Japan Geoscience Union Meeting 2016

Presentation information


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

[A-HW19] Water Environment and Geology in Urban Areas

Wed. May 25, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Takeshi Hayashi(Faculty of Education and Human Studies, Akita University), Hiroaki SUZUKI(Strategic Technology Development Dept. Research & Development Center, Nippon Koei Co., Ltd.), Kei Nishida(Interdisciplinary Centre for River Basin Environment, Interdisciplinary Graduate School, University of Yamanashi), Motoyuki Asada(Shimizu Corporation), Satoshi Takizawa(Department of Urban Engineering, Graduate School of Engineering, the University of Tokyo), Masaya Yasuhara(Rissho Univ.)

5:15 PM - 6:30 PM

[AHW19-P02] Evaluation of subsurface warming in the Tokyo metropolitan area, Japan

*Akinobu Miyakoshi1, Takeshi Hayashi2, Masafumi Kawai3, Shinichi Kawashima3, Kuniki Kokubun3, Hideki Hamamoto4, Shoichi Hachinohe4 (1.Geological Survey of Japan, AIST, 2.Faculty of Education and Human Studies, Akita University, 3.Civil Engineering Center, Tokyo Metropolitan Government, 4.Research Institute, Center for Environmental Science in Saitama)

Keywords:subsurface temperature, groundwater flow, subsurface warming, groundwater environment, urbanization, Tokyo metropolitan area

Three-dimensional subsurface temperature distribution and its long-term change were examined by repeated observations of temperature-depth profiles at monitoring wells from 2000 to 2015 and groundwater temperature monitoring from 2007 or 2012, to evaluate effects of regional groundwater flow and environmental changes due to urbanization on subsurface thermal environment in the Tokyo metropolitan area, Japan.
Subsurface warming has been found at shallow depths in the whole study area by our previous study (Miyakoshi et al., 2010). Especially, subsurface temperature beneath the city center was particularly high not only at shallow part but also deep part. In contrast, relatively low temperatures were found beneath the suburban area. Comparison result between past subsurface temperature data (2003 to 2005) and present subsurface temperature data (2013 to 2015) shows that subsurface warming is found at the shallow part in the last 9 to 10 years. Subsurface temperature increase in the city center is larger than the suburban area, and the temperature difference between both areas shows an increasing tendency. Additionally, subsurface warming in the present data was recognized deeper than the past data. This result suggests that distribution of subsurface warming is expanding toward the deeper part.
Moreover, results of subsurface temperature monitoring showed difference of subsurface warming tendency by area and depths. The difference suggests that subsurface warming was affected by not only surface warming but also many factors such as geological condition, groundwater flow and waste heat from subsurface structure. Results of this study suggest that mechanism of subsurface warming is able to be evaluated by combined analysis of geological condition, groundwater flow and subsurface temperature changes. This study was supported by JSPS KAKENHI Grant Number 25871190. This study was conducted as a part of Civil Engineering Center, T.M.G.- Akita Univ. - AIST Joint Research and Saitama Pref. – Akita Univ.– AIST Joint Research.