Studies on the Conveyance and Distribution of Geothermal Hot Water. Results of Effective Geothermal Water Supply System at Shuzenji Hot Springs, Shizuoka Prefecture

Abstract

Shuzenji spa is situated on the northern ,part of Izu Peninsula. About 73 thermal springs (drilled wells) with a total discharge rate about 1000 l/min. are scattered along the Katsura River, a tributary of the Kano River. Formerly, all springs were of naturally issuing type, and the first shallow wells dug in the end of the 19th century. Pumping-up of the water (by suction pump) started at 1930, and deeper wells have been bored after 1950. Total number of wells and total discharge rate of the water had increased with the increase of demands for the water du~ to the development of spa, and then, marked drawdown of thermal water level had occured. The lowering of the water temperature and decrease of the content of major constituents (Cl-and SOt-) had been observed. It was clear that these changes had been caused by the exhaustion of thermal water resources, and not only the conservation of the resources but also the measures for the exhaustion had become a matter of great concern.