Fig. 3

Example of well temperature logging data quality. The blue section in the background (0–10 m depth) is affected by seasonal variations in surface temperature, artificial ground modification, and soil cut and fill and is excluded from the evaluation. The section in the beige background (10–30 m depth) is excluded from the evaluation because it is mainly affected by the temperature increase over the past 100 years. Sections that may be affected by groundwater are shown with a sky-blue background. Class-A data are considered high data quality, while Class-D data are considered unsuitable for heat flow analysis