Japan Geoscience Union Meeting 2016

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW16] Water and material transport and cycles in catchment ecosystems: from headwater to coastal area

Thu. May 26, 2016 3:30 PM - 4:45 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Seiko Yoshikawa(Narional Institute for Agro-Environmental Sciences), Masahiro Kobayashi(Forestry and Forest Products Research Institute), Noboru Okuda(Research Institute for Humanity and Nature), Shin-ichi Onodera(Graduate School of Integrated and Arts Sciences, Hiroshima University), Kazuhisa Chikita(Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University), Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Shinji Nakaya(Department of Water Environment and Civil Engineering, Faculty of Engineering, Shinshu University), Mitsuyo Saito(Graduate School of Environmental and Life Science, Okayama University)

3:30 PM - 4:45 PM

[AHW16-P20] Heat budget of hydrothermal ponds and its relation to geothermal flux in a neighboring deep lake: Kuttara Volcano, Hokkaido, Japan

*Kazuhisa Chikita1, Taiki Shibata2 (1.Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, 2.Department of Earth and Planetary Sciences, School of Science, Hokkaido University)

Keywords:hydrothermal flow system, geothermal heat flux, volcanic activity

In order to know the geothermal activity of Kuttara Volcano, Hokkaido, Japan, heat budget of internal hydrothermal ponds is estimated and its geothermal influence on the neighboring deep Lake Kuttara (148 m depth in maximum) is explored. The major hydrothermal area in the geothermal region of Noboribetsu town consists of three hydrothermal ponds, Oh-yunuma (water surface area, 1.61×104 m2), Okunoyu (9.0×102 m2) and Taisho-Jigoku (2.6×102 m2), and a small bubbling pond (4.1 m2), where the bubbling of hot water continuously occurs. Heat budget of Oh-yunuma, Okunoyu and the small bubbling pond in 2013 – 2015 showed mean geothermal flux at 2.8, 22.0 and 32.0 kW m-2, respectively. It was found out that the neighboring Lake Kuttara increases both water temperature, T (℃), and electric conductivity, EC25 (mS/m), at 25 ℃ near the bottom at the deepest point (148 m) in thermally stratified periods of 2013 - 2015. The linear relationship between T and EC25 suggests that geothermal water leaks to the bottom. The geothermal flux at the bottom was calculated at a range of 0.50 - 9.3 W m-2 with mean of 2.9 W m-2. With respect to the interannual geothermal-flux variations, a comparison between Okunoyu and Kuttara indicates that Kuttara responses to the geothermal variation of Okunoyu with a time lag of 5 months on average. Supposing a hydrothermal reservoir at ca. 100 m below the lake bottom, the time lag is explained by the Darcy law between the reservoir and lake bottom.