Groundwater Balance for Volcanic Island

Research Project

Project/Area Number	61540553
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	地質学一般
Research Institution	Shinshu University
Principal Investigator	KUMAI Hisao Department of Geology, Faculty of Science, 理学部地質学教室, 助教授 (40020680)
Project Period (FY)	1986 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	volcano / Groundwater / Infiltration capacity / Surface runoff / Geological structure / Water balance / 水収支 / モデル / 島 / 循環 / バランス / 帯水層 / 滲透 / 降水
Research Abstract	It can be observe the constant surface runoff water in Mihara Volcano, Hachijo Island, uncommonly in Izu Islands. In this investigation, the groundwater spouting mechanism has been studied by geological survay,and groundwater balance model was estimated. Results of this work are as follow. 1. Mihara Volcano consists of Pleistocene volcanic rocks such as Pre-Mihara Volcanic Rocks, Lower mihara-yama Formation, Middle Mihara-yama Formation and Upper Mihara-yama Formation in ascending order. 2. Because the surface consists of pyroclastic material, almost of precipitation on the slope of Mihara Volcano seeps down into the aquiferes. 3. Geological structure of volcano is not symmetric, Upper Mihara Formation distributes thick on west side of volcano.So that, there are no surface water in this area. 4. The aquifers of this area consist of lavas and pyroclastic materials in Upper Mihaea-yama Formation and Middle Mihara-yama Formation. 5. The groundwater recharge volume has been caluculated as total precipitation - (total evaporate x evapotranspiration rate). 6. It was caluculated that the total volume of runoff from groundwater,and these groundwater runoff rate of this area are different earch other depended on the geological structure.