Assessment of Hydrogeological and Hydrochemical Conditions in Kazanlak Basin (Bulgaria)

Abstract

Kazanlak geothermal basin is located in Central Bulgaria. It is an intermountain depression covering an area of about 780 km2. Tectonically it represents a graben formed by bordering faults from the surrounding mountain ridges (Balkan mountain to the north and Sredna gora to the south). The basin has an extensional tectonic setting and is characterized by active subsidence and uplift of the surrounding mountain chains.
The four geothermal fields in Kazanlak basin, located along the Tundza River from west to east, are as follows: Pavel banya, Ovoshtnik, Yagoda and Korten. All of them are associated with intrusive Paleozoic granites. Geothermal water is accumulated in the granite rocks, which are covered by Pliocene-Quaternary sediments of different thickness in each area. Water temperature is varying in the range of 33 to 78oC and the total flow rate amounts to about 88,2 l/s.
The current assessment of hydrogeological and hydrochemical conditions of the region is based on information acquired from various explorations (geological, hydrogeological and hydrochemical) provided by many sources. Zones of different chemical characteristics are formed in the region. Thermal waters are currently used mainly for balneotherapy and relaxation. Special attention is paid to further possibilities of thermal water utilization in the region.