U.S. Geological Survey Scientific Investigations Report

Quality-Assurance Plan for Discharge Measurements Using Acoustic Doppler Current Profilers

In cooperation with the U.S. Army Corps of Engineers, Detroit District
by Kevin A. Oberg, Scott E. Morlock, and William S. Caldwell

U.S. Geological Survey Scientific Investigations Report 2005-5183

The full report is available as a pdf.
The full report is available as html online.


This report describes the quality-assurance measures implemented by the U.S. Geological Survey (USGS) for discharge (streamflow) measurements using acoustic Doppler current profilers (ADCPs). The report is an update of a 1995 quality-assurance plan for ADCPs and addresses the many changes in ADCP technology and procedures since 1995. An ADCP is an electronic instrument used to measure water velocity, water depth, boat velocity, and discharge in rivers by means of underwater acoustic signals. ADCPs have been used by the USGS to measure streamflow in rivers and estuaries since 1985. Techniques for the measurement of discharge and for assuring the quality of the data have been developed and documented by the USGS Office of Surface Water (OSW). The OSW supports ADCP use through training classes, Web pages on the use of ADCPs, software and hardware testing, and the Hydroacoustics Work Group.

Quality-assurance measures include selection of measurement locations, use of suitable deployment platforms, performing diagnostic and moving-bed tests, configuration of the ADCP, techniques for the collection and review of ADCP discharge measurements, and instrument tests. During discharge measurements, proper boat control and speed is critical to ADCP data quality. A minimum of four transects should be made in reciprocal pairs and the four transect discharges averaged to obtain the measured discharge for normal flow conditions. Procedures are described for streams where the flow is changing rapidly. Edge distances must be measured with a distance-measuring device or tagline. Following the discharge measurement, all ADCP files collected on the field computer should be backed up on non-volatile storage media. Tests of each ADCP should be conducted after an ADCP is first acquired, after factory repair, after firmware or hardware upgrades, and at some periodic interval. Each USGS office must also develop an office ADCP quality assurance plan that includes procedures specific to the office ADCP models, users, and measurement sites.

ADCP data collected in the field should be reviewed as soon a practical in the office. All measurement data should be transferred to an office server within 2 work days of returning to the office from the field, and archived within a directory structure similar to that used for other electronically collected data. Approximately every 3 years, ADCP measurement, documentation, and data-archival procedures will be reviewed during an OSW Surface-Water Technical Review.

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