The Southern foot area of Mt. Fuji, including its lower flank and the coastal plain to the south in Shizuoka Prefecture, is a suitable field to study the relationship between hydrogeology and chemical characters of ground water.
Aquifers in the area are distributed in the volcanic strata from the volcanoes [Ko(Old)-Fuji, Fuji, and Ashitaka] and in the alluvial deposits. These aquifers are under a mineralogically uniform condition. Analytical data of natural ground water and leaching experiments on the rocks indicate that the ground water can be grouped by the water temperature, ratio of chemical constituents, bicarbonate (HCO₃-) content, total dissolved solids, and others. The g -ound water borne at the depth of 150-250 m in coastal area has a matked discontinuity of HCO₃- concentration, which is related with the geology.
Chemical constituents in water of the volcanic layers seem to originate from processes of weathering of volcanic rocks. The constituents in water can be explained as a results of weathering reactions.