After World War il (In1950's), there were about 230 collieries in Chikuho, but they were diminished by fuel revolution in 1960 's. And, in 1976, no coal mine were worked in Chikuho coal field. As the results of decreasing number of coal mine worked, groundwater level in coal mine began to rise to surface gradually. At last, gorundwater of coal mine flowed out on low ground area along river side or on foot of hills and mountains and made many springs or humid area. Furuto-sui is groundwater

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... fills Furuto (goaf) or flows through Furuto. Water table elevation of Furuto-sui is coincident with topography and rises up in rainy season and lowers down in dry season. Furuto-sui has many kinds of chemical contents. In this paper, the author discribes three typical types are such as 1 .pH3-5, Ca-SO4 type and, lower than 1000n -cm in resistivity, 2.pH7, Na-SO4 type and, lower than 1000 n -cm in resistivity, 3 .pH8-9, Na-HCO3, SO4 type and, lower than 1000n-cm in resistivity.