2018 Volume 60 Issue 4 Pages 495-510
Repeated measurements of subsurface temperature-depth profiles have been conducted eight times between May 2000 and December 2015 at the Kawaguchi groundwater observation wells in southeastern Saitama Prefecture, Japan to evaluate distribution and causes of subsurface warming in an urban area. Additionally, monitoring has been conducted since April 2007 to observe long-term changes in subsurface temperature. Subsurface warming was observed at depths shallower than 40m. Subsurface warming decreased with depth, and at depths of 20m, 30m and 40m had rates of 3.4×10-2 oC/year, 2.30×10-2 oC/year and 1.93×10-2 oC/year, respectively. Results of comparison between calculated temperatures and observed temperatures indicate that surface warming estimated by secular changes in air temperature, starting in 1983, has led to subsurface warming that has been observed after 2003.
