The influence of the fault on Saijo Plain, Ehime Prefecture on groundwater level in the plain based on long-term observation data

Abstract

To contribute to the sustainable use of groundwater on Saijo Plain, Ehime Prefecture, groundwater level data from 15 wells over 36 years was analyzed. The groundwater level in the aquifer south of the fault running across the plain east to west was about 3 m higher than the aquifer on the north side. Changes in the groundwater level in each aquifer were similar. Long-term precipitation and responses to water use in the basin were also different in the north and south aquifers. In addition, the groundwater level in the south aquifer is not affected by the tide, but the level in the north aquifer responds to the tide level. These results indicate that this fault seems to play a role as a low-permeable layer for the groundwater flowing from south to north, and in effect, a dam that divides the aquifer into two water masses.