Abstract
In the river basins exposed to volcanic activity, volcanic deposits and water quality change of springs may affect the water environment qualitatively. On June 29, 2015, an eruption occurred in Owakudani at Mt. Hakone, and subsequently, strong turbidity was observed in the Owakusawa River and the Hayakawa River. To clarify the cause of these phenomena, river waters and rainwaters were collected in the Hayakawa River basins include Owakusawa River every one to three months for analysis. As for the Owakusawa River, high electrical conductivity was observed after the eruption and subsequently decreased gradually. The ratio of Cl- concentration in anions in the Owakusawa River was found to be high immediately after the eruption but decreased after one year. The geochemical composition of rainwater was affected by volcanic gas, and it was found that the rainwater at the observation points closer to Owakudani, the main fumarole, contains more dissolved components.
