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The spatial distribution of trace metals and metalloids in surface water bodies and their sediments caused by natural processes and human activities is a complex problem, due to the water importance for drinking water, irrigation, and industry. For this reason, the accurate mapping of those water bodies is from great importance. In this work, we used optical Sentinel-2A image data from 2021 (Copernicus European Union's Earth observation programme) to extract water bodies in two case study areas – the Ogosta Reservoir (Ogosta River) and the Danube River (Archaro-Orsoyska Lowland) based on the following water indices: second normalized water body index (NDWI 2), modified Normalized Water Body Index (MNDWI), Re-NDWI, AWEIsh and AWEInsch, as well as object-based image classification (OBIA). One of the challenges were to define threshold values of the water indices layers for binary maps creation to generate realistic water bodies maps. The obtained results were compared to the obrained data from OBIA analysis and highresolution data.

The study aimed to identify land cover and land use transformations in the Lom River valley to reveal how the pressure of agriculture on the environment in the southwestern part of the Lower Danube basin has changed over the last 60 years. The classes at the fourth level of the CORINE Land Cover nomenclature were mapped using aerial photographs of 1961, 1985 and 1998, complemented with a detailed orthophoto mosaic of 2019. While the changes in the main classes were relatively small over the years, the transformations of the land cover in the lower classes reached up to 60% of the study area at the end of the investigated period. We have identified constant trends of expanding pastures and shrinking labour-intensive crops such as vegetables, fruits, and vines over the past 60 years. The land cover classes were classified into four groups according to pesticides use and the related load of heavy metals for soil. Changes in land use suggest a reduction in the use of pesticides and less intensive accumulation of contaminant metals in the soil of the southwestern part of the Lower Danube Basin

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.

The purpose of this study is to categorise 21 groundwater monitoring points in the mining-affected valley of the Ogosta River in Northwestern Bulgaria according to the conditions for arsenic contamination of the alluvial aquifer. The grouping of the sites has been performed based on geochemical and geographical indicators using cluster analysis. Representative monitoring wells have been selected from each group so as to optimise the monitoring program and reduce the related expenditures. An attempt has been made to link the categories of piezometers to the main geomorphological features of the river floodplain and to certain levels of arsenic pollution of groundwater. The revealed patterns can be used for further examination of the link between arsenic dynamics and the geographical settings of the river floodplain. The established relationships are relevant to the environmental settings of a mountainous river of medium size under temperate climate conditions., Problems of Geography, 2020, Vol.1-2, p. 79-100

Database used to classify the distribution of the small-scale farms according to its structural to economic dimensions across Europe and at the scale of the NUTS-3 regions, and the respective results of the clustering process.Guiomar, N., Godinho, S., Pinto-Correia, T., Almeida, M., Bartolini, F., Bezák, P., Biró, M., Bjørkhaug, H., Bojnec, Š., Brunori, G., Czekaj, M., Davidova, S., Kania, J., Kristensen, S., Marraccini, E., Molnár, Zs., Niedermayr, J., O’Rourke, E., Ortiz-Miranda, D., Redman, M., Sipiläinen, T., Sooväli-Sepping, H., Šūmane, S., Surová, D., Tcherkezova, E., Tisenkopfs, T., Tsiligiridis, T., Tudor, M.M., Wagner, K., Wästfelt, A., 2018. Typology and distribution of small farms in Europe: towards a better picture. Land Use Policy 75: 784-798. doi: 10.1016/j.landusepol.2018.04.012

Настоящата статия представя резултатите от извършен ГИС-базиран анализ за идентифициране и екстрахиране на формите на релефа в Арчаро-Орсойската низина (Северозападна България). На базата на използваната методология, включваща цифров морфометричен анализ и ГИС функции за пространствен анализ са идентифицирани основните форми в изследвания район. Получените резултати са сравнени с предишни геоморфоложки изследвания и сателитни изображения и ще бъдат използвани за рекогносцировъчно изследване и геоморфоложка картировка с цел създаване на геоморфоложка класификация на генетичните типове форми и наслаги в изследвания район., Problems of Geography, 2019, Vol.3-4, p. 73-86

