DOI: 10.3897/jbgs.e168786

Authors: Davis Dinkov, Lyubka Pashova

Abstract: High-resolution Digital Elevation Models (DEMs) are critical for accurate coastal flood risk assessment, particularly in low-lying areas vulnerable to sea-level rise, storm surges, and other natural hazards. This study presents a comparative evaluation of five DEMs with varying spatial resolutions and data sources for a test area along the northeastern Bulgarian Black Sea Coast around the Durankulak Lake—an area identified as at risk of coastal flooding. A high-resolution Uncrewed Aerial Vehicle (UAV) derived DEM was generated using Structure-from-Motion and Multi-View Stereo (SfM-MVS) photogram-metry and compared against three other DEMs: BG DSM (4 m), MGS DEM (10 m), and re-sampled TanDEM-X (10 m). The vertical accuracy of DEMs was assessed using control points (CPs), including GNSS-measured and geodetic reference points, and parametric and non-parametric statistical methods, along with statistical tests to assess the error distribution. Results indicate that the UAV and BG DSM models exhibited normal error distributions with high vertical accuracy (root mean square error: 0.098 m and 0.776 m, respectively), while the MGS and TanDEM-X models display significant deviations from normality and lower precision. The UAV-derived DEM has offered the highest accuracy and reliability, though it requires significant field and processing resources. The findings highlight the importance of selecting DEMs based on the required precision, available resources, and application-specific context, particularly for hydrologic and hydrodynamic modeling and flood risk mapping under the EU Floods Directive. This study provides a robust methodological framework for evaluating DEM quality and suitability in coastal hazard assessments and contributes to improved geospatial data practices in flood-prone regions.

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DOI: 10.3897/jbgs.e185535

Authors: Saleh Eddine Zahli

Abstract: Soil erosion and sediment transport represent major environmental challenges in semi-arid Mediterranean watersheds, where high erosion rates do not necessarily translate into high sediment delivery to river systems. This study assesses sediment regulation ecosystem services in the Nfifikh watershed (Morocco) to clarify how landscape connectivity controls sediment export, retention, and internal buffering processes. A spatially explicit connectivity-based modelling approach was implemented using the InVEST Sediment Delivery Ratio (SDR) model, integrating a 30 m digital elevation model, land use and land cover data (2019), soil properties, and rainfall erosivity factors within a GIS environment. The results reveal a marked decoupling between potential soil erosion and effective sediment transfer. Despite high erosion potential in upstream areas, sediment export remains spatially limited due to reduced connectivity, whereas midstream sectors with moderate erosion exhibit higher sediment delivery efficiency. High SDR values are confined to a limited number of well-connected zones, while large portions of the basin function as sediment sinks. Valley-floor deposition locally exceeds 1100 kg yr-1, under-scoring their buffering capacity. Ecosystem service indicators further show spatial differentiation between avoided soil erosion and avoided sediment export, reflecting the role of land-cover configuration in regulating sediment fluxes. Overall, the findings demonstrate that sediment regulation is primarily governed by landscape connectivity and land-cover structure rather than erosion intensity alone, providing transferable insights for ecosystem-based watershed management in semi-arid Mediterranean environments.

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DOI: 10.3897/jbgs.e177213

Authors: Mariyana Nikolova, Miroslav Ivanov, Xu Shengdi

Abstract: The Shared Socio-economic Pathways (SSPs) presented in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) indicate that increased variability and more frequent extremes in precipitation are expected to raise the risk of droughts and floods in South-Eastern Europe. According to climate projections, the potential increase in precipitation in the region is insignificant, while the rising temperatures and the associated increase in potential evapotranspiration may lead to a substantial intensification of drought severity in the future. This study reviews previous research on droughts in Bulgaria and the analytical methods applied, thereby justifying the selection of the proposed methodological approach based on the Standardized Precipitation Evapotranspiration Index (SPEI-12 and SPEI-48). The SPEI data were obtained from the Global SPEI Database and cover the period from 1950 to 2024. The spatial characteristics of the index for the territory of Bulgaria are represented by grid cells with a spatial resolution of 0.5 degrees. The study examines changes in drought conditions across Bulgaria over the period 1950–2024, using SPEI-48 data. Long-term fluctuations in average SPEI values reveal a pronounced negative trend since 1984. The index reached its lowest value during the period 2000–2003 (−1.6), which is classified as a severe drought. Average SPEI-48 values range between 0.8 and −0.8 across the decades from 1950 to 2024, and have remained predominantly negative over the last five decades. In this context, the study highlights the need to implement measures for climate change adaptation and to address the increasing risk of drought.

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DOI: 10.3897/jbgs.e166425

Authors: Fiorella La Matta Romero, Vanessa Arevalo-Seijas, David Valqui-Peña, Moya MacDonald, Jemma Wadham, Raul Loayza-Muro

Abstract: The retreat of tropical glaciers in the Peruvian Andes, particularly in the Cordillera Blanca, has significantly altered hydrogeological and geochemical processes in mountain water-sheds. This study investigates the influence of glacier change-driven acid rock drainage (ARD) upon benthic macroinvertebrate communities in 19 glacier-fed streams of the Santa River watershed over two consecutive dry and wet seasons (2019–2020). The findings reveal that ARD driven by glacier melt and sulphide oxidation has led to increased metal concentrations (e.g., Fe, Mn, Al, Pb) and pH reductions (of 2–3 in some sites), creating a “toxic or treat” scenario for aquatic biodiversity. Statistical analyses, including principal component analysis (PCA), principal coordinate analysis (PCoA), and canonical correspondence analysis (CCA), indicate significant correlations between physical and chemical changes and macroinvertebrate assemblages. Collector-gatherers (e.g., Chironomidae, Baetidae) were dominant in sites impacted by ARD, while sensitive functional feeding groups, such as scrapers and shredders, declined under high metal stress. Seasonal variations also affected taxonomic richness, with greater abundance observed during the dry season. These results highlight the cascading effects of climate-induced glacier loss on freshwater ecosystems and provide critical insights into the ecological consequences of ongoing environmental changes in high-altitude Andean rivers.

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DOI: 10.3897/jbgs.e169740

Authors: Hrachya Astsatryan, Rita Abrahamyan, Artur Gevorgyan, Hasmik Panyan, Furtado Kalli

Abstract: Droughts cause danger to human health and socioeconomic development worldwide. The traditional station-based analysis of droughts has limitations. The most relevant is the insufficient spatial resolution of the observations, particularly over mountain topography. This study evaluates the performance of two satellite precipitation products—the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) and the Climate Prediction Center Morphing Method (CMORPH)—for monitoring meteorological droughts in mountainous environments, using the Armenian Highlands as a case study. We focused on a drought event in June 2021, which was the hottest and driest month in Armenia in nearly nine decades. The performance of gridded global precipitation products was evaluated against in-situ observations for June 2021. Statistical evaluation using the Pearson correlation coefficient, root mean square error, mean absolute error, mean bias, and standard deviation has been analyzed. Results indicate that both products have challenges in accurately estimating the Standardized Precipitation Index (SPI) under severe drought conditions. However, IMERG’s drought detection aligned more closely with in-situ observations than CMORPH’s, which tended to underestimate drought severity. In addition to precipitation-based indices, Landsat-8 and Sentinel-2 vegetation and moisture indices (NDVI, NDMI, NDWI) were evaluated, yielding complementary data regarding the impact of drought on the environment. We found a correlation between low SPI values and stressed vegetation (low NDVI/NDMI), validating the ecological impact of the meteorological drought. Outcomes discuss the merits and disadvantages of satellite precipitation records over mountainous regions and advise operational drought monitoring and early warning systems within data-limit-ed topographically complex areas worldwide.

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DOI: 10.3897/jbgs.e177296

Authors: Dmytro Kasiyanchuk, Yaroslava Atamaniuk, Mykola Deputat, Svitlana Gavdey, Pavlo Horishevskyi

Abstract: The objective of the present study is to undertake a quantitative assessment of the spa-tial impact of tourism on natural complexes in the Carpathian region. This is achieved by employing geostatistical modelling methods. The present study deviates from con-ventional buffer methodologies insofar as it employs an integrated algorithm founded upon Kernel Density Estimation (KDE), thereby amalgamating multivariate analysis with detailed land use classification (LULC). In the analysis, each of the seven factors ̶ hydro-graphic network, relief, transport accessibility, hotels, tourist routes, land use types and nature conservation areas ̶ is standardised on a scale of 1–10 and synthesised into a single model of the vulnerability of natural landscapes to tourist pressure. The spatial integration of the factors demonstrates that areas exhibiting high and very high vul-nerability encompassed a total area of more than 310 km², constituting approximately 34% of the total area under consideration. These areas are predominantly concentrated within mountain valleys and along major transport axes. The findings demonstrate the substantial analytical superiority of KDE in comparison to buffer models, owing to its capacity to accommodate continuous impact gradients and its strong alignment with actual urbanisation patterns. The proposed approach can be applied to spatial planning for sustainable tourism and environmental monitoring in mountain regions.

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DOI: 10.3897/jbgs.e153003

Authors: Tsvetan Parov

Abstract: During the 33rd Bulgarian Antarctic Expedition, field studies were conducted to examine the internal microclimate of crevasse-drainage systems of the three glaciers: Balkan Ice Field, Johnsons and Contell Glaciers. The research is focusing on the relationship between fluctuations of surface meteorology parameters, internal air glacier temperatures in the crevasses and possible connection with solar activity. The total duration of the study exceeds 60 days, making it the longest temperature monitoring of glacier crevasses in Antarctica. Measurements of air temperature, humidity, and atmospheric pressure were carried out using autonomous sensors, while ultrasonic anemometers recorded airflow direction and speed inside the crevasses. Sensors were placed at depths of up to 25 m in central zones and 10 m near the glacier edges. The study identified a distinct temperature gradient at 3-meter intervals and mapped the depth of zones with persistently negative temperatures. Increased solar activity was associated with lower internal glacier temperatures and stronger air circulation. A negative correlation was found between solar activity and both temperature and downward airflow within crevasses. A glacial cave under the Balkan Ice Field allowed access to subglacial waters and sediment sampling. For the period of one year, the ablation zone of the Balkan Ice Field had expanded, and the constant negative temperature zone had deepened by 6–7 m since the previous expedition. Contell Glacier showed greater thermal stability and resistance to change compared to the larger ice fields. The extended daylight in January (approximately 20 hours) facilitated reliable correlation with solar activity patterns.

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DOI: 10.3897/jbgs.e168308

Authors: Fiorella La Matta Romero, Todd R. Lewis, Chad Staddon

Abstract: Understanding the factors that shape household water and energy use is essential for designing targeted conservation interventions that promote both sustainability and well-being. While studies in this area often rely on traditional “frequentist” statistical methods, which can struggle to capture the complex interdependencies among demographic, behavioural, psychological, and material influences. This paper introduces Bayesian network (BN) analysis as a novel and adaptable method with useful applications in water and energy studies and a wide variety of other social sciences. The paper offers a primer on how to conduct BN analysis, including underlying logic and range of choice of software platforms, before presenting a brief worked example based on the authors’ current research into household water and energy consumption in a UK city. The paper shows how Bayesian networks can generate valuable insights from relatively small and complex datasets, capture non-linear relationships, and support scenario-based reasoning, making them well-suited for exploratory studies, “what if?” scenario-testing and policy effectiveness review. The findings contribute to a more nuanced understanding of domestic water and energy consumption and offer a practical framework that can inform the design of targeted, evidence-based interventions to encourage sustainable water and energy use in households. We argue that there is much to be gained by proliferation of this analytical approach throughout the social sciences.

