DOI: 10.3897/jbgs.e149029

Authors: Nikolai Dobrev, Plamen Ivanov, Konstantin Kostov, Emil Oynakov, Nina Nikolova, Boyko Berov, Orlin Dimitrov, Elena Koleva-Rekalova, Miroslav Krastanov, Rosen Nankin

Abstract: This article aims to present the results of an 11-year monitoring of micro-tectonic movements along dangerous cracks opening in caves at Cape Kaliakra, Northeast Bulgaria. Two 3D monitoring devices TM71, were installed in two caves, the purpose of which is to monitor the movements of the rock blocks along dangerous cracks. The obtained results of microdisplacement measurements from 2013 to 2023 show active movement along the observed cracks. This is expressed not only in linear trends but also in sudden shifts and short-term shifts followed by recovery (oscillations). The comparison with the local and regional seismicity shows a correlation between the abrupt movements and seismic events along the Batovo fault. Data from the automatic weather station in the town of Kavarna point to a possible link between some oscillation type movements and heavy rainfall in the research area. The results of the analyzes show the importance of long-term monitoring in clarifying the recent geodynamics in the research area. The results obtained provide valuable information about the dynamics of this region, and hence about the geomorphological evolution and the physical-geological hazardous phenomena. The registered movements show the connection between gravitational movements and tectonic ones. For the first time, data obtained through instrumental observations are published, proving the activity of fault structures in this part of Bulgaria. The results can also be used to predict dangerous slope destabilizations, as well as to reduce the risk of their occurrence.

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DOI: 10.3897/jbgs.e117725

Authors: Vanya Vasileva, Sevdzhan Sabrieva, Dora Kabakchieva, Maksimiliana Emilova

Abstract: Protected territories have great potential for nature-based forms of tourism. These specific forms of tourism have also been considered as a tool for developing sustainable forms of tourism. Therefore, they have been a subject of scientific research in recent years. The purpose of this study is to evaluate the tourist functions of the Shumen Plateau Nature Park in North-East Bulgaria. It is among the small natural parks in terms of area, but it is a valuable natural site among the vast, highly anthropogenically modified territory of the eastern part of the Danube plain. By using the survey method, the study determines the overall recognition of the area and analyzes the visitor‘s opinions regarding the tourist use of the park territory. According to the results of this study the Shumen Plateau Nature Park has potential for protection and management of natural processes and, in parallel, an opportunity for the development of sustainable tourism and the implementation of ecological-educational and tourist programs. Visitors are well aware of the possibilities for tourism and sports, while they do not take advantage of all possibilities, but only the ones that are a priority for them. 100% of respondents answer positively when asked “Would you visit the Shumen Plateau again?”. Further research could combine more innovative and mixed methodologies to broaden the research interest.

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DOI: 10.3897/jbgs.e120301

Authors: Emil Gachev, Erald Meshini, Simeon Matev, Martin Iliev, Georgi Gachev, Maria Gacheva

Abstract: Several perennial snow and ice bodies have been recently studied and monitored in three mountain massifs across the Balkan Peninsula: Prokletije (Northern Albania), Durmitor (Montenegro) and Pirin (Bulgaria), the two glacierets in the Pirin Mountains until soon considered as southernmost of their kind in Europe. In September 2022 a relatively large snow field (about 1.5 ha) was discovered and described for a first time in the glacial cirque Gryka e Kazanit in the Nëmerçka Mountains of Southern Albania. The snow accumulation lies on 1550–1650 m a.s.l. below a vertical limestone cliff with a height of almost 1000 m. The site was visited again in November 2023, when the snow field diminished its size to less than 1 ha. At the same time, multi-annual firn layers were exposed under the last year snow, with depth at least several metres, and indications were observed of ice, buried in the debris cover below. Newest findings indicate that the studied snow-firn body is a glacieret similar to those found in the Pirin Mountains. On a longer-term, nine perennial snow/firm bodies on the Balkans resemble small glaciers rather than snow and ice patches at least under current climatic conditions. Situated on 40°08′ Northern latitude, the newly discovered Nemërçka Glacieret is nominated to be the southernmost glacier in Europe.

