1. Senior Researcher, Institute of Geography, Romanian Academy, 12 Dimitrie Racoviţă St., sector 2, Bucharest 023993, Romania.
2. Senior Researcher, Institute of Geography, Romanian Academy, 12 Dimitrie Racoviţă St., sector 2, Bucharest 023993, Romania (corresponding author). ORCID: .
3. Senior Researcher, Institute of Geography, Romanian Academy, 12 Dimitrie Racoviţă St., sector 2, Bucharest 023993, Romania. ORCID: .
4. Senior Researcher, National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 3, Sofia 1113, Bulgaria.