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DOI: 10.3897/jbgs.e155799

Authors: Astisiasari Astisiasari, Wisyanto Wisyanto, Dian Melati, Sukristiyanti Sukristiyanti, Raditya Umbara, Yukni Arifianti, Trinugroho Trinugroho, Lian Andikasari, Taufik Ramdhani

Abstract: Landslide exposure is an adept approach to measuring the consequences of a landslide hazard on elements at risk. Landslides in the Bogor area, Province of West Java, Indonesia, have increased in number and consequences since 2015. The Bogor area also has a fairly large population that may aggravate the impact. Accordingly, this study aims to measure the landslide exposures over two substantial elements (i.e., population and land use). The actual resources for these exposed elements are available from the open-access geodata and the Google Earth Engine (GEE) platform. For the land use classification, this study employs two robust machine-learning (ML) algorithms on a GEE-based Object-based Image Analysis (OBIA), i.e., Random Forest (RF) and Gradient Tree Boosting (GTB). Moreover, the population data were retrieved from WorldPop estimates. Landslide exposures were then analyzed through an overlay between these two elements with a landslide hazard map sourced from the former study. The results show that in 2020, the Bogor area had an exposed population of 885,353 people, with Bogor Selatan District having the highest exposed population (135,475 people). Moreover, in 2021, the Bogor area had a total exposed land use reaching 347.9 km2, with built-up area having the most extensive, reaching 45.9% of the total exposed area. Here, Sukajaya District had the largest exposed land use (39.1 km2). This study is expected to reach multifaceted entities that contribute to strengthening landslide risk reduction. Through this spatial awareness of the highly exposed areas to landslides, mitigation measures can be taken accordingly.

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DOI: 10.3897/jbgs.e159980

Authors: Aditya Kumar, Pankaj Kumar, Rumi Rongpi, Prabhat Ranjan, Aditi Kumari, Anju Singh

Abstract: Forests are vital to terrestrial ecosystems and they offer essential services for climate regulation and human welfare. However, the increasing trend in forest fires poses a significant threat to these ecosystems. This study aims to map and assess forest fire vulnerability zones within Almora district, Uttarakhand, India, using geospatial technologies and the Artificial Neural Network (ANN) technique. Twelve environmental indicators related to forest fire vulnerability, including elevation, slope, land use/land cover (LULC), Normalized Difference Vegetation Index (NDVI), Vegetation Health Index (VHI), temperature, precipitation, humidity, wind speed, Land Surface Temperature (LST), and distance from settlements and roads, were considered. The study revealed that a strip running from northern to southern Almora, including Someshwar, Dwarahat, and Ranikhet, is highly vulnerable to forest fires. This region is characterized by moderate to high elevation, a moderate to steep slope, and well-connected roads and settlements, particularly in Dwarahat and Ranikhet tehsils. The central and southern parts of Almora also exhibit good road connectivity, dense human settlements, and receive moderate to low precipitation, all of which contribute to a higher fire risk. In contrast, the eastern and western parts of Almora, comprising northern Sult, northern Bhikiyasain, and Banoli tehsils, are significantly less vulnerable to forest fires. These areas have moderate slopes, low to moderate elevation, higher precipitation in the eastern parts, and lower precipitation in the western parts, making them comparatively less prone to fire incidents. Validation through the Receiver Operating Characteristic (ROC) curve confirmed the accuracy of the model, with an 82% area under the curve.

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DOI: 10.3897/jbgs.e159722

Authors: Igor Leščešen, Pavla Pekárová, Zbyněk Bajtek

Abstract: Accurate forecasting of river discharge is critical for the sustainable management of water resources, influencing applications such as irrigation planning, flood and drought mitigation, and infrastructure development. This study investigates the application of the Seasonal Autoregressive Integrated Moving Average (SARIMA) model to forecast minimum monthly discharges of the Danube River, addressing challenges posed by nonlinear and time-dependent hydrological processes. The study utilizes an extensive dataset comprising daily discharge records from ten stations across seven countries, spanning over a century. Monthly minimum discharges were computed and analyzed to identify long-term trends and seasonal patterns. The SARIMA model was selected for its proven ability to capture seasonal variations and optimize forecasting accuracy in da-ta-limited environments. Model performance was evaluated using statistical measures such as mean absolute error and root mean square error with results indicating robust predictive capabilities across the studied stations. The findings reveal significant vari-ability in discharge trends, with notable decreasing trends in minimum flows at several upstream and midstream stations, highlighting potential impacts of climate change and anthropogenic influences. In contrast, downstream stations exhibited relatively stable discharge patterns. These insights underscore the need for adaptive water manage-ment strategies to mitigate the risks associated with decreasing low flows. The study demonstrates the utility of SARIMA models in hydrological forecasting and provides a foundation for future research exploring hybrid modeling approaches incorporating climate variables. The results offer valuable inputs for policymakers and stakeholders in managing water resources under evolving climatic conditions.

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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.e144897

Authors: Altyn Zhanguzhina, Zhanar Ozgeldinova, Zhandos Mukayev, Meruert Ulykpanova, Perizat Zhanuzakova

Abstract: The article presents the results of an analysis of natural forest regeneration after a wildfire in the Amankaragay Forest Massif, Kostanay Region, Republic of Kazakhstan, during the post-fire period. The forest landscapes of the Kostanay Region are subject to pyrogenic impacts of both natural and anthropogenic origin, leading to changes in the phytocenosis of ecosystems. The study integrates field research findings with remote sensing data and methods (dNBR, NBR, NDVI) to assess post-fire conditions and forest regeneration in the Kostanay Region through the comparison of three sample plots. Changes in summer dNBR values indicate the severity of the fire, while annual and seasonal variations in NDVI values, particularly during the summer, reflect the intensity and level of post-fire forest recovery. The analysis of natural forest regeneration after the wildfire in the Amankaragay Forest Massif was conducted using field research methods, ArcGIS 10.8 software, and spectral index analysis of multi-temporal high- and medium-resolution satellite imagery. Based on the research objectives and the specific characteristics of the study area, necessary calculations and analyses were conducted for each sample plot. As a result, the natural regeneration of forest landscapes was assessed, and relevant findings were obtained. Fire intensity and type determine the rate of forest recovery. dNBR and NDVI indices confirm the effectiveness of remote sensing for monitoring post-fire forest recovery. Remote sensing data and field assessments enable not only the evaluation of current forest conditions but also predictions of future development. The changes in the structure of dominant tree species in the Amankaragay massif, detected through satellite monitoring after exposure to the pyrogenic factor, were verified using field research methods.

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DOI: 10.3897/jbgs.e143055

Authors: Dimitar Doychev, Kristina Gartsiyanova, Gratsiela Yordanova, Lidiya Taneva

Abstract: The moderately salty and lightly salty lakes and marshes near the Black Sea are specific in terms of their high degree of physical alteration; intensive hydromorphological pressure; and point-source and diffusive enrichment with biogenic, organic and inorganic compounds. Nutrients are among the most regularly measured variables in monitoring programs, providing the most complete information for long-term analysis and assessment. Nonetheless, their results need a final summary score, such as the water quality index, which assesses spatial and temporal conditions very well. In this study, we used all available data for Varna and Burgas Lakes from state monitoring for six years (2016–2021), using the parameters monitored with the greatest frequency. The aims were to trace temporal changes in the water quality parameters to determine which of the biogenic elements had the greatest significance for the variance in water quality while seeking the most contributing elements for the formation of the Canadian Council of Ministers of the Environment water quality index (CCME-WQI). The objectives were achieved via multiple factor analysis (MFA) loaded with the results for the environmental variables and the final scores of the CCME-WQI since this multivariate analysis allows simultaneous consideration of multiple data series while balancing the influence of each set of variables. MFA revealed that CCME-WQI scores were influenced solely by total phosphorus (TP) in Varna Lake, where TP was negatively correlated with total nitrogen. In Burgas Lake, TP had the greatest influence on the CCME-WQI, but in this slightly saline lake, pH and dissolved oxygen were also negatively correlated with the complex assessment scores. The approach developed in this study is simple to implement and provides information for the simultaneous use of both the CCME-WQI and the MFA, which could optimize monitoring programs by directing sampling efforts on fewer parameters that could be analyzed more often or from more sampling sites.

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DOI: 10.3897/jbgs.e143846

Authors: Kulyash Kaimuldinova, Shakhislam Laiskhanov, Duman Aliaskarov, Rakhat Tobajanov, Zhulduz Nizamatdinova

Abstract: This article considers the nature of climate changes in the Middle Ages of Central Asia and the influence of these changes on the toponymy in the region. The aim of the study is to analyze the manifestation of climate changes in the names of natural objects described in historical data of Central Asia and to study whether the semantic load of toponyms corresponds to the current geographical reality. The spatial identification of toponyms found in medieval historical sources, their etymological and semantic analysis, determination of the correspondence between toponyms and the present geographical nature of objects are carried out in accordance with the aim of the research. Climate changes will lead to changes in soil, vegetation and fauna. The presence of information describing the natural conditions in the period of their appearance in toponyms makes it possible to use them as indicators of landscape changes in historical geography. It was found that toponyms reflect climate changes in Central Asia, and thus they can be used as a source of information in the reconstruction of landscapes of past periods as a result of the research. It was found that the meaning of historical names preserved in the region from the period called “medieval pluvial” or “medieval climate anomaly” (between 900–1300 AD) does not correspond to the nature of the present landscape as a result of climate changes. The research methodology and results can be used in the future on a wider scale for other regions or in historical-geographical studies related to certain time periods.

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DOI: 10.3897/jbgs.e142535

Authors: Hristina Prodanova, Vanya Stoycheva

Abstract: Ecosystem services research in Bulgaria has been actively studying different aspects of this concept and its implementation. Although it is widely recognizable, the concept has still not been sufficiently implemented in Bulgaria’s decision-making process. Following the European and global initiatives for implementing biodiversity and ecosystem services (BES) into the decision-making process, we have identified the stakeholders’ perceptions regarding the possible initiatives for improving the uptake and the lack of sufficient education program coverage within secondary and higher education. In this short communication, we suggest practical priorities for the future development of BES activities enabling the uptake in Bulgarian education and policy.

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DOI: 10.3897/jbgs.e136806

Authors: Samy A. Anwar, Latifa Zhouri, Bilel Zerouali, Yong Jie Wong

Abstract: This study aims to reduce uncertainty in future projections of potential evapotranspiration (PET) across Egypt by utilizing the regional climate model (RegCM4) under two distinct Representative Concentration Pathways (RCP): RCP4.5 and RCP8.5. The RegCM4 was downscaled using the medium-resolution Earth System Model from the Max Planck Institute, achieving a horizontal resolution of 20 km over Egypt. Initially, the spatial distribution of simulated PET was assessed, followed by the orrection of historical PET calculations using long-term gridded data from the Climate Research Unit (CRU) through a linear regression model (LRM) at twelve locations representing diverse climate zones in Egypt. The LRM was then applied to adjust future PET projections covering the period from 2006 to 2100. Significant spatial anomalies in PET were observed, articularly during the periods 2061–2080 and 2081–2100, with more pronounced anomalies under the RCP8.5 scenario compared to RCP4.5. Across all locations, the RegCM4 effectively captured the monthly variability of PET in relation to CRU data. Furthermore, the application of the LRM substantially improved the accuracy of simulated PET, demonstrating the ffectiveness of this approach in enhancing model performance and reducing uncertainty in future projections.

