Book excerpt: The thermal use of the shallow subsurface is increasingly being promoted and implemented as one of many promising measures for saving energy. A series of questions arises concerning the design and management of underground and groundwater heat extraction systems, such as the sharing of the thermal resource and the assessment of its long-term potential. For the proper design of thermal systems it is necessary to assess their impact on underground and groundwater temperatures. Thermal Use of Shallow Groundwater introduces the theoretical fundamentals of heat transport in groundwater systems, and discusses the essential thermal properties. It presents a complete overview of analytical and numerical subsurface heat transport modeling, providing a series of mathematical tools and simulation models based on analytical and numerical solutions of the heat transport equation. It is illustrated with case studies from Austria, Germany, and Switzerland of urban thermal energy use, and heat storage and cooling. This book gives a complete set of analytical solutions together with MATLAB® computer codes ready for immediate application or design. It offers a comprehensive overview of the state of the art of analytical and numerical subsurface heat transport modeling for students in civil or environmental engineering, engineering geology, and hydrogeology, and also serves as a reference for industry professionals.