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DOI: 10.3897/jbgs.e114034

Authors: Tsvetan Parov

Abstract: This study focuses on the meteorological parameters of the near atmosphere, the surface of the Earth and karst areas, such as temperature of water and air, relative humidity, and wind speed. These parameters are significantly influenced by solar activity, which in turn affects the temperature distribution in karst underground cavities, specifically in the “Kolkina Dupka” cave located within the Ponor Mountain of the Western Balkan Mountains range in Bulgaria. This is the deepest and longest cave in Bulgaria with a length of more than 20 km and a calculated depth of 800 m. Meteorological data within the cave was collected using data loggers, while surface weather data was sourced from National Institute of Meteorology and Hydrology of Bulgaria. Solar activity information was obtained from the website of the Royal Observatory of Belgium. The impact of solar activity on karst regions is substantial and affects temperature, precipitation, and atmospheric circulation. Changes in solar radiation can alter heat absorption on the surface of the Earth, leading to shifts in temperature and precipitation patterns. We performed statistical analysis and modeling to understand the complex interactions between Earth's near atmosphere, the karst system of the Kolkina Dupka cave, and the role of air and water flows in regulating cave temperatures. Results showed a significant negative correlation between air temperatures in the deep underground airflows (at a depth of 130 m below the surface) and temperatures at the cave entrance (at a depth of 40 m during the winter months. Conversely, during spring and summer, an intriguing reversal occurs where higher external temperatures are linked to increased air temperatures at the cave entrance, accompanied by lower temperatures in the deeper zone. Furthermore, by employing “lagged correlations” in result analysis, investigating correlations between internal temperatures and external temperatures over the preceding and subsequent seven days, cyclic variations in heat exchange between the near-surface atmospheric layer and the underground temperatures within the karst system were observed. Specifically, a consistent temperature elevation was noted at the cave entrance three days prior to an increase in external temperatures during the spring-summer season. This temporal relationship was also observed in the solar activity data, where an increase in temperature at a depth of -40 m was registered three days prior to the escalation of solar activity within the measured range of 2800 MHz. The obtained results formed the basis for the development of new theories in solar-terrestrial physics. In summary, there is a connection between solar activity and Earth's climate, but it is not a direct and simple correlation, and it is just one piece of the larger puzzle that shapes temperature variations of the Earth. Climate science involves studying these interactions over extended periods to gain a more comprehensive understanding of the climate system of the Earth.

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DOI: 10.3897/jbgs.e101301

Authors: Petar Stefanov, Hristina Prodanova, Dilyana Stefanova, Vanya Stoycheva, Gergana Petkova

Abstract: Karst is a widely spread natural phenomenon which provides essential benefits to human society, such as drinking water. The water cycle in the karst geosystems is the main factor for their formation and at the same time one of the main drivers for ecosystem services (ES) provision. The monitoring of the water cycle can provide valuable information regarding its functioning and ensure data for ES assessment. This paper aims to present an overview of the monitoring of the water cycle in the karst geosystems and the opportunities to integrate the monitoring data into the water regulation ES assessment. The monitoring of the water cycle is based on the methodological framework ProKARSTerra. It is applied in model karst geosystems, which are representative of the main karst types in Bulgaria. One of them is the Brestnitsa karst geosystem, which is the case study of this work. The monitoring ensures data for analyses of the water cycle which can be used in the assessment of water-related ecosystem services. The results from the analyses of the data requirements and availability show that some services such as water flow regulation and regulation of chemical condition of freshwaters can be easily provided through data for quantification, while for others further studies are needed. The results of the long-term integrated monitoring in Brestnitsa karst geosystem provide the foundation for important conclusions and models for the karst genesis and function under global changes and active anthropogenic pressure. Their integration into the assessment framework and mapping of ecosystem services is an essential step towards the development of models for sustainable use of natural resources in the karst areas.

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DOI: 10.3897/jbgs.2020.42.17

Authors: Hristina Prodanova, Mariya Petrova

Abstract: The paper is devoted to Assoc. Prof. PhD Nikola Todorov’s life and professional contributions (1955- 2018) – a prominent Bulgarian geographer, unreservedly dedicated to the science and field researches, who left а rich creative heritage in the field of Physical Geography and Landscape Science. He was the leading author in the development of the second landscape classification system of Bulgaria and in the creation of а landscape map of Bulgaria on a 1:500 000 scale, which is one of his main contributions. An important contribution in his research activity is the developed classification system of anthropogenic changes and landscape disturbances in Bulgaria, which is applicable to the whole country and encompassing the enormous variety of natural-territorial complexes and their changes. He was a scientific mentor for 26 master students and 4 PhD students. Assoc. Prof. Nikola Todorov was a Lecturer who inspired generations of students and many young researchers with his erudition and oratory skills.

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DOI: 10.3897/jbgs.2020.42.12

Authors: Svetla Stankova, Tzanko Tzankov, Raina Hristova, Milena Stoyanova, Milen Penerliev

Abstract: The article is dedicate to the life and the creation of one notable Bulgrian investigator, scientist and pedagogue – Prof. Todor Ivanov Krastev DSc (Geography). The principal features of his personality are the big creative energy, impressive capacity for work and restless research spirit. It worldly and creative way is a splendid example for a dedicated work for the science. The results of Prof. Krastev investigations belong to the most Bulgarian Natural Geography achievements for the second part of the twenty century.

