The River Vistula features various stages in the development of training measures that started in the 19th c. and aimed to convert it into a waterway. This study focuses on a foreland stretch between the towns of Skoczów and Puławy where the channel, originally meandering, sinuous or braided, has been shortened, narrowed and deepened as a result of engineering projects (Fig. 1, Fig. 2). Big differences were identified in the reshaping of the channel studied following the training measures, resulting in a reduced flood risk along those reaches where the channel depth was increased the most and in a considerable increase of this risk below Zawichost, where the measures were carried out last. The one morphological effect of the engineering that has the greatest impact on the discharge regimen is the increased channel compactness, especially along the originally meandering reaches (Fig. 3). The bank height along the deepened channel reaches increased by 3.5 metres on average since the project started. The changes in the channel morphology are conducive to faster flow rates (Tab. 1), which means that the bankfull discharge increases fast along the considerably deepened channel reaches with built-up banks. This rate is much slower along reaches with less ...
The paper summarises research into the geomorphological and hydrological effects of river training and improvement measures taken 45 years ago in the Nida valley. Positive and negative effects were identified, the latter including an increased flood exposure in half of the study area. The study aimed to find a feasible solution that would mitigate the flood risk. The valley is protected as a landscape park and belongs to a network of environmental corridors of national importance. Prior to the training measures, the River Nida, down from the confluence of the Czarna Nida and Biała Nida, ran in an entirely meandering channel with a minimal gradient causing long-term stagnation of the floodwater in the floodplain. The training and melioration measures were aimed at mitigating the flood risk, accelerating flood water drainage and draining part of the valley that had been used solely as meadows and pastures (Fig. 1). Vast wet marsh areas prone to cyclical channel avulsion were predominant along the braided reaches, such as near Umianowice (Fig. 2). As the engineering project started in the upper river course and continued downstream, the channel reaches directly below the newly deepened reaches became shallower. The process was documented by records of minimum ...
Groins are structures often used in lowland river regulation. The main goal of their construction is protection of coast and narrowing of the river channel to increase water depth and prolongation of the navigation period. Analysing the influence of groins on hydrodynamics and sediment transport in rivers it is necessary to consider two cases: (1) non-submerged groins, when the groins top is above the water surface, and (2) submerged groins. In case of nonsubmerged groins the narrowing of the main channel is observed; it is accompanied by increase of water velocity leading to further deepening of the main channel. In the groin fields water flows much slower, supporting sediment deposition. In case of submerged groins water flows in the whole channel, but increase of resistance due to groins causes reduction of its capacity, being an important aspect in flooding periods. Water flow is always accompanied by sediment transport, but the existing knowledge in this respect is still insufficient to allow prediction of morphological changes with high accuracy. Groins are constructed since few centuries but not always the expected results are reached; it is not unique that they create new problems (deepening, sediment deposition). Recently laboratory experiments are carried out to ...
The most important factors causing deep erosion in the river side arm include positive bedload balance and hindered ice progress in the main river bed. Another factor is formation of near-bank channels along high banks or banks covered with high and dense vegetation. Those factors also lead to partial destruction of dams and washing out of silted material. Thus, access of predators to an island is restricted. That provides favourable conditions for natural development and for establishing nature reserves in regulated rivers. ...
Using rivers and mountain streams for economic purposes led to the loss of ecological balance and to the intensification of morphological processes, which in most cases caused erosion as well as the lowering of riverbed. Such changes have made stabilising the river bed and its banks necessary. In our work, on the basis of the analysis of project documentation and the simulations of flood events on several mountain streams, we made an attempt to answer the question: are the river training works enough to let the catastrophic floods pass safely and do they take into account the morphological processes which have a formative influence on the riverbeds? It has been proved that as far as hydraulic structures are concerned, the adjustments that are being planned comply with the requirement of ensuring the required capacity of the river channel. Maintaining the required capacity of the river channel creates the need for constant remedial works. When dimensioning cross-sections with stable bottoms, the width of the river valley is a serious limitation which, in urban environment, does not allow the engineers to design a crosssection of a river channel whose shape would be most efficient one. In case of river channels with moveable ...
In order to protect the areas against the floods and droughts effect, we need to slow down the outflow in the scale of the whole catchment. The streams and rivers training are one of many possibilities of floods and droughts mitiga-tion. However, these activities often were done without any respect on the basic principle on keeping the ecological continuity of river corridor. In the paper, we propose improving the activities in the rivers and streams channels, in order to al-leviate effects of the technical training. ...
Dependly on the the land-use management, there are different technics of river training. The main aim of river training is floods mitigation. However, these activities often were done without any respect on the basic principle on keeping the ecological continuity of river corridor. In the current paper we present four types of trained river cross-sections, depend on their shapes, the material which forms them, and the condition for fauna and flora. There are also performed the patterns of the regulated channels, which are located in the different kind of urban area. For the selected trained river courses, which are located in the Upper Wisła catchment, the possibility of restoration has been analyzed.
...
The long-term evolution of the river beds of Nida River in Pińczów and Wiślica gauging station as well as an analysis of the causes of significant cases of lowering of the bottom of stream beds are presented in the paper. The intensity of river bed evolution as a stochastic process is described with the use of a statistical model. The analysis of the intensity of the process of river bed erosion was con-ducted under the assumption that the observed long-term trend of the lowest annual water levels reflect the elevation of the river bottom in the same years. The recorded observations at the Pińczów and Wiślica gauging stations on the Nida River, covering over 70-year period of time, are analyzed. Observations of the variability in the studied bottom levels over the decades allow concluding that the great transformation of riverbeds occurred there. The observations and calculations show that in Pińczów multi-stream or meandering river bed changed into straight channel and the process of shallowing of the river bed appeared. At the Wiślica gauging station the process of riverbed erosion with the variable intensity was observed. The research shows that the causes of these changes observed in Pińczów and Wiślica are ...
The paper presents the influence of river training works, carried on the part of the Słomka stream, on hydrodynamic conditions. The measurements carried out in 2004 and 2005 included following parameters: surveys of cross-section of the channel and the granulometric composition of bed material. Results of these work were used to calculate the hydrodynamic condition as shear stress, stream power, unit stream power, mean velocity and finally bedload intensity transport (by Bag-nold's formula). Then the comparison and analysis calculated parameters were performed. In sections A1, A3 and A5 the increase of considering parameters and intensity of lateral erosion after regulation were observed. In the other sections these values remained at a comparable level (section A4) or decreased (section A2). In cross-section no. 2 and no. 9 the percentage contents of fine grains increased in comparison with measurement results made before regulation. The characteristic diameter d50% in these sections considerably decreased by 1.8 cm and 2.8 cm respectively. ...
