Pub Date : 2022-11-01DOI: 10.52215/rev.bgs.2022.83.2.11
D. Antonov, Aglaida Toteva, S. Kolev, A. Benderev, M. Trayanova, P. Andreeva, K. Ivanova, Simeon Valchev
Natural radon (222Rn) is a radioactive noble gas that occurs in every rock or soil due to the content of radium (226Ra), part of the 238U family, in the lithosphere. One of the indicators for evaluating the impact of radon on a certain area/terrain, including on the biota, is the so-called geogenic radon potential. Different types of rocks and soils possess different 226Ra content and different permeability. Radon gas has high mobility and is driven by diffusion and convection with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Therefore the geogenic radon potential at the surface could be affected by the geological settings as a content of uranium and also by the hydrogeological settings as a degree of saturation near the surface. The present study mainly deals with the different by genesis shallow groundwater in Bulgaria based on the published since 1960’s sources. After analysis of the collected data several distinct regions have been determined regarding lithological and geomorphological conditions, and the 0–3 m depth of the groundwater table. In addition, a GIS-based map was elaborated relating the rocks with expected geogenic radon potential and shallow groundwater areas.
{"title":"Impact of the geological and hydrogeological settings on the radon potential \u0000in Bulgaria","authors":"D. Antonov, Aglaida Toteva, S. Kolev, A. Benderev, M. Trayanova, P. Andreeva, K. Ivanova, Simeon Valchev","doi":"10.52215/rev.bgs.2022.83.2.11","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.2.11","url":null,"abstract":"Natural radon (222Rn) is a radioactive noble gas that occurs in every rock or soil due to the content of radium (226Ra), part of the 238U family, in the lithosphere. One of the indicators for evaluating the impact of radon on a certain area/terrain, including on the biota, is the so-called geogenic radon potential. Different types of rocks and soils possess different 226Ra content and different permeability. Radon gas has high mobility and is driven by diffusion and convection with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Therefore the geogenic radon potential at the surface could be affected by the geological settings as a content of uranium and also by the hydrogeological settings as a degree of saturation near the surface. The present study mainly deals with the different by genesis shallow groundwater in Bulgaria based on the published since 1960’s sources. After analysis of the collected data several distinct regions have been determined regarding lithological and geomorphological conditions, and the 0–3 m depth of the groundwater table. In addition, a GIS-based map was elaborated relating the rocks with expected geogenic radon potential and shallow groundwater areas.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42410512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.52215/rev.bgs.2022.83.2.17
E. Koleva-Rekalova, N. Dobrev, Rosen Nankin
This article aims to present the results of geotechnical studies of the main rock complexes that compose the periphery of the Dobrudzha Plateau in the area from Cape Kaliakra to Cape Shabla (Bulgarian Black Sea Coast), directly related to the development of hazardous geological processes. Sediments of the Sarmatian age were studied: carbonate tempestites, Mactra limestones (Karvuna Formation), nubecular (foraminiferal), reef and bioclastic limestones (Odartsi Formation). The corresponding microscopic and petrographic analyses of the studied sediments are also presented. Studies of collapses in caves near Cape Kaliakra show that they occur in friable peloidal limestones, with disturbances following stratification. This is confirmed by laboratory tests of samples showing lower strength indicators, namely in the direction to the layering. The results of laboratory tests of specimens from the sections between the village of Tyulenovo and Cape Shabla, including foraminiferal, reef and bioclastic limestones, show higher values of physical and mechanical parameters compared to limestones at Cape Kaliakra. In the case of the bioclastic limestones, higher strengths are found crosswise to the layering, and in the case of compressive strength, the ratio is double. The obtained data provide valuable information about the engineering geological parameters of the main varieties in which the rock deformations are developed, which can be used in the analysis of slope stability.
