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This study deals with the possibilities of expertdriven semi-automated recognition of planation surfaces and other flat landforms in the area of the Aggtelek Karst, Hungary. Planation surfaces are the most debatable and vague landforms and can be defined as parts of terrain formed by long-lasting erosion-denudation processes under the stagnant erosion base conditions. In terms of denudation chronology they can be considered as morphological indicators of different evolution stages of area. In karst areas planation surfaces and river terraces are mostly correlated with cave levels, which originated in relation to the same stagnant erosion base. Because there is no general method of delineation of planation surfaces, the main objective of the study was to find a suitable method for semi-automated recognition of flat landforms in the Aggtelek Karst, which should correspond to different phases of the Jósva River incision and therefore could be correlated to the multilevel cave system of the study area. Several methods for semi-automated landform classification were tested for recognition of flat surfaces in a relatively objective way. Slope gradient thresholding tool, and r.param.scale and r.geomorphon modules implemented in GRASS GIS were tested. As a result, the r.geomorphon module was proven as the most suitable method for delineation of relatively flat surfaces. Findings of the presented work can be used as a morphological indicator of the comprehensive reconstruction of evolution of the Aggtelek Karst and the Slovak Karst.

Umbrisols generally develop in a cool and humid climate. Therefore, occurrence of these soils in the Borská lowland of southwestern Slovakia is very uncommon, and this inspired the aim of this paper: Analysis of the natural conditions suitable for Umbrisol development. Umbrisols in the Borská lowland developed from aeolian quartz sands accumulated on Neogenne marine clay sediments. Their occurrence is connected with the groundwater table relatively close to the ground surface and this particularly determines Umbrisol genesis in this area. Sufficient input via organic matter is an important factor for formation of the umbric horizon, and only the rich herbaceous undergrowth of the prevailing planted pine and mixed pine-oak forests is capable of providing it. A growth of diep-rooted grass is closely connected with higher soil moisture content, and quite moist areas occur in the deeper inter-dunes depressions. Constant soil moisture in these sites is facilitated by water capillary elevation. While Umbrisols are transformed to Arenosols at increased altitude, they can be transformed to Gleysols in deep depressions. Herein, induced polarization provided suitable geophysical method for detection of arenic Umbrisol inclusions. Sharp transformation of the humus layer to dry non-polarized aeolian quartz sands enabled the surface horizon to be distinguished by induced polarization

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Abstract:In this paper we analyse the dependence between gully networks, networks of valleys and faults in the area of Hronska pahorkatina Hill Land. The work is based on the analysis of directions and densities of these three networks in the study area and subunits of lower hierarchical level. The coincidence of all three networks is rare. This scenario occurs when networks of gullies are situated on the bottom of shallow valleys which are conditioned by the presence of faults. More often scenario is only the coincidence of network of valleys and gullies. The last scenario appears in areas with low fault density. The most specific scenario is perpendicularity between network of gullies and network of gullies. Gullies are situated on steep slopes of incised valleys in this case. The last scenario appears the most frequently and was also proven by findings from other studies. We propose three comprehensive explanations of the possible dependence between network of gullies and faults. We also suggest the draft of the possible dependence between network of valleys and gullies.

Erosion is a frequently studied natural process. Unfortunately, detailed analysis mostly requires longterm field monitoring or detailed digital elevation models (DEM) which are still absent for many areas. For these reasons we used the dendrogeomorphic method, a valuable tool for erosion analysis. The slopes of a~220 m long gully close to the Kozárovce village (Slovakia) were the object of our study. We analyzed 53 tree root samples coming from 16 broad-leaved trees of different species. 23 erosion event years were explored during the reconstruction period AD 1972-2013. The mean erosion rate E R was 1.00 cm/year. We were able to create four erosion patterns of slope erosion based on subsequent exposure of different parts of root. These erosion patterns serve as a base for a model of gully cross profile development. The highest values of erosion rate were reconstructed in the lowest parts of gully slopes. The gully sides formed by volcanic rocks are affected by lateral retreat here. Upward erosion dominates in the middle parts of slopes in loess, and downward erosion in the highest parts of the slopes.

Utilization of a new geomorphometric variable for land surface segmentation -the angle of absolute curvatures -is a main goal of the paper. The angle of absolute curvatures is defined as the difference between the orientation of maximal curvature (field independent) and the orientation of the greater of the profile or the tangential curvature. Land-forms separated by three types of borders (A, B, C) can be delimited from the field of angles of absolute curvatures. Borders of A type are connected with a local extreme of slope. Borders of B and C type are connected with a change to the priority of either profile or tangential curvature, as shown in computation, respectively. Fields of altitude, slope, profile curvature, tangential curvature and rotor curvature are reflected by an algorithm. Distinct borders in the field of the angles of absolute curvatures are connected with a sudden change of value and with zero isolines in the previously mentioned fields. Spatially closed entities generated by this proposed algorithm are considered to be a variant of the elementary forms of the land surface. The quality of information generated by this algorithm depends on the size of the grid mesh of the input digital elevation model. The algorithm in its current state is suitable for locating the borders of some elementary forms in the first stage of geomorphology mapping.

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