Acoustic Velocimetry for Riverine Environments

Abstract

Acoustic instruments are rapidly replacing conventional current meters for measurement of velocities in natural and man-made open channels. Greater efficiency, improved performance, and numerous safety considerations at comparable costs have provided the motivation for their broad adoption in hydrologic datacollection operations. They have no moving parts, offer relatively high spatial and temporal sampling resolution, and require fewer calibrations. Moreover, they allow measurements in field settings where conventional measurements were very difficult or costly to obtain and facilitate documentation of flow features that previously could only be documented in the laboratory Dinehart and Burau 2005 . Rapid development of acoustic velocimeters has continued since the early work on acoustic Doppler current profilers ADCPs by Christensen and Herrick 1982 , Simpson 1986 , and Gordon 1989 . Likewise, the development of acoustic Doppler velocimeters ADVs in the early 1990s Kraus et al. 1994 has revolutionized the measurement of twoand threedimensional mean velocities and turbulence characteristics in both laboratory and field studies. These technologies have profoundly changed the way that hydraulic data are collected by researchers, engineers, and technicians alike, being applied to measure velocity and thereby estimate important velocity-derived hydrodynamic quantities in support of riverine research and to complement numerical simulations and laboratory studies. Acoustic instruments are currently used for routine operations on water delivery projects, water treatment plants, stream gauging stations, and many other water resources-related projects. Given the growing interest in acoustic measurements and associated instrumentation, the Hydraulic Measurements and Experimentation Committee HME of the Environmental and Water Resources Institute EWRI decided in 2005 to produce a special issue of the Journal of Hydraulic Engineering focused on Acoustic Velocimetry for Riverine Environments. The HME is a technical committee founded in 1989 within the American Society of Civil Engineers and more recently its Environmental and Water Resources Institute. The committee consists of volunteer scientists and practitioners from academia, federal and state water