PRZEBIEG ZJAWISK LODOWYCH NA WARCIE W REJONIE UNIEJOWA

The article synthesises the results from observations of ice phenomena on Warta River in Uniejów in years 1947−2012. From beginning of 1980s average time, in yearly perspective, in which the river was frozen was over two months, with ice cover appearing almost annualy. The years in which the river was frozen the longest are were 1947, 1954−1955, 1962−1964 and 1979, which coincides with the occurrences of coldest and longest winters in this region of Poland. The research shows however, that the ice phenomena on Warta River in vicinity of Uniejów, are determined not only by climate factors, but also, in a great extent, by Jeziorsko Reservoir, from the very beginning of its utilization. Construction of this reservoir, completed in 1986, resulted in a decrease of the duration of ice occurrences by nearly three times, and the complete freezing of the river became a rare phenomenon.