Analysis of surface changes in the Walbrzych hard coal mining grounds (SW Poland) between 1886 and 2009

Underground coal mining causes surface changes such as subsidence and land transformation. The knowledge of the character of subsidence in the past and in the present provides useful information for example for spatial development. In this paper the methodology of determining surface height changes based on cartographic modelling in geographic information system (GIS) is presented. It has been applied to two test areas in a former coal basin in the Walbrzych region (SW Poland) that is characterised by complex geological conditions. In the result of a set of interpolation and map algebra operations surface height changes have been determined and the character of subsidence in a period of over 120 years (1886-2009) has been assessed. These results have been compared with the results of predictions based on the empirical Knothe theory of subsidence calculations using spatial statistics parameters. It has been found that theoretical modelling when applied in areas of complex mining and geological conditions produces lower subsidence values and more uniform subsidence surface than the applied method based on actual elevation data. The calculated surface height changes in the analysed period have been presented graphically and described.