中海本庄工区北部承水路堤潮通しパイプ付近の水の動き

For examining the effect of the water-alternating pipe at the dike of North Channel in Honjo water-area, a brackish-water lake Nakaumi, current velocity, salinity and temperature of the water passing through it and its adjacent channel were continuously observed. The movement of the water through the pipe is mainly controlled by tide with weak secondaly oscillation caused by the water movement in the adjacent North Channel. The water-mass exchange through the pipe is estimated about 313 ×103 m^3/day. On the other hand, the water passing through the mouth of the North Channel is changing the direction in such shorter periodicity as about 35 minutes, which may be controlled by the topography of the channel. The opening of the water-alternating pipe affected no remarkable change in the water movement of the channel.