Japan Geoscience Union Meeting 2015

Presentation information


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

[A-HW27] Water and material transport and cycle in watersheds: from headwater to coastal area

Sun. May 24, 2015 2:15 PM - 4:00 PM 301B (3F)

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

3:30 PM - 3:45 PM

[AHW27-20] Active and Partial River-Groundwater Interaction and the Influence of Nutrient Cycle in the Asahi River Floodplain

*Yutaka MARUYAMA1, Shin-ichi ONODERA1, Mitsuyo SAITO2, Koichi KITAOKA3 (1.Graduate School of Integrated Arts and Sciences, Hiroshima University, 2.Graduate School of Environmental and Life Science, Okayama University, 3.Okayama University of Scienece)

Estimation of the groundwater flux and the groundwater residence time in a local actively River-Groundwater interaction field is difficult, although it is important to understand river and groundwater quarity. In this study, to make a model of estimation of groundwater flux using temperature variation and validation of groundwater flux, to classify the River-Groundwater interaction fields using some tracers, and to estimate a nutrient mass flow. In the floodplain in the downstream area of the Asahi River watershed in Okayama prefecture, the analyzed result of the river and groundwater temeperature in 2010-2012 estimated to groundwater flux as 2.9-6.5 m/d. Simulated horizontal temperature distribution showed that there is a limit to estimate groundwater flux. Delta 18-oxygen variations and chloride concentration variations gave support to the groundwater flux estimated by the temperature model. Furthermore, these tracers teached how to classify the River-Groundwater interaction fields; Zone A-C in the waterside land; Zone D in the others. In Zone A-C, groundwater discharge is 8.2% of the river discharge, though 10% of the river nitrate nitrogen mass flow and 5.9% of the river phosphate phosphorus mass flow. It might be influence for river habitats.