島しょ部における地下水汚染に関する研究(1)
-興居島における地下水への海水侵入-
1986 年 47 巻 1 号 p. 37-51
詳細
1986 年 47 巻 1 号 p. 37-51
This report deals with the problem of the groundwater pollution caused by seawater intrusion into phreatic and confined aquifers of Gogo Island, Ehime Prefecture. Groundwater levels and chloride ion concentrations in shallow wells were measured in five districts on this island from August 1983 to December 1984. High chloride ion concentrations far greater than 200 ppm, the standard value of city water, were found in coastal regions of the Yura district, whereas the level were very low in other districts. In the Yura district, groundwater levels and chloride ion concentrations in deep wells as well as tide levels were measured. Chloride ion concentration profiles show the rapid increase of the concentration in the neighborhood of the well bottom. A modified KISHI and INOUCHI' s model to analize the variation in the groundwater level and fresh-salt water interface in response to the tide was applicable to a confined aquifer with an exponentially varying thickness. The thickness of the confined aquifer estimated from this analysis was in fairly good agreement with the one obtained by the boring examination.
