CHARACTERISTICS OF THE CATCHMENT BAJERKA STREAM (SOUTHERN POLAND) IN ANTHROPOPRESSURE CONDITION.

The Bajerka Stream (16 km long), besides the Vistula River, is a tributary to the Goczałkowice reservoir. It is the main reservoir of drinking water for 3.5 million residents of the Silesian agglomeration. It is an artificial reservoir, created after the construction of the dam on the Vistula River. The Bajerka stream takes its origin in the dig from the Vistula River and enters into the southern part of the Goczałkowice reservoir. This is a semi-natural stream, which is used to supply the numerous fish ponds, and it is connected with them by numerous channels. It is flowing throughout farmlands, partially built-up areas and the wooded areas. The article presents results of hydrological and hydrogeological research, intended to illustrate the relationship between surface water and groundwater in the catchment. As a part of the investigation, the hydrogeological mapping was performed four times as well as four series of hydrometric measurements of the stream flow. This made it possible to indicate drainage and infiltration sections of the Bajerka stream. Analysis of the results indicates that the nature of some section of riverbed may be variable depending on the water levels of the stream. It have been also made the study of the chemical composition of water, also in the vicinity of potential sources of pollution. The obtained results allowed to identify threats to the quality of surface and groundwater of the Bajerka catchment and consequently the Goczałkowice Reservoir. For example, in 2012, only from the one wastewater treatment 11.3 tonnes of chlorides, 6.5 tons of sulfates, 2.7 tons of nitrate and 150 kg of phosphate were cast to the Bajerka stream and thereby to the Goczałkowice reservoir. There was also included the impact of fish breeding ponds on flows in the Bajerka stream. [ABSTRACT FROM AUTHOR]