set of buttons
that allow the animation to be played, stopped, and advanced or reversed one
frame at a time. The same controls are available on all of the animations,
and they are as follows:
The Michigan Department of Natural Resources, in cooperation with the
U.S. Geological Survey, is conducting a source water assessment of public
water supply intakes on St. Clair River. As part of this assessment,
14 deployments of drifting buoys were used to investigate flow patterns
and turbulent dispersion characteristics in ten reaches of St. Clair River
from October 3-5, 2000. As many as eight spherical and seven cylindrical
drifting buoys were used in each deployment. The spherical buoys
transmitted identification, time, and position information as frequently
as every 90 seconds to a receiver carried aboard the Environment Canada
research vessel the Pelican. The cylindrical buoys carried a handheld GPS
device that stored time and positional information at 45-second intervals.
Data on buoy movements during the deployments were animated and referenced
to a navigational chart to help visualize the results. The animations
are available through the Internet to those interested in the flow
characteristics of St. Clair River.
Coordinating Committee on Great Lakes Hydraulic and Hydrologic Data, 1988,
Lakes Michigan and Huron Outflows: St. Clair and Detroit Rivers 1900-1986:
Unpublished report, Detroit, Michigan and Cornwall, Ontario, 48 p.
Garmin Corporation, 1999, GPS 12 Personal Navigator: Owner's Manual &
Reference: Garmin Corporation, Olathe, Kansas, 59 p.
National Oceanic and Atmospheric Administration, 1999, Recreational Chart
14853--Detroit River, Lake St. Clair, and St. Clair River (12th Ed.):
Marine Chart Division, National Ocean Service.
U.S. Army Corps of Engineers, 1983, St. Clair River aerial drogue survey
surface velocities and directions spring of 1982: Great Lakes Hydraulic
and Hydrology Branch, U.S. Army Corps of Engineers, Detroit Michigan,
28 plates, 7 p.
Abstract
Blue Water Bridge Transect [240 Kb]
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