Limits for use of thermal waters in the Benesov-Usti (Bensen-Aussig) aquifer system - Vortrag entfällt

Josef V. Datel1
1 Dpt. of Hydrogeology, Charles Uniersity in Prague, Faculty of Science

O 2.10 in Aquifer systems in Europe and beyond

15.04.2016, 10:00-10:15, Audimax B, Geb. 30.95

The largest thermal water accumulation known so far in the Czech Republic with temperatures 30-40 degrees centigrade can be found in the aquifer system of the Benesov (Bensen) and Usti nad Labem (Aussig) area of the Bohemian Cretaceous Basin. Exploitation of these thermal waters has thus far been concentrated in the Usti nad Labem and Decin (Tetschen) regions. Thermal waters are used now for recreational purposes (swimming pools and spas) or as a source of thermal energy for heating. A crucial impulse for the formulation of the conceptual model of thermal groundwater flow was new exploratory work in approximately the last 15 years, whose intention was to intensify thermal water resources exploitation.

Before deep boreholes have helped discover the thermal water resources, the whole area of thermal waters known now represented a hydrogeological structure with very slowly flowing, almost stagnating groundwater. Exploiting the resources (from the end of the19. century) has made the groundwater flow significantly faster. Limiting factors for the use of thermal waters consist both in the balance of the amount of water in the structure and also the balance of the amount of heat flowing into the structure. The conceptual model was based on all the available information that could be collected. The collected data were evaluated in three basic areas: definition of hydrogeological bodies (aquifers and aquitards), evaluation of regional groundwater flow, interpretation of data on groundwater quality (chemical composition, temperature).

Some of the main conclusions of the research:

-     Based on the flow method the sustainable yields of natural thermal waters in the drainage areas were calculated – 43 L.s-1 in the Usti (Aussig) area and 292 L.s-1 in the Decin (Tetschen) area.

-     Professional closing and liquidation of older boreholes in the drainage areas substantially reduced unregistered losses of hot water, which was favorably reflected in the piezometric conditions in the structure

-     The main drainage sites for the whole structure were defined – in addition to the Usti and Decin areas, the Kamenice (Kamnitz river) area in the north and the Litomerice (Leitmeritz) area in the south are important drainage areas.  

-     6 geological and hydrogeological cross-sections were constructed across the studied area in order to show a three-dimensional view of groundwater flow

-     The warmest water is concentrated in the Decin and Usti areas, and the greatest temperature gradients were also found here, confirming higher heat flow along to the Ohre (Eger) river tectonic structure

 

-     Methodical evaluation of the use of geophysical well-logging methods was performed for evaluating data from new boreholes, for both lithological purposes and for determining hydrogeological data.



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