Środowiskowe uwarunkowania skutków odkrywkowej eksploatacji węgla brunatnego na Pojezierzu Gnieźnieńskim

The paper focuses on the problem of water draining from brown coal pits, which has occurred since the 1950s in the Gniezno Lakeland in the western part of central Poland. Threats to hydrogeological systems and related lake systems under conditions of mining-induced drainage near the lakes located in the Powidz Landscape Park (PLP) are indicated. The lowering of water level in the PLP lakes exceeds 5 m, as compared to the pre-mining-induced drainage state. Such a rapid change may cause ecological disaster for these deep-water, healthy lake ecosystems with abundant submerged macrophyte (Charophyte) habitats (Natura 2000 protected area). Considering the regional context, the causes of hydrodynamic pressure leading to degradation of Lake Wilczyńskie and neighbouring, hydrologically connected lakes, are presented. The proposed mitigation actions for improving the ecological state of these lakes are presented in the contexts of (1) water balance assessment, (2) hydrotechnical issues related to the redistribution of water from the Slesiňski Canal (the Warta River - Lake Goplo) through water pipeline transmission, and (3) the accelerating groundwater reclamation of the Jóźwin IIB open mine pit area.