Grain Size Distribution of Stabilised Aeolian Dune Sediments in Inner Somogy, Hungary

In Inner Somogy the former researches concluded that the grain size of stabilised aeolian dunes decreases from north to south fitting to grain size distribution of the alluvial fan the dunes were built of and to the prevailing wind. However, the trend is not so evident, if considering the dune types and sand moving periods. The aim of this paper is to analyse the grain size distribution trends from the point of view of (1) different dune classes, (2) OSL age and (3) general morphological characteristics of the region. During the analysis the grain size distribution of 345 samples from 17 cores (120-300 cm in depth) was determined, and 15 OSL samples were dated. According to the results, the material of simple forms and level 1 dunes (these are the lowest dunes on the surface of the alluvial fan) becomes finer southward, in accordance with the structure of the alluvial fan and prevailing wind direction. Similar trend applies for level 2 dunes (which were formed on the top of level 1 dunes), but it does not apply for level 3 dunes, which are situated on the top of other dunes. It seems that the grain size is inversely proportional to the size of a dune and its age, thus younger and smaller dunes have coarser and less well sorted material. The sediments of the oldest, large parabolic dunes are the finest, younger, medium size parabolic forms have fine material, and the youngest hummocks contain the coarsest sand. The decreasing grain size towards south is the most apparent along longitudinal residual ridges, while within parabolic dunes the wings contain finer material than their elevated head

Mennyiben pontosíthatja a georadaros vizsgálat a homokterületek geomorfológiai kutatásának eredményeit? : Komplex tanulmány egy belső-somogyi homokbuckán = Can georadar surveying contribute to clarifying aeolian research results? : Complex study on a sand dune in Inner Somogy, Hungary

A complex geomorphological research was carried out on an aeolian sand dune in Inner Somogy, Hungary. Sedimentological analysis showed three layers of sediment composed of sand with differing characteristics (Györgyövics et al., 2014) which suggested at least 3 aeolian phases in the region. OSL dating of samples from the same boreholes confirmed these periods and determined that sand was deposited during the Late Glacial, the Dryases and Boreal phase (Kiss et al. 2012). However, carrying out a GPR survey revealedmuch more detailed structure of the particular dune. Comparing research results and applying GPR profiling in the early stages of geomorphological investigation could help choosing the OSL sampling points and depths resulting in a more precise study

Landscape metrics applied in geomorphology: hierarchy and morphometric classes of sand dunes in Inner Somogy, Hungary

Landscape metric is mostly used to quantify landscape patches. However, these patches could also be geomorphological forms, thus using traditional landscape metrics their shape and spatial distribution, or their dynamics could be analysed. The aim of the paper is to study the geomorphological applicability of different indices studying the aeolian forms of Inner Somogy (SW Hungary). In the present research 15 landscape metric indices were calculated with Patch Analyst 5.1 and vLATE 2.0. The negative aeolian forms (blowout depressions and holes) have high number but small size, whilst the positive forms (parabolic dunes and hummocks) have large number and complex spatial structure, thus the negative and positive forms can not be directly connected. The spatial distribution revealed by the applied indices refers to differences in moisture content, abundance of sand supply and relief on a regional scale. The negative forms appear in a considerable distance from each other, while the positive forms tend to cluster. Based on the spatial distribution of the forms the matrix could be described as an erosion-transportation zone, and in three accumulation zones the dune size and superimposition increases downwind

Grain size distribution of stabilised aeolian dune sediments in Inner Somogy, Hungary

In Inner Somogy the former researches concluded that the grain size of stabilised aeolian dunes decreases from north to south fitting to grain size distribution of the alluvial fan the dunes were built of and to the prevailing wind. However, the trend is not so evident, if considering the dune types and sand moving periods. The aim of this paper is to analyse the grain size distribution trends from the point of view of (1) different dune classes, (2) OSL age and (3) general morphological characteristics of the region. During the analysis the grain size distribution of 345 samples from 17 cores (120-300 cm in depth) was determined, and 15 OSL samples were dated. According to the results, the material of simple forms and level 1 dunes (these are the lowest dunes on the surface of the alluvial fan) becomes finer southward, in accordance with the structure of the alluvial fan and prevailing wind direction. Similar trend applies for level 2 dunes (which were formed on the top of level 1 dunes), but it does not apply for level 3 dunes, which are situated on the top of other dunes. It seems that the grain size is inversely proportional to the size of a dune and its age, thus younger and smaller dunes have coarser and less well sorted material. The sediments of the oldest, large parabolic dunes are the finest, younger, medium size parabolic forms have fine material, and the youngest hummocks contain the coarsest sand. The decreasing grain size towards south is the most apparent along longitudinal residual ridges, while within parabolic dunes the wings contain finer material than their elevated head

The evolution of the Great Hungarian Plain fluvial system - Fluvial processes in a subsiding area from the beginning of the Weichselian

In the Great Hungarian Plain (GHP), one of the most complex fluvial systems of Europe developed through tectonic and climatic factors and vegetation change. The aim of the present study is to summarise these controlling factors and to describe the evolution of the GHP. Special attention is paid to the latest results on late Weichselian and Holocene development in the Tisza River and their effects on the river's largest tributary: the Maros River. Several tectonically active subsiding basins existing in the GHP have determined the direction of river courses and erosional- accumulational fluvial processes. As a result of uneven subsidence, the river's flow routes have shifted frequently. For example, the Danube and the Tisza shifted 80-100 km, abandoning their alluvial fans where extensive aeolian processes started. Upstream from the subsiding areas, incision propagated headward, which resulted in the development of floodplain levels and terraces. Though climate and vegetation changes also simultaneously influenced the rivers' hydro-morphology, channel pattern changes were found just along the margin of the plain, and only meandering paleo-channels remained in the center of the GHP. During dry and cold periods, braided patterns appeared in the alluvial fans, most likely the result of abundant sediment supply and due to the inability of sparse riparian vegetation to stabilise the banks effectively. Based on paleo-discharge calculations, by the end of the Pleistocene the rivers of the GHP produced three to eight times more discharge than they do currently, and discharge levels continuously decreased during the Holocene. However, due to the long length of the rivers, there is a considerable time lag between the response rates of the different river sections, which makes creating paleo- hydrological reconstructions even more difficult. © 2014 Elsevier Ltd and INQUA