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Integrated Synoptic Surveys Using an Autonomous Underwater

Vehicle and Manned Boats

New Technology Answering Age-Old Questions

Traditional surface-water surveys are being combined 

with autonomous technology to produce integrated surveys

of bathymetry, water quality, and velocity in inland lakes 

and reservoirs. This new technology provides valuable, 

high-resolution, integrated data that allow a systems-based 

approach to understanding common environmental problems.

What are Integrated Synoptic Surveys?

A synoptic survey produces a nearly instantaneous picture 

of a characteristic of interest (for example, water temperature) 

over a broad area. Synoptic surveys of a water body often 

require many people and many hours to complete, depending on the extent of the survey and the purpose of the study. 

Typically, these surveys target only a single characteristic, such 

as bathymetry or the extent of algal blooms. Interdisciplinary studies require integrated datasets that include geologic, 

biologic, hydraulic, and chemical data collected simultaneously 

and under a common sampling strategy and with similar spatial 

and temporal resolutions. To complete these complex synoptic 

surveys, a combination of new technology and proven survey 

techniques is used. Traditional manned-boat surveys might use 

acoustic Doppler current profiling, single-beam echo sounding, sediment sampling, and water-quality point sampling to 

meet data needs. Generally, these traditional surveys are not run 

simultaneously; however, running these surveys simultaneously 

with a high-resolution three-dimensional survey of bathymetry, 

water quality, velocity, and side-scan sonar imagery using an 

autonomous underwater vehicle can greatly enhance the dataset. 

Because the surveys are integrated, the datasets can allow for a 

systems-based approach to analysis.

The Autonomous Underwater Vehicle (AUV)

The autonomous underwater vehicle (AUV) is a specialized submersible instrument equipped with integrated 

water-quality sensors, acoustic Doppler current profiler and 

Doppler velocimetry log (DVL), single-beam echo sounder, 

side-scan sonar, and a differential global positioning system 

(GPS) receiver (fig. 1). The AUV operates by propelling itself 

through the water body (surface or subsurface) between way 

points along a constant depth, constant height above bottom, or 

undulating survey path (fig. 2), as set by the user in the mission 

plan. The AUV monitors its position using a GPS receiver and 

bottom-tracking DVL. The AUV dataset is unique, providing 

high spatial resolution of key physiochemical water-quality 

characteristics (temperature, specific conductance, dissolved 

oxygen, pH, and turbidity). Additional optical sensors provide 

measurements of chlorophyll, blue-green algae, and rhodamine WT dye concentration. Depth soundings, water-velocity 

profiles, and side-scan sonar imagery also are collected. Data 

are collected at 1 hertz. Operational limits of the vehicle include 

speeds up to 4 knots (7 feet per second) and dive capability to 

200 feet.

Global positioning system/

wireless antenna

Ballast weights

Doppler velocimetry log (DVL)/altimeter

Propeller

Water-quality sensors

Independent fins

Side-scan sonar

Up-looking beam

Pressure sensor

Compass and

pressure sensors

14.7 centimeters

 (5.8 inches)

160.8 centimeters (63.6 inches)

U.S. Department of the Interior

U.S. Geological Survey

Figure 1. Schematic of an autonomous underwater vehicle (Yellow Springs Instruments EcoMapper®).

Fact Sheet 2013–3018

April 2013
a ¢⁄ ‹ ¶ ⁄ ¢• • ƒ· ? hfl• ƒfl¶ “ • ...? G¥aH

Acoustic 

beams

Bed

Acoustic 

Doppler 

current 

profiler

(ADCP)

Global positioning system 

(GPS) receiver

Undulation

Constant depth

Constant 

height

EXPLANATION

Colder

Temperature

Warmer

Figure 2. Schematic of a typical integrated survey with a manned boat equipped with an acoustic Doppler current profiler (ADCP) and differential 

global positioning system (GPS) receiver and the autonomous underwater vehicle (AUV) equipped with a suite of water-quality sensors, ADCP and 

Doppler velocimetry log, and side-scan sonar. The three primary survey modes (constant depth, constant height above bottom, and undulation) are 

shown for the AUV.

Beyond a Typical Bathymetric Survey

A high-resolution bathymetric survey of a surface-water 

body might require significant time on the water and as many as 

200 transects of the lake or reservoir spaced at 0.5 percent of the 

length of the water body (Wilson and Richards, 2006). Although 

a traditional single-beam survey of a lake will provide only a 

bathymetric map such as that shown in figure 3A, an integrated 

survey can include water-quality and velocity data with little 

additional effort in the field. These additional data can provide 

valuable information about the water body; for example the distribution of chlorophyll a for better understanding of the extent 

of an algal bloom (fig. 3B), the distribution of dissolved oxygen 

in a lake during an algal bloom in the vicinity of a tributary 

inflow (fig. 3C), or the depth-averaged velocity 

distribution in a shallow basin driven predominately by wind (fig. 3D).