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DOI: 10.3897/jbgs.e135422

Authors: Peter Nojarov

Abstract: This study examines the total evaporation and precipitation-evaporation difference in Bulgaria. Data from ERA5-Land reanalysis for the period 1979–2023 were processed using statistical methods. The results show that the main factors for evaporation in Bulgaria are air temperature and precipitation. Evaporation has a positive trend due to the rise in air temperature. This trend is significant only in mountainous regions, which are well-supplied with water. Evaporation is somewhat limited in the other parts of the country because of the water deficits in the warm part of the year. Precipitation is a possible source of water for the earth’s surface, but there has been only an insignificant increase in it in recent decades. Precipitation-evaporation difference remains relatively unchanged during the studied period, which is a favorable trend, as there is no increase in the water deficit in Bulgaria on an annual basis. In addition, most of the country has positive values in terms of the average annual values of precipitation-vaporation difference. However, there is a need to introduce monitoring of actual evaporation, because this study has shown that different calculation methods give different results, which is a significant problem in determining how much precipitation remains in a given area. The exact values of this indicator are extremely important for various sectors of the economy such as agriculture, water supply and sewage, transport, energy, etc.

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DOI: 10.3897/jbgs.e128961

Authors: Hanene Guergour, Mohammed Cheraitia, Assoule Dechaicha, Djamel Alkama

Abstract: Climate-aware urban environments pose a significant imperative to obtain thermally comfortable outdoor areas. The present study addresses the optimization of urban block morphology in Guelma City, Algeria, to enhance thermal performance in a semi-arid climate. Using in-situ measurements and simulation generated by the ENVI-met simple forcing scheme, the impact of urban morphology on the variation of outdoor comfort factors, including air temperature, relative humidity, and wind speed arameters, is identified. The conducted investigation illustrates building configuration, orientation, and street canyon geometry as key indices affecting thermal comfort. Results pointed out urban green cover’s role in mitigating heat island effects. In conclusion, the study underscored the significance of an interconnected analysis of urban patterns and heir correlated influence on urban microclimate for achieving thermally comfortable outdoor environments.

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DOI: 10.3897/jbgs.e126650

Authors: Tsvetan Parov

Abstract: Discovered only about 200 years ago, Antarctica is the poorest and most isolated ecosystem on Earth. Its thinner atmosphere, due to the centrifugal forces of Earth’s rotation, the ozone hole, and stronger solar radiation, creates a natural laboratory that provides information about the state and trajectory of Earth’s climate condition. This study aimed to determine the depth of heat penetration from the surface of the glacier into the crevasses in the ablation zone and establish the zone of constant temperatures in the glacier. It explored the relationship between the air temperature at the glacier surface and the temperature distribution in the crevasses, including the temperature gradient at different levels and the direction of the airflow. We used autonomous data loggers for measuring and recording temperature and relative humidity. The measured depth reached 18 m in the central part of the glacier and 9 m in the periphery. An ultrasonic anemometer was installed in the deepest crevasse in to the center of the glacier to determine the size and direction of air flows. Meteorological parameters such as air temperature, humidity, atmospheric pressure, and solar radiation were measured on-site using autonomous sensors and recording devices mounted on installations on the glacier surface and at depth using alpine techniques. The results show a temperature gradient through 3-meter layers, a relatively clear boundary of the constant temperature zone, and a significant infiltration of cold air through the crevices driven by turbulent wind processes. Additionally, a weak negative correlation was found between solar activity and temperatures in the crevasses. It appears that as solar activity increases, the temperature decreases. There are also weak but consistently positive correlations with air movement both upward and downward. The temperature becomes constant with the increase of the depth until a zone of constant temperatures is determined and the temperature variance becomes insignificant. This zone varies in different crevаsses, meaning it is influenced by the specific characteristics of each crevasse location. At shallow depths, temperature is influenced by external temperature, but with the depth increasing this influence decreases. On windy days, the zone of constant temperature expands. During higher solar activity, air circulation accelerates—both upward and downward. The relationship between solar activity and climatic processes in glacier drainage systems adds new insights to solar-terrestrial physics.

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DOI: 10.3897/jbgs.e128013

Authors: Melike Durak

Abstract: Kuruçay Stream basin, located in the Edremit district in northwest Turkey, is a small, narrow and long basin with an area of 17.3 km2, extending in the N–S direction, located on the southern slopes of Mount Ida. The study was carried out to determine the soil erosion susceptibility and distribution of Kuruçay Stream basin, as well as to estimate the annual average amount of soil loss through the Revised Universal Soil Loss Equation (RUSLE) model using Geographical Information Systems (GIS). To apply the equation to the basin, data layers for rainfall erosivity (R), soil erodibility (K), slope length (L) and slope steepness (S), landcover management (C), and support practice (P) factors were generated. The layers were then overlaid, calculations were made and erosion susceptibility classes were generated. Thus, the spatial distribution of erosion susceptibility classes and the annual estimated amount of soil loss were determined. Based on the results, the Kuruçay Stream basin was found to have five distinct erosion susceptibility levels: low, moderate, high, severe, and extremely severe. Accordingly, 76% of the basin has low, 11.3% moderate, 6% high, 2.9% severe and finally 3.7% very severe erosion susceptibility. The Kuruçay Stream basin shows similar characteristics with the neighbouring river basins in terms of erosion sensitivity.

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DOI: 10.3897/jbgs.e126690

Authors: Tabaro Kabanda

Abstract: This study examines the effects of extreme temperature events, defined explicitly as the 98th percentile temperature for heat, in Tanzania from 1981 to 2023. The study utilises percentile analysis, z-score calculations, and trend mapping to highlight the prevalence of extreme temperatures. The z-score analysis examines the occurrence of extreme temperatures and their distribution in terms of frequency and space. It identified Tanzania’s mid-eastern and north-western regions as areas with a high concentration of extreme temperatures over the previous 43 years. The study analyses the length of extreme occurrences and reveals changing patterns. In 2020, the events were shorter, while in 2021 and 2022, they became longer-lasting, and there was a notable concentration of extended anomalies near the northern coastline. In 2023, the highest temperatures ever recorded were observed, with more than half of the regions seeing prolonged periods of extreme temperatures lasting for a week and significant deviations from the norm staying for four weeks or more. This was particularly notable in the southern regions of Lindi and Mtwara. The harmonic trend analysis of temperature shows an upward temperature trend noticeably in regions such as Arusha, Kilimanjaro, Kagera, Morogoro, Simiyu, and Shinyanga and is somewhat inconspicuous in most areas.

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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.e116695

Authors: Boyko Berov, Antoaneta Frantzova, Plamen Ivanov, Nikolai Dobrev, Miroslav Krastanov, Rosen Nankin

Abstract: As part of the Reimbursable Advisory Services on Accelerating Resilience to Disaster Risks, the World Bank worked with the Interior Ministry of Bulgaria to develop a proposal for the National Disaster Risk Profile of Bulgaria. The purpose of this document, which is the fourth technical annex to the proposal for the National Disaster Risk Profile, is to provide particular conclusions, information, and techniques that were utilised to evalu-ate the risk of landslides in Bulgaria. For the first time at the national level, landslide risk assessment procedures based on ISO/IEC 31010:2019 Risk assessment techniques are being developed and applied in Bulgaria. The five primary categories in which the results are presented are physical safety, economic security, social well-being, environmental security, and security of tangible assets and critical infrastructure. The uncertainty (confidence) parameter is utilised, and it is subdivided into the following three basic categories: low uncertainty, medium uncertainty, and high uncertainty. The produced results demonstrate consistent applicability to empirical data analysis and real-world situations.

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DOI: 10.3897/jbgs.e124098

Authors: Ibrahim Olatunji Raufu

Abstract: In an era of rapid urbanization, understanding the complex relationship between vegeta-tion dynamics and land surface temperature (LST) is crucial for addressing the challeng-es posed by urban heat island (UHI) and promoting sustainable urban development. Our study aimed to explore these dynamics in a rapidly urbanizing environment by analyzing the relationships between remote sensing-based vegetation indices and LST through quantitative analysis. A cloud-free Landsat 8 OLI/TIRS level 2 satellite imagery of Ibadan region city for 2022 was obtained from the United State Geological Survey (USGS) and LST was estimated using the radiative transfer approach. Utilizing different combina-tions of spectral bands, seven vegetation indices including Normalized Difference Veg-etation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Atmospherically Resistant Vegetation Index (ARVI), Green Normalized Difference Vegetation Index (GNDVI), Ratio Vegetation Index (RVI), Optimized Soil Adjusted Vegetation Index (OSAVI), and Green Chlorophyll Index (GCI) were analyzed. Combined with the spatial distribution of LST in Ibadan, regression analysis were performed to explore the relationship between vege-tation indices and LST. Results indicate that among the seven vegetation indices, ARVI has the strongest correlation with LST in the study area (R2 = 0.65). Additionally, urban cores experience lower vegetation density and higher LST values, which can be attribut-ed to land use intensity, anthropogenic heat release, and impervious surface cover while the peripheral areas exhibit higher vegetation indices and lower LST values. The findings of this study contribute to a deeper understanding of urban environmental dynamics and provide valuable insights for sustainable urban planning, ecosystem management, and climate adaptation strategies in rapidly urbanizing areas.

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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.e119556

Authors: Petko Bozhkov

Abstract: Block streams, also known as stone rivers, are common periglacial landforms in the alpine and subalpine zone of the Balkan Peninsula. These features are especially widely spread in the valleys, slopes and summit of Vitosha Mountain. The presented research aims to estimate the total area of block streams and perform morphometric analysis of these landforms within the basin of Vladayska River. Block streams are digitized man-ually from orthophotographs and topographic maps using GIS software. Morphometric parameters such as area, length, width, elongation ratio and mean elevation are calcu-lated or extracted from a digital elevation model for each polygon. A linear regression test was conducted to evaluate the relationship between morphometric properties. Results indicate a significant correlation between the area and perimeter (R2 = 0.93) and between the length and width (R2 = 0.94) of the block streams. Block streams are present in the elevation range between 1177 and 2244 m, covering a total area of 169.7 ha. The largest ones occupy the area of Zlatnite Mostove and Yurushki Most, as well as the vicinity of Cherni Vrah Peak. Their length varies from 5–6 m up to 2.2 km, while their width changes from a few meters up to 0.6–0.7 km. Comparisons between block streams from different sites within the catchment area yield new insights into the diver-sity of these landforms. Their dimensions and spatial distribution are key to understand-ing the processes of their formation and evolution.

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DOI: 10.3897/jbgs.e115814

Authors: Valbon Bytyqi, Tropikë Agaj

Abstract: The study aims to analyze the availability of renewable freshwater resources and their spatiotemporal distribution in the Eastern Region of Kosovo (ERK). As a crucible resource for agricultural, industrial, and commercial activities, water scarcity will lead to water shortages. Kosovo is a landlocked country, and ERK is the most important region for industrial activities (coal, mines) and agricultural use (plains). Located in continental climate conditions, surrounded by middle to high-altitude mountains, the region does not have a favorable spatio-temporal distribution of freshwaters. The determination of the water resources is based on the amount of surface runoff, which being divided per capita, gives indications of the water resources of a region (catchment). For our aims, main river discharge and population statistics are used to analyze the spatiotemporal distribution and availability of renewable freshwater in ERK. Falkenmark Freshwater Indicator with 1.483 m³/capita/year shows that ERK lies under water scarcity, and existing water reservoirs offer low security for water withdrawals, and further reservoirs would prevent water scarcity in the region.

