Wykorzystanie wielowymiarowych metod statystycznych w analizie stanu fizykochemicznego wód w systemie rzeka – zbiornik retencyjny na przykładzie zbiorników retencyjnych Pakosław i Jutrosin położonych w zlewni rzeki Orli

The paper presents a preliminary study of analysis water quality in the off-channel reservoirs Pakoslaw and Jutrosin using the multivariate statistical techniques. Because of high biogenic pollution in Orla and Radeca rivers, Jutrosin and Pakoslaw reservoirs were based on an innovative concept in which the reservoirs were built on areas directly adjacent to rivers. Series of studies in the off-channel reservoirs were compared with water quality of Orla and Radeca rivers. The Orla together with the water reservoirs forms a right-bank tributary of the Barycz river. The storage reservoirs, built in the year 2007 (Pakoslaw) and 2011 (Jutrosin) represents off-channel reservoirs placed outside of the water course, but in its direct neighborhood. The reservoirs are filled by the water of Orla river from the water intake localized before the weir, while the water discharge into the river bed takers place through a discharge construction localized below the weir. Area of the Pakoslaw water reservoir is 26.6 ha and Jutrosin 90.5 ha. The multivariate statistical techniques such as cluster analysis (CA), factor analysis (FA), principal components analysis (PCA), and discriminant analysis (DA) were taken advantage to interpretation and evaluation data. The aim of the present research was to use chemometric techniques (CA, PCA, FA and DA) in order to: discover similarities and differences in the pchysico-chemical composition of water in off-channel reservoirs and rivers, identify water quality indicators suited to its temporal and spatial variability, expose hidden factors accounting for the structure of the data, and identify man-made sources of water pollution. Cluster analysis (CA) showed that there is unmistakable difference between water quality in the reservoirs and rivers. More evident fluctuation in the physico-chemical composition were observed in reservoirs compared to rivers. This is the result of unique location and theirs maintenance. Factors of water quality during the refilling reservoirs were comparable. Afterwards the off-channel reservoirs and rivers works separately. Factor analysis (FA) confirmed different process of self-purification in reservoirs due to rivers. Typical for pchysico-chemical composition of water are indexes like Conductivity, Fe, Cl, BOD, SO4, Ca, Hardness, Mg, O2 and PO4. This is the result of discriminant analysis (DA).