Supplementary data collected during integrated surveys can be processed and analyzed if 

deemed important for the study or archived for 

future use. Processing any supplemental data 

requires additional resources; however, automated processing via computer scripts reduces 

time requirements. At their basic level, these 

scripts can be used to generate quick visualizations of each of the datasets to allow review in 

the field. The full functionality of the scripts 

allows for complete review, screening, and 

correction of the data. Processed data can be 

exported to two- and three- dimensional mapping and visualization applications for additional processing, visualization, and analysis 

when required.

A

B

C

83.0 - 88.9

77.1 - 83.0

71.1 - 77.1

65.2 - 71.1

59.3 - 65.2

53.3 - 59.3

47.4 - 53.3

88.9 - 94.9

41.5 - 47.4

Hazard

7.83 - 9.71

9.71 - 11.2

11.2 - 12.3

12.3 - 13.2

13.2 - 13.9

13.9 - 14.5

14.5 - 14.9

14.9 - 15.3

15.3 - 15.5

15.5 - 15.7

15.7 - 15.9

15.9 - 16.0

16.0 - 16.2

16.2 - 16.4 

16.4 - 16.6 

B. Chlorophyll a

 concentration, in 

 micrograms per liter

EXPLANATION

C. Dissolved oxygen,

 in milligrams per liter

A. Water depth

Shallow

Deep

16.6 - 17.0

17.0 - 17.4

17.4 - 17.9

17.9 - 18.7

18.7 - 19.6

Unmeasured

D

D. Depth-averaged velocity, 

 in feet per second

0 0.2

Nippersink 

Creek

Figure 3. Several products of an integrated synoptic survey 

of Wonder Lake, Illinois, August 2010: A, Bathymetric map with 1-foot contours. B, Near-surface 

chlorophyll a concentration. C, Near-surface dissolved oxygen concentration. D, Depth-averaged 

velocity with generalized circulation patterns.
Universal Transverse Mercator easting, in meters

Universal Transverse Mercator northing, in meters

451500 452000 452500 453000 453500

 4603200

 4603400

 4603600

 4603800

 4604000

 4604200

 4604400

 4604600

 4604800

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Depth-averaged velocity, in feet per second

L a k e E r i e 

General circulation of 

Euclid Creek water

Alongshore current

Euclid 

Creek

V i l l a A n g e l a B e a c h

20

25

10

10

20

25

18

16

14

12

18

16

14 12

Start survey

08:26 (EDT)

End survey

11:17

Euclid Creek

Specific conductance 

0.851 to 0.894 mS/cm

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

0 425 850 1,700 Feet

Specific conductance, 

in millisiemens per centimeter (mS/cm)

0.298–0.299

0.299–0.300

0.300–0.301

0.301–0.302

0.302–0.303

0.303–0.304

0.297–0.298

Combined sewer overflow (CSO)

permit point

EXPLANATION

8 Survey cross section

Bathymetric contour, in feet

Figure 4. Distribution of near-surface specific conductance overlaid by depth-averaged velocity vectors, generalized circulation patterns, and 

alongshore-current distribution in Lake Erie near Villa Angela Beach and Euclid Creek, Ohio, on September 11, 2012. Specific-conductance data were 

collected with the AUV (undulating between the surface and 5 feet above the bed at a speed of 2 knots), and velocity data were collected with a boatmounted ADCP and processed with the Velocity Mapping Toolbox (Parsons and others, 2013).

Currents Help Explain Water-Quality Distributions

Combining observed currents with water-quality distributions allows for an integrated analysis and greater understanding of the system being studied. For example, figure 4 shows 

nearshore Lake Erie near Villa Angela Beach and Euclid Creek, 

Ohio. A recirculation zone along the beachfront traps Euclid 

Creek water and related contaminants. Specific conductance, 

which was three times higher in the creek than in the lake, 

serves as an excellent tracer to map the river plume. This 

mixing pattern was observed in both 2011 and 2012 during 

integrated surveys; three-dimensional data from the AUV and 

ADCP show the formation of density currents along the lakebed 

and the subsequent mixing of the dense, near-bed river water to 

the surface through the action of large-scale eddies (fig. 5).

