Impact of the sampling duration on the uncertainty of averaged velocity measurements with acoustic instruments |
| |
| Authors: | Muste Marian Jongmin Kim Dongsu Kim |
| |
| Institution: | 1. IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa, USA;2. River Experiment Center, Korea Institute of Civil Engineering and Building Technology, Andong-si, South Korea;3. Department of Civil and Environmental Engineering, Dankook University, Yongin-si, South Korea |
| |
| Abstract: | Average velocity in streams is a key variable for the analysis and modelling of hydrological and hydraulic processes underpinning water resources science and practice. The present study evaluates the impact of the sampling duration on the quality of average velocity measurements acquired with contemporary instruments such as Acoustic Doppler Velocimeters (ADV) an Acoustic Doppler Current Profilers (ADCP). The evaluation combines considerations on turbulent flows and principles and configurations of acoustic instruments with practical experience in conducting customized analysis for uncertainty analysis purposes. The study sheds new insights on the spatial and temporal variability of the uncertainty in the measurement of average velocities due to variable sampling durations acting in isolation from other sources of uncertainties. Sampling durations of 90 and 150 s are found sufficient for ADV and ADCP, respectively, to obtain reliable average velocities in a flow affected only by natural turbulence and instrument noise. Larger sampling durations are needed for measurements in most of the natural streams exposed to additional sources of data variability. |
| |
| Keywords: | acoustic Doppler current profilers acoustic Doppler Velocimeter average velocity uncertainty hydrometric measurements sampling duration |
|
|
