Drought and Abnormal Rise of the Ground Water Table of the Musasino Upland during the Spring and Summer of 1938

Abstract

The interstices in the lower zone of the loam and gravel beds in the eastern part of the Musasino Upland is filled with ground water, but those in the upper part of gravel bed in the western part are beyond the water table. At the time of the drought in the spring of 1938, the ground water in the gravel beds of the northwestern part of the upland separated into the main body of the ground water, the scanty water resting upon a thin clay stratum between thick gravel beds. There is a true perched water zone which fills the lower part of the loam bed underlying the thin clayey loam bed. Confined wells, which are however not discussed in the present paper, are rarely met with on the upland at present.
Owing to small precipitation in the previous season, the level of the water table of the main ground water table sank during the spring of 1938. Some of water table wells in the northeastern part of the upland dried up for about three months. The writer has drawn contour maps of the three kinds of water tables of of that time (Fig. 2, 3). The water table of the eastern part was from 5 to 10m and that
of the western part was 15 from to 25m below the surface. There are several perched water zones in the latter part, where the water table was only a few meters below the surface even during the drought. They may be called “oasises” in the upland, where there are some rural settlements dating back to older times.
There was heavy rain (over 600mm) between June 28 and July 4, 1938. The water table of the upland rose from 3 to 12m. At several places, the ground water stagnated the surface and destroyed the vegetables cultivated there. The upper part of the main water body, united with the lower part and formed a great thickness of water in wells that were dug in the northwestern part of the upland.