Building of the Brzeg Dolny dam in 1958 has changed the influence of the Odra River on the adjacent areas. After damming up the water the Odra River supplies the valley of waters filtering from reservoir. Drainage devices did not fulfill its role and some part of terrain was flooded. The regulation of the Jeziorka stream was done and in 1967 the drainage set was completed of deep channel built along the side dam of reservoir and in distance about 80 m from it. The analysis of flow intensity in the channel on the background of water levels in the Odra in the Brzeg Dolny – Wały section (up the dam) is presented in the paper. The base of investigations were the direct flow intensity measurements in the channel in the Warzyna section in 1971–2004. The analysis of these results showed that with passing the time on the same table of damming up the water on weir the more and more smaller values of flow intensities in the channel are observed. It is caused by clogging processes of the Odra bed and the terrains within embankments.

The article presents the results of site surveys made in 2003–2005. The main purpose of the investigation was to determine: grain size distribution of the material that fitls the grid elements (it was investigated two type of stones: crushed stones and cobble), porosity of the medium, parameters of hydraulic flow on two stages made from the gabion elements, changes in the construction of gabions structure after several years of its operating. The results show: 1) stones can be characterized by the same rules such as mineral ground, 2) porosity of gabions filled witch cobble is larger in comparison witch gabions of the same size but filled witch crushed stones, 3) coefficient of turbulence filtration of gabions filled witch cobble is larger in comparison witch the gabions filled witch crushed stones, 4) the surface flow in comparison witch filtration on wire built with gabions is increasing follow increasing volume of inflow water to the construction. There was not any essential deformation of the gabions construction after three years of their using

In paper is presented investigation results of scour in downstream of weir for different length of bed protection. Investigations were conducted on model taired construction with the over of water above the gate, with stilling pool and horizontal bed protection about lengths 50, 100 and 200 cm. Model was made in geometrical scale 1 : 30. As eroded material in experiments was used sand, d₅₀ = 1,1 mm, (d₈₄/d₁₆)^0,5 = 1,77. Increase length of bed protection in downstream influence on slow down of scouring process, what is due of decrease turbulence intensity of stream below hydraulic jump. For longer bed protection obtained smaller upstream slope of the scour hole and further location place of occurrence maximum depth of scour. Reduction maximum scour depth and the upstream slope of the scour hole minimise the risk of weir failure.

The study presents the application of a numerical model to analyze conditions under which tree stands may lose wind firmness. Using the ArcView software and a Rismo two-dimensional flow pattern model an application software was created to calculate critical holding moment values of trees. Riparian forests of the Vistula River valley near the town of Puławy were selected to verify the numerical model of tree stand wind resistance. Those forests were destroyed on August 4th, 2001 during a violent storm. The storm in the area of Puławy coincided with the passage of a flood wave on the Vistula River. On the selected stretch of the Vistula detailed measurements of tree and subsoil parameters were taken. Using hydrological and meteorological data it was possible to simulate conditions, under which wind falling occurred.

Floods of 1997 and 2001 revealed a grave flood hazard for the areas located along the Czarna Woda stream. Intensive high bankfull fl ows cause flooding of the Czarna Woda valley. The areas are used as grasslands or arable lands and also constitute a loosely built up village localized along the upper course of the stream and road. In its lower part the stream fl ows through Łącko village to its outlet into the Dunajec River. As shown by an analysis, the stream overflowing in the sections above Łącko village occurs already at water flows lower than the reliable discharge Q1% used for dimensioning stream channels. In order to determine the stream conveyance, two measuring sections were designed for which reliable discharge was assessed, computed from the empirical Punzet formula for the Carpathian catchments. The analysis of the Czarna Woda Stream channel conveyance considered the actual state of the channel and the effect of technical development. There are seven bridges within the first section joining the settlements situated on the left bank with a municipality road running along the stream. There are five bridges within the second section.

Laboratory studies of wastewater treatment in hybrid reactors with moving bed are presented. The biomass in reactors exists as a suspend – activated sludge – and as an attached – biological biofilm. Laboratory research on 3 parallel reactors in continuous – flow ad batch system was realized. Reactors were periodically aerated. As moving carriers for biomass cylindrical PE elements were used. Domestic sewage after preliminary treatment in septic tank was treated. The study revealed, that the suspended biomass in systems has decreased and the attached biomass has increased with an increase in organic loading. Likewise contents of suspended solids in the treated sewage has increased. Biomass growth was higher in batch system and was independent of technological parameters of the process.