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DOI: 10.3897/jbgs.e113695

Authors: Mohamed Brahimi, Moussadek Benabbas, Djamila Djaghrouri

Abstract: Urbanization has radically transformed natural landscapes, giving rise to complex urban environments worldwide. This transformation poses unique challenges in terms of climatic conditions. We emphasize the crucial importance of understanding urban microclimates shaped by geographical, architectural and human factors, requiring meticulous management for sustainable urban planning. These multifaceted factors interact to produce spatial variations in solar exposure, temperature and wind conditions, leading to distinct microclimatic pockets within cities. This underlines the imperative need for sustainable urban planning and design that takes account of their impact. Our field survey is located in Djelfa, Algeria, featuring a semi-arid to arid climate with continental influences. This article presents a methodology involving a detailed morphological analysis of the urban fabric, focusing on its structure, vegetation cover and spatial characteristics. It describes the use of ENVI-met, a powerful microclimate simulation tool offering a complete three-dimensional modeling system that integrates various urban elements, including buildings, streets and green spaces. Our spatial considerations guarantee model accuracy, with a rigorous geometry validation process maintaining model fidelity. The tool produces invaluable output data, including air temperature, relative humidity and thermal comfort indices. This paper emphasizes on the application of the model in Djelfa, Algeria, highlighting its potential in evaluating thermal condition in urban environments. The results of our study highlight significant temperature and humidity disparities between urbanized and green areas in the survey area, with temperature differences of up to 6°C during the day. Urbanized areas consistently have higher air temperatures and lower humidity levels, particularly during the day. Conversely, green spaces, including gardens and tree-lined areas, exhibit lower temperatures and higher humidity levels, offering valuable respite from heat stress. The use of the Physiological Equivalent Temperature (PET) index allows us to assess thermal comfort, revealing variations in heat stress levels across the urban landscape. This research highlights the crucial importance of integrating green infrastructure into urban planning to improve thermal comfort and livability in cities. Furthermore, our study reveals the value of advanced tools like ENVI-met in understanding urban microclimates and provides valuable information for sustainable urban development and climate adaptation strategies.

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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.e113364

Authors: Meryem Koncak Doğruer, Mustafa Kahraman, Mesut Doğan, Aigul Yeginbayeva

Abstract: Detection of the exchange and distribution of agricultural lands allows many projects and plans to be made and interpreted correctly, such as food safety, planning, and environmental risk analysis. From this point of study in the spatial changes and distribution of agricultural land in time across Turkey were examined. CORINE Land Cover (CLC) data was used to identify agricultural land and examine changes over time. As a result of the study, it was observed that agricultural lands increased slightly from 1990 to 2018, but this increase has not always been in the form of preserving existing agricultural lands and adding existing agricultural lands. While some areas have lost their agricultural land characteristics, some areas have become agricultural land. New agricultural areas are usually realized by the transformation of forests and semi-natural areas while the agricultural areas that disappear are provided from heterogeneous agricultural areas. The Central Anatolia region stands out in the distribution of agricultural areas by region. The region with the highest concentration of agricultural land in terms of both proportion and area is the Central Anatolia region. Also, the Central Anatolia region is the region with the most intensive Non-irrigated agriculture. The area where irrigated agriculture is proportionally most made is the southeast Anatolia region. According to province-based, the provinces with more than 40% of the provincial surface area are Kırıkkale, Kırşehir, Nevşehir, Aksaray in the Central Anatolia region, Gaziantep and Şanlıurfa in the Southeastern Anatolia region, Edirne and Tekirdağ in the Marmara region. The provinces of Artvin, Tunceli, Bingöl, and Hakkari are the provinces where the percentage of agricultural land is below 10%.

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DOI: 10.3897/jbgs.e110454

Authors: Patrick Sunday Asa, Ambrose Audu Zemba

Abstract: Urban climatologist particularly those interested in Urban Heat Island (UHI), require some form of explanations to UHI variations at both spatial and temporal scales in cities. Temperature cooling and warming rate can be use as a form of explanations for spatial and temporal variations for UHI intensity characteristics of an area. This study therefore, assessed variations in temperature warming and cooling rates in Jalingo. The study used temperature data collected at six locations representing six different thermal climate zones in the study area. Temperature data were collected for the period of 90 days thirty days in each of rainy season, dry season, and hamattan period. Simple statistical analysis was performed to determine the warming and cooling rates. The results indicate that temperature warm and cool differently in the study area. The results also revealed that general warming in the area within the study period begins at 8:00 h local time (GMT +1) with warming rate ranging from 0.94°C to 1.75°C across locations with a mean of 1.30°C. Cooling starts at 15:00 h ranging from -0.88°C to -1.84°C with an average of -1.48°C. It is recommended that environmental planners particularly the urban planners and Architectures should take into considerations the warming and cooling rates in their building design and also embrace appropriate landscaping to improve thermal comfort.

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DOI: 10.3897/jbgs.e109172

Authors: Bilyana Borisova, Maria Glushkova, Stoyan Nedkov, Miglena Zhiyanski, Vanya Stoycheva

Abstract: Habitat maintenance as an ecosystem service (ES) is essential for the protection of natural capital, however, it is among the most challenging services for definition and evaluation. The present study is focused on assessing and mapping habitat maintenance ecosystem service in Rila and Pirin Mountains in Bulgaria for strategic planning purposes by better understanding the link between the potential of providing this ecosystem service and biodiversity in five protected areas (PAs). An integrated approach for the assessment of the condition of ecosystems in PAs and their potential to provide ecosystem services was applied and further developed in the present study. The results showed that the conservation regime allowed the territories to preserve a high degree of naturalness in a very good ecological condition – 96477 ha (73%) of the total case-study area, and 33078 ha (77%) of the target PAs, respectively. The potential of ecosystems to provide habitat maintenance ES is high to very high for 84% of the total studied area (81258.9 ha) and for 96.4% (31906 ha) of the area of the target PAs. A current assessment and mapping show the role of protected areas as spatial natural capital assets that purposefully and actively support their prioritized habitat maintenance functions as spatial guarantors for the sustenance of rich packages of material, regulating, and cultural functions in significant geographic areas. The results demonstrate the importance of protected site management in mountain areas in ensuring sustainable cooperation and consumption of ecosystem services in peripheral mountain communities of the European Union highly dependent on available natural capital.

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DOI: 10.3897/jbgs.e108747

Authors: Peter Nojarov, Vladimir Vlaskov, Yoana Vatova

Abstract: The study aims to reveal spatial distribution of precipitation in the area of Sofia city during the decade 2013 - 2022 and the influence of atmospheric circulation. Statistical methods and cartographic approach are the main tools in this research. The spatial distribution of precipitation is characterized by low amounts (560 mm) in the northern and northeastern parts of Sofia depression and high amounts (760 mm) in the southern part. The main factor for this spatial distribution of precipitation is atmospheric circulation. The relief has a significant modifying effect and affects precipitation through several mechanisms. The most important is the location of mountain slope relative to the main direction of transport of air masses. Leeward slopes receive less precipitation and windward slopes receive more. The second mechanism of influence is anthropogenic relief (high buildings), which is a positive relief form compared to the surrounding plane having respective windward and leeward slopes. This study revealed a third mechanism of relief influence on spatial distribution of precipitation. The large difference in the height of the mountains located south of Sofia creates a significant difference in the air temperature in Sofia depression during a transport of air masses from south and southwest. This is due to the stronger foehn effect of the higher mountain (Vitosha) compared to the foehn effect of the lower mountains (Lyulin, Lozenska Planina), which creates a tongue of higher air temperature northeast of Vitosha, which reaches the southern and southwestern slopes of Stara Planina. The higher temperatures in this tongue create stronger upward air movements, which in turn increase the amount of precipitation. Secondary, but still important factors that affect the spatial distribution of precipitation in Sofia region are the urban heat island and the increased content of aerosols in the air in and over the city.

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DOI: 10.3897/jbgs.e105178

Authors: Patrick Sunday Asa, Idris Shehu Umar, Ambrose Audu Zemba

Abstract: The paper presents the results of studying the spatial and seasonal atmospheric temperature characteristics of Jalingo metropolis, Nigeria, with the aim of assessing seasonal temperature variations for thermal comfort planning. Temperature data for this study was collected across the local climate zones, otherwise known as thermal climate zones (TCZ), following the TZC classification of the area. Temperature data was collected for 30 days continuously and simultaneously across the TCZ. The collection of temperature data was done in the months of April and August 2021, and January 2022 – representing the dry season, the rainy season and the Harmattan period respectively. A Thermochron Ibutton sensor by Maxim Incorporation was used to collect temperature data, while the specific series used was DS1921. An improvised automated weather station was constructed to house the sensor. The result of the study indicates that air temperature varies considerably within Jalingo metropolis, as well as throughout the seasons, thus affecting human thermal comfort in the study area, as temperature is found to correlate well with both human morbidity and mortality, especially regarding cardiovascular diseases. The paper recommends increasing ventilation and nature-based solution to reduce high temperatures through tree planting in order to improve human thermal comfort in Jalingo metropolis area.

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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.e99206

Authors: Zvezdelina Marcheva, Tsvetan Kotsev, Assen Tchorbadjieff, Velimira Stoyanova

Abstract: This study aims to reveal the arsenic dynamics in groundwater of а river floodplain contaminated with mine tailings under temperate climate conditions and natural river hydrodynamics. Arsenic concentrations were monitored in the primary morphological units of the floodplain in the upper stretch of the Ogosta River in NW Bulgaria. Iron, lead-silver, and gold mining heavily affected the river valley in the second half of the 20th century. We used groundwater monitoring data from 21 piezometers for the period 2016-2020. Based on the geochemical and geomorphological conditions in the valley, the piezometers were grouped into three clusters. Regression models were developed for each cluster and representative piezometers to predict arsenic concentrations. In the active floodplain, seasonal fluctuations in arsenic concentrations followed the river and groundwater regime. In this part of the valley floor, we determined two periods of elevated arsenic concentrations during the spring and autumn/winter seasons that coincide with high river water stages. Arsenic content in the groundwater of the higher floodplain was less dependent on the water level fluctuations but followed changes in redox potential, electrical conductivity, and water temperature. The obtained results showed the elaborated models as valuable tools for studying arsenic dynamics in alluvial aquifers of contaminated river floodplains. The suggested models could be coupled with groundwater monitoring systems to monitor arsenic concentrations and identify periods of the year with levels below and above threshold values.

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DOI: 10.3897/jbgs.e97974

Authors: Ianko Gerdjikov, Zornitsa Dotseva, Eli Pavlova-Traykova, Dian Vangelov

Abstract: One of the biggest rivers in the southern part of the Balkan peninsula – the Mesta River is wellknown for frequent flash floods, especially in the upper river course. As a result of severe storms and related heavy rain in mid-July 2019, the Cherna Mesta River flooded, and this resulted in heavy damage to the road infrastructure and water-supply systems. All data indicate that this was not a usual water flood, instead at peak flow, the river carried a huge amount of gravel. Our mapping of erosional and depositional features related to the 2019 event, as well as geomorphological analysis, allows for distinguishing distinct sectors along the river valley. Most hazards are defined in the lower reaches of the Cherna Mesta River, where the processes of channel aggradation and lateral erosion are pronounced. The field analysis of the flood-related deposits indicates the operation of debris flood and hyperconcentrated and water flood processes.

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DOI: 10.3897/jbgs.e98660

Authors: Petko Bozhkov, Borislav Grigorov, Alexandar Sarafov

Abstract: The present study deals with the investigation of soil organic carbon in two water catchments in Northern Rila, Western Bulgaria. Field research, combined with analysis, provided sufficient data. Six key sites were selected and sampled in order to estimate and compare the amount of organic and inorganic carbon in the topsoil. The applied criteria for the choice of sites included: vegetation cover, predominant soil group, level of anthropogenization and transport accessibility. A total number of 13 samples from both catchments were collected and analyzed in the Central laboratory of the Institute of Soil Science, Agrotechnologies and Plant Protection (ISSAPP) “N. Pushkarov“. The results concern the amount and composition of soil organic matter in different soils – Cambisols (Albic, Humic, Dystric), Fluvisols and Umbrosols. The total carbon content of all samples varies between 1.23 and 9.69%. The amount of organic carbon ranges between 0.45 and 3.73%. The results of the study prove once again that the preservation of natural vegetation and current condition of the soil is of great importance for carbon sequestration and climate change mitigation.

