Author(s): Andrew Craig; Marian Muste; Jason Mcvay
Linked Author(s): Marian Muste
Keywords: No Keywords
Abstract: Hydro-acoustics have undoubtedly been a positive influence on the measurement of stream discharge within the United States Geological Survey (USGS). The advancements that have taken place over the past 15 years have increased the accuracy and efficiency of discharge data collection. This advancement is attributed in part to the testing of new equipment that has been offered by the market. One of the newest introduced instruments is the Ott Q-Liner. Initial results from direct comparison of Q-Liner discharge data with approved discharge measurement devices have been promising and have lead to the need for further testing. The present paper describes a laboratory study aimed at investigating several key Q-Liner performance issues including: a) required sampling time for capturing the mean flow characteristics; b) the contribution of individual acoustic beams to the accuracy of the overall measurement; and, c) estimation of the velocity and discharge measurement accuracies;. The study was conducted in a large-scale flume using the Acoustic Doppler Velocimeter (ADV) as a reference instrument. The main findings are that: a) Q-Liner measurements are generally biased low when compared to the ADV reference profile; b) Q-Liner is relatively noisy but can achieve acceptable accuracy if enough sampling (exposure) time is allowed. Results demonstrating the required sampling time are presented; c) the near-transducer bias is not a concern for measurements taken with Beams 1 and 2 (as they are far from the region disturbed by the float).
Year: 2009