Prof. dr hab. inż. Włodzimierz Parzonka

Dr hab. inż. Władysław Buchholz

Dr hab. inż. Ryszard Coufal

Dr inż. Andrzej Kreft

Prof. dr hab. inż. Zygmunt Meyer

Preliminary estimation of silting conditions of Lake Dąbie

Estuary. During the winter inundations, this lake constitutes the receiver of ice jam from the river. This lake is intensively silted by river sediments type sand, silt and clay, delivered mainly by Regalica (the eastern branch of Odra) and by the rivers Ina and Płonia. The water volume of the lake decreased during 34 years (1962–1996) by 12,1 mln m3. The mean increase of sediments volume is equal 356 000 m3 * year-1. The processes of sedimentation and erosion of muds are complicated by the waving of water level and by superficial and bottom currents. These currents are generated so by river inflow as by wind, causing changes of sea level during storms. Through this lake goes the main navigation way between Schwedt and the Pomeranian Bay. Its deepening is planned in the period 2007–2011, by dredging of 810000 m3 of bed sediments. This fairway has following parameters: length 14,5 km, width 150 m and depth 10m. The geotechnic measurements have shown that the thickness of muds is equal 3-5 m. The cohesive sediments contain 10-30% of organic matter and have a liquid consistency. Below the organic sediments, mainly fine sands occur. The muds are polluted, mainly by heavy metals ...

Prof. dr hab. inż. Bernard Wiśniewski

Dr Tomasz Wolski

Dr hab. inż. Władysław Buchholz

Dr inż. Andrzej Kreft

The water balance of lake Dąbie

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. ...