GEORADAR SURVEY OF THE BRZOZÓWKA RIVER VALLEY (NE POLAND)

The investigated meandering Brzozówka River, a left tributary of the Biebrza river, is located in NE Poland in Podlasie Voivodeship. The river flow in a wide N-S orientated tunnel valley (glacial depression) between the Goniądz and Suchowola-Janów Uplands. The valley bottom is covered by peats. The aim of geo-radar research (GPR) was to identify the geological structure of the depression bottom, determine the peat thickness and its mineral base. First, two main research profiles on both sides of the river have been defined in the GIS environment. Then they have been divided into a number of sections, each of which has known spatial coordinates. The field, where GPR profiling was performed using the Mala ProEx geo-radar with a 500 MHz shielded antenna. The obtained data was processed in the program Ground Vision. In total, 21 echograms were obtained in the research area, with a total length of 3525 m. The result was the creation of a GPR profile crossing the Brzozówka River Valley in the W-E orientation. A number of anomalies at different levels have been recorded on echograms. There can be interpreted as an irregular mineral base covered with an organic layer. These anomalies may be evidence of a remnant of the Pleistocene braided river system.