DBPapers
DOI:10.5593/SGEM2013/BC3/S12.030

MORPHOGENESIS OF RESERVOIRS IN A MINING-SUBSIDENCE ZONE (A CASE STUDY OF THE BOBREK RIVER BASIN, SOUTHERN POLAND)

M. A. Rzetala
Monday 5 August 2013 by Libadmin2013

References: 13th SGEM GeoConference on Water Resources. Forest, Marine And Ocean Ecosystems, www.sgem.org, SGEM2013 Conference Proceedings, ISBN 978-619-7105-02-5 / ISSN 1314-2704, June 16-22, 2013, 237 - 244 pp

ABSTRACT

One of the most spectacular subsidence basins of the Upper Silesian upland is found in the Bobrek river valley. Subsidence basins form above underground mining activity. Over time, cavities left by extracted coal cave in or collapse under the pressure of overlying formations and concave landforms develop on the surface. This leads to new landscapes and infrastructure damage. The objective of this study was to assess the rate of change in the subsiding surface and the conditions for the formation of reservoirs. The geology of the Bobrek river basin was reviewed up to a cross-section at the end of the subsidence zone. A geomorphological mapping exercise was performed in the area and its land use was broken down into water bodies, forests, industrial and urban areas and agricultural land. Maps were used for measurements and cross-sections were drawn. The quality of the material accumulated in the subsidence zone was tested in a laboratory using ICP and INAA methods and samples of bottom sediments. The study revealed that marshes and small ponds evolved near the main river channel at every stage in the development of the subsidence zone, now more than two kilometres in diameter. During the study period (1933-2000), the valley bottom sank by several metres. It was found that the subsidence basins functioned as sedimentation zones for atmospheric deposition, as receiving areas for rubble material from the valley sides and for sedimentation material. The bottom sediments in the subsidence basin are highly contaminated and display links with the geology of the catchment and its land use.

Keywords: lake, water body, subsidence basin, bottom sediments, Silesian Upland