The paper presents a new method of estimation of the effect of a river on the ground waters of the adjacent area, different than the one used so far and based on the application of geostatistical methods and the fractal theories. An analysis was performed of a 14-year series of daily observations of ordinates of water level in the river Oder and ordinates of ground water levels in five piezometers situated at various distances from the riverbed, within the range from 120 to 1000 m. The first stage of the analysis was devoted to evaluation of the applicability of classical statistical measures. It was found that only selected ones display a relation with the distance. Those included maximum value, ranges, coefficients of variation, and variances. The remaining ones proved to be non-applicable. The next stage was the analysis of correlations between the parameters of semivariograms of ground water levels in the piezometers and the parameters of semivariograms of water levels in river Oder. It was demonstrated that the values of each parameter were related with the distance of a given piezometer from the riverbed. This means that they are useful for the estimation of the effect of the river Oder on the adjacent areas, as are the fractal dimensions.

The finalisation of the construction of the Malczyce barrage is planned for 2015. Damming of the river will cause a change in the water and ground conditions in the adjoining areas. The paper analyses the influence of the water level in the Oder River dammed by the barrage on groundwater table level in the left bank valley. A model which allows the prediction of groundwater levels depending on the assumed water level in the Oder was constructed. The analysis was conducted for three different variants: for the initial stage before damming the Oder River and for the conditions after damming the water up with and without the drainage devices included in the project. The calculations were done in several chosen transects across the river valley. The mathematical model of flow in the aquifer based on the Richards equation was applied. The results of calculations were presented as the spatial distribution of piezometric pressures which were used to determine the groundwater table for each of the transects. The calculation results from the vertical models were transposed into a horizontal model. The comparison of appropriate results allowed to positively verify the designed model and to analyse the effectiveness of the realised project solutions.

The paper analyses the amount of water flowing into the drainage canal in comparison to the levels of the Odra waters in the Brzeg Dolny – Wały cross section (upper water in the barrage). The results of the measurement of the flow intensity in the canal in 1971–2009 provided the basis for the evaluation. The analysis led to the conclusion that with the same ordinate of damming in the barrage the average yearly flow in the canal in the Warzyna section decreased from 196 m3s–1 to about 80 dm3s–1 as the Odra's riverbed and the area between the embankments became tighter. The flow into the canal changes in time and depends on the difference between water levels in the Odra and in the canal. The paper presents the dynamics of changes in the water flow into the canal in relation to 1 m of difference between the level of water in the Odra and the drainage canal. It was shown that in a similar location, ground and water conditions as well as similar damming levels, the value of the drained water can be estimated to be about 35–40 dm3s–1km–1 for 1 meter of difference of the water level in the river and the canal.

STRESZCZENIEPola irygacyjne Osobowice pełniły przez przeszło 100 lat funkcję naturalnej oczyszczalni ścieków wrocławskiej aglomeracji miejskiej. Obiekt ten położony jest na Równinie Wrocławskiej, w północnej części Wrocławia -pomiędzy korytami dwóch rzek: Odry i Widawy. Początki funkcjonowania oczyszczalni sięgają lat 80. XIX w.-powierzchnia pól irygacyjnych zajmowała wtedy około 560 ha. Z czasem obszar ten ulegał systematycznemu powiększaniu, prawie do 1300 ha. W związku z uruchomieniem (i modernizacją w 2012 r.) Wrocławskiej Oczyszczalni Ścieków na Janówku, udział pól irygacyjnych w procesie oczyszczania ścieków ulegał systematycznemu zmniejszaniu -zarówno pod względem ilości ścieków, jak i powierzchni zalewanej. Eksploatację pól zakończono ostatecznie w roku 2013. W znacznej części powierzchni obszar ten stanowi obecnie użytek ekologiczny, w związku z występowaniem na tym obszarze bogatej fauny i flory. W pracy przedstawiono historię obiektu, szczegóły jego funkcjonowania i gospodarki wodnej w trakcie eksploatacji a także obecny stan pól, głównie pod kątem wód gruntowych, które po zakończeniu zasilania tego terenu ściekami obniżyły się wyraźnie na znacznej jego części. Słowa kluczowe: rolnicze wykorzystanie ścieków, glebowa oczyszczalnia ściekówOsobowice irrigation fields -history and present time ABSTRACT Osobowice irrigation fields served as a natural sewage treatment plant of the Wroclaw urban agglomeration for over 100 years. The object is located on the Wroclaw Plain, in the north part of Wroclaw -between two river beds: Odra and Widawa. The beginning of the exploitation of the fields dates back to the year 1880. The irrigated area, at that time, was about 560 ha. In next years, the fields were systematically expanded almost to 1300 ha. After the Janowek Sewage Treatment Plant start-up (and its modernization in 2012) the share of irrigated fields in the sewage treatment process has been systematically decreased, both in terms of the amount of sewage and the flooded area. The fields exploitation was finished in 2013. A large part of the area, now constitutes the ecological area, due to the occurrence of a rich fauna and flora in this area. The work presents the history of object, details of the facility's operation and characteristics of water management during its operation, as well as the current state of the fields, mainly in terms of groundwater levels, which -without flooding this area with sewage -have decreased in a significant part of this terrain.