Статията представя резултатите от направен анализ на земното покритие и земеползване в района на водосборния басейн на р. Крумовица (Източни Родопи) спрямо локалните морфометрични променливи на релефа надморска височина, наклон и експозиция на склон и форма на склоновете. Използвани са данни за земното покритие и земеползване „КОРИНЕ 2012“. Получените резултати представят морфометрична характеристика на релефа по тези променливи и средните стойности на пространственото им разпределение за отделните класове земно покритие чрез използване на географски информационни системи (ГИС)., Problems of Geography, 2018, Vol.1-2, p. 125-138

This paper presents the results of computer based landform classification of the area between the settlement Gavril Genovo and the “Ogosta” reservoir (NW Bulgaria). Data obtained from Airborne Laser Scanning using RIEGL LMS Q680i long range and RIEGL VQ 820 G hydrographic airborne laser scanner with online waveform processing were used for generation of a precise Digital Terrain Model (DTM) 1x1 m. A methodological approach was proposed und tested for delineation of landform patterns in the floodplain. It includes delineation and cross classification of Topographic Classification Index for lowlands and Vertical Distance to Channel Network in 56 classes using SAGA GIS. In order to achieve more real landform units the result was reclassified in 26 classes and verified through field investigation after a flood event in April 2014. Other compound geomorphometric variables e.g. SAGA Wetness Index Multiresolution Index of Valley Bottom Flatness were calculated. The obtained result can be used for detailed geomorphologic field mapping and can be applied in areas with similar geomorphographic and geomorphologic conditions.

The paper is aimed at an analysis and comparison of two karst areas. Among common problems of both territories are: sewage of untreated waste water from settlements and industrial plants to the underground space, infiltration of fertilizers and pesticides to underground spaces during torrential rains, washing away the topsoil into the underground space. The main difference consist in geographical positions. Whereas Moravian Karts is situated in the vicinity of the regional center Brno and is partly a subject of suburbanization, Devetashko Plato marked depopulation tendencies. From it follows that Moravian Karst is under pressure of urbanization and tourism which compete with landscape protection. On the other side, Devetashko Plato area is not socially sustainable. These conditions create different approaches for the future management. In any case, the imaginations about the quantitative development should be abandoned. In both the cases the territories have to ensure sustainability in all three pillars: environmental, social and economic., Problems of Geography, 2016, Vol.3-4, p. 65-84

Database used to classify the distribution of the small-scale farms according to its structural to economic dimensions across Europe and at the scale of the NUTS-3 regions, and the respective results of the clustering process.Guiomar, N., Godinho, S., Pinto-Correia, T., Almeida, M., Bartolini, F., Bezák, P., Biró, M., Bjørkhaug, H., Bojnec, Š., Brunori, G., Czekaj, M., Davidova, S., Kania, J., Kristensen, S., Marraccini, E., Molnár, Zs., Niedermayr, J., O’Rourke, E., Ortiz-Miranda, D., Redman, M., Sipiläinen, T., Sooväli-Sepping, H., Šūmane, S., Surová, D., Tcherkezova, E., Tisenkopfs, T., Tsiligiridis, T., Tudor, M.M., Wagner, K., Wästfelt, A., 2018. Typology and distribution of small farms in Europe: towards a better picture. Land Use Policy 75: 784-798. doi: 10.1016/j.landusepol.2018.04.012

Database used to classify the distribution of the small-scale farms according to its structural to economic dimensions across Europe and at the scale of the NUTS-3 regions, and the respective results of the clustering process.Guiomar, N., Godinho, S., Pinto-Correia, T., Almeida, M., Bartolini, F., Bezák, P., Biró, M., Bjørkhaug, H., Bojnec, Š., Brunori, G., Czekaj, M., Davidova, S., Kania, J., Kristensen, S., Marraccini, E., Molnár, Zs., Niedermayr, J., O’Rourke, E., Ortiz-Miranda, D., Redman, M., Sipiläinen, T., Sooväli-Sepping, H., Šūmane, S., Surová, D., Tcherkezova, E., Tisenkopfs, T., Tsiligiridis, T., Tudor, M.M., Wagner, K., Wästfelt, A., 2018. Typology and distribution of small farms in Europe: towards a better picture. Land Use Policy 75: 784-798. doi: 10.1016/j.landusepol.2018.04.012