{"title":"Sedimentological and engineering geological features of the Sarmatian limestones along the Black Sea Coast between the capes of Kaliakra \u0000and Shabla","authors":"E. Koleva-Rekalova, N. Dobrev, Rosen Nankin","doi":"10.52215/rev.bgs.2022.83.2.17","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.2.17","url":null,"abstract":"This article aims to present the results of geotechnical studies of the main rock complexes that compose the periphery of the Dobrudzha Plateau in the area from Cape Kaliakra to Cape Shabla (Bulgarian Black Sea Coast), directly related to the development of hazardous geological processes. Sediments of the Sarmatian age were studied: carbonate tempestites, Mactra limestones (Karvuna Formation), nubecular (foraminiferal), reef and bioclastic limestones (Odartsi Formation). The corresponding microscopic and petrographic analyses of the studied sediments are also presented.\u0000Studies of collapses in caves near Cape Kaliakra show that they occur in friable peloidal limestones, with disturbances following stratification. This is confirmed by laboratory tests of samples showing lower strength indicators, namely in the direction to the layering. The results of laboratory tests of specimens from the sections between the village of Tyulenovo and Cape Shabla, including foraminiferal, reef and bioclastic limestones, show higher values of physical and mechanical parameters compared to limestones at Cape Kaliakra. In the case of the bioclastic limestones, higher strengths are found crosswise to the layering, and in the case of compressive strength, the ratio is double.\u0000The obtained data provide valuable information about the engineering geological parameters of the main varieties in which the rock deformations are developed, which can be used in the analysis of slope stability.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49201816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.52215/rev.bgs.2022.83.2.3
T. Ganchev, Valentina P. Markova, Ivalena Valcheva-Georgieva, I. Dobrev
We present the results from the first large-scale study on pollution in the Varna Lake sediments, which was implemented in two preselected zones with significant importance for developing economic activities and urban planning. Based on 140 probes, we developed a digital map of the pollution gradients in these zones. The sediment analysis shows that the pollution levels at specific locations significantly exceed the international standards for contamination with heavy metals and petroleum products. The reported pollution concentrations can be linked to various contamination sources, such as rivers, ports, the chemical industry, and WWTPs (Waste water treatment plants), located on the shores of the lake. The high values of pollution with iron, copper, and petroleum product registered in the sediments of Lake Varna indicate the need for sustainable management of human activities in the area. The presented findings motivate urgent measures for cleaning and improving the ecological situation in Varna Lake, which is an integral part of the ecosystem of the city of Varna and other municipalities bordering the lake. The results of the study indicate that urgent action is needed to address the high risks associated with the observed sediment contamination.
{"title":"Assessment of pollution with heavy metals and petroleum products \u0000in the sediments of Varna Lake","authors":"T. Ganchev, Valentina P. Markova, Ivalena Valcheva-Georgieva, I. Dobrev","doi":"10.52215/rev.bgs.2022.83.2.3","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.2.3","url":null,"abstract":"We present the results from the first large-scale study on pollution in the Varna Lake sediments, which was implemented in two preselected zones with significant importance for developing economic activities and urban planning. Based on 140 probes, we developed a digital map of the pollution gradients in these zones. The sediment analysis shows that the pollution levels at specific locations significantly exceed the international standards for contamination with heavy metals and petroleum products. The reported pollution concentrations can be linked to various contamination sources, such as rivers, ports, the chemical industry, and WWTPs (Waste water treatment plants), located on the shores of the lake. The high values of pollution with iron, copper, and petroleum product registered in the sediments of Lake Varna indicate the need for sustainable management of human activities in the area. The presented findings motivate urgent measures for cleaning and improving the ecological situation in Varna Lake, which is an integral part of the ecosystem of the city of Varna and other municipalities bordering the lake. The results of the study indicate that urgent action is needed to address the high risks associated with the observed sediment contamination.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42287403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.52215/rev.bgs.2022.83.1.39
P. Gerginov, N. Stoyanov, S. Valtchev, A. Benderev
The regional hydrogeological conditions in Northern Bulgaria determine the existence of a large artesian basin consisting of layered aquifers. The groundwater temperature increase with depth and the conditions in the deeper layers are favourable for the formation of stratified hydrothermal reservoirs with potential for heat extraction. Although it was initiated in the 1980s, the utilization of this green energy resource is still in a pre-feasibility phase. The Upper Jurassic–Lower Cretaceous aquifer has the highest yield and it is the most prospective geothermal source in the multi-layered sedimentary complex in Central Northern Bulgaria. This study provides new understanding of the formation and potential for extraction of thermal energy from this stratum, which has all characteristics of a low temperature hydrothermal reservoir. The study includes delineation of its boundaries, evaluation of hydrogeological and thermal parameters and data on hydraulic connectivity. The flow and temperature fields, the elements of the water and heat balance, as well as the groundwater quality, have been assessed. The groundwater and thermal energy resources in the hydrothermal reservoir have been estimated on a regional scale, including a scenario with reinjection. Different options for potential utilization of the thermal energy using reinjection wells have been put forward.
