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Over the past decades, in the mountainous, hilly and/or urban areas of Hungary several high-intensity storms were followed by severe flash flooding and other hydrologic consequences. The overall aim of this paper was to upgrade the national flash flood susceptibility map of Hungary first published by Czigány et al. (2011). One elementary watershed level (FFSIws) and three settlement level flash flood susceptibility maps (FFSIs) were constructed using 13 environmental factors that influence flash flood generation. FFSI maps were verified by 2,677 documented flash flood events. In total, 5,458 watersheds were delineated. Almost exactly 10% of all delineated watersheds were included into the category of extreme susceptibility. While the number of the mean-based FFSIs demonstrated a normal quasi-Gaussian distribution with very low percentages in the quintile of low and extreme categories, the maximum-based FFSIs overemphasized the proportion of settlements of high and extreme susceptibility. These two categories combined accounted for more than 50% of all settlements. The highest accuracy at 59.02% for class 5 (highest susceptibility) was found for the majority based FFSIs. The current map has been improved compared to the former one in terms of (i) a higher number of conditional factors considered, (ii) higher resolution, (iii) being settlement-based and (iv) a higher number of events used for verification.

Small catchments in mountainous regions affect downstream rivers as a primary source of sediment supply and also generate flash swasfloods, especially during extreme events. These floods have significantly shaped the catchments of small streams in the Mecsek Hills and some rural areas over the past two decades. However, there has been no previous study examining the hydromorphology of headwater catchments in low mountain environments in Hungary. The present study was meant to investigate the fundamental hydrogeomorphological properties of a first-order catchment. A customary and detailed GIS survey of 50-metre sections was aimed at deciphering flash flood vulnerability and geomorphic interrelations within a micro-watershed. We found moderate susceptibility to flash floods compared to the whole Mecsek Hills. Stable large woody debris jams were identified during the field survey as major geomorphic channel features functioning as natural barriers which drive channel evolution and reduce flood hazards. [ABSTRACT FROM AUTHOR]

As a tool for high precision deformation monitoring in broader areas, interferometric (In- SAR) time series of space-born Synthetic aperture radar (SAR) imagery are used. Nowadays, ERS, Envisat archives and Sentinel-1 images are open for the public to analyse slow moving landslides activated between 1990 and 2017. Since Sentinel-1 satellites are considered to be the workhorse of EO by the ESA during next decades, it is important to assess its applicability in landslide monitoring and mapping. In this paper, the southern part of Dunaszekcső village was analysed with PSI interferometric stacking algorithm, using SAR imagery. The advantages and limitations of the applied interferometric stacking techniques and sensors have been analysed, such as the movement history of the test site between 1992 and 2017. It was proven that Sentinel-1 PSI scatterers far exceeds the spatial coverage obtained by earlier sensors. Two orbital geometries of Sentinel-1 enabled larger spatial coverage and extract 2D displacements. The comparison of the two geometries, however, was only possible for small surfaces in the area of interest. The displacement data in the central part of the study site indicate the subsidence of the sliding block along the escarpment and in the east its movement towards the Danube. This displacement then triggered the uplift of the floodplain edges, or generated a slight eastward displacement. [ABSTRACT FROM AUTHOR]

Modern geomorphological analyses largely benefit from GIS tools developed for landform and landscape mapping. Semi-automated methods with the use of public domain elevation datasets ensure the mapping of large areas with relatively low time and cost requirements, leaving less space for subjectivity. For our analysis we chose the geomorphons approach, a robust cell-based method to identify landform elements at a broad range of scales. Based on the delineated landforms and auxiliary morphometric parameters it was possible to map the geomorphological landscapes occurring in Hungary with the supervised classification algorithm implemented in the GeoPAT toolset. The scientific output of the presented work is twofold: one aspect is the creation of an objective and quantifiable map of landforms and geomorphic landscapes of Hungary, while the successful application of the available methodology and the evaluation of SRTM1 model's applicability for geomorphological purposes are also significant results. [ABSTRACT FROM AUTHOR]

Wedge structures and involutions suggest that Late Pleistocene frozen ground, either permafrost or deep seasonal frost, extended at least as far south as latitude 47° N in central Europe (the Pannonian Basin). Optically stimulated luminescence dating of the sand infill from a number of wedges indicates that emplacement of the sand infill occurred during the Late Pleistocene (22.2-15.7 ka). This suggests that during this time the mean annual air temperature was depressed by at least ∼15° C relative to the present. Either continuous or discontinuous permafrost was probably present in the north and NW of the Pannonian Basin. The subsequent thaw of frozen ground is indicated by the widespread occurrence of deformed sediments. The presence of soil (ground) wedges suggests conditions of deep seasonal frost probably existed during the period when climate ameliorated following the Last Permafrost Maximum ( LPM). [ABSTRACT FROM AUTHOR]

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