[Acoustics] Legal challenges to the validity of flow data derived from an ADCP.

[Marian Muste]

Hi Richard,

Legal disputes in ADCP measurement applications can be addressed only by
using a sound, widely-recognized uncertainty analysis [UA] framework.  Such
a framework provides not only mean values and uncertainty estimates but also
the prescribed confidence level. 

In 2002, the IIHR - Hydroscience & Engineering (IIHR) and the South Florida
Water Management District (SFWMD) have initiated a cooperative study to
identify and assess such frameworks and to apply them to ADCP velocity and
discharge measurements.  Following the assessment, the IIHR-SFWMD study has
adopted the American Institute of Aeronautics and Astronautics Standard
(1995).  This standard, similarly to the ASME (1998), is a direct outgrowth
of the ISO (1993) standard "Guide to the expression of uncertainty in
measurement" for specific engineering areas.  The final report describing
the AIAA (1995) framework and its implementation to ADCP measurements will
be completed soon.  The main results of the IIHR-SFWMD study will be
submitted to peer reviewed journals shortly after, but there conference
papers summarizing aspects of the study that the PI's have presented to the
EWRI-ASCE Congresses in 2004, and 2005.  A software (for Windows
environment) fitted with Graphical User Interfaces has been also developed
to facilitate analysis implementation by users with various degrees of
preparedness. The UA was subject of discussions with ADCP manufacturers, a
UNESCO working group on data acquisition, and with ISO representatives (Dr.
Herschy).

During the conduct of the study we understood the complexity and extent of
the task and the need for collaboration and exchange of information among
all relevant contributors (manufacturers, operators, researchers). Large
number of samples and inter-agency/laboratory information exchange are key
ingredients for a robust UA.  We are aware about some other on-going efforts
for estimating ADCP measurement errors, such as the the USGS-RDI
collaborative work.  The two collaborative teams have already exchanged
their analysis results.  

A collective coordinated action along this line can speed up the elaboration
of a thorough ADCP uncertainty assessment that not only that can withstand
legal challenges, but also enhance quality assurance and guide manufacturers
in further improvement of the instrument.  Any practical suggestions?

Best regards,
marian

Marian Muste 
Research Engineer 
IIHR-Hydroscience & Engineering 
The University of Iowa 
323E Maxwell C. Stanley Hydraulics Laboratory 
Iowa City, IA 52242-1585 
Phone: (319) 384 0624 
Fax:     (319) 335 5238 
Website: www.iihr.uiowa.edu/people/details.php?id=27 
Personal Website: http://www.iihr.uiowa.edu/~muste



-----Original Message-----
From: acoustics-bounces at simon.er.usgs.gov
[mailto:acoustics-bounces at simon.er.usgs.gov] On Behalf Of Richard Iredale
Sent: Monday, June 13, 2005 10:57 AM
To: acoustics at simon.er.usgs.gov
Subject: [Acoustics] Legal challenges to the validity of flow data
derivedfrom an ADCP.


Has anybody out there had to defend the validity of an ADCP flow
measurement against a legal challenge from a third party? 
The Environment Agency manage Water Resources in England and Wales. One
of the Agency's duties is to enforce the terms of water Abstraction
Licences. From time to time the Agency prosecute water abstractors for
taking water in excess of their abstraction licence conditions. This
has, on a number of occasions, involved the Agency having to present
flow measurement evidence in a court of law to substantiate our claim
that the abstractor was taking more water than his license allowed.
The robustness of our flow measurement method has in the past been
tested in court under cross examination from the abstractors legal
team.
When current meters were used to undertake these measurements  we could
claim that the flow measurement was undertaken in conformance with
British and International standards for current meter gauging and that
the current meter had a valid calibration certificate. If necessary the
current meter was calibrated both before and after the measurement was
taken.
In the case where flow measurements are now taken using ADCPs we feel
more vulnerable to legal challenges. This is for two reasons.-
1. There is no ISO document in place. The Agency has to rely on its own
internal document on gauging procedures which is based on the draft ISO
document.
2. ADCPs do not have "certificates of calibration" . The only checks on
the performance that can be made are against other ADCPs or other types
of flow monitoring equipment. 
On the latter point.  Does anyone have any suggestions the may help our
case if we had to defend  ADCP flow measurement in a court of law.
Has anybody out there been in a similar position of having to defend
the robustness of an ADCP flow measurement technique. 
All responses gratefully received
Richard Iredale
Technical Advisor 
The Environment Agency of England and Wales.

Richard Iredale
Technical Advisor, Hydrometry Process
Head Office , Water resources

Int Number 7 22 4650
External Number 0121 708 4650

Hydrometry Process Intranet Site :
http://intranet.ea.gov/organisation/df/water_management/process/field_monito
ring_and_data/contents.htm


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