{"title":"Heat potential of the Upper Jurassic–Lower Cretaceous aquifer in Central Northern Bulgaria: conditions and prospective use","authors":"P. Gerginov, N. Stoyanov, S. Valtchev, A. Benderev","doi":"10.52215/rev.bgs.2022.83.1.39","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.1.39","url":null,"abstract":"The regional hydrogeological conditions in Northern Bulgaria determine the existence of a large artesian basin consisting of layered aquifers. The groundwater temperature increase with depth and the conditions in the deeper layers are favourable for the formation of stratified hydrothermal reservoirs with potential for heat extraction. Although it was initiated in the 1980s, the utilization of this green energy resource is still in a pre-feasibility phase. The Upper Jurassic–Lower Cretaceous aquifer has the highest yield and it is the most prospective geothermal source in the multi-layered sedimentary complex in Central Northern Bulgaria. This study provides new understanding of the formation and potential for extraction of thermal energy from this stratum, which has all characteristics of a low temperature hydrothermal reservoir. The study includes delineation of its boundaries, evaluation of hydrogeological and thermal parameters and data on hydraulic connectivity. The flow and temperature fields, the elements of the water and heat balance, as well as the groundwater quality, have been assessed. The groundwater and thermal energy resources in the hydrothermal reservoir have been estimated on a regional scale, including a scenario with reinjection. Different options for potential utilization of the thermal energy using reinjection wells have been put forward.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48449064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.52215/rev.bgs.2022.83.1.27
V. Kostov-Kytin, P. Petrov, S. Encheva
The structure of a disordered IIb chromian clinochlore from the chromitites of Golyamo Kamenyane serpentinite (Eastern Rhodopes) was studied using Rietveld refinement techniques and powder X-ray diffraction (CuKα, 3–100° 2Θ in 0.013° 2Θ increments). The refinement in space group C–l yielded the following lattice parameters: a = 5.299(2) Å, b = 9.2625(5) Å, c = 14.4726(6) Å, α = 90.103(7)°, β = 97.191(13)°, γ = 90.320(11)°, and cell volume of 704.69(21) Å3. The structure of the studied mineral is characterized by a semi-random stacking of adjacent chlorite layers creating a situation in which not all atoms positions could be precisely located. Despite this limitation, the crystal chemical plausibility of the final structural model could be achieved due to the fact that most of the atomic positions (all octahedral cations and anions) repeat at intervals of ±b/3 and could be uniquely determined. The type of structural information that can be derived from the test compound and similar structurally related materials by applying the Rietveld method is discussed and ways to achieve this are considered.
