新庄盆地の地下水観測資料(I) : 浅層地下水の水位・水温変化(1970〜1975)

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The data included in this paper are concerned with the continuous changes of ground water level and ground water temperature in the Shinjo Basin which is situated at the northern part of Yamagata Prefecture in Japan (Fig.1). In the snowy region, the snow melting method by sprinkling ground water is becoming very popular as it is easily executed with low cost. In Shinjo (Fig.2), a large amount of ground water is pumped up for melting snow in winter. So it is necessary to gain trustworthy data to grasp the ground water conditions. As the change of ground water level was not observed continually and regularly before, we selected four observation wells and have continued observation by self-recording gauges from 1970. The position and the structure of each well are shown in Fig.2, Fig.3 and Table 2. All the data of ground water level and water temperature are included in Figs.4〜11 and Table 3. Observation well No.1 (Phot.5) is located at the premises of the Shinjo Branch, National Research Center for Disaster Prevetion (127m M.S.L., 38°47′17″N, 140°18′59″E). This well with a diameter of 2m is 7.5m in depth. Its geologic profile is as follows : about 30cm dark brown humic soil, about 40cm brown loam with pebbles and gravel bed in descending order. The change of water level is about 3m in a year. The lowest water level depends on the meteorological conditions of the year. The annual change of water temperature is as wide as 7〜8℃. Water temperature shows the lowest in April or May and the highest in September or October. Observation well No.2 (Phot.7) is an abandoned one, formerly for domestic use. The annual change of ground water level indicates a tendency toward high in winter and low in summer. As to the annual change of water temperature, the lowest temperature appears in April and the highest in October. The irregular change of water temperature during the winter of 1973-1974 is due to the heavy snowfall because this station has no shelter except a wooden box. Every time the water level is measured and the recording chart is renewed in the snowy season, the snow cover over the well must be removed. Though the removal is carefully made, some snow blocks fell down into the well water and lowered the water temperature. On the other hand, a heavy rainfall caused the abnormal high water level and the abnormal high water temperature (on August 5th, 1974). Observation well No.3 (Phot.9) is located at the Mogami Park and shows little change of water level because it is surrounded by a moat. The water level is also high in winter and low in summer and the water temperature changes in the same way as observation well No.2. Observation well No.4 (Phot.11) is also an abandoned one which used to supply water for an office.
独立行政法人防災科学技術研究所の論文
1979-03-30

新庄盆地の地下水観測資料(I) : 浅層地下水の水位・水温変化(1970〜1975)

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