DEM based examination of pediment levels: a case study in Bükkalja, Hungary (original) (raw)
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Hungarian geographical bulletin, 2022
Units with extremely variable erodibility are typical in the succession of pyroclastic-dominated volcanic fields. Welded ignimbrites are usually resistant to erosion, thus, they often appear as positive landforms, i.e., mesas or tilted plateaus after millions of years of denudation. The Bükkalja Volcanic Area being part of the most extended foothill area of the North Hungarian Mountains, is composed predominantly of Miocene ignimbrites, where the frequency distributions of elevation a.s.l., slope, aspect, as well as topographic openness, were investigated using a 30 m resolution SRTM-based digital surface model at four sample areas located at different relative distances from the assumed source localities of the ignimbrites, showing both non-welded and welded facies. The degree of dissection was also examined along swath profiles. The topography of the sample area closest to the source localities is dominated by slabs of moderately dissected welded ignimbrites, gently dipping towards SE. Farther away from the source the topography is dominated by erosional valleys and ridges, resulting in a narrower typical elevation range, a higher proportion of pixels with greater than 5° slope, higher frequencies of NE and SW exposures, and more significant incision resulted in more frequent pixels with positive topographic openness less than 1.5 radians here. Higher thicknesses and emplacement temperatures of ignimbrites, often showing welded facies are more common closer to the source vent. Thus, the erosional pattern around calderas can be used to draw conclusions on the spatial extent of the most intense ignimbrite accumulation, i.e., the location of eruption centres even in highly eroded ignimbrite fields.
DEM based morphotectonical analysis of the Kisgyőr Basin (Bükk Mts – Hungary)
Acta Montanistica Slovaca, 2021
The south-eastern part of the Bükk Mountains and the eastern side of its foothill, the Bükkalja are among the less explored regions of Hungary. Based on our examinations on the field, we found that the asymmetrical valley sections, the tipped escarpments and the formation of the Kisgyőr Basin cannot be explained by the differences in the rock quality. The asymmetrical shape of these landforms and the stream captures identified in the research area indicate significant structural geological changes. In our work, we proved the asymmetry in the topography by performing swath profile analysis, and we also examined the elevation data of the areas covered by the welded ignimbrites of the Tar Dacite Tuff Formation. The results confirmed our field observations. We found that, contrary to the results of previous research, the geological structural processes played a fundamental role in the formation of the Kisgyőr Basin and its surroundings.
Geomorphology, 2004
A complex application of digital elevation model (DEM) derivatives is presented for a highly degraded volcanic area, the Miocene Börzsöny Mountains, Hungary. We propose unconventional geometrical and mathematical transformations of the original DEM data in order to enhance the topographic features of the volcanic relief that stem from the primary landforms. It is the actual ridges that represent the least degraded surfaces of an original, hypothetical volcanic cone. Therefore, the statistical DEM properties such as ridge pattern (1), slope angle distribution (2) and higher-order slope derivatives (3) should be strongly correlated with the paleosurface. Automated creation of a ridge pattern image is based on the local histogram of the DEM, and helps to outline the original surface remnants. A local slope angle histogram may point out structurally coherent parts of the original cone: for instance, tectonic displacements or large-scale sector slumping does not affect the slope angle histogram of the original relief. Evaluating the ridge maps and slope aspect maps of the Börzsöny Mountains allows various cone sectors to be identified and connected to the original volcano-structural elements. Finally, the polar coordinate-transformed (PCT) image (4) centered on a hypothesized eruptive vent enhances the original, radial valley pattern. In the case of multiple eruptive centers and/or post-eruptive tectonic modifications, the radial pattern is changed, which may be evidenced in the PCT image. In fact, the PCT image analysis for the Börzsöny Mountains suggests a complex post-eruptive tectonic scenario. The presented methods can be recommended to infer the original configuration of highly degraded volcanic structures with poorly known tectonic and erosional history. D
The quantification of petrophysical features instead of descriptive characterisation and the identification of relationships between geomorphic and geological factors has always been of key importance not only in engineering but in geomorphology as well (KAWABATA ET AL. 2001, . This study aims to investigate the relationship between geomorphic and geological endowments based on a wide-scale database using geoinformatics with the aid of statistical methods such as correlation, regression analysis and cluster analysis, and to quantify the rock resistance to erosion by combining and comparing traditional experiments and investigations applied mainly in engineering. The adaptibility and reliability of these methods in measuring rock strength was also investigated.