{"title":"Rietveld refinement of chromian clinochlore from the chromitites of Golyamo Kamenyane serpentinite (Eastern Rhodopes)","authors":"V. Kostov-Kytin, P. Petrov, S. Encheva","doi":"10.52215/rev.bgs.2022.83.1.27","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.1.27","url":null,"abstract":"The structure of a disordered IIb chromian clinochlore from the chromitites of Golyamo Kamenyane serpentinite (Eastern Rhodopes) was studied using Rietveld refinement techniques and powder X-ray diffraction (CuKα, 3–100° 2Θ in 0.013° 2Θ increments). The refinement in space group C–l yielded the following lattice parameters: a = 5.299(2) Å, b = 9.2625(5) Å, c = 14.4726(6) Å, α = 90.103(7)°, β = 97.191(13)°, γ = 90.320(11)°, and cell volume of 704.69(21) Å3. The structure of the studied mineral is characterized by a semi-random stacking of adjacent chlorite layers creating a situation in which not all atoms positions could be precisely located. Despite this limitation, the crystal chemical plausibility of the final structural model could be achieved due to the fact that most of the atomic positions (all octahedral cations and anions) repeat at intervals of ±b/3 and could be uniquely determined. The type of structural information that can be derived from the test compound and similar structurally related materials by applying the Rietveld method is discussed and ways to achieve this are considered.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48477382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.52215/rev.bgs.2022.83.1.51
Y. Yanev
In the siliceous volcanoes, the transition between rhyolites and perlite is carried out through a zone with the following morphology: i) rhyolite balls (spheruloids with spherulitic or felsitic texture) among the perlites; ii) alternation of subparallel perlite and rhyolite bands with felsitic texture; iii) a combination of the above two morphologies – rhyolite bands with spheruloids adhering to them; iv) alternation of finger-like wedge-shaped perlite and rhyolite wedges. The rhyolite spheruloids have Na composition (they are composed of tridymite and Na-K feldspar), while the perlites including them, as well as all rhyolites in the Eastern Rhodopes, are potassic. This chemistry, as well as many morphological features, show their immiscibility origin, which has been recently proven also experimentally (Kotel’nikov et al., 2016, 2019). Complex spheruloids are also observed, which consist of two types of spheruloids with different distribu¬tion of alkalis in them: small, in which Na>K and large spheruloids, which include small ones and in which potassium predominates. It is assumed that they are a product of a two-step immiscibility – in the first step large drops and matrix are formed, and in the second the large drops decompose into small drops (enriched with Na) and a new matrix (enriched with potassium), which is the building element of the large drops. The drops crystallize as spherulites, while the matrix solidifies as perlite. The spheruloids are products of nucleation and growth mechanism, i.e. they are formed in the fields between the binodal and spinodal curves. The other type of transition – the alternation of perlite and rhyolite bands is assumed to be formed by the spinodal decomposition, i.e. in the field limited by the spinodal curves.
在硅质火山中，流纹岩和珍珠岩之间的过渡是通过一个具有以下形态的带进行的:1)在珍珠岩之间的流纹岩球(具有球粒或长晶石质地的球体);Ii)近平行的珍珠岩和流纹岩带交替存在，具有长绒质结构;Iii)上述两种形态的结合——流纹岩带上附着球状体;指状楔状珍珠岩与流纹岩楔的交替。流纹岩球粒由钾钾长石和钾钾长石组成，含钠球粒的珍珠岩以及东罗杜贝所有流纹岩均为钾质。这种化学性质以及许多形态特征显示了它们的非混溶性起源，这一点最近也得到了实验证明(Kotel 'nikov et al.， 2016, 2019)。还观察到复杂的球体，它由两种类型的球体组成，其中碱的分布不同:小球体，其中Na bbbbk和大球体，其中包括小球体，其中钾占主导地位。假设它们是两步不混溶的产物——第一步形成大液滴和基质，第二步大液滴分解成小液滴(富含Na)和新基质(富含钾)，这是大液滴的构建元素。液滴结晶为球晶，而基体凝固为珍珠岩。椭球体是在双节曲线和单节曲线之间的场中形成的，是形核和生长机制的产物。另一种类型的过渡-珍珠岩和流纹岩带的交替被认为是由旋多分解形成的，即在受旋多曲线限制的场中形成的。
{"title":"Rhyolite-perlite transition zone in the acid volcanoes of the Eastern Rhodopes Paleogene volcanic area (SE Bulgaria)","authors":"Y. Yanev","doi":"10.52215/rev.bgs.2022.83.1.51","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.1.51","url":null,"abstract":"In the siliceous volcanoes, the transition between rhyolites and perlite is carried out through a zone with the following morphology: i) rhyolite balls (spheruloids with spherulitic or felsitic texture) among the perlites; ii) alternation of subparallel perlite and rhyolite bands with felsitic texture; iii) a combination of the above two morphologies – rhyolite bands with spheruloids adhering to them; iv) alternation of finger-like wedge-shaped perlite and rhyolite wedges. The rhyolite spheruloids have Na composition (they are composed of tridymite and Na-K feldspar), while the perlites including them, as well as all rhyolites in the Eastern Rhodopes, are potassic. This chemistry, as well as many morphological features, show their immiscibility