The effect of urban heat island on groundwater located in shallow aquifers of Kütahya city center and shallow geothermal energy potential of the region, Turkey

Abstract

As a result of urbanization, natural surfaces are replaced by artificial surfaces that trap heatsuch as buildings, pavements and asphalt, so residential areas have higher temperature values than rural areas. This effect, defined as the urban heat island, causes an increase not only in air temperature but also in the subsurface and groundwater. Groundwater temperature values were measured during one year in an area approximately 53 km2 consisting of different types of settlement areas to determine the urban heat island effect on the subsurface of Kütahya. As a result of the measurements, urban heat island maps were prepared. It was observed that the groundwater temperature anomalies increased towards the urban/industrial areas. The difference of groundwater temperature in urban / rural areas reached up to 7°C by well. This heat energy increasing with the effect of urban heat island can be used in the heating processes of buildings by utilizing systems called “shallow geothermal energy”. For this reason, the heat potential of the alluvial aquifer under Kütahya was calculated. The theoretical heat potential values of the this aquifer range between 1.64 × 1013 kJ K-1 and 5.55 × 1013 kJ K-1 with a mean value of 3.50 × 1013 kJ K-1. It is thought that urban heat island maps and the heat potential calculations of the aquifers may be important parameters for applicability of shallow geothermal systems in the city center of Kütahya.

Keywords

• urban heat island
• shallow geothermal energy
• renewable energy
• groundwater
• heat capacity