Articles

• Mapping aquatic vegetation of the Rakamaz-Tiszanagyfalui Nagy-Morotva using hyperspectral imagery

  1-10

  Péter Burai

  Gabriella Lövei

  Csaba Lénárt

  Ildikó Nagy

  Enyedi Enyedi

  Views:

  188

  Rapid development in remote sensing technologies provides more and more reliable methods for environmental assessment. For most wetlands, it is difficult to walk-in without disturbing the endangered species living there; therefore, application of opportunities provided by remote sensing has a great importance in population-mapping. One effective tool of vegetation pattern estimation is hyperspectral remote sensing, which can be used for association and species level mapping as well, due to high ground resolution. The Rakamaz-Tiszanagyfalui Nagy-morotva is an oxbow lake, located in the north-eastern part of Hungary. For this study, a wetland area of 1.17 km2 containing the original water bad and shoreline was selected. For the image analysis, images taken by an AISA DUAL system hyperspectral sensor were used. At the same time, 7 main vegetation classes were separated, which are typical for the sample plot designated on the test site. Classification was performed by the master areas signed by the most common associations of the Rakamaz-Tiszanagyfalui Nagy-morotva with determined spectrums. During the image analysis, SAM classification method was used, where radian values were optimized by the results of classification performed at the control area.

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  118

• The effect of aridification on dry and wet habitats of Illancs microregion, SW Great Hungarian Plain, Hungary

  11-22

  Zsuzsanna Ladányi

  Áron Deák

  János Rakonczai

  Views:

  111

  By the beginning of the 21st century, investigations aiming landscape history and landscape changes became especially important in the environmental research. The decreasing number of natural areas called the attention of the world to the rapid changes in the landscape caused by human activities and climate change. Certain places are facing with increased problems caused by the sensitiveness of landscapes. In Hungary, in the Danube–Tisza Interfluve a continuous groundwater-table sinking process was observed, as a result of anthropogenic effects of the last century and the consequences of climate change. On the highest part of this mesoregion (e. g. Illancs microregion), the decrease of the groundwater-level has reached 7 metres compared with the 1970s which affected significantly the nature and the local inhabitants as well. This study aimed to investigate the effect of this aridification process on dry and wet habitats of Illancs microregion. It reveals the ongoing processes in the landscape, referring to the previously affecting factors. In case of dry habitats, fragmentation and invasive species play important role as threatening factors. Wet habitats are significantly decreasing, shift of the vegetation zones can be observed. The stands are degraded, their steppification is dominant and can be observed only in the deepest parts of the depressions.

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  57

• Stream gradient investigation in the Bükkalja using interpolated surfaces

  23-36

  János Vágó

  Views:

  122

  The geological, tectonic settings of an area can be examined with the analysis of drainage network. In the Bükkalja, the Miocene pyroclasts – mainly the welded ignimbrites – had taken decisive part in the evolution of drainage network. For the confirmation of their role, the breakpoints of stream profiles were analysed. However this method provides information only about the direct surroundings of the creeks. In the aim of getting informations about the areas between the streams, surfaces were interpolated from stream gradient data and analysed as stream gradient maps. The stream gradient data were calculated with Hack J.T.’s formula, but due to the false results it was necessary to modify this formula and to recalculate the values. According to the map interpolated from the modified stream gradient values, there is a clearly identifiable relationship between the location of the welded ignimbrites on the surface, and the gradient values. Areas with high values are on the eastern part of the study area, where these pyroclasts can be found, while in the west, where the surface is covered by less resistant rock types, the gradient values are much lower.

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  80

• Unsupervised classification of high resolution satellite imagery by self-organizing neural network

  37-44

  Árpád Barsi

  Katalin Gáspár

  Zsuzsanna Szepessy

  Views:

  42

  The current paper discusses the importance of the modern high resolution satellite imagery. The acquired high amount of data must be processed by an efficient way, where the used Kohonen-type self-organizing map has been proven as a suitable tool. The paper gives an introduction to this interesting method. The tests have shown that the multispectral image information can be taken after a resampling step as neural network inputs, and then the derived network weights are able to evaluate the whole image with acceptable thematic accuracy.

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  39