origin, which has been recently proven also experimentally (Kotel’nikov et al., 2016, 2019). Complex spheruloids are also observed, which consist of two types of spheruloids with different distribu¬tion of alkalis in them: small, in which Na>K and large spheruloids, which include small ones and in which potassium predominates. It is assumed that they are a product of a two-step immiscibility – in the first step large drops and matrix are formed, and in the second the large drops decompose into small drops (enriched with Na) and a new matrix (enriched with potassium), which is the building element of the large drops. The drops crystallize as spherulites, while the matrix solidifies as perlite. The spheruloids are products of nucleation and growth mechanism, i.e. they are formed in the fields between the binodal and spinodal curves. The other type of transition – the alternation of perlite and rhyolite bands is assumed to be formed by the spinodal decomposition, i.e. in the field limited by the spinodal curves.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42148958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.52215/rev.bgs.2022.83.1.15
P. Pavlishina
First record of early angiosperm pollen from the lower Aptian sediments in the Butovo section, Central North Bulgaria is documented. It is represented by monocolpate crotonoid grains attributed to the Stellatopollis genus and the species Stellatopollis barghoornii Doyle, Van Campo, Lugardon, 1975. The encountered sporomorph association also includes abundant gymnosperm pollen from the Classopollis and Araucariacites genera as well as a variety of pteridophyte spores from the Cretaceous genera Appendicisporites, Cicatricosisporites, Bikolisporites, Trilobosporites, Klukisporites and Deltoidospora. The palynological association indicates that the studied area was part of the ––Southern Laurasian floral province. The persistent record of pteriodophyte spores in the assemblages with the relatively abundant gymnosperm pollen from the Classopollis group suggests a warm and relatively less humid climate for this part of the province during the early Aptian. The results imply that early angiosperms still played minor role in lower Aptian Bulgarian floras.
{"title":"Palynomorphs from the Trambesh Formation, lower Aptian, Central North Bulgaria","authors":"P. Pavlishina","doi":"10.52215/rev.bgs.2022.83.1.15","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.1.15","url":null,"abstract":"First record of early angiosperm pollen from the lower Aptian sediments in the Butovo section, Central North Bulgaria is documented. It is represented by monocolpate crotonoid grains attributed to the Stellatopollis genus and the species Stellatopollis barghoornii Doyle, Van Campo, Lugardon, 1975. The encountered sporomorph association also includes abundant gymnosperm pollen from the Classopollis and Araucariacites genera as well as a variety of pteridophyte spores from the Cretaceous genera Appendicisporites, Cicatricosisporites, Bikolisporites, Trilobosporites, Klukisporites and Deltoidospora. The palynological association indicates that the studied area was part of the ––Southern Laurasian floral province. The persistent record of pteriodophyte spores in the assemblages with the relatively abundant gymnosperm pollen from the Classopollis group suggests a warm and relatively less humid climate for this part of the province during the early Aptian. The results imply that early angiosperms still played minor role in lower Aptian Bulgarian floras.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46434062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-01DOI: 10.52215/rev.bgs.2022.83.1.3
V. Nikolova, Milena Mitova, E. Dimitrov
Soil erosion is the most serious soil degradation factor on the territory of Bulgaria. Nearly 66 % of its area have slopes in a range greater than 3°. The predominant hilly-mountainous relief and high slope degrees are prerequisites for development of water erosion. The properties of the topographic surface as a conditioning factor of erosion processes are evaluated in the current study on the example of the Dzhebelska River watershed (Southern Bulgaria). The following morphometric parameters are considered: basin relief, Melton index, slope and stream power index (SPI). Slope length and steepness factor (LS factor) is calculated using the slope degree and specific contributing area. The values vary between 0 and 43.36. The results of the analysis of the morphometric parameters indicate high erosion susceptibility in the upper and the middle part of the watershed but active erosion can be observed too in the low part of the watershed, where first order streams (Strahler’s method) flows directly to the river of fifth order. The current study is done in GIS environment on the base of 12 m digital elevation model.
