Refined Protocols to Mitigate User-induced Uncertainty for ADCP Moving-boat Discharge Measurement in Irrigation Canals

Abstract

A Teledyne RD Instruments StreamPro ADCP was used to quantify flow rates between 0.5 and 8 m3/s in man-made irrigation canals with the aim of determining best practices for the method of deployment of an ADCP using a moving boat when computing mean steady discharge. Prescription for total sampling duration is refined here as the product of the duration of a single measurement transect and the total number of transects taken in reciprocal directions. The purpose of this enhancement is to lessen measurement uncertainty arising from insufficient resolution of the turbulent fluctuating velocity signal as determined by the sampling duration chosen by the user. These guidelines also estimate the point of diminishing returns for additional data collection in order to optimize time efficiency for measurement of mean steady discharge. Suggested protocols developed from field experimentation indicate that a significant reduction in the values of uncertainty metrics can be accomplished utilizing a remotely-operated tagline deployment method with a minimum transect duration of 240 s, equivalent to 240 velocity ensembles of an ADCP measuring at 1 Hz. Concurrently, at least four total transects in reciprocal directions should be measured. This expands and refines, in application to small-to-moderate sized irrigation canals, the currently held 720 s minimum total sampling duration guideline established by the USGS. These findings will equip ADCP users across a wide range of experience with further guidance to achieve more reliable direct flow quantification and hydraulic structure calibration.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

ADCP; Flow measurement; Irrigation water management; Measurement protocols; Turbulent timescales; Uncertainty analysis

International Standard Serial Number (ISSN)

0955-5986

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

01 Dec 2021

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