Thermal groundwater utilization of the unconsolidated aquifer in the Rhine Valley of St.Gallen

In the Rhine Valley of St.Gallen a large number of thermal uses of the unconsolidated aquifer for heat and cold exist. In the authorization procedure, up to now the influence of these facilities has been solely considered individually.

The Office for Water and Energy (AWE) of the Canton of St.Gallen has now aimed at considering the thermal uses in the Rhine Valley of St.Gallen integrally. currently forces an integral validation of the thermal uses in the Rhine Valley of St. Gallen. Important questions are:

• the impact of currently approved installations and further human interventions on the groundwater temperature
• the existing thermal potential under consideration of the Swiss water protection legislation.

A hydrothermal groundwater model was used to answer these questions. The use of a model allows the integral consideration of all possible variables that affect the groundwater balance both hydraulically and thermally. In addition, a groundwater model can be used in the future to simulate various scenarios at low cost.

The results of the study form a powerful tool to serve the AWE St.Gallen as a basis for decision-making processes for the future licensing practice for thermal groundwater usage. This should prevent overuse of the aquifer and protect the aquatic ecosystem and groundwater in the long term. In addition, the results of the study should assist the communities of St.Gallen for energy planning in the area of heat supply (heat supply concepts) concerning the intended implementation of the energy and climate policy.