Occurrence and Quality of Groundwater in the Tunnels of the Rokko Mountain Area, Kinki District, Japan

Abstract

Since 1960, several tunnels were excavated through the Rokko mountain area which is chiefly composed of granitic rocks. The routes of these tunnels are shown in Fig. 1.
The geology and the occurrence of groundwater along each tunnels are shown in Fig. 2-5. So close relations were observed between the fault zones and the fountain of groundwaters, that the groundwater of this area is defined as fissurewater along the fault zone.
The results of chemical analyses of the groundwaters and the surfacewaters in this area are shown in Table 1.2., and water qualities are also summarized in Fig. 6-9. Judging from these results, it is clear that the groundwater is chracterized by heigher alkalinity, heigher pH and being rich in F content than the surfacewater. But, on the other hand, the former is lower in hardness.
No special abnormality of the water quality is recognized in the annual variation diagram (Fig. 10) which were measured at the Rokko tunnel from Apri1, 1967 to Februay, 1970.