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DOI: 10.3897/jbgs.e97971

Authors: Kalin Seymenov

Abstract: The present article seeks to estimate water pollution with nitrogen and phosphorus and to analyse the territorial specifics in the content of those physicochemical variables along the length of a river. As a case area, the watercourse of the Osam River (Northern Bulgaria) is selected. Data concern the values of the following parameters: ammonium nitrogen (N-NH4), nitrate nitrogen (N-NO3), nitrite nitrogen (N-NO2), total nitrogen (N-tot), orthophosphates (P-PO4), and total phosphorus (P-tot), collected at four sampling points during the period 2015–2020. The assessment is based on the guidelines of Regulation 4/2012 for characterization of the surface waters. The spatial changes in the content of the examined variables are related to land use and for this purpose a map of CORINE Land Cover (2018) is prepared. The resulting information reveals that parameters with the most frequent excesses over the reference norm include N-NO3, N-tot, P-PO4, and P-tot, whose highest observed concentrations remain up to four times above the permissible limits for ”Good status” recommended in Regulation 4/2012. However, the reported values appear to be lower than those established for previous periods, which shows a positive tendency in water quality. There are also spatial features as moving from upstream to downstream – the upper part is contaminated with P-PO4 and P-tot due to the release of raw municipal and industrial effluents, while the lower section is loaded with N-NO3 and N-tot as a result of the excessive fertilization of arable lands. This work enriches past studies with new data for a recent period.

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DOI: 10.3897/jbgs.e97168

Authors: Tsvetan Kotsev, Velimira Stoyanova

Abstract: The present study aims to determine the spatial distribution of soils with lead (Pb) content above the quality thresholds in a section of the Ogosta River valley (NW Bulgaria). The study area was contaminated with mine waste from the extraction and flotation of iron, lead-silver, and gold-bearing ores in the second half of the XX century. Predictive modeling was performed with the software Maximum Entropy Species Distribution Modeling (MaxEnt), Version 3.4.4, which uses machine learning algorithms and applies the maximum entropy method. The choice of predictors of contaminated soil distribution is consistent with the main factor for Pb dispersal within the valley floor - flooding from the Ogosta River. The following six parameters explained the environmental settings related to the accumulation of contaminated floodplain sediment: vertical distance to the river channel, lateral distance to the Ogosta River, terrain slope, land cover (CORINE Land Cover, 2019), morphographic units of topography, and elevation. The results represent the average values of 10 replicates of the model. We evaluated the individual models by the value of the area under the relative operating characteristic curve (AUC) and the geographic logic of the obtained results. The AUC score for the test samples was 0.666 for the soil group 1 with Pb ≤120 mg/kg, 0.782 for group 2 with Pb (120-500] mg/kg, and 0.934 for group 3 with Pb>500 mg/kg. The most significant predictors for the models are the vertical and lateral distance to the river and the slope of the terrain. Lead concentrations tend to decrease with the distance from the main river and by increasing the elevation above the river channel due to lower inundation frequency and deposition rate of polluted river sediments. The soils with a Pb concentration below the permissible threshold of 120 mg/kg cover more than 58.42% of the valley floor of the studied section, and lands with Pb content above the intervention value of 500 mg/kg occupy nearly 10.82% of the investigated territory. The selected predictors describe the distribution of highly contaminated soils well and define the range of soils with lower Pb content worse. Combining clean and contaminated soil samples into one group is considered the main reason for the poor performance of MaxEnt for soils with Pb ≤120 mg/kg. However, the results prove the model's ability to predict the spatial distribution of not only biological species but also the dispersal of hazardous substances in soil.

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DOI: 10.3897/jbgs.e94913

Authors: Petko Bozhkov, Borislav Grigorov, Alexandar Sarafov

Abstract: The following paper represents results from a research focused on the soil associations and their corresponding vegetation communities (soil-plant catenas), located on the northern slopes (N, NW, NE) of the Rila Mountains. Data from eight key sites located between 815 and 2041 m above sea level is discussed. The slope in each site varies from 2° to 25°, and most often the tests and descriptions were carried out on sites with a slope of 10-15°. Vegetation cover is analyzed with plant community plots which provides data on species composition, abundance and coverage. The size of each plot varies from 16 up to 225 m2 depending on the vegetation type. Topsoil horizons were tested in each site in order to diagnose the subspecies diversity of brown forest soils (Cambisols) using ratio of humic acids to fulvic acids. That ratio varies from 0,69 up to 1,61 in all studied sites. Both acids are associated with the dominance of different vegetation types – deciduous, mixed or coniferous forest or herbaceous canopy. The results are interrupted in terms of the diagnosis and classification of Cambisols and Umbrosols in the area of interest. Differences in soil and vegetation cover of Northwest and Eastern Rila Mountain are highlighted and analyzed.

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DOI: 10.3897/jbgs.e87816

Authors: Alexandru Marius Tătar

Abstract: This study aims to analyze urban landscapes by assessing the development of built space, one of the most dynamic elements within them. The spatial development of built environments is a phenomenon present in most urban areas. The study looks at the relationship between patterns of built space and urban green spaces. Implications on the connectivity of urban space, the planning of urban functions in their proximity, and the spatial distribution of recreational potential based on the perceived recreational value of the landscape by the local community are investigated. The theme of the paper is a topical issue in the study of urban landscapes, while at the same time it is an ongoing phenomenon - the growth of built space - for which optimal planning solutions are being sought. The analysis and results presented seek to increase understanding and awareness in addressing the dynamics of built space in the urban environment. The data used are collected both from official sources and from the ground. Urban regeneration aims to revitalize distressed urban spaces: The development and beautification of public spaces - squares, squares, parks, street furniture. The links between this category of urban space and the rest of the urban infrastructure are analyzed, as well as the role that urban planning plays in the development of built space in the vicinity of forest areas. The study area comprises territories in the municipality of Bistrita. The socio-economic context of the area has been the basis for understanding the patterns of evolution identified in the urban landscape, as well as being a driver in ongoing urban transformations and processes.

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DOI: 10.3897/jbgs.e85567

Authors: Eugenia Sarafova

Abstract: Bulgaria, located in the Balkans, is subject to a number of natural disasters including floods, earthquakes, landslides, forest fires, strong winds, droughts, heavy snowfall and extreme temperatures. In addition to natural disasters, the country is at risk for man-made events like industrial and nuclear accidents, transport accidents, and infectious diseases. Disaster planning and prevention is a complex process that requires multiple data sources. At the same time, spatial data are often not available on-line, so the country's GIS specialists may find existing spatial data to be a great challenge. This research analyses the application of the health sector data provided by the Copernicus Climate Change Service to support the development, implementation and evaluation of disaster risk management plans in Bulgaria. The climate data visualizations provided by the service enable scientists and other stakeholders to view climate change data in a format that is simple to use, visually understandable, and usable for decision makers in government, business, and non-governmental organizations. Many of these visualizations are interdisciplinary and may be critical for gathering and applying information needed to develop disaster risk reduction plans.

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DOI: 10.3897/jbgs.e86288

Authors: Petar Nikolov, Desislava Hristova, Vanya Stoycheva

Abstract: The System of Environmental-Economic Accounting – Ecosystem Accounting (SEEA-EA) is a spatially-based, integrated statistical framework for organizing biophysical information about ecosystems, measuring ecosystem services (ES). Water flow regulation ES and biophysical modeling are among the main topics in the individual ES part of the SEEA-EA framework and flood regulation ES is one of the important services. Characterizing and assessing flood regulation is a challenging task as both assessment and accounts of this ES need various data which are usually not available through direct or indirect measurements, therefore modeling approaches of water regulation are much needed. Despite growing attention and studies using hydrologic models to assess and/or map flood regulation ES, the accounting of this service is still not well developed. In this paper, we present an approach for accounting flood regulation at a local scale using ArcSWAT modeling. It is based on the results of flood regulation ES assessment, where modeling results are used to quantify the ES indicators and delineate the service providing areas (SPA) and service demand areas (SDA). The actual flow of flood regulation is calculated as a ratio between ES demand and ES potential and it represents the area of SPA which corresponds to the demand for flood regulation represented by SDA. The results show that predominant flood regulations ES supply is provided by the forest ecosystem as well as the actual flow. The accounting of flood regulation is strongly determined by ecosystem extent mapping. The CORINE Land Cover (CLC) provides the most appropriate and available data for mapping ecosystem extent at smaller scales. However, at a larger scale, it is too coarse and the combination of Mapping and Assessment of Ecosystems and their Services (MAES) national ecosystem mapping gives better results.

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DOI: 10.3897/jbgs.e78709

Authors: Mariyana Nikolova, Peter Nojarov, Stoyan Nedkov

Abstract: The area of the Seven Rila Lakes is situated in the North-West part of the Rila Mountain at an altitude between 2100 and 2500 m a.s.l. within the borders of Rila National Park. There are 140 glacial lakes in Rila Mountain but the area of the Seven Rila Lakes is the most visited and famous with its natural beauty and sacred significance. It is a valuable part of the national natural heritage. The popularity of this area grows constantly with the number of visitors from the country and abroad. This process leads to the deterioration of the natural conditions in the site. At the same time, it is not clear what is the effect of climate change on the environment in the lake’s area. There are many factors that contribute to the degradation of ecosystems in the protected area of the Seven Rila Lakes and pose risk to this valuable natural heritage. These factors are natural (mainly climate change-related), anthropogenic (associated with the excessive tourist pressures on the ecosystems in the protected area), and management (stemming from the ongoing conservation policy over the years). This study explores to what extent climate change may put at risk the ecosystems of Seven Rila Lakes. Mean monthly data from The European Center for Medium-Range Weather Forecasts (ECMWF) ERA5-Land reanalysis were used in this study. The resolution of these data is 0.1 x 0.1 (9 x 9 km) and their period is 1981-2020. Reanalysis data include air temperature, precipitation, evaporation, snow depth, etc. Based on data from various sources such as reanalysis data, in situ measurements, and statistical modeling, a scenario, based on current trends in different climatic elements, has been developed in order to project future changes and their impact on lake ecosystems. The results of the modelling of climate change show that in the coming decades an increase in temperature is expected in the high mountain regions of South-western Bulgaria and in particular in the Seven Rila Lakes area. This, combined with the ever-increasing flow of tourists, and high demand for the provided cultural ecosystem services, and insufficient management practices, put at risk the state of the lakes and their capacity to provide the same quality of cultural ecosystem services in the future, which attracts tourists in the area now. Recommendations have been made for the optimization of the management of the protected area in accordance with the observed trends.

