抄録
A large number of hot springs in Beppu City are discharged through bored wells. In former times, thermal water was found under water-table condition in some inland area in that city over 1000 m distant from the sea-shore, where temperature and water level of a well have been observed once a day during the past 35 years by Geophysical Laboratory, Kyoto University. Its temperature has gradually lowered and is now about 25°C. This shows the decrease of hot water leakage through semi-impervious bed from deeper confined aquifer, in which the water pressure has lowered owing to the increase of withdrawals in the city.
It is observed that the other artesian well of 50 m deep in Beppu shows the obvious rise of temperature under the effect of heavy draft from nearby area and recover after the end of draft. It means that more thermal water rises from the deeper bed with the drawdown of water pressure in the upper aquifer by the pumping effect.
It is found that each aquifer layered vertically is not perfectly bound by confining bed but interchanges water in accordance with pressure gradient through the semi-impervious stratum.