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DOI: 10.3897/jbgs.2020.42.6

Authors: Valentin Nikolov

Abstract: The article is dedicated to the creative path and the scientific heritage of Vladimir Popov – one of the remarkable scientists for the Bulgarian geography of the last century. The experience during the professional development from a research precision and focused interest in geomorphology, karstology and physical geography. In this respect, original are the researches on the contemporary relief genesis and evolution, karst region and caves in Bulgaria. The karst in Bulgaria occupies an area of 26 170 km2 or 22.7 % of the territory of the country (Popov 1970). It is distributed in carbonate bodies with a different structure, dynamics and spatial relationships. New zoning of karst is being carried out for the Bulgarian territory. It is divided into: plain; marine and transformed marine karst into plain and plain-marine karst; plateau-like karst; mountain and intermountain karst; karst wetlands and gravitation karst, provoked by catastrophic earthquakes. Karst in Bulgaria is characterized by great diversity due to the complex combination of the factors and conditions of its formation (geological, tectonic, geomorphologic, hydrological and hydrogeological, climatic, etc.) and to the geodynamic development. Regardless of the fact that karst is well studied, there are still fundamental problems in karstology that have not been solved as a whole. In 1970 and 1976yy Popov made the first zoning of surface and underground karst in Bulgaria according to the geological base.

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DOI: 10.3897/jbgs.2020.42.5

Authors: Velimira Stoyanova, Gergana Metodieva

Abstract: The paper is dedicated to the life and scientific activity of prof. Zheko Radev, in commemoration of the 145th anniversary of his birth. The paper focuses on his background and family, his education and professional career. An overview of his renowned and significant scientific publications has been made. Prof. Zheko Radev is the first Bulgarian scientist in the field of physical geography and one of the most distinguished Bulgarian geographers of the XX century. For the generations to come, Zheko Radev left 29 scientific works, some of them topical even a hundred years after they were published. He worked as a university professor for 25 years, during which he laid the foundations of physio geographical disciplines in Bulgaria. His scientific and pedagogical work is worthy of respect and admiration, and should serve as a bright example today and in the future.

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DOI: 10.3897/jbgs.2019.41.2

Authors: Stoyan Kyurkchiev

Abstract: Chelevchinitsa Cave is formed in the southwestern part of the Dobrostan karst region, Western Rhodopes. It has been subjected to microclimatic monitoring since April 2016. Air temperature, cave water and sediments are periodically measured at eight points, and thus the air humidity is determined. A micro-climatic zoning of the cave was being done on the basis of the analysis of the data on the temperature regimes for the period 2016–2018. A link has been sought between cave microclimate and global climate change using available data for the period 1979–2017 . The issue of the influence of the anthropogenic load on the speleomicroclimate as well as the impact of the cave enviorment on the health and safety of the tourists is also discussed. Particular attention is paid to the role of cave ventilation on the gas composition of the cave atmosphere, and especially on the regime of carbon dioxide (CO2 ) and radon (222Rn).

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DOI: 10.3897/jbgs.2019.40.4

Authors: Zornitza Cholakova

Abstract: The essence of karst landscapes is considered. The content of Cu, Zn, Pb, Cr, Ni, Co, Mn, Cd trace elements in the soils of karst landscapes in the Ponor, Vrachanska and Vlahina Mountains, as well as those in The Western and Middle Fore-Balkan (Arbanassi Plateau), Bulgaria, is analyzed using landscape-geochemical, laboratory, mathematical and statistical methods. The obtained results are compared with the average content in the carbonate rocks of Bulgaria (Kuikin et al., 2001), the rendzina (Rendzic Leptosols, LPk, FAO) and the gray forest soils (Haplic Luvisols, LVh, FAO) in the country (according to Atanassov et al., 2002). The importance of the carbonate rock substrate on the concentration of the chemical elements - heavy metals in the studied zonal and azonal soil types was determined.

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DOI: 10.3897/jbgs.2018.39.6

Authors: Maria Temelkova

Abstract: Karst waters are widespread in the studied area. In the area of the Misia Platform karst aquifers are formed, and in the zones of the Pre-Balkan and the Western Balkans are numerous karst basins formed. The aim of this work is to evaluate the resource in the area and the possibilities for its use in the water management sector. A map of the karst basins in the area is drawn up and a table with their characteristics is made. For this purpose, cartographic methods have been applied using GIS technology. On the basis of the collected data, recommendations have been made for the more efficient utilization of karst waters in the area.

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