Anthropogenic transformations of the Bytom area relief in the period of 1883-1994

In this article an attempt was made to analyse the Bytom city relief changes in 1883-1994 years. It concentrates on the forms which are an effect of the mining and metallurgical activity such as subsidence depressions and dumps. Two digital relief models representing a topographic situation in year 1883 and 1994 were made by the Vertical Mapper tool in order to determine changes in the relief. The models were made by linear vectorization of contour lines, which then were processed into points. The made points were interpolated by the natural neighbour method. Maps of slopes, area profiles, contour line sketches and hypsographic curves were generated for two time periods on basis of the digital relief models. An area and values of subsidence for areas subjected to the mining activity, changes of the slopes, an average land altitude in 1883 and 1994 year were determined and an anthropogenic denudation ratio was also calculated. As the result of the research made, it has been established that the area of the subsidence is 3727 ha (about 54% of the city area) and the maximum value of subsidence is about 37 meters, there was a growth of the slopes at a simultaneous drop of the land average altitude, and the anthropogenic denudation ratio is 44 mm/year (800 greater than the natural denudation ratio).