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Unit area discharge of groundwater, Z(m^3/day/km^2) can be expressed by the following equation, Z=n/AQ^^- where Q^^- is the average discharge (l/sec) of well or spring, A is the area (km^2) of the surrounding terrain having the same hydro-geologic condition at the well site. N/A is called the coefficient of well distribution or of spring distribution. This paper deals with the calculation of Z values for Tokai and Chugoku-Shikoku districts with the amount of free groundwater and with that of artesian groundwater. The Z values of artesian groundwater in those districts were plotted on the inter-section chart, Z-Q^^--n/A diagram, with reference to several well-known land subsidence area. On the diagram, the regression equation based on the method of least squares for 10 sites in the spring area is as follows : log Z=0.772 log Q^^-+2.357 and that for 4 sites in the land subsidence area is log Z=0.890 log Q^^-+2.617 The value of n/A in the land subsidence area was high as 2.5〜4. This result suggests that the land subsidence might be due to the overdraft of artesian groundwater rather than that of free groundwater.
Journal of the Japan Society of Engineering Geology 19(1), 1-11, 1978 [Table of Contents]
Japan Society of Engineering Geology