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DOI: 10.3897/jbgs.e72500

Authors: Mladen Silvestriev, Bilyana Borisova, Radenka Mitova

Abstract: Nature-based tourism and recreation are attracting attention today as the most favourable form of direct connection between people and nature, and as a very successful tool to motivate people to protect their natural heritage. This study aims to develop and test a methodology to assess the potential of an acknowledged natural heritage site in Bulgaria - Malyovitsa Range and Urdini Cirque in ‘Rila’ National Park to provide cultural ecosystem services. A holistic approach is applied, using landscapes as the main territorial unit, and source of information. For the purpose of practicing representative types of mountain tourism: ‘mountain hiking’, ‘nature education’ tourism, ‘ski touring’ and ‘mountaineering’ a total of 15 ecosystem services were assessed based on 25 biophysical and social indicators. ‘Primary forest landscapes on moraine materials’ and ‘Primary landscapes with mugo pine on igneous rocks’ receive the highest score. Based on the results obtained, an assessment of the mainstream activity - access to mountain hiking provided by the landscapes was carried out and two touristic routes with very high potential to deliver this service were identified. The results of the study are directed towards the responsible parties in support of the natural heritage conservation in Rila National Park through sustainable management the potential to provide cultural (recreational) ecosystem services. The research was conducted within the scientific programme of the project “Conceptualization, Flexible Methodology, and a Pilot Geospatial Platform for Access of the Bulgarian Natural Heritage to the European Digital Single Market of Knowledge and Information Services” within the project BG05M2OP001-1.001-0001 Establishment and Development of “Heritage BG” Centre of Excellence (Operational Program “Science and Education for Intelligent Growth”, priority Axis 1 “Research and technological development”).

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DOI: 10.3897/jbgs.e78692

Authors: Hristina Prodanova

Abstract: The importance of the landscapes for the development of recreation and ecotourism is significant but very little studied. Usually, scientists use spatial units to map and assess the ecosystem services CORINE land cover or similar classifications. Traditional multi-level landscape classifications, very well-known and developed in the XXth century in Bulgaria, Russia, and other Eastern and Central European countries, could give valuable information for various indicators for ecosystem services assessment. From another hand, these classical landscape ecological maps are very little- known for the international scientific audience. We decided to conduct an experimental mapping and assessment of ecosystem services based on multi-level landscape classification. For this, we have chosen a case study area with hilly karst relief, which is part of the inner Predbalkan Region, located in North-Central Bulgaria. The site represents a scientific interest in terms of its transitional position between the Stara Planina Mountain and the Danube Plain and the presence of various anthropogenic changes. The study aimed to develop and test an original methodology for mapping and assessment of the capacity of the contemporary landscapes in the Strazhata syncline upland and Melovete hills to provide cultural ecosystem services – recreation and ecotourism. The results showed that 70% of the territory has medium or higher capacity, dominated mainly by karst areas with natural vegetation in protected sites.

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DOI: 10.3897/jbgs.e77102

Authors: Hristo Popov, Jelena Svetozarevich

Abstract: The Republic of Serbia is а continental country located in the western part of the Balkan Peninsula, in Southeast Europe. In terms of physical characteristics, Serbia is divided into two parts: Pannonian part and mountainous part. The northern part of the country is located in the valley of the Middle Danube, the Sava River valley and the Tisza River valley. In the middle part of the country, the river valleys of the Drina, the Kolubara and the Morava are located. For the purposes of this research, the authors have used the annual precipitation data from 15 meteorological stations distributed throughout the Republic of Serbia. The data from these meteorological stations for the period between 1991 and 2019 has been provided by The Serbian Institute of Meteorology and Hydrology. This data has been used to calculate the annual amount of precipitation, and the trends in annual precipitation.

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DOI: 10.3897/jbgs.e73825

Authors: Peter Nojarov, Todor Arsov, Ivo Kalapov, Hristo Angelov

Abstract: This study reveals the effect of aerosols and water vapor on downward longwave radiation in the high mountain region of Musala peak, Bulgaria. The investigated period is 01/01/2017 (Jan. 1st 2017) – 30/09/2019 (Sep. 30th 2019). Statistical methods are the main tool for discovering the relationships between the different elements. The results indicate that air temperature is the leading factor for downward longwave radiation, specific humidity, and amount of aerosols in the air. That is why, in order to reveal the pure relationship between downward longwave radiation, specific humidity and amount of aerosols in the atmosphere, the air temperature was cleared from the data series. After this procedure, the results show that specific humidity has a significant influence on the downward longwave radiation flux, and an increase of 1% of the specific humidity results in an increase of about 12-15% in the values of the downward longwave radiation. At air temperatures around 0ºC the influence of water vapor on the downward longwave flux is highest, which is due to the phase transitions of the water – a process during which release/absorption of radiation in the longwave spectrum occurs. The amount of aerosols in the atmosphere also has a significant effect on this type of radiation, and an increase of 1% of the amount of aerosols in the air at air temperatures above –5.5°C results in an increase of the downward longwave radiation of about 2-4%. The findings of this study show that coarser and opaque aerosol particles have a stronger effect on downward longwave radiation. In the area of Musala peak, as the air temperature rises, there is an increase in the amount of aerosols in the air, a decrease in their size, and a transition from transparent to opaque aerosols. The combination of these different tendencies causes the influence of aerosols on downward longwave radiation to be strongest in the middle temperature interval – air temperatures between –5.5°C and +5.5°C. Due to the increased total amount of aerosols and increased amount of opaque aerosols, their influence on downward longwave radiation is significant also at air temperatures above 5.5°C.

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DOI: 10.3897/jbgs.e68982

Authors: Emil Gachev

Abstract: Periglacial landforms are typical features of the high mountain environment on the Balkan Peninsula. Their formation and diversity is determined by climatic, topographic and geological factors. Presently active periglacial processes occur above 1700-2000 m a. s. l., while relict features are observed down to 1100-1400 m a. s. l. Among the most prominent periglacial landforms are the extensive talus screes and fans, the numerous rock glaciers (especially in Rila, Pirin, Shar and Prokletije Mountains) – considered mostly relict – and nivation features (nivation cirques, long-lasting snow patches), as well as cryo-clastuc landforms (stone seas and strips). The present study aims to focus on the importance of geological conditions (bedrock composition and structure, tectonic settings) for the diversity and style of periglacial landforms – a factor, whose role has often been underestimated. The analysis and the derived conclusions are based mainly on regional and local comparisons between the high mountains throughout the peninsula.

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DOI: 10.3897/jbgs.e66377

Authors: Borislav Grigorov, Nikolay Velev, Assen Assenov, Momchil Nazarov, Mladen Gramatikov, Beloslava Genova, Kiril Vassilev

Abstract: The current research focuses on the investigation of shrubland vegetation in Dragoman municipality. The study is motivated by the willingness of the authors to check the shrubland habitats’ territorial extent and their importance to ecosystem processes, following the increased degree of succession over the last three decades. On the other hand, governmental subsidizing has been common for the last decade, leading to a clearance of lands with shrubs. Shrublands were studied through the application of the Braun-Blanquet approach and were defined by the European Nature Information System (EUNIS) classification. One main habitat type with three subtypes have been defined. Those are the Subcontinental and continental deciduous thickets (F3.24) that covers the largest area, Peri-Pannonic dwarf almond scrub (F3.24122), Moesian oriental hornbeam thickets (F3.2431), Moesian lilac thickets (F3.2432), covering a total area of 52.32 km2. Secondary succession has to be considered among the main reasons for shrubland distribution. The lower number of grazing animals and forest clearings act as boosters for this ecological process. Large areas in Dragoman municipality are characterized also by shallow soils that are unable to sustain forest vegetation, thus giving way to shrubs.

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DOI: 10.3897/jbgs.e68981

Authors: Stoyan Nedkov, John Pickles, Kliment Naydenov, Hristina Prodanova

Abstract: The Journal of Bulgarian Geographical Society was the first scientific geographical journal in the country established in 1933. During the long period of its development, it became a leading journal for publishing scientific results in geography and related interdisciplinary fields in Bulgaria. Geography of the 21st century is expected to contribute to the development of human capital and the knowledge society, to offer place-specific solutions for sustainable regional development and use of the planet’s natural and human capital. One of the main goals of the Bulgarian Geographical Society is to stimulate the geographic community to search for smart spatial solutions which can contribute to meet the challenges of modern society. The Journal of the Bulgarian Geographical Society will contribute to the achievement of this goal by providing a platform for scientists in the main fields of geography and the interrelated sciences as well as decision-makers, and the interested public to share their knowledge in an efficient and open manner. In these days of continuous speeding up of paces of work and life, the idea of facilitating the sharing of existing knowledge in order to create synergies, new knowledge, and innovation is more than timely and our journal can join the efforts to achieve these goals.

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DOI: 10.3897/jbgs.2020.43.17

Authors: Stoyan Nedkov, Hristina Prodanova, Kliment Naydenov

Abstract: The article presents a comprehensive historical review of the development of “Journal of the Bulgarian Geographical Society” since its establishment, and points out the perspectives that lie ahead. We highlighted three periods of development of the journal: First (1933–1943), Second (1953–1993), and Third (2018–2020) based on key moments within the life-cycle of the Society caused by various socio-political situations in Bulgaria across time. We conducted the review following several key points: (1) periodization; (2) analysis of the publications based on the publishing language, types of the articles, and the major research topics; (3) expansion of the editorial board; and (4) design of the journal including its format, cover and paper layout. We pointed out a few challenges in the present state of the publication process in Bulgaria within the geographic community in particular, and gave valuable recommendations on how to deal with them in the light of the global tendencies in the academic publishing process. For the future development of the journal, we have marked major goals and changes that will lead to improving the quality of the geographic publications in the country. They are as follows: building a journal management concept, determination of the focus and scope, types and characteristics of the publications, and improvement of the graphic design. In conclusion, we highlighted the strengths and the weaknesses of the past development of the journal, and underlined the new changes, which will give the journal an international recognition.

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DOI: 10.3897/jbgs.2020.43.11

Authors: Stefan Petrov, Ivan Drenovski

Abstract: Air as a component of the natural environment is subjected to constant pollution caused by anthropogenic impact. Air can be considered polluted when the concentration of pollutants is higher than in a normal environment and this leads to a deterioration of the ambient air quality. This problem is also relevant for the region of Vidin and the town of Vidin in particular. Every year the city holds one of the highest ranks for the most polluted air in Bulgaria, even though the city has not been a place with a developed industrial activity that can be linked to air pollution for years. This report aims at identifying the causes of pollution and whether the measures taken in the “Programme for reducing the levels of PM10 and reaching the established norms of their content in the air in the region of Vidin for the period 2015-2020” are effectively implemented.

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DOI: 10.3897/jbgs.2020.43.4

Authors: Rumen Penin, Dimitar Zhelev

Abstract: The article depicts the biogeochemical properties of the landscapes in the area of the Ada Tepe gold mine (Krumovitsa River Catchment, Eastern Rhodopes) before its launching as an active ore-extraction site. The research is conducted by examination of heavy metals content in particular samples of representative native plant species in the local landscapes. The conducted research surveyed the content of 7 chemical elements (heavy metals) in the tissues of native plants from the landscapes in the Eastern Rhodopes. These microelements are generally prioritized in terms of environmental protection. The interpretation of the obtain results was made by applying the Coefficient of Biological Absorption (Ax). It is as a result of the proportions between the chemical content in the plant tissue (lx) and the chemical content in the local soil/bedrock (nx). By default, this coefficient represents the absorption (and accumulation) intensity of chemical elements in the plants.

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DOI: 10.3897/jbgs.2020.43.3

Authors: Milka Asenova

Abstract: In the present article, there are investigated, analyzed and interpreted opportunities for geoecological education activities in out-of-school environment. Didactic aspect is the principle of homeland studying, which allows realization of associative connections and consideration, evaluation and understanding of the student’s surroundings in order to form personal qualities as responsibility, environmentally friendly behaviour, care for nature and its resources. A generalized variant of geoecological homeland science in non-formal training on environmental protection has been developed as a version of pedagogical technology for formation of basic skills of the teacher for planning, organizing and conducting educational process in integrative environment.

