次世代超音波流速計による感潮河川流量の長期連続モニタリング

抄録

Water discharge in a shallow tidal channel, which is 120 m wide and 0.3 ~ 3m deep, had been continuously measured using a next-generation acoustic velocitimeter (NAV). The NAV takes advantage of innovative acoustic tomography technology. In addition to discharge, mean water temperature and salinity were deduced from processing the sound speed data collected by the NAV. The NAV has a few noticeable functions represented by the accurate measurement of travel time using the GPS clock and the attainment of high signal-to-noise ratio as a result of transmission signal modulation by the 10th order M-sequence. The NAV, operated at the shallow tidal channel with large changes of water depth and salinity, successfully measured the cross-sectional mean velocity over a long duration. The water discharge deduced from the NAV was compared with that measured by ADCPs.