DETECTION METHOD FOR VARIATION IN SALINE WATER AND FRESH WATER BOUNDARY OF GROUND WATER

To provide a detection method for variation in saline water and fresh water boundary of ground water, the method being hardly affected by specific resistance variation of water in an observation hole, and enabling recognition of variation in saline water and fresh water boundary in an aquifer layer upon the time of water pumping and also being contributable to proper groundwater utilization.SOLUTION: A detection method for variation in saline water and fresh water boundary of ground water includes detecting variation in a saline water fresh water boundary A which is the boundary between a salt groundwater aquifer B and a fresh groundwater aquifer F by performing time-series measurement of electric exploration using four electrodes 10, and is constituted in such a manner that two transmission electrodes 11, 12 are arranged on the ground surface, two reception electrodes 13, 14 are arranged below a groundwater surface S across the saline water fresh water boundary A, an electric current is supplied to the ground by the transmission electrodes 11, 12 and a potential difference is measured by the reception electrodes 13, 14, and specific resistance variation of the ground found from the value of the current supplied from the transmission electrodes and the potential difference measured by the reception electrodes is detected, and as variation of the saline water fresh water boundary A, specific resistance variation of the ground found from the value of the current supplied from the transmission electrodes and the potential difference measured by the reception electrodes are detected.SELECTED DRAWING: Figure 1 【課題】観測孔の孔内水の比抵抗変化の影響を受けにくく、揚水時の帯水層中の塩淡境界変動を把握することができ、適切な地下水利用に資することができる地下水塩淡境界変動の検知方法を提供すること。【解決手段】本発明の地下水塩淡境界変動の検知方法は、４本の電極１０を用いた電気探査の時系列測定を行うことで、塩水地下水帯水層Ｂと淡水地下水帯水層Ｆの境界である塩淡境界Ａの変動を検知する地下水塩淡境界変動の検知方法であって、2本の送信電極１１、１２を地表に配置し、２本の受信電極１３、１４を地下水面Ｓより下方で、塩淡境界Ａを挟むように配置し、送信電極１１、１２によって地盤に電流を流し、受信電極１３、１４で電位差を測定し、送信電極から流す電流値と受信電極で測定される電位差から求められる地盤の比抵抗変化を、塩淡境界Ａの変動として検知することを特徴とする。【選択図】図１