The balance of Dąbie Lake water has been analysed in three ways: as daily balance, averaged balance in a decade calculated on the basis of Regalica river flows determined by Mikulski and Ostapska-Bojanowicz (1965), and the water balance based on flows in water-courses reaching Dąbie lake, which has been determined using the model of lower Odra steady flow (Buchholz 1991). The method based on Odra river hydraulic model has turned out to be most important in the examination of Dąbie lake water balance. The share of Regalica river in the general inflow to the lake (calculated on the basis of this model) is 73,5%, (6557,8 millions m3), Orli Przesmyk canal has 23,9% (2135,3 millions m3), drainage area contribution is 2,3 % (205,5 millions m3) and precipitation brings 0.33% (29.3 millions m3). The outflow is shared by Iński Nurt canal (84%, 7503,2 millions m3), Babina (15,63%, 1395,5 millions m3) and evaporation – 0,33% (29,9 millions m3). Total inflow in the average year of multi-year period is 8927,9 millions m3 of water. On the basis on 1948-1990 period it has been calculated that on average 65 water exchanges take place in the lake yearly. ...
As natural river-courses, according to the Act on Water Law (Dz.U. 2005.239.2019 (U)), are recognized: rivers, streams, brooks or other waters, flowing continually or periodically, in their natural river-beds. Urbanized water–courses, in turn, constitute streams and brooks, of draining character, within city areas (Osmulska- Mróz, 1990). Their average daily rate of flow is not higher than 1,5 m3/s, and maximum ratio of breadth to depth equals 20:1. The urbanized water courses, often with developed small retention, as a consequence of urbanization, either disappear or become sewers (open or partly covered), transporting pollutions to the greater rivers 169 or water regions. Within their catchments, particularly, takes place the accumulation of heavy metals in bottom sediments. The latter process combined with eutrophisation and increased salinity, causes degradation of ecological potential and extinction of sensitive species of water plants. The Prądnik–Białucha River is an example of such water-courses. In order to assess the quality of water, its pH, EC, Eh and heavy metal contents in water, water suspension matter and bottom sediments, have been determined. The concentration of anions: chloride, sulfate, nitrate and phosphate have also been analyzed. The results obtained were referred to the standards obligatory in Poland and in EU. The ...
