Biogenic loads carried by the Raba river into the dobczyce reservoir in 2002–2005

The Dobczyce Reservoir is especially important because it is a source of potable water for the inhabitants of Krakow. The source of the reservoir feeding is the Raba river, whose catchment still lacks properly managed sewage disposal, therefore the water inflowing to the reservoir contains pollutants which decide about the insufficient water quality in the reservoir and to a considerable degree also determine the processes occurring in it, including eutrophication and overgrowing. In the work analysed was the loading of the Dobczyce Reservoir with biogenic compound load carried by the waters of the Raba river. The analysis based on tests of the Raba water quality and the flow volume on the inflow to the reservoir in the Osieczany cross section. The tests covered the period from May 2003 until October 2005. Investigations of biogenic compounds concentrations were conducted with average frequency twice a month. Concentrations of NH4, NO2, NO3,PO4 and total P were determined. The loads of individual biogens were computed for days, months and years of the analysed period. The obtained results point to a considerable diversification of mean daily values of loads in the analysed years. They were the highest in 2005 for NO3, NO2 and total P, ...