Natural and anthropogenic indicators of fluvial system changes, the Bobrza Valley (Holy Cross Mts) as an example

Transformations of a fluvial system are caused both by natural factors and human pressure. These factors model the system independently at different times and with different intensities or they affect it simultaneously. The aim of this study is to identify the transformation of the Bobrza river valley system occurring under natural conditions and that occurring under the influence of human activity. The identification was based on specific indicators The study was conducted in the valley mouth of the Bobrza River (Holy Cross Mountains), where three research sites were located. The investigation concerned the relief of the valley and the mineral and organic deposits. A wide range of research methods were used during the study e.g. analysis of LiDAR data, macronutrient analysis, and radioactive dating. The analyses enabled the natural and anthropogenic transformations of the Bobrza river system to be distinguished using the following indicators: morphometric and sedimentological characteristics of the palaeomeander (natural transformation), the sequence of mineral and organic deposits in exposures on the contemporary floodplain (natural and anthropogenic transformation) and transformation associated with the operation of a water mill (anthropogenic transformation). In addition, it is worth mentioning that the Bobrza channel is the location which has provided the only fossils of Juncus subnodulosus in south-east Poland

Geneza i zasięg vistuliańskiego zespołu terasowego Odry-Osobłogi pod Krapkowicami

The system of morphological levels occurs on the slopes of the Odra and Osobłoga valleys in the vicinity of Krapkowice, southern Poland. Their genesis, range and age have been the subject of lively scientific discussion since the 1930s. Geomorphological analysis confirmed the fluvial origin of these flats. The use of LIDAR data allowed for precise height determination and revision of the range of indivi-dual river terraces, which rise above the valley bottom to a height of about 166 m a.s.l. (more or less 6 m above the Osobłoga/Odra channel), 168 m a.s.l. (8 m), 172 m a.s.l. (12 m), 174 m a.s.l. (14 m) and 181 m a.s.l. (21 m) res-pectively. The dating of sediments building the terrace elevated to 172 m a.s.l. using the OSL-SAR method gave a result of 87.7 ± 5.7 ka (GdTL-2820) indicating that it originated from the last cold stage of the Pleistocene. The ter-race surface was shaped by a sand-gravel braided river, which has developed on the substratum of the alluvium do-cumenting the period of intense valley-floor aggradation