Effective thermal diffusivities of the ground to a depth of 10 m in a field was investigated by periodic heating method using solar energy as heat source from 2015 to 2018. Measurement point was within College of Engineering, Nihon University located in Koriyama city, Fukushima prefecture. The effective thermal diffusivities in depth from 1 to 6 m was from 0.42 to 1.07 mm2/s and average value was 0.67 mm2/s, in depth from 7 to 10 m was from 0.58 to 2.72 mm2/s and average value was 1.49 mm2/s. The ground temperature distribution at the measurement point was obtained by a Computational Fluid Dynamics analysis tool, and thermophysical property value was used the value obtained by experiment. The relative errors between the calculated value and the experimental value were from −0.20 to 0.39.
