Morphology of landforms and granulometry of aeolian sand deposits in the inland dune field, the southern part of the Jersika plain | Jersikas līdzenuma dienvidu daļas iekšzemes kāpu masīva morfoloģija un eolo nogulumu granulometrija
2017
Soms, J., Daugavpils Univ. (Latvia) | Biruma, R., Daugavpils Univ. (Latvia) | Strode, S., Latvian Geospatial Information Agency, Riga (Latvia) | Markots, A., Metrum, SIA, Riga (Latvia)
In the present study, the detailed geomorphological framework of landforms within the inland dune field has been established using airborne LiDAR data. Additionally, the spatial variability of Folk and Ward (1957) indicators as granulometric characteristics of aeolian sands has been investigated in the southern part of the Jersika Plain. The LiDAR elevation data used in this study were collected with a fixed-wing aircraft by the limited liability company SIA “Metrum”. The laser altimetry output 17 data were converted to point shape files using ArcGIS 10.0. Subsequently the ESRI regular grid raster high-precision DEM was generated. Thereafter this DEM was utilised to identify dunes and to extract geomorphological information about topographic characteristics of the aeolian landforms. Granulometric analysis of the aeolian sand deposits has been carried out in this study in order to obtain data on the differences in the mean grain size of sediments and other Folk and Ward indicators, as well as to elucidate spatial distribution of these parameters across the inland dune field. To obtain statistically meaningful data, 144 samples of sand were collected from the crests of inland dunes. After these samples were analysed at the Laboratory of Quaternary Research, Daugavpils University, by Malvern Mastersizer 2000 laser diffraction particle size analyser. Statistical processing of granulometric data was carried out by GRADISTAT module (Blott and Pye, 2001), which can be integrated into MS Excel environment. Results of the granulometric analysis indicate that medium size of sand grains in samples from different places within the dune field varies from 89 μm to 280 μm. The geographic distribution of Folk and Ward (1957) indicators demonstrates that size of sand grains in general decreases from south-east to north-west; this direction coincides with the distal direction of the paleodelta of the River Daugava.
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