0.36 feet per second

General

circulation

Large-scale eddies

Lake bed

Downwelling

Onshore

Offshore Offshore/onshore velocity scale Density current

(being mixed upward)

NE alongshore current (recirculation) SW alongshore current

0

0

10

20

5

15

25

500 1000 1500

Distance offshore, in feet

Depth, in feet

0.295 0.296 0.297 0.298 0.299 0.300 0.301 0.302 0.303

Specific conductance, in millisiemens per centimeter

Cross 

section 9

Line of zero

alongshore current

Figure 5. Distribution of specific conductance in cross section 9 (see fig. 4) overlaid by onshore/offshore velocity vectors, generalized circulation 

patterns, and alongshore-current distribution. Specific-conductance data were collected with the AUV (undulating between the surface and 5 feet above 

the bed), and velocity data were collected with a boat-mounted ADCP and processed with the Velocity Mapping Toolbox (Parsons and others, 2013).
Highly Resolved Datasets Allow Multi-Dimensional 

Analysis

Currents and water-quality distributions often vary with 

depth. A three-dimensional integrated synoptic survey provides 

the appropriate vertical resolution to allow data analysis in 

three dimensions. By using custom processing scripts, the full, 

three-dimensional dataset can be sliced along a horizontal plane 

to examine water-quality distributions in plan view (fig. 6) 

or sliced into a series of vertical planes along transect lines 

and aggregated into a single, three-dimensional visualization 

(fig. 7). A thorough analysis would incorporate both methods of 

visualization to take advantage of the strengths of each method. 

In the example provided for the Milwaukee River, Wisconsin, 

the three-dimensional distribution of specific conductance in the 

harbor (fig. 7) shows the river plume of high specific conductance entering the harbor and forming a plume to the south. 

This distribution is complicated by a wastewater-effluent outfall 

near the river mouth, which also has high specific conductance 

(fig. 6). The outfall is clearly visible when the distribution of 

specific conductance is viewed in plan view with data in the 

harbor and three tributaries (fig. 6). A manned boat was used 

to collect the riverine data while the AUV ran the survey of the 

harbor.

Specific conductance,

 in millisiemens per centimeter

EXPLANATION

0.300 0.575 0.850

Based on 17, 619 surface-water 

samples from 0 to 5 feet depth on 

September 7-9, 2010.

0 3,500 feet

Menomonee River

Kinnickinnic River

Milwaukee 

Harbor 

Sewage 

effluent 

outfall

LAKE MICHIGAN

Milwaukee River

Jones

Island

Figure 6. Distribution of near-surface (0 to 5 feet depth) specific 

conductance in Milwaukee Harbor and the lower Milwaukee, 

Menomonee, and Kinnickinnic River, Wisconsin, September 7–9, 2010. 

Data also show the location of the effluent outfall from the Jones Island 

wastewater treatment plant.

References Cited

Parsons, D.R., Jackson, P.R., Czuba, J.A., Engel, F.L., Rhoads, 

B.L., Oberg, K.A., Best, J.L., Mueller, D.S., Johnson, K.K., 

and Riley, J.D., 2013, Velocity Mapping Toolbox (VMT)—A 

processing and visualization suite for moving-vessel ADCP 

measurements: Earth Surface Processes and Landforms, 

online Early View, 17 p., DOI: 10.1002/esp.3367.

Wilson, G.L., and Richards, J.M., 2006, Procedural documentation and accuracy assessment of bathymetric maps and area/

capacity tables for small reservoirs: U.S. Geological Survey 

Scientific Investigations Report 2006–5208, 24 p. plus oversize figures.

10 16 0.285 0.600 9 13

Temperature, 

in degrees Celsius

Specific conductance, in 

millisiemens per centimeter

EXPLANATION

Dissolved oxygen,

in milligrams per liter

Lake Michigan

Flow

N

0 feet

30 feet

Figure 7. Three-dimensional views of water quality in outer 

Milwaukee Harbor on September 9, 2010. A, Temperature. B, Specific 

conductance. C, Dissolved oxygen. Images shown looking down and to 

the north. Flow into the harbor from the three tributaries is from the left, 

and Lake Michigan is on the right. Note how the river plume deflects to 

the south.

Front page boat photograph: Manned boat equipped with an ADCP, differential 

GPS receiver, single-beam echo sounder, and multiparameter sonde. The AUV 

is being recovered at the end of an integrated manned boat and AUV survey on 

Wonder Lake, Illinois, August 2010. Photograph by Peter Berrini, HDR, Inc., used 

by permission. 

Any use of trade, product, or firm names is for descriptive purposes only and 

does not imply endorsement by the U.S. Government.

Author: P. Ryan Jackson, U.S. Geological Survey,

Hydrologist, Illinois Water Science Center,

Urbana, IL 61801, USA; pjackson@usgs.gov

For information contact: Director: 

U.S. Geological Survey Illinois Water Science Center

1201 W. University Ave., Suite 100, Urbana, IL 61801

(217) 328-8747

http://il.water.usgs.gov