TRANSVERSE PROPAGATION CHARACTERISTICS OF SOUND AND MEASUREMENT OF CROSS-SECTIONAL AVERAGE VELOCITY IN TIDAL RIVER WITH A NEXT-GENERATION ACOUSTIC VELOCITY METER

Abstract

An acoustic velocity meter (AVM) has been developed to measure river discharge continuously. The AVM has breakthroughs as follows : 1) accurate time with GPS clock signals, 2) high signalto-noise ratio with tenth order M-sequence, 3) thrifty power consumption, reduction in size and weight. The AVM installed at the Ohtagawa diversion channel, where the water level and salinity change significantly, successfully measured the cross-sectional average velocity and discharge for a spring tide. In addition, the intrusion of saltwater was detected from the sound speed data of the AVM. The cross-sectional average velocity and discharge give close agreement with those deduced from an acoustic Doppler current profiler.