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 ...
The muds settled in the Lake Dąbie have visco-plastic properties. They contain many organic matter and are polluted by sewage from communities and industry. The presence of this substances changes clearly the dynamic properties of the fine grained material, as well the conditions of sedimentation and resuspension of solid particles. An important navigation way is located in the lake Dąbie with following parameters: length 14.5 km, width 150 m and guaranteed depth 3.2 m. This way is periodically deepened by dredgers. The authors have performed a preliminary estimation of the physical and rheological features of mud samples from the Lake Dąbie in the region of the navigation way. The thickness of the mud layer is equal 3–5 m. The fine grined sediments have a liquid consistency, and their water content is equal to some 300- 500%. The nominal granulometric size d50 changes between 12–15 μm for superficial muds and between 44-95 μm for bottom muds, and the organic matter content varies between 10 – 30%. The studies on rheological features of organic sediments proved that they behave as non-newtonian liquids. Their behaviour can be described by the twoparameter rheological model of Bingham. ...
The hydrotechnic structures of the flood protection system of the Wrocław city were realized after the flood in 1903. They protected the city against the discharges equal 2400m3/s. During the catastrophic flood in 1997 the maximal discharge in Odra river was much higher, about 3640m3/s. The stages and discharges in the whole Wrocław Hydrotechnic System (WHS) were also higher then in 1903. It concerned also the knot Odra-Widawa. The high stages and discharges leaded to the destruction of the inlet weir to the channel Odra-Widawa and of the channel’s embankments, what caused the inundation of the city quarters Kowale and Wojnów. The presented paper is an attempt of the determination of causes of the weir Odra-Widawa destruction. The hydrogrammes of stages during the flood were determinated on the base of measurement performed by the Water Administration in Wrocław on the upstream gauge of the sluice Bartoszewice. It could be stated that the destruction of the weir and embankments was related mainly to the blockage of a part of weir by branches brought by the stream and to the small hydraulic capacity of the Strachociński bridge on the channel Odra-Widawa. ...
The degradation of the Odra river bed is observed mainly below each last barrage of the channelized river sector Koźle - Wrocław. The mean river bed level is decreasing of some 4-8 cm yearly, causing the corresponding drop so of water surface in the river as of the ground water level in the valley. This degradation causes great problems so for navigation, as for agriculture and environment. The construction of successives last barrages Wrocław (1897), Rędzin (1922) and Brzeg Dolny (1958) had only a temporary effect. Below each of these barrages the river bed erosion continued, concerning a river reach of some 50-60 km. In 1994 Parzonka has proposed the conception of the "feeding" of the Odra just below the new barrage Malczyce (km 300,0), entering in action probably in 2012. The ad-ministration has decided in 2008, that this barrage can enter in work only after the accomplishment of important restoration works, taking in account the needs of environment, of navigation and agriculture and of the human population. The programme of restoration works provides two steps:- Step I: the elevation of the Odra bed level on the sector Malczyce-Ścinawa (km 300 - km 335) minimum by the half on the eroded ...
The authors performed an estimation of the dynamic of the river bed changes caused by sedimentation and erosion processes. The physical and rheological parameters for chosen cohesive and semi-cohesive sediments were investigated. Mud samples were taken from 3 different localisation on Middle Odra (Poland) and from 2 localisations on Warnow river (Germany). Rheological characteristics were studied with use of the rotative viscometer. Erosion characteristics of the mud’s were studied accordingly to methodology of Migniot [1968]. Results for Middle Odra were verified in the natural scale during the passage of the catastrophic flood through barrage Brzeg Dolny in 1997. This flood caused partly erosion of mud’s from the upstream part of this barrage. ...
These issues concern a section of the Lower Oder River which is approximately 110 km long, as well as the Lake Dąbie. They are jointly addressed by the two neighbouring countries. The key objective of the modernisation is to improve the conditions for navigation on the whole border section of the Oder River. It is supposed to ensure minimum depths of about 1.8 m at minimum firm flows in the Oder River, equal to 228 m3·s-1 on the section from the outlet of the Warta River to Widuchowa and 151 m3·s-1 from the outlet of the Lusatian Neisse River to the outlet of the Warta River. Another important objective is to improve the efficiency of ice-breaking operations and thus mitigate the risks caused by ice jamming. The channel of the Oder River was regulated in early 19th century with the use of a system of spurs located on both river banks. The regulation structures did not ensure the expected channel stability and navigable depths. In 1924–1941 corrections were made to the river regulation system with the use of spurs for the socalled low water level, however the efforts have never been completed. The crowns, heads and main bodies of the ...
