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• Assessing data quality of remotely-sensed DEM's in hungarian sample area

  42-47

  Gergely Szabó

  Nikoletta Mecser

  Anita Karika

  Views:

  55

  Nowadays the free-access digital elevation models are getting more and more popular. The SRTM and ASTER GDEM databases are the most widespread. However, there are numerous situations and weaknesses we have to take into account during their usage, such as direction-dependent accuracy and difference between digital and real surfaces. Our goal was to examine these kinds of deficiencies of surface models.

• Morphometric changes of the River Bodrog from the late 18th century to 2006

  28-40

  Nikoletta Mecser

  Gábor Demeter

  Gergely Szabó

  Views:

  40

  The river regulations of the 19th century have affected each of our rivers to a different degree. In the case of the River Bodrog it was stronger than the average. In our paper a section of the river between Bodroghalász and Szegi was examined, the extent and intensity of river channel changes was intended to be determined. The applied series of maps and aerial photos was georeferred and the river channel was vectorized. The morphometric parameters of the channel were measured and the changes were evaluated using the created database. From methodological aspect we concluded that the 9 variables can be grouped into 3 factors therefore most of the indexes can be substituted. We measured the changes of length and lateral shift of the channel using GIS methods. Three development periods were identified based on our results. In the first period the development of the river was characterized by natural processes. Then, the development of the river altered owing to the antropogenic impacts. In this transient phase the average shifting of the channel was 7.43 m/y. In the third term this value reduces to 0.2 m/y as the river is getting to reach the equilibrium stage.

• UAS photogrammetry and object-based image analysis (GEOBIA): erosion monitoring at the Kazár badland, Hungary

  169-178

  László Bertalan

  Zoltán Túri

  Gergely Szabó

  Views:

  264

  A remarkable badland valley is situated near Kazár, NE-Hungary, where rhyolite tuff outcrops as greyish white cliffs and white barren patches. The landform is shaped by gully and rill erosion processes. We performed a preliminary state UAS survey and created a digital surface model and ortophotograph. The flight was operated with manual control in order to perform a more optimal coverage of the aerial images. The overhanging forests induced overexposed photographs due to the higher contrast with the bare tuff surface. The multiresolution segmentation method allowed us to classify the ortophotograph and separate the tuff surface and the vegetation. The applied methods and final datasets in combination with the subsequent surveys will be used for detecting the recent erosional processes of the Kazár badland.