International Journal of Applied Earth Observation and Geoinformation, 2005
A procedure for the consistent application of digital terrain analysis methods to identify tectonic phenomena from geomorphology is developed and presented through two case studies. Based on the study of landforms related to faults, geomorphological characteristics are translated into mathematical and numerical algorithms. Topographic features represented by digital elevation models of the test areas were extracted, described and interpreted in terms of structural geology and geomorphology. Digital terrain modelling was carried out by means of the combined use of: (1) numerical differential geometry methods, (2) digital drainage network analysis, (3) digital geomorphometry, (4) digital image processing, (5) lineament extraction and analysis, (6) spatial and statistical analysis and (7) digital elevation model-specific digital methods, such as shaded relief models, digital cross-sections and 3D surface modelling. A sequential modelling scheme was developed and implemented to analyse two selected study sites, in Hungary and NW Greece on local and regional scales. Structural information from other sources, such as geological and geophysical maps, remotely sensed images and field observations were analysed with geographic information system techniques. Digital terrain analysis methods applied in the proposed way in this study could extract morphotectonic features from DEMs along known faults and they contributed to the tectonic interpretation of the study areas. #
Landside Problem and Its Investigations in Miskolc (Hungary)
Engineering Geology for Society and Territory - Volume 5, 2014
The importance of Cultural Heritage has emerged since the early 1970s, including cultural, natural and mixed properties. Hungary is also one of those countries having great properties of importance such as historical castles, settlements, wine cellars. Northern Hungary has good advantage to develop man-made structures such as wine-cellars. The developments of wine cellars in Northern-Hungary were due to the suitable geological conditions, the social and the economical expectations in the 15th or 16th century. Recent rapid urban development and the population growth is causing damages within the infrastructures both on and under the surface that emerges geotechnical and engineering geological solution. In the city centre of Miskolc (Hungary) can be found the Avas hill, which contains more than 530 underground wine cellars and a church registered as a cultural heritage built in the 13th century. The hill is composed of late Badenian-mid Sarmatian (13.7-12.5 million years) acid dust tuff, variably bentonitic rhyolite tuff, and re-worked sandstone, intercalated placer and extraclastic andesite tuff. This article aims to reveal the cultural importance of the Avashill where reconstruction works should take place. The geological framework of the area significantly aggravates the stability problems, which is due to the heterogeneous geological strata. Identifying each layers in geotechnical aspects a 'bimrock' type of rock was found within the strata. Matrix and block contrast of the bimrock can define the behavior of this type of rock either under the surface or in outcrops. Our aims, to determine its rock mass and geotechnical classification and identify each bimrocks according to their matrix content as well as investigate its role within the geological strata. The heterogeneity of the hill reveals the question whether the poor geological characteristic of the rocks mainly determine the stability of the hill.
Environmental Geology, 2009
A digital terrain model and a 3D fly-through model of the Nigde province in central Anatolia, Turkey were generated and quantitatively analyzed employing the shuttle radar topographic mission (SRTM) digital elevation model (DEM). Besides, stream drainage patterns, lineaments and structural-geological features were extracted and analyzed. In the process of analyzing and interpreting the DEM for landforms, criteria such as color and color tones (attributes of heights), topography (shaded DEM and 3D fly-through model) and stream drainage patterns were employed to acquire geo-information about the land, such as hydrologic, geomorphologic, topographic and tectonic structures. In this study, the SRTM DEM data of the study region were experimentally used for both DEM classification and quantitative analysis of the digital terrain model. The results of the DEM classification are: (1) low plain including the plains of Bor and Altunhisar (20.7%); (2) high plain including the Misli (Konakli) plain (28.8%); (3) plateau plain including the Melendiz (Ciftlik) plateau plain (1.0%); (4) mountain including the Nigde massif (33.3%); and (5) high mountain (16.2%). High mountain areas include a caldera complex of Mt Melendiz, Mt Hasan and Mt Pozanti apart from the Ala mountains called Aladaglar and the Bolkar mountains called Bolkarlar in the study region (7,312 km 2 ). Analysis of both the stream drainage patterns and the lineaments revealed that the Nigde province has a valley zone called Karasu valley zone (KVZ) or Nigde valley zone (NVZ), where settlements and agricultural plains, particularly the Bor plain in addition to settlements of the Bor town and the central city of Nigde have the most flooding risk when a heavy raining occurs. The study revealed that the NVZ diagonally divides the study region roughly into two equal parts, heading from northeast to southwest. According to the map created in this study, the right side of the NVZ has more mountainous area, where the Aladaglar is a wildlife national park consisting of many species of fauna and flora whereas the left side of the NVZ has more agricultural plain, with exception of a caldera complex of Mt Melendiz and volcanic Mt Hasan. The south of the study region includes the Bolkarlar. In addition, the Ecemis fault zone (EFZ) lying along the Ecemis rivulet, running from north to south at the west side of the Aladaglar, forms the most important and sensitive location in the region in terms of the tectonics.
Geomorphology, 2019
Travertines are continental carbonates that precipitate from spring waters, mainly due to CO 2 degassing. They are widely quarried as building stone, which has led to numerous (often abandoned) travertine quarry outcrops. These and other outcrops, however, merely represent the surface expressions of the complex architecture of travertine bodies and their deep-rooted feeding systems. Integration of field observations and geochemical analyses with crucial subsurface geophysical data is required in order to fully understand travertine systems and their relationship to the local geological framework. Such a multi-methodological approach is illustrated here for the case of the abandoned Cukor quarry. Radio-magnetotelluric (RMT) and Electrical Resistivity Tomography (ERT) surveys provide unique insights into local tectonics, geobody architecture and the topography preceding travertine deposition. Altogether, the lens-shaped, isolated domal geobody with spring-proximal lithofacies and subvertical bedding, in addition to the contrasting geochemistry and age with surrounding travertine, enabled the unequivocal reconstruction of the dismantled Cukor fissure ridge. This study illustrates the high potential of this multi-methodological approach on poorly exposed, strongly weathered, quarried and tectonically deformed travertine bodies, and provides information on the complex feeding system beneath travertine deposits. Their reconstruction can be interpreted in light of the neo-tectonic expression of regional uplift, helps to complete the regional tectonic history and provides insights into older landscapes that lack preservation or would no longer be immediately recognized at the surface.