中海本庄水域周辺承水路の水塊動態

抄録・要旨

In two artificial channels, North and West Channels around the Honjo area, constructed in relation to the reclamation work of Lake Nakaumi, the water-mass movement was measured during the summer and the autumn of 1997. In the North Channel, the water moves rapidly (sometimes at more than 70cm/sec) with change in the current direction to west and east in a short time (in less than 20 minutes or 1 hour). Apparently tidal waves are not responsible for this short cyclic movement, but provoked by the internal seich with fluctuation of halocline. The large scaled water movements with drastic change in water temperature and salinity are caused by the temporal upheaval of the sea-water level related to such meteorological phenomena as lowering of atmospheric pressure and the Ekman effect caused by continuous strong west-wind along San'in coast. In the south opening of the partition bank between the West Channel and the Honjo area, rapid westward currents of more than 30cm/sec are observed for a short time during the rise of water-level related to tidal change, but usually slow eastward currents of less than 15cm/sec are dominant. Salinity of the water-mass in the channehs affected directly by heavy rainfalls. In the north opening of the bank, the water moves to west and east according to the high and low tide level respectively, but the velocity of both currents are very slow (less than 10cm/sec).