Transformations of river bed pattern of a lowland river inferred from aerial surveys and ground penetrating radar (GPR)

摘要

Aerial surveys and GPR measurements have been carried out to study an anthropogenic transformation of a lowland river bed pattern. The research was done in the Obra River valley (western Poland) which was subjected to intensive hydro-technical works at the beginning of the 19th century. Historical maps indicated functioning of braided, meandering channels that disappeared in wetlands before the period of human intervention. Three research areas representing different river bed patterns and its alterations have been selected for detailed study. Combining the aerial and the GPR surveys allowed us to discern migration phases of the Obra River meander bends, retrace the braided pattern of the river and analyse traces and forms of the anthropogenic impact. The traces of the natural river course discerned from aerial photos correspond with the spatial extent of the channel fills inferred from the GPR surveys.