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DOI: 10.3897/jbgs.2020.43.6

Authors: Lachezar Filchev

Abstract: In the article is made an overview of the application of different satellite remote sensing methods and technologies in detection of the abiotic stress in coniferous landscapes. The review paper is discussing in short the application of different remote sensing technologies such as: satellite multispectral and infrared (thermal), imaging spectrometry and fluorescence imaging. The studied period spans from the onset of the satellite remote sensing in the 1960s until present day. In conclusion, are drawn requirements for the perspective technologies in satellite remote sensing which should address the fast and reliable detection of the manifestation of abiotic stress in coniferous landscapes.

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DOI: 10.3897/jbgs.2020.43.10

Authors: Alexander Yanakiev

Abstract: Rapid development of remote sensing technologies, including the introduction of new sensors and platforms opened up a whole new field of their application such as monitoring of vulnerable habitats without direct contact, bearing potential harm of the ecosystems within them. The paper explores such opportunities and looks at the conditions of riverine forests along Kamchia river in 2019, using Sentinel-2a, b imagery.

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DOI: 10.3897/jbgs.2020.43.13

Authors: Mariya Petrova

Abstract: The term synergetic is proposed by the german physicist Henry Hacken as the name of a new interdisciplinary scientific field studying the processes of origin and evolution of space-time structures. The main task of synergetics is to reveal the general ideas, methods and patterns of self-organization processes in various fields of science - from nature science to the humanities. Synergetics seeks to reveal the internal mechanisms of self-organization, the general laws of these processes, their synergy. In landscape synergetics, the problem of time is related to the irreversibility of processes, which leads to the idea of instability and chaos. In this regard, the present study is aimed at exploring the possibility of using the synergetic approach in landscape research, and in particular in the study of self-restoration of landscapes after the weakening of anthropogenization.

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DOI: 10.3897/jbgs.2020.43.12

Authors: Tzanko Tzankov, Svetla Stankova

Abstract: The article represents the author’s contemporary mobility concept about the morphotectonic nature of the South Moesian Morphostructural Zone in North Bulgaria. The mentioned morphounit corresponds with the Moesian Continental Microplate South Margin between Timok River to the west and Kamchia River to the east. The north boundary of the zone coincides with fault bundle system along the Lower Danube River between Timok River Infuse to the west and the town of Cherna Voda to the east and between the towns of Cherna Voda and Constantsa in Nord Dobrudzha. The south boundary of the zone is following on the north slopes of the Fore Balkan and Stara Planina Mountain Ranges. The short west boundary near the Timok River separates the zone from the Carpathian Continental Microplate. The east zonal boundary limits it from the Black Sea Oceanic Microplate. The South Moesian Morphostructural Zone is representing one of the most contemporary fragments from the large post Early Pleistocene Orthoplain in the Balkan Peninsula North-East Part. It plane-lowland zonal relief contrasts with the relief of the neighbor first-rare morphotectonic units. The internal zonal pattern includes the Lower Danube Morphostructural Area (with Lom and Lovech Morphostructural Regions) and Ludogorie Morphostructural Area (with Isperih, Shumen and Dobrich Morphostructural Regions). The South Moesian Morphostructural Zone is a north part of the Maestrichtian-Early Neozoic Morphotectonic Suture between the Bulgarian and Moesian Continental Microplates during the New Europe Continental Massif Building. The till today continued Gondwana-New Europe Transcontinental Collision in the Mediterranean Region has bring very intensive Post Early Pleistocene Orthoplain Destruction and high mountain relief building (Rila, Pirin, Rhodope Mountain Massifs) in the Bulgarian Continental Microplate South-West Parts. The mentioned collision has causes the Fore Balkan and Stara Planina Syncinematic Uplifting in the suture zone between the Bulgarian and Moesian Continenta Microplates to. The South Moesian Morphostructural Zone has stay unaffected from those morphotectonic processes.

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DOI: 10.3897/jbgs.2020.43.2

Authors: Kristina Gartsiyanova, Marian Varbanov, Atanas Kitev, Stefan Genchev, Stela Georgieva

Abstract: In this article the current changes in the water quality of rivers Topolnitsa and Luda Yana have been analyzed and evaluated. The river basins are under the significant anthropogenic impact of various origins and nature. The main sources of pollution, the emitted substances and the spatiotemporal features of the change of the water quality are determined. Several indices for complex assessment of river waters have been used to assess the status of water - (Water Quality Index - Canada; Water Pollution Index - Russia; Chemical Index for River Water Quality (CJ) - Germany).

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DOI: 10.3897/jbgs.2020.42.2

Authors: Georgi Zhelezov, Mariyana Nikolova

Abstract: This article aims to fill the honorary place, which is laid on the founder of the Bulgarian Geographic Science, Acad. Anastas Ishirkov, in this collection of papers, but also to highlight some lesser known details of his research, socio-political and charitable activities. At the same time, the authors removed some inaccuracies in his biography accumulated over time and added new information about his life and activity. This was made possible by our research in the Archive of the Bulgarian Academy of Sciences, and from the materials for him in the Gipson Archive, as well as by the careful reading of the handwritten autobiography of Acad. Ishirkov.

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DOI: 10.3897/jbgs.2020.42.7

Authors: Velimira Stoyanova

Abstract: The present paper is dedicated to the life and scientific work of Corresponding Member of the Bulgarian Academy of Sciences Professor Kiril Mishev Ivanov because of the 15th anniversary of his death in 2020. The article focuses on his background and family, his education and professional career. An overview of his renowned and significant scientific publications is made.

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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.2020.42.16

Authors: Zornitza Cholakova

Abstract: The article is dedicated to a scientist who has contributed to the establishment and development of landscape science in Bulgaria. Associate Professor PhD Mimoza Konteva worked in the Department of Landscape Ecology and Environmental Protection at the Faculty of Geology and Geography at Sofia University “St. Kliment Ohridski” throughout her whole scientific and teaching experience. She created about 70 scientific papers, participated in numerous scientific and educational projects, successfully advised more than 30 graduates and 2 doctoral students, worked for the promotion of geographical science in higher and secondary education in Bulgaria. Leading lecturer in the courses “Physical Geography of Continents”, “Landscape Ecology”, “Physical Geography of the Balkan Peninsula” and others. A long-term member of the editorial board of the Sofia University Yearbook, Faculty of Geology and Geography, vol. 2 - Geography. She was a good leader and an active member of the geographic community at Sofia University and the Bulgarian Geographical Society.

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DOI: 10.3897/jbgs.2020.42.15

Authors: Angel Velchev

Abstract: This paper reviews the life and creativity of one of the most famous Bulgarian geographers of 20th century – Prof. Petar Penchev. He is the founder of the genetic branch of the Bulgarian Hydrology. His scientific works are related to the problems of the karst hydrology, genetic contents of water flow, methodology for mapping of hydrological objects. He creates the first hydrological regionalization of Bulgaria.

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DOI: 10.3897/jbgs.2020.42.14

Authors: Zoya Mateeva

Abstract: This study is dedicated to the bioclimatic studies of Prof. DSc Haralampi Tishkov concerning the mountainous territories of the country. The work presents the basic methods covered in the bioclimatic approach of these studies, namely the complex climatic method, the method for studying the stability of weather classes and the degree of contrast of their changes, as well as the method for assessing the degree of suitability for stay of person outdoors. The work provides an overview of the results obtained from the application of these methods to vast sub-mountain and mountain areas in the country, covering hypsometric belts through 200 m starting from 200 m asl. and reaching 2800 m asl.

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DOI: 10.3897/jbgs.2020.42.13

Authors: Bistra Vekilska

Abstract: Based on the review and analysis of existing scientific publications in the Bulgarian literature on geography and climatology, the present paper provides main biographical information about Prof. Dimitar Dimitrov and highlights his contributions in the field of climatology and geography. The article also presents the author's personal assessment of the scientific and teaching activities of Prof. Dimitar Dimitrov as a weather forecaster, climatologist and geographer.

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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.2020.42.11

Authors: Georgi Zhelev, Alexander Gikov, Eugenia Roumenina

Abstract: This paper presents the biography of the scientist Professor DSc Hernani Borisov Spiridonov. July 2020 marks the 85th anniversary of his birth. His scientific achievements are related to geomorphology, geotectonics and the development remote sensing methods, He is one of the founders of the scientific major Remote Sensing of the Earth from Space in Bulgaria.

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DOI: 10.3897/jbgs.2020.42.10

Authors: Yulia Kroumova, Vladimir Vlaskov, Valentin Nikolov

Abstract: The article is dedicated to the creative path and the scientific heritage of Prof. Ivan Vaptsarov – one of the remarkable scientists for the Bulgarian geography of the last century. The experience during the professional development from technician-geologist to professor and director of the Institute of Geography is accompanied by a research precision and focused interest in geomorphology, geology and physical geography. In this respect, original are the researches on the contemporary relief genesis and evolution, on the ore-controlling morphostructures of Southern Bulgaria, on the denudation surfaces number and age, as well as on the genesis of the piedmonts surfaces of the "glasis" type. As a leader of many large scientific teams and an initiator of large-scale projects, Prof. Ivan Vaptsarov successfully unites the highly professional knowledge on structural geomorphology and on geomorphological mapping with the qualities of a skilful administrator and a prominent and valorous geographer.

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DOI: 10.3897/jbgs.2020.42.9

Authors: Emilia Tcherkezova

Abstract: Prof. PhD Dinyo Dimitrov Kanev was one of the most distinguished Bulgarian scientists and university lecturers in geomorphology of Bulgaria and the Balkan Peninsula. The paper presents prof. Kanev’s main scientific works. On the basis of their analysis, they have been grouped into books, maps and atlases, as well as publications related to various thematic topics, e.g. investigations of denudation surfaces, the impact of the base level of erosion on the relief development, studies of the geomorphological evolution of various areas in Bulgaria, morphostructures and morphostructural development of Bulgaria’s relief, the neotectonic movements and their geomorphological response, studies of the volcanic relief in Bulgaria, as well as analysis of the seismic activity and the impact of the relief on the seismic effects, etc. Other works, such as ones related to the problems of the geomorphological investigations in Bulgaria, the geomorphological specifics of the Main Watershed of the Balkan Peninsula, the relation between relief and recreational resources, etc., have also been presented in the paper. Additionaly, the contributions of Prof. PhD Dinyo Kanev to the establishment of section “Geomorphology and Cartography” (now “Climatology, Hydrology and Geomorphology”) in the Faculty of Geology and Geography at the Sofioter University “St. Kl. Ohridski”, Sofia and to the development of geomorphology and cartography as scientific fields in Bulgaria are highlighted.

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DOI: 10.3897/jbgs.2020.42.8

Authors: Angel Velchev

Abstract: Assoc. Prof. Martin Glovnia works on the problems of the relief in high mountainous areas, especially the glaciation and periglacial zones with appearance of cryogen processes. He publishes many learning books for students in the universities and high schools.

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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.2020.42.1

Authors: Mariyana Nikolova

Abstract: The article traces the development of geographic research in Bulgarian Academy of Sciences since the creation of the Bulgarian Literary Society until today. The purpose of this study is to show that from the time of historical and political vicissitudes in Bulgaria after the Liberation, the Bulgarian geographic science has always been at the height of the public needs and its achievements was highly valued by world geographical community and the Bulgarian state. The development of geographic science after the establishment of the Institute of Geography at Bulgarian Academy of Sciences was traced in three conditional periods of development, which shows the strong influence of the socio-political changes in the country on the priorities and objectives of the geographical research.

