RELIEF AND SEDIMENTS OF NIDA RIVER VALLEY NEAR PIŃCZÓW GAP-SECTION - FIRST RESULTS

Abstract

The study area is located in central Poland in the S part of Nida Basin between two elevations: Umianowice marl monadnock and Pińczów Horst. This is the part of a gap-section of the Nida river near Pińczów. Nida is the 2nd order river, tributary of the Vistula river. The work aims to recognize the relief and the structure of the Nida valley and to establish the chronology and origin of these structures. The results indicate differentiation in the sedimentation on the wide floodplain and in the vicinity of the riverbed. On the wide floodplain (more than 2 km) between Umianowice and Pińczów, based on aerial photo and digital terrain model, (DTM) we can notice remains of the multichannel river system (probably anastomosing river). Based on the historical maps the changes in the development of the riverbed in this area are visible. Nowadays, in the study section, we can observe the meandering river pattern.The A-B schematic geological cross-section was created based on the series of geological boreholes. Based on the field and laboratory detailed sedimentological analysis we can certainly say that the western part of the A-B profile is significantly different from the eastern part (closer to the river). In the western part, we can distinguish more organic deposits (mostly peaty silts and peats), while in the eastern part sediments are more mineral (mostly sands, sands with gravels and sandy silts). These differences in the geological structure could be caused by the distance from the riverbed and and activity of of fluvial processes.

Keywords

• nida basin
• morphodynamic processes
• large-radius palaeomeander
• anastomosing alluvial plain