Author(s): Y. Yoshikawa; Y. Watanabe

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Abstract: Hydraulic phenomena in freezing waters in the tidal region of a river are difficult to observe, as these occur in the severest part of winter and are obscured by ice sheets. Much about such phenomena remains to be clarified. Our study used field observations to clarify hydraulic phenomena in such a river. Field observations were carried out at a cross-section in the tidal region of the Tokoro River in Hokkaido. Observation was conducted during the freezing period (the day of the full-moon flood tide in February, and the day before and after it) and during the open water period (the day of the full-moon flood tide in August, and the day before and after it), to obtain data for comparison. Water levels were measured immediately upstream and downstream of the cross section. At the observation cross-section, flow velocities were measured using an acoustic Doppler current profiler (ADCP), and salinity was measured. Based on observations and analyses of the data, commonalities and differences between the freezing (ice-covered) and open water periods were identified. One commonality is that the stream centerline shifts with the tide. One difference is that the direction of the primary flow in the freezing period differs greatly from that in the open water period.

DOI:

Year: 2006