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DOI: 10.3897/jbgs.2019.41.4

Authors: Alexander Gikov

Abstract: Maps of contemporary landscapes for 1966, 1980, 1997 and 2016 in key area "Bogdaia" have been made by processing and visual interpretation of historical aerial photographs and recent satellite imagery. The identified changes in the study area show that there is a clear trend of increasing the area of forest landscapes and decreasing the area of grass landscapes which are of secondary origin. For the same period, the transitional forest-shrub landscapes show fluctuations without a clear trend. The restoration of natural forest landscapes is explained by the changed land use and the almost complete lack of grazing in recent years. The process of natural forest landscapes restoration is more active in the coniferous landscape belt and on slopes with northern exposure while in the lower deciduous belt and on slopes with southern exposure component it is slower.

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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.2019.41.1

Authors: Tzanko Tzankov, Svetla Stankova, Rosen Iliev, Ilia Mitkov

Abstract: The Complex Morphostructural Passages are the first rare negative morphostructural units in the Late Quaternary (Late Pleistocene- Holocene) Relief of the Balkan Peninsula East Part. They are composed by morphostructural passages, kettle morphostructures, morhostructural thresholds, river valley morphostructures and morphostructural gorges. The mentioned negative compound morphounits present the contemporary relicts from the post Early Pleistocene Orthoplain Denudation or Denudation-accumulative Plane. The Complex Morphostructural Passages participle together with the younger positive dome-like and mountain arched morphostructures in the contemporary relief building.

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DOI: 10.3897/jbgs.2019.41.18

Authors: Pelo Mihaylov

Abstract: Prof. Anastas Ishirkov, apart from a remarkable scientist, was also a good writer. Only recently did it become known that he was among the first tourists to have climbed Cherni Vrah in August 1894. The object of the article is Ishirkov's other talent – painting. A small drawing on a postcard is testified to him. An unknown archivist considers Anastas Ishirkov as its creator. Because of this, in the only one account to his authorship the adjective ’unproven’ is used. And his pictorial talent, albeit a little, is already known, as the watercolor have already been seen by a considerable number of people. The drawing is a seal of a lifetime of Bulgarian students in Leipzig. Memorable texts testify that an important part of the student's being was formed by the picnics on Sunday in the vicinity of the city. Among the characters of the painting are the poet Pencho Slaveikov, the lawyer Joseph Fadenhecht, the author of the Bulgarian anthem Tsvetan Radoslavov and Ishirkov himself. Two pictures also show the recipient of the card – Ivan Ivanchev from Lovech. It is possible that unsigned cartoons in the humorous newspaper „Farkat List“ are also the result of the drawing talent of Anastas Ishirkov.

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DOI: 10.3897/jbgs.2019.41.6

Authors: Veselin Boyadzhiev, Neli Veselinova, Vasil Zarkov

Abstract: The theme of the article is from the historical geography of Bulgaria. It reveals the complex interaction of human society in the past with the nature. The analysis is based on the relationship between natural and humanitarian geography. It helps to compare the past and the present day and, if it is necessary, conclusions to be used for the future. In this case, the mountain Sredna Gora is an environment for the creation and development of the ethnic diversity of the Bulgarian society. The article is oriented to the scientific researches, but also to the authors of textbooks, to the teachers and to all who love the bulgarian nature.

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DOI: 10.3897/jbgs.2019.41.5

Authors: Kamen Nam, Ilia Tamburadzhiev

Abstract: The present research covers the lowland part of the catchment area of Luda Yana River. This is those part of the catchment area of the river, which is in the range of Pazardzhik-Plovdiv field. Object of research are the contemporary landscapes in the lowland part of the catchment area of Luda Yana River. Subject of research are the processes of differentiating and classifying the anthropogenic landscapes in the considered area and determining the degree of anthropogenization of the landscapes. The differentiation of the landscapes is carried out by the interaction between the landscape-forming factors – the natural components and the types of land use. The classification of the landscapes used in the present research is based on the information in the European Landscape Character Areas. There are differentiated 17 types of landscapes in the studied area. The determining of the degree of anthropogenization is realized by implementing the "Distance to Nature" compiled indicator, which is calculated by the combination of the individual indicators „Degree of Naturalness” and „Distance to Natural Habitat”. A map of the contemporary landscapes in the lowland part of the catchment area of Luda Yana River, representing the degree of naturalness of the types of landscapes, is generated in GIS.

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DOI: 10.3897/jbgs.2019.41.3

Authors: Mariya Petrova

Abstract: Field surveying and mapping of anthropogenic landscapes, their analysis, and modelling of the complex processes and structure that are formed in them are all relevant questions in contemporary landscape studies. Numerous territories can be observed in our country where, after reducing or terminating of the anthropogenic activity, landscapes that were impacted to various degrees by human activity start gradually restoring to their previous state, having, however, a modified structure with specific complexity. The present piece of research deals with some theoretical and methodological aspects of the study of the self-restoration of anthropogenic landscapes in Bulgaria.

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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.2019.40.5

Authors: Galin Petrov, Hristina Prodanova

Abstract: The names of geographical objects on a particular area are peculiar store for conservation of historical-geographical information. Typical versatility of the toponymic system gives possibility for usage of different approaches for analysis of it, including spatial analysis. Information for state of natural environments and their changes is coded in the toponymic system. Historical localization of landscapes with coniferous vegetation on the northern slopes of Shipchenska Mountain (Balkan Mountains, Bulgaria) on toponymic basis is presented in the article. Some conclusions about probability for existence of coniferous belt in the past are formulated. The study is an initial attempt to build a link between toponymy and onomastics on the one hand and historical geography of landscapes on the other. The used approach has some weaknesses and could be used successfully in combination with the results of other studies such as paleobotanical, paleoecological, etc.

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DOI: 10.3897/jbgs.2019.40.3

Authors: Kalin Seymenov

Abstract: The study of high flow characteristics within the Alpine catchments represents one of the most challenging tasks for the modern hydrological science, because of high vulnerability response of these areas to the global and regional climate changes, including to the proven positive air temperature trends. The current picture of the hydro-climatic processes in the Rila Mountain – the highest mount within the Balkan Peninsula, is not exception. Study area covers eight Alpine catchment areas, located above 1600 m sea level in the Rila Mountain. The aim of this research is to perform a spatio-temporal analysis of the extremely high streamflow characteristics within the researched drainage basins. Study period includes six years in the beginning of the XXІ century: there are very dry (2001), very wet (2005) and four normal water years. The analysis is based of Threshold level method (TLM) with fixed constant threshold value: 5th percentile of all discharge daily data for the given term. Results obtained show the number of extremely high streamflow events ranges from 6 to 26 – for the catchments of the Stara River at Kostenets and the Blagoevgradska Bistritsa River at Bistritsa, respectively. The maximal duration of these events varies from 15 (for the Mesta River at Yakoruda) do 39 days (the Stara River at Kostenets), but the oneweek extremely high flow periods are most typical here (a frecquency to 88% of all cases). The temporal analysis shows a concentration of studied hydrological events during the spring season (in the months of April, May and June), when occurs also a high streamflow phase, due to the snow melting and rainfalls. An exception of this statement is the wettest year in Bulgaria from the beginning of this century – 2005. Then because of heavy prolonged rainfalls during the months of July, August and September, were detected sharp peaks of the hydrographs. Present work establishes some spatial differences of extremely high flow characteristics (time of occurring, duration, frequency) in study area due to the slopes exposition peculiarities. Results obtained supplement previous scientific works and give new information about the risk hydrological processes within the mountainous catchment areas in Bulgaria.

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DOI: 10.3897/jbgs.2019.40.1

Authors: Emil Gachev, Predrag Djurović, Krasimir Stoyanov, Galina Bezinskа, Miroslav Ivanov, Stefan Petrov

Abstract: The article presents the latest views about the origin of Hridsko lake in the mountain range Bogicevica, an eastern part of Prokletije massif (Dinaric range). Previous studies define the lake, which is situated at 1980 m a. s. l., and occupies an area about 3,5 ha, as a cirque lake, formed after the retreat of wuermian glaciers following the classical mechanism of glacial lakes formation. In result of our researches, which started in 2013, a new hypothesis evolved that the lake lies inside a large relict rock glacier, formed in the period after the termination of glaciers, which means that the lake depression has a rather periglacial origin. The new bathymetry mapping of the lake done in 2017 provides a support to this hypothesis.

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DOI: 10.3897/jbgs.2018.39.15

Authors: Assen Assenov, Borislav Grigorov

Abstract: The current study investigates the development of the land cover in the mountainous territory of Mala Planina, located in the western part of Stara Planina. It focuses on cameral and terrain research in which basis is the CORINE Land Cover (CLC), initiated by the European Union. All existing databases for the country were applied (CLC 1990, 2000, 2006 and 2012). Each updated version of the CLC data shows typical transformation in Mala Planina’s land cover. A thorough investigation is made about all parts of the mountain and published within the results. Four GIS derived maps are published. The results show that the most significant dissonance occurs between CLC 1990 and the rest CORINE Land Cover data sets (CLC 2000; 2006; 2012) and the reason for the imparity lies mainly in the extensive timeframe. Almost no distinction is observed, when we compare CLC 2006 and 2012. The most common changes are connected with the transition to land principally occupied by agriculture, with significant areas of natural vegetation, which is explained by the decreasing number of population and abandonment of the agricultural areas.

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DOI: 10.3897/jbgs.2018.39.10

Authors: Alexander Peychev

Abstract: The object of the study is separate territory with natural boundaries - the water catchment of the river Struma. Within these limits is digitized (in the environment of GIS) soil map of Bulgaria (S 1:200000). Рolygons of 18 different soil types are established. From large-scale (S 1:10000 and S 1:25000) soil survey of the country is extracted and processed a large database of both characteristics – soil texture and humus content. With generalized data on these characteristics the identified 18 polygons are filled. Two thematic maps are composed. Area distribution of soil (classified according to two studied characteristics) is established.

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DOI: 10.3897/jbgs.2018.39.7

Authors: Rumen Penin, Dimitar Zhelev

Abstract: The mud volcanoes in the valley of the Sazliyka River and its tributaries are a geological phenomenon that has attracted scientific attention for decades. They are a specific element for the local lowland landscapes. This study focuses on the content of heavy metals in mud volcanoes. The total content of the elements: copper (Cu), zinc (Zn), lead (Pb), manganese (Mn), nickel (Ni), cobalt (Co) and chromium (Cr) in mg/kg (ppm) has been identified. The obtained contents have been analyzed by the clarke of concentration indicator (KK) - the ratio between the content of a given element in a given natural component (soil horizon, vegetation, surface water, etc.) - Ci, and a clarke of the same element in the lithosphere - K: The researched geochemical nature of the local litho-geochemical and soil-geochemical conditions may have been influenced by the geochemical specifics of the materials entering the earth’s surface upon activation of mud volcanoes in the area of study. They might have an impact on the geochemical structure of the bottom sediments in the local river currents and hence the influence on the main river artery Sazliyka River. The obtained results give to some extent information about the geochemical nature of this rare phenomenon for our country.

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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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DOI: 10.3897/jbgs.2018.39.4

Authors: Alexandar Sarafov, Emilia Tcherkezova

Abstract: This paper presents the results of soil investigation in the archaeological site 27 near the settlement Kapitan Andreevo (SE Bulgaria). The following soil types are recognized: Fluvisols, Vertisols, Luvisols and Planosols. Their spatial distribution is closely related to the Pliocene facial surface that consists of erosion, abrasion and accumulative deposits in the region and presents a transitional zone in the investigated archaeological area.These circumstances depend on the terrain and climate conditions over thousands of years and have determined the mosaic nature of the three soil types. The results support the archaeological investigation in the study area and were additionally filled with GIS-based analysis of the Digital Terrain Model (DTM) using open software GRASS GIS.

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