Analiza rozwoju leja depresji odkrywki węgla brunatnego Tomisławice w latach 2009–2019 i jego wpływu na stosunki gruntowo-wodne Pojezierza Kujawskiego

Analysis of the development of the depression cone of the Tomis³awice lignite open pit mine in 2009–2019 and its impact on the soil and water relations of the Kujawy Lakeland. Geol., 70: 527–542; doi: 10.7306/2022.18 A b s t r a c t. The Tomis³awice lignite deposit is located in the Kujawy Lakeland (central Poland), on the water-shed between the Noteæ River (including Gop³o Lake) and the Zg³owi¹czka River (including Lake G³uszyñskie) catchment areas. The dewatering began in January 2009. In June 2011, the lignite seam was uncovered. The deposit was formed in a local Mesozoic depression within a tectonic structure, copmosed of Upper Cretaceous fractured marls. The average thickness of the lignite seam is about 7 m. All the boundaries of the Tomis³awice deposit are ero-sional. The top of the lignite seam, which is lowered to the north is at the average depth of between 38.3 m and 46.8 m. In the study area of the Kujawy Lakeland, groundwater with mineralization of up to 1g/dm 3 occurs down to a depth of 200 m in the Quaternary, Neogene-Paleogene, Cretaceous and Jurassic aquifers in the SE part of the area. The paper provides an analysis of the mine dewatering impact on aquifers within the cone of depression, over 270 km 2 in area, and the mine water drainage rate up to 90 m 3 /min. It is based on the data from the monitoring of the soil and water environment from 2008–2019 (groundwater, lakes). The analysis showed a particular mine dewatering impact of the developmnent of the Upper Cretaceous aquifer on the large-scale cone of depression around the Tomis³awice open pit mine. The described situation caused the mass drying up of farm wells and wetlands over a distance of up to 9 km from the open pit. The groundwater level on the moraine plateau has been almost completely drained and only to a small extent can it be periodically restored after longer periods of heavy rainfall.