This paper is a study on effects of urbanization on gronndwater runoff of small rivers in Tama Hilly Land. In winter, the authors observed groundwater discharge of small rivers in Tama Hilly Land.
The basins of five rivers are natural and those of four rivers are urbanized From results of the observation, it was made clear that groundwater discharges of urbanized rivers were less than those of natural rivers, and volume of groundwater discharge of urbanized rivers depended on hydro--geological structure.

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In hydrological cycle investigations in large area which has severe' river basins, first of all we must define a general boundary condition considering ground water flow inter basins, before the application of detailed numerical models such as for ground water resource management.
Thus, in this paper, we take up as an applied problem of water balance method in the western piedmont of Aso volcano, because in such volcanic basin lava flows may be found as widely spread plains over some river basins and the lava beds include highly developed fractures and are highly permeable along the fractures, so ground water artery tend to spread widely beyond the divide.
Then in this study, we can estimate E (τ) with water balance equation ( 1 ) in a closed basin. Because P(τ) (precipitation), O(τ) (depth of run-off) are known quantities obtained by observation and ds (change of basin storage) can be neglected to first approximation by taking to an annual period of hydrological balance. Standard value of an annual loss E(τ) is equal to an annual evapo-transpiration in basin, so we assume first a standard value of an annual evapo-transpiration, next we estimate E(τ) each basin and compare estimated E(τ) with a standard value. The difference of the two represents unknown ground water flow rates inter basin. we investigated the actual circumstances to be based on the results. In this way a result which supports the assumption was obtained, that is, the following became clear, in the case of annual evapo-transpiration in basins = (700mm), ground water flows into the Kase River basin from the Shira River basin, the Gohshi River basin, the Midori River basin, their respective rates of ground water movement are 1.8×10⁸m³/year, 0.6×10⁸m³/year, 0.7×10⁸m³/year. On the other hand from the Gohshi River basin ground water flows out to other basins rate of 1.2×10⁸m³/year.

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This paper is concerned with the changes of vertical water movement procsses in unsaturated sand under nonponding condition during and after a steady rain. In order to reveal the mechanism of vertical water movement, experiments were carried out by, using a large rainfall simulator, which can generate artificial rains with various intensities and durations, and two iron boxes filled with fine and coarse sands, repectively.
Water contents were measured by using a neutron scattering moisture meter, and capillary potentials were obtained simultaneously from eight porous cups buried vertically at different drpths, each one being connected to a tensiometer.
The mechanism of vertical water movement was studied by analyzing the changes of water content and capillary potential at selected depths. This analysis showed that the processes of vertical water movement (infiltration, percolation, redistribution, drainage) can be determined individually with water gradient and total potential gradient, that vertical water movemnt is affected by the presence of entrapped air near the ground surface during a heavy rain, that the early outflow begins as a result of the propagation of the air and water prssures in the suspended water and the upward transition zones before the wetting front reaches an upward infiltration zone, and that water and total potential profiles of water gradient G-≈ 0 and total potential gradient G° ≈ 1 (coarse sand) andC° ≈ 0.75 (fine sand) move paralle to each initial profile with time during drainage, respectively.

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