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Abstract:

The problem of water eutrophication of the shallow water reservoirs is known about for some considerable time. Monitoring of surface water quality in the canals and ditches is an important part of the diagnosis process of eutrophication in freshwater ecosystems. There are several ways to assess water eutrophication. In this paper, assessment of water eutrophication based on diversity of macrophytes, index of trophic state and nutrients in the irrigation system of the manor-park complex in Breń (the south of Poland) is presented. The irrigation system constituting an integral part of the manor-park complex (from the 18^th century) consists of open channels with a total length of about 1400 m with a total surface area 15000 m². The water artificial watercourses with macrophytes can fulfill the role of the constructed wetland system which affected to the reduction in concentration of biogens in water flowing away from the irrigation system. The knowledge about the processes of self-purification is important for the management of small water reservoir like canals or ditches, where "water blooms" are frequent. The water analysis of surface water carried out during the vegetation seasons (from March to October) in the years 2015, 2016 and 2017 in the three measurment-control points situated in the supply ditch, the main park channel and the discharge channel. The concetration of amonium nitrogen (N-NH₄⁺), nitrite nitrogen (N-NO₂^-), nitrate nitrogen (N-NO₃^-), phosphate-phosphorus (P-PO₄^3-) and also pH values, oxygen saturation and water temperature were assessed. Macrophytes inventories were carried out during the vegetation season of 2017, on five sections of channels and ditches. The results of the research showed a positive effect of the irrigation system in the park on the aquatic ecosystems. The results confirmed that the water in the canals has a eutrophic state, but as a result of slow water flow and macrophytes presence (e.g. Typha latyfolia, Lemna minor, Sparganium ramosum) causeed statistically signitifance decrease of biogenic compounds. It means that the presented a three ways of evaluation eutrophication risk of water may be successfully used to monitoring of surface water in the shallow water reservoirs like canals, ditches or ponds with controlled flow of water.