Hydroacoustic Current Meters for the Measurement of Discharge in Shallow Streams and Rivers

Project Updates

ADV

On January 22, 2001, SonTek representative Craig Huhta delivered a new ADV prototype to the Indiana District and participated in testing of the new instrument. The new ADV prototype has been improved over the first proof-of-concept (POC) prototype for the wading-rod application. This "second-generation" prototype is an intermediate model between the POC prototype and the first commercially available units that SonTek plans to offer.  The purpose of the second-generation prototype is USGS testing - testing intended to produce data and suggestions that SonTek can use to refine ADV design and features for development. New features of the second-generation prototype follow.

• The probe head is detached from the ADV electronics.
• The ADV electronics and power supply are integrated within an interface that includes a keypad for entering discharge measurement parameters and a LCD screen for displaying information; the probe head is attached to this interface by a cable.
• The probe head has a mounting peg attached that allows it to be attached quickly to a standard wading rod.
• The interface allowed entry of the basic parameters required to make a discharge measurement: station, distance, depth, and vertical location of the measurement (0.6, or 0.2 and 0.8 of the depth).
• The interface displayed computed discharge at the end of a measurement.
• Several files for each measurement were stored on the interface, including a discharge summary and raw-data file.
• The discharge-computation algorithms were based on USGS standards for discharge measurements.

Second-generation ADV prototype probe head

Second-generation ADV interface box that contains a keyboard, display screen, ADV electronics and power supply.

The testing of the second-generation ADV wading-rod prototype consisted of making discharge measurements at eight USGS streamflow-gaging stations. One ADV discharge measurement was made per station. A mechanical current meter (conventional) discharge measurement was made concurrently for comparison. The same tag line and stations were used for both measurements, to the extent possible. The following table is a summary of the discharge-measurement tests.

[ADV; acoustic Doppler velocimeter; ft², square feet; ft/s, feet per second; ft³/s, cubic feet per second; all data are provisional and subject to revision]

Stream conditions varied from site to site: water velocities ranged from nearly zero to more than 25 ft/s, depths from 0.2 to 2.8 ft, and streambed conditions ranged from rocky to smooth and sandy. The following conclusions were drawn from the tests:

• The discharge computation algorithms appear to be correct.
• Analysis of the data indicated that channel areas differed by as much as 9 percent between ADV and conventional for some measurements; because duplicate stationing was used, these differences appear to be depth-reading errors.
• Only one ADV and one conventional measurement were made per station – in future testing two conventional  measurements per site will be made where possible in case a meter had any bias errors.  Performing a second ADV measurement also would be prudent for repeatability.
• The  ADV sampling volume is about 4 inches to the side of the wading rod, which could impact measurement accuracy on smaller streams.  Plans are for commercially available units to have the probe attached to the wading rod so that the sampling volume is closer to the rod.

Concurrent ADV and conventional discharge measurements.  

On January 24 a test plan was discussed with Craig Huhta for ADV tow-tank tests at Stennis Space Center; the tests were conducted on February 1.  The tests involved towing the ADV through the tank at various known speeds to collect data on water velocity measurement accuracy.  Preliminary results of the tests will be posted here when they become available. 

With initial testing of the second prototype complete, the project now will proceed along the following general schedule:

1. The ADV prototype will be returned to the SonTek factory for upgrades.
2. After the upgrades, the ADV will be returned to Indiana for further testing; a second identical prototype will be shipped to the Maryland-Delaware-D.C. District for testing.
3. After a week of further testing in Indiana, the ADV will be shipped to other USGS districts for additional testing. Districts that have agreed to participate in the testing include Alaska, Florida, New Hampshire, Wisconsin, Kentucky, and Ohio. These testers will be asked to follow a test plan (i.e. comparison measurements, documentation).
4. Test data and comments from testers will be forwarded to SonTek as the company works toward release of its first commercially-available units.  

Profiler

In December, the Indiana District received the Nortek proof-of-concept (POC) profiler integrated with a custom transducer head for the profiler application.  Nortek supplied software modules so that Indiana District personnel can begin work on data-collection programs for a field computer.  The District also received a prototype "boogy board" floating platform from the OceanScience Group; this platform will be used to float the profiler during data collection on streams.  Indiana District personnel will begin data collection with POC prototype by February 23.  

Proof-of-concept profiler mounted to floating platform to be used for field tests.

Next: References

Indiana District Hydroacoustics Main Page
Office of Surface Water Hydroacoustic Support Pages

• The use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the United States Government.
• All information herein is provisional and subject to revision.
• Emphasis on the instruments described in these pages does not imply that these are the only instruments that can be used for this purpose. The instruments were selected for the following reasons: the instruments are readily adaptable to this purpose, the instruments are on Federal purchase schedules, and the instrument vendors have voluntarily committed resources to this application. Other instruments will be investigated within the limits of project funding and schedules.

U.S. Department of the Interior
U.S. Geological Survey
5957 Lakeside Boulevard
Indianapolis, Indiana
46278-1996
USA
Phone: (317)290-3333
Fax: (317)290-3313
URL: http://sunrise.er.usgs.gov/hydroacoustics/acoustic_wading_rod_updates.shtml
Last modified:Monday, 13-Aug-2007 15:58:47 EDT
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