{"title":"Topographic factor of water erosion – analysis of watershed morphometry and RUSLE LS factor in GIS environment","authors":"V. Nikolova, Milena Mitova, E. Dimitrov","doi":"10.52215/rev.bgs.2022.83.1.3","DOIUrl":"https://doi.org/10.52215/rev.bgs.2022.83.1.3","url":null,"abstract":"Soil erosion is the most serious soil degradation factor on the territory of Bulgaria. Nearly 66 % of its area have slopes in a range greater than 3°. The predominant hilly-mountainous relief and high slope degrees are prerequisites for development of water erosion. The properties of the topographic surface as a conditioning factor of erosion processes are evaluated in the current study on the example of the Dzhebelska River watershed (Southern Bulgaria). The following morphometric parameters are considered: basin relief, Melton index, slope and stream power index (SPI). Slope length and steepness factor (LS factor) is calculated using the slope degree and specific contributing area. The values vary between 0 and 43.36. The results of the analysis of the morphometric parameters indicate high erosion susceptibility in the upper and the middle part of the watershed but active erosion can be observed too in the low part of the watershed, where first order streams (Strahler’s method) flows directly to the river of fifth order. The current study is done in GIS environment on the base of 12 m digital elevation model.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42210955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-01DOI: 10.52215/rev.bgs.2021.82.3.91
Dian Strahilov, I. Dimitrov
The structural geological features defining the discontinuity network in metamorphic rocks hosting railway tunnels are described. Discussion on the faults, joints, lineation and stresses found from fault population is presented. It is demonstrated that the formation of some brittle joints is related to the ductile stretching lineation. The geotechnical situation for the tunnel construction is complicated and requires reassessment of the design solutions in order to accommodate substantial lateral forces and prevent shear of the tubes.
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Pub Date : 2021-12-01DOI: 10.52215/rev.bgs.2021.82.3.129
B. Valchev, H. Dimitrov
Based on lithostratigraphic reinterpretation of five borehole sections and lithostratigraphic interpretation of two seismic profiles, new data on the Dvoynitsa Formation’s lithology, subdivision and spatial distribution were obtained. The Armera and Gebesh Members were recognized in the area of the villages of Solnik and Bardarevo, as their spatial relationships and distribution are visualized by drawing up of four geological cross-sections.
{"title":"New data on the stratigraphy of the Paleogene in Solnik area, Eastern Bulgaria","authors":"B. Valchev, H. Dimitrov","doi":"10.52215/rev.bgs.2021.82.3.129","DOIUrl":"https://doi.org/10.52215/rev.bgs.2021.82.3.129","url":null,"abstract":"Based on lithostratigraphic reinterpretation of five borehole sections and lithostratigraphic interpretation of two seismic profiles, new data on the Dvoynitsa Formation’s lithology, subdivision and spatial distribution were obtained. The Armera and Gebesh Members were recognized in the area of the villages of Solnik and Bardarevo, as their spatial relationships and distribution are visualized by drawing up of four geological cross-sections.","PeriodicalId":40733,"journal":{"name":"Spisanie Na B Lgarskoto Geologichesko Druzhestov-Review of the Bulgarian Geological Society","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46503183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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