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

Comparison of Pipette and Laser Diffraction Methods in Determining the Granulometric Content of Fluvial Sediment Samples

Nowadays there is a growing demand for rapid and accurate determination of grain size distribution. The conventional pipette method is time-consuming and provides less detailed data compared to recently introduced methods. However, in Hungarian practice the pipette method is still considered to be the standard one, as there are a long series of measurements, and grain size thresholds used in sedimentology and soil sciences are based on this approach. The aim of our research was to determine the comparability of the laser diffraction method (LDM) with the conventional pipette method (PM), in order to investigate the controversial question on the interchangeability of the two methods. Based on our measurements on some representative fluvial sediment samples, we found that the largest difference in results can be expected in the silty grain size range. However if the main fractions (clay, silt, sand) are considered the methods provided similar very results, and correlation factors were above 0.92. In all, the LDM has a clear advantage because of its speed, reproducibility and fewer possibilities for operator failure

Reconstruction of Palaeo-hydrology and fluvial architecture at the Orosháza palaeo-channel of River Maros, Hungary

Several studies have addressed the impact of climate change and tectonic activity on fluvial systems. When investigating these systems palaeo-hydrological and geomorphological data on abandoned channels can yield valuable results. The main aim of our work was to reconstruct morphological conditions at the Orosháza palaeo-channel and to estimate the bankfull discharge which characterized the channel during its formation. There are several equations predicting bankfull discharge on the basis of planform parameters, but these only work for meandering rivers. In case of braided channels flow reconstruction can only be made by using cross-sectional parameters. The Orosháza palaeo-channel provided the means of a comparative analysis in this respect. By a sudden pattern change both meandering and braided reaches, supposedly having a very similar bankfull discharge, could be simultaneously studied. Planform parameters and present cross-sections were determined on the basis of a high resolution DEM, while original cross-section parameters were assessed using sedimentological and geophysical methods. Based on sedimentological data, channel pattern transition was mainly driven by intensive bedload accumulation at the edge of the Maros Alluvial Fan (MAF). Slope differences could not be evened out due to an avulsion close to the apex of the fan. Concerning discharge calculations a good agreement was found between a region-specific planform based equation and the cross-section based Grauckler-Manning equation. Values determined for the braided and meandering reach were also in a good correspondence. Consequently, the presented approach is suitable to determine the discharge of other braided palaeo-channels on the MAF and elsewhere

Mapping Freshwater Carbonate Deposits by Using Ground-Penetrating Radar at Lake Kolon, Hungary

Freshwater carbonate deposit, as a special phenomenon in the Danube-Tisza Interfluve, located in the centre of Hungary, is a significant geological heritage in the Carpathian Basin. At present there is not any applicable method to investigate the presence of carbonate layers in an undisturbed way, as neither vegetation nor morphological characteristics indicate unambiguously these formations. Ground-penetrating radar technology is widely used in various earth science related researches, and the number of applications is steadily increasing. The aim of the study was to determine the spatial extension of freshwater limestone using geophysical methods near Lake Kolon, Hungary. The lake, which is now a protected wetland area with opened water surfaces, was formed in the paleo-channel of the River Danube. Measurements were performed with the help of ground-penetrating radar, the results were calibrated by high spatial resolution drillings. Investigations have been made since 2012, and freshwater limestone was detected at several locations determining the more exact extension of the formation. Ground-penetrating radar proved to be an appropriate method to detect the compact and fragmented freshwater limestone layers in such an environment. However, based on the results the method can be best applied under dry soil or sediment conditions while the uncertainty of the results increases significantly as a matter of higher soil moisture. Further control measurements are necessary verified by several drillings in order to give an exact method to determine freshwater limestone

A Maros hordalékkúp elhagyott medreinek hidromorfológiai és hidrodinamikai vizsgálata

A negyedidıszakban a Maros igen kiterjed hordalékkúpot épített ki az alföld DK-i részén. A hordalékkúp elhagyott medrei, méretük, mintázatuk és szedimentológiai felépítésük alapján különbözı paleo-klimatikus és morfológiai viszonyokat tükröznek (Borsy 1989, Bridge 2003). A mederkitöltı, egyben mederformáló vízhozam (Schumm 1985), meghatározása keresztmetszeti paraméterek alapján történt. A kutatás célja a vízhozam meghatározása, az energiaviszonyok rekonstruálása, valamint a fluviális formák azonosítása szedimentológiai vizsgálatok segítségével. A szemcseösszetételi vizsgálatok során megállapítottuk közepes szemcseméretet, illetve a minták osztályozottságát. Ezen adatok alapján határoztuk meg az egykor medrek keresztmetszetét, melybıl a paleo-vízhozam számoltunk. Mindezen túl a szedimentológiai vizsgálatok során kapott statisztikus paraméterek alapján következtettünk az energiaviszonyok változására, az utólagos feltöltıdés mértékére (Bérczi és Balogh 1992, Folk és Ward 1957)