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Analysis of landscape geographic impacts of potential climate change in Hungary
41-50Views:153Change of climate can be a remarkable turning point in the 21st century history of mankind. An important task of landscape geographic research is forecasting environmental, nature protection, land use demands and helping mitigation of disadvantageous processes from the aspect of society. ALADIN and REMO numeric climate models predict strong warming and lack of summer precipitation for the area of Hungary for the period between 2021 and 2100. There is a predicted growth in frequency of extreme weather events (heat waves, droughts hailstorms). Changes have been forecasted using data presented in table 1. For analyses of complex landscape geographic impacts of climate change the area of Hungary have been divided into 18 mesoregions with 5.000-10.000 km2 area each (figure 1). The main aspect of choosing the regions was that they should have homogeneous physical, geographic and land use endowments and, for this reason, they should react to climate change the same way. Relationships between landscape forming factors and meteorological elements examined by us have been taken into consideration. Results of analyses of impacts of the meteorological factors on the changes of relief through the mass movements are presented in this paper. Changes of landscape sensibility of mesoregions to mass movements have been presented in the last chapter for the periods between 2021-2050 and 2071-2100 according to numeric climate models.
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Investigation of the wind power potential of the Hernád valley
93-107Views:45The University of Debrecen, Department of Meteorology has carried out research into the climatic and social-economic conditions of the Hernád valley in the scope of a scientific project (OTKA K 75794) between 2009 and 2012. The aim is to find out the optimal area for wind and solar energy, as well as biomass utilization. Our purpose is to work out a model wherein the complex evaluation of natural and social-economic conditions and effects can eventually result in a sustainable and conflictfree land use. The results of the research will be useful in working out a regional improvement based on the use of renewable energy sources to help the local decision-making process.
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Studying floodplain roughness in an Upper Tisza study area
85-90Views:200Floods slowing down due to the significant decrease of the gradient have considerable sediment accumulation capacity in the floodplain. The grade of accumulation is further increased if the width of the floodplain is not uniform as water flowing out of the narrow sections diverge and its speed is decreased. Surface roughness in a study area of 492 hectares in the Upper Tisza region was analysed based on CIR (color-infrared) orthophotos from 2007. An NDVI index layer was created first on which object-based image segmentation and threshold-based image classification were performed. The study area is dominated by land cover / land use types (grassland-shrubs, forest) with high roughness values. It was concluded that vegetation activity based analyses on their own are not enough for determining floodplain roughness.
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Morphological grouping of fossil floodplain forms in the northeastern part of the Pannonian plain
21-33Views:40The Bereg Plain is located in the northeastern part of the Pannonian Plain, close to the Carpathian Mountains. Clarification of the evolution of its topography is essential for the development of the whole area. The former single alluvial cone has been fragmented, some parts of it subsiding and others rising. The displacements of the subsided parts of the area were dominated by erosion processes, as in the Bereg Plain. As a consequence, a significant part of the sand in the area has been degraded and only traces of it remain in the Bereg Plain. The existing sand patches have been identified and classified using DEM. In the area identified 10 floodplain islands not yet mentioned in the scientific literature. The investigation of the numerous islands – hitherto unknown and be-longing to different morphological types – enabled us a reconstruction of the surface development of the Bereg Plain that is more differentiated and precise than ever before. Based on their morphogenetic properties, these floodplain islands can be divided into three main types: (1) erosion islands, (2) point-bars, (3) coastal dunes. In the area, I could recognize no pattern or re-gularity in the position of the individual forms of any type. In many cases, the direction of the longitudinal trends is perpendicular to one another, which excludes their Aeolian origin. The sediment of the floodplain islands mainly consists of medium-, small- and fine-sized sand, but the settlement of loess-mantled and loess-like layers among the sandy sediment of certain forms can also be observed. The layer with 15 % lime content and 53–60 % loess fraction (0.05–0.01 mm) – found in the 110–50 cm high section of the erosion island called the Homok-tanya in Mátyus – can be considered a typical loess, based on the detailed parameters. Its formation in all probability took place at the same time and under similar conditions than that of the more than 2 m thick aeolian loess mantle found in the Nyírség area, some 10 km west from there, which had accumulated before the Bölling period. In case of an erosion island 2.5 km to the south and lying some 2 m lower, such a loess mantle cannot be found anymore, despite the fact that the sandy layers of the two sediment series are almost completely identical. The background of this phenomenon is the more active and frequent, mainly erosional fluvial processes – because of the lower position –, which eroded the loess mantle. The composition of the surface sediments is de-termined by the absolute altitude as well. The cover sediment of the lower-lying islands is identical to the finishing silt-clay deposits found at the alluvial parts of the Bereg Plain, whereas the surface of higher-lying forms that have not seen flood for ages, is covered by sand or loessy sand.
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Accumulation studies at specific sampling areas of the active floodplain in the Upper-Tisza region
14-22Views:179In this paper the rate of accumulation was studied along four VO floodplain cross sections of the UpperTisza region between 1974 and 2014. VO floodplain cross sections are based on a mapping base-point grid (established in 1890), and they are located a few kilometers from each other. Furthermore, the roughness changes of different surface types, crossed by the VO floodplain cross-sections, were also determined between 1965 and 2015. The accumulation studies were extended to include the accumulation rates of the cut off meanders located along and/or close to the VO cross-sections. The roughness values increased in all four floodplain VO cross-sections since 1965; in two of them it reached or approximated 100 %. The average accumulation along the VO cross-sections was between 28 and 47 cm (0.73–1.23 cm/year) during the 38-year period. However, its areal distribution showed large differences. The highest values (169–309 cm, i.e. 4.44–8.13 cm/year) were found at the lowest points of the cut off meanders and swales in every case. The accumulation rate of the examined three cut off meanders near the floodplain cross-sections (140 and 1570 meters from the river bed) was lower (0.84–2.5 cm/year), but the study period was significantly longer (154 and 161 years, respectively). Comparing the values of the two periods, it is obvious that the accumulation of the active floodplain accelerates, presumably due to the significant increase of surface roughness.