Acknowledgements:
This study is funded by the BNSF research projects “Development of an experimental model of integrated monitoring for sustainable development and management of protected karst areas” (ProKARSTerra), contract № DO 02.260 / 18.12.2008 and “Current impacts of global changes in evolution of karst (based on the integrated monitoring of model karst geosystems in Bulgaria) ”(ProKARSTerra-GlobalChange)“, contract № DN 14/10 of 20.12.2017. The organization and implementation of monitoring in Saeva Dupka became possible thanks to a series of projects on bilateral academic cooperation between BAS (NIGGG) and the Academy of Sciences of the Czech Republic: “Application of Radio-Nuclear investigations and Radio-Nuclear dating in surveying anthropogenic impacts at vulnarable geosystems ”(2008-2010),“ Radionuclide methods in experimental design of an integrated monitoring of karst geosystems ”(2011-2013) and“ Application of radiocarbon dating in the research of karst systems ”(2014-2016), implemented jointly with the Department of Radiation Dosimetry of the Nuclear Physics Institute, and “Tectonic activity of the significant karst systems (development correlation of the Central Europe and Mediterranean area)” (2014-2016) and “Plate-wide tectonic pressure pulses (correlation of the extensometric monitoring in Mediterranean) and Central Europe) ”(2017-2019) in collaboration with the Institute of Rock Structure and Mechanics.
For our long-term assistance in conducting the monitoring, we express our heartfelt gratitude to the guides in the Saeva Dupka cave, and in particular to Georgi Georgiev, who is personally committed to maintaining some of the observations. We also thank Georgi Manev from NIGGG-BAS for the assistance in carrying out part of the field work.