Cities represent thermal load areas compared with their surrounding environments. Due to climate change, summer heat events will increase. Therefore, mitigation and adaptation are needed. In this study, meteorological measurements in various local climate zones were performed to demonstrate the influence of evaporation surfaces and other factors on thermal comfort, as determined by the physiologically equivalent temperature (PET). Furthermore, a quantification of the thermal effects of several adaptation measures and varying meteorological parameters was made using model simulations (ENVI-met) in an inner-city neighborhood (Oberhausen, Germany). The results show that the most effective adaptation measure was increased wind speed (maximal 15 K PET reduction). Moreover, vegetation areas show greater PET reductions by the combination of shading and evapotranspiration than water surfaces. The creation of park areas with sufficient water supply and tall, isolated, shade-providing trees that allow for adequate ventilation can be recommended for planning.

Soil temperature (t B ) 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.

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