Influence of agricultural anthropopression on water quality of the dam reservoirs

Abstract

The research evaluated the quality of surface waters subject to agricultural anthropopressure. The authors analyzed river water feeding dam reservoirs and water in reservoirs. The research covered the catchment areas of reservoirs Kozlowa Gora, Przeczyce and Laka, located in the Upper-Silesian region (southern Poland). The dominating form of land management in the catchments is agriculture. The reservoirs were found to be often fed with running waters whose parameters suggested eutrophication, especially with regard to the concentration of nitrates (mean yearly concentration of − 3 NO > 10 mg/dm3). Eutrophication also concerned reservoir water, which could be seen in frequent water blooming. The reaction of water in the reservoirs happened to increase up to strongly alkaline (pHmax > 8.5). The highest fertility of waters was that of reservoir Laka, mainly alimented from agricultural lands (77% of the catchment area) also situated within its direct catchment. This was reflected in high phosphate concentrations in the water of the reservoir (average 0.389 mg 3−4 PO /dm3). The research showed that agricultural anthropopressure is a significant threat to functioning of dam reservoirs because it fosters the process of eutrophication and thus affects the quality of disposable water resources.