Analysis of the subsurface urban heat island in Oberhausen, Germany

Soil temperature (tB) was determined down to 2 m below ground level at 8 locations in the city of Oberhausen, Ruhr area, Germany, between August 2010 and July 2011 to investigate the subsurface urban heat island (SUHI) and its impact on drinking water quality. The soil temperatures obtained in Oberhausen demonstrate typical location-dependent behaviour. At the depth of drinking water pipes (1 to 2 m subsurface), the daily average soil temperature ranges from 3°C in the winter (at the coldest location) to 24°C in the summer (at the warmest location). A maximum SUHI (70 cm below ground level) of almost 9 K on hourly average was found between the city centre station and the open country station. Soil temperatures were measured to be >20°C at the drinking water pipeline level in the city centre over the course of 89 d, which could have an impact on drinking water quality.