Characteristics of thermal water flow conditions and an analysis of changes in the main hydrodynamic parameters of the Jelenia Góra geothermal system hosted by the Karkonosze Granite Massif (Sudetes, SW Poland)

Abstract

The Jelenia Góra thermal system is related to deep groundwater flow along numerous fractures and faults, into the granite Karkonosze massif in the Sudetes. The Upper Carboniferous granite of the Karkonosze is an aquifer with main identified dislocations with NW-SE, NE–SW and NNE-SSW trends. Thermal waters occur in three explored deposits of Cieplice, Karpniki and Staniszów. In Cieplice, thermal waters flow out of 6 springs and 2 wells: C-1 and C-2. In Karpniki, waters are captured from KT-1 well, and in Staniszów –ST-1 well. The thermal waters are low-TDS waters of the Na-SO4-HCO3 or the Na-HCO3- SO4 type. They are deep circulation waters, whose flow time is over 10 thousand years, and their recharge area lies at a considerable distance from drainage zones. In contrast to more shallowly circulating cold waters, thermal waters are characterized by higher concentrations of the fluoride ion and metasilicic acid. An analysis of changes in the hydrodynamic parameters was conducted for exploited flowing wells C-1, KT-1 and the Basenowe Męskie spring. Correlations between the studied hydrodynamic parameters in the Cieplice and Karpniki intakes have a very similar character. What is characteristic is a strong, almost immediate and simultaneous response to extreme changes in exploitation conditions caused by deep drilling, hydrogeological surveying or by a change in water abstraction volume.