Numerical 2D Simulation of Morphological Phenomena of a Block Ramp in Poniczanka stream: Polish Carpathians

Description of flow in streams is a very complex problem. Physical analyses of this phenomenon provide a quantitative description of water flow, allowing creating mathematical models having practical meaning. Fast development of programs has improved their practical implementations, so the results of analyses and solutions of flow problems in both open channels and pipes, obtained through numerical modelling, can be applied in practical solutions. Numerical models are often very useful in studies covering a wide range of analyzed parameters. However one must understand that the similarity between a real river and its model could only be partially verified. The main purpose of this paper is to investigate the effect of the selected boulder block ramp hydraulic structure on Poniczanka stream on sediment transport, using the numerical model CCHE2D, assuming several situations, depending on the type of the river bed (erodible, non-erodible, rocky) and kind of rock blocks used for hydraulic structure construction. The obtained results were compared with the Hjulström graph, which is a classic approach for the identification of fluvial processes in the river channel (erosion, sedimentation, transport). In addition to these two methods, field observations were carried out which included the determination of changes in the horizontal and vertical changes of the riverbed morphology of the examined section river reach. The obtained results allowed determining the compatibility of these three methods for evaluation of sediment transport rate of river bed material in the analyzed sections of Poniczanka stream which are engineered with boulder block ramp hydraulic structures (BBR)

Polish Carpathians

Ramps and Fishway

Adjustment of the river channel due to block ramps introduction: Porębianka mountain creek, Polish Carpathians

The paper includes a description of 25-five interlocked boulder block ramps with increased roughness located on Porębianka creek and presents an analysis how those low head hydraulic structures fit to a natural river system: riffle-pool. These block ramps with increased roughness structures might be called "close to the nature", and in hydraulics engineering they are replacing traditional drop hydraulic structures. One of the main advantages of block ramps is that they are supposed to be placed in a natural sequence distances which follows pools and riffles pattern along a river, also block ramps allows free movement of fish upstream and downstream without necessity of fish pass constructio

A Preliminary Study of Field Scour Morphology Downstream of Block Ramps Located at River Bends

Most of the studies present in the literature deal with block ramps located in straight channels. This is an evident limitation not allowing for a generalization of laboratory model findings. Generally, these structure typologies are located in natural rivers, that are characterized by both quasi-straight branches and bends. In particular, the location of the structure in river bends contributes to deeply modify both the upstream in-flow conditions and the downstream erosive mechanism. Only recently, the scour process downstream of block ramps was analyzed in curved channels and useful relationships were proposed to compute the maximum scour depth. Furthermore, the mentioned analysis was supported by field data validation, resulting in the understanding of the effects of river curvature on downstream scour process in the presence of a protected stilling basin. Despite of the recent study on the topic, there is still a lack of knowledge regarding the equilibrium morphology configuration and the effect of hydraulic parameters on the erosive process. Based on field measurements collected at the Porębianka river (Poland) after flood events, this paper aims to deep the downstream scour hole characteristics and the erosive dynamics. In particular, both the effects of in-flow conditions and river curvature are analysed in terms of resulting equilibrium morphologies, highlighting both similarities and differences with the corresponding configurations occurring in quasi-straight river branches

Using Genetic Programming to Predict Scour Downstream Rapid Hydraulic Structures from Experimental Results

Experimental Studie

Quelles améliorations sont nécessaires pour garantir la qualité des eaux de nos rivières? : nouveau regard sur l'utilisation d'indices biot iques dans l'évaluation de la santé des cours d'eau

Benthic invertebrate-based indexes are commonly used as proxies for river health, especially river water quality. Scores of BMWP-PL index (a Polish equivalent of the British Biological Monitoring Working Party score system) were determined for 20 unmanaged and channelized cross-sections of the Biała River and compared with water quality and physical habitat parameters in the cross-sections. The two types of cross-sections clearly differed in the physical habitat conditions, whereas physico-chemical parameters of the river water mostly varied in the downstream direction. The number of recorded taxa ranged from 3 to 26 and the respective scores of the BMWP-PL index indicated the water to vary between high and poor quality. Since the analysed water quality was consistently high, the BMWP-PL scores were not related to physico-chemical parameters of the water but to physical habitat parameters, with the number of low-flow channels explaining the largest proportion of the variance in the index values. The lacking dependence on physico-chemical water parameters renders the BMWP-PL as indicator of the ecological integrity of rivers, related to their hydromorphological and physico-chemical characteristics, rather than of water quality

The influence of a drop-hydraulic structure on the mountain stream channel regime - case study from the Polish Carpathians

Basic hydraulic parameters such as shear stress, stream power, unit stream power and water velocities were calculated and measured within the region of a drop hydraulic structure erected on the Kasinczanka stream in the Polish Carpathians. Besides examining the hydrodynamics of the stream the study investigated also the distribution of grain size in the bed-load at the upstream and downstream aprons of the structure. It was revealed that grains deposited at the upstream apron were finer than those deposited at the downstream apron. At the same time, shear stresses and unit stream power values were found to be quite stable upstream of the drop structure, but to change significantly along the stream channel downstream of the structure’s energy dissipating poo

Niekontrolowany pobór rumowiska z dna potoków górskich jako jedna z przyczyn degradacji środowiska przyrodniczego

W artykule zwrócono uwagę na konsekwencje niekontrolowanego poboru żwiru i otoczaków z dna potoków górskich. W wyniku rabunkowej eksploatacji koryt rzecznych ulega zniszczeniu naturalne obrukowanie dna chroniące ciek przed nadmierną degradacją, ulegają zniszczeniu i podmyciu budowle wodne oraz budowle regulacyjne i chroniące przed powodzią, a także podpory mostowe. ponadto ulegają eliminacji organizmy żywe wskutek usunięcia naturalnych miejsc bytowania makrofauny bezkręgowej

Flow and sediment size variability near gravel bars in the Beskidy Mountains in the Polish Carpathians

The purpose of the paper is to identify differences in hydraulic conditions in the areas closest to already-developed gravel bars situated in a small, mountain stream in the area of the Polish part of the Carpathian Mountains. Basic hydraulic parameters of flowing water, including velocity, shear stress, Froude number, Reynolds number and flow resistance coefficient were examined within the region of two different gravel bars in a mountain stream. At the same time, sediment samples were drawn from the riverbed in the area in which the hydraulic measurements were taken. After analysing the data, several conclusions were presented concerning sedimentation of gravel and hydraulic parameters within the cross section of a mountainous stream. The study was undertaken on Skawica-Jałowiecki Stream in the Polish part of the Carpathian Mountains called the Beskidy Mountains12112