Paper concerns the investigations of riverbed sediments in the meandering sector of the Border Odra, In the frame of meander I. As a result of fluvial processes the Odra riverbed is exposed to deformations, leading to often changes of the river itinerary. In the historical time, many meander breaks were registered, the last in 1967 (Meander IV) and in 1997 (Meander I). In the old river bed the discharge is gradually decreasing and the substantial part of the discharge is flowinging through the new channel. It leads to gradual silting of the old river part. The intensive formation of bars and of islands is observed. In the upper part of the old meander, mainly the bed load is deposed, and in the middle and lower part – the suspended load. The superficial part of the layer (cover) is exposed to the formation of pavement. The size of the pavement cover is equal 8,4–9,8 cm, and the granulometry of the lower layer (20–40 cm) equal to d50 = 2,3–2,9 cm. The islands formed by fine sediments were covered in 3-4 years by intensive vegetation (trees and bushes). This process causes an important decreasing of flow velocity in the old channel. The ...
The Lake Dąbie is located in Lower Odra estuary. That water region plays very important role for navigation, because through the Lake Dąbie the main seaway between Schwedt and Pomeranian Gulf is running. The Lake in strongly silted with polyfractional sediments with high clay and silt particles content and also with high organic matter content. That high clay and silt particles content causes that muds from the Lake have semi-cohesive or cohesive properties. Settled muds cause difficulties in seaway exploitation and significant decrease of its capacity. During 34 years the Lake Dąbie capacity decreased about 12,1 mln m3. The estimated mean year increase of sediments volume is equal about 356 000 m3. The authors performed the preliminary estimation of erosion parameters for sediments from Lake Dąbie on the base of theirs physical and rheological properties. ...
The Lower Odra is located between the Warta mouth and the Odra Roztoka. It has the character of lowland river, with low averaged energy gradients, smaller than 0.3‰. The flow of water and sediments takes place in the zone of subcritical movement. One can distinguish three sectors of Lower Odra, having different character: – the reach between the Warta mouth and Bielinek, behaving as a typical river, – the sector Bielinek – Gryfino, with influence of both river and sea, – the reach below Bielinek, typical for sea influence. The influence of wind and of high sea levels is marked mainly on the two last sectors. The transport of bed load, suspended load and wash load is observed in the whole Lower Odra. The bed sediments are composed mainly of sands and of fine gravels. Their grain size is decreasing in the downstream direction. The continuous bed load transport takes place in principle during the whole year. An important resistance component is this one concerning the bed load transport, related so to the grain roughness as to the bed forms roughness. The global coefficients of flow resistance for the Lower Odra were determined on the base of classic Manning formula ...
The authors performed the preliminary analysis of the silting conditions of the reservoir Otmuchów. The specific of this reservoir is it's geographic localiza-tion in catchment and hydrotechnic functions. The reservoir Otmuchów-Nysa cascade is localized in the middle sector of the Nysa Kłodzka river in south-west, upland region of the Opole District. The main characteristic of the amount of se-diments settled in the reservoir, the physical sediment properties for different re-servoir zones are presented. The authors have also analyzed the silting conditions in this reservoir, and the changes of the reservoir capacit.
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The Upper Odra valley on sector between Chałupki (km 20,0) and Olza mouth (km 28,0) is subject of deformations caused by natural factors and by human activity. This sector constitutes the border river between Poland and Czech Republic. Seven unique meanders exist here. The I-st and the IV-th meander have been broken during the floods in 1997 and 1967. Together with road bridge (km 20,530) they constitute three critical places with regard to flow capacity of Odra valley in its upper course. The problem of the border between both states Poland and Chech Republic on this sector is still not solved, what causes serious lawful and economic complications. The studied sector is distinguished by intensive bank erosion and sedimentation. The dynamic of Odra morphological processes is high here, so changes of water course as well as shape of the riverbed are very indicative. At present, the new channels formed within the meanders I i IV are characterized by the rapid flow caused by the high bed slope. From the authors’ studies it follows, that the old river branches permit to pass only a small percentage of the average discharge. Great outwashes, islands and dense vegetation within the meanders cause a ...
