Identification of the sava river temperature influence on the groundwater temperature of the zagreb and samobor-zaprešić aquifers as a part of shallow geothermal potential

Abstract

Based on the statistical analysis of the time series of data, the influence of the change of the Sava River temperature on the changes of the groundwater temperature of the Zagreb and Samobor-Zaprešić aquifers is described. In the analysis, data was used from daily measurements of the Sava River temperature and from the quarterly measurements of the groundwater temperature. Statistical methods of correlation and linear regression were applied and the maximum, mean and minimum groundwater temperatures were analysed. The obtained results are presented in the form of statistical parameters, diagrams and maps of isotherms. This data is indispensable for the development of shallow geothermal applications related to open loop groundwater heat pump systems. Since the efficiency of a heat pump is directly dependent on the source temperature, the presented analyses are necessary for a prefeasibility study of geothermal projects and a comparison between different designs. Furthermore, currently operating projects in the Zagreb and Samobor-Zaprešić area are systematically elaborated, giving a first approximation of energy consumption from this renewable energy resource.