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Numerical Modelling of Fish Passage with Turning Pools

Maniecki Ł.

Archives of Hydro-Engineering and Environmental Mechanics

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2018

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Vol. 65, nr 1

41--66

EN

An assessment of operating conditions in a baffled fish passage with pool dimensions of 2:2 3:0 m, and 180 horizontally turning pools, was carried out using numerical computations and a site survey of water flow velocity distribution. Velocity was measured with a PMS electromagnetic flowmeter and a hydrometric current meter in representative cross-sections of the fish passage in the pool centres and in the baffle barrier cross-section area. Numerical computations were also performed for two alternative baffle locations in the fishway. One reflected the actual conditions, and the other was an alternative arrangement designed to improve hydraulic conditions for fish migration. The numerical model used the Large Eddy Simulation (LES) method, which makes it possible to detect large vortexes. The study pays close attention to the velocity field analysis as well as the distribution and sizes of vortexes in the turning pool of the culvert. The results of numerical computations and the site survey show high consistency, and the proposed baffle placement modification significantly improves flow conditions, especially in the entry section of the passage.

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Sedimentation of load in a step-pool rock ramp fishway with biotechnical embedded elements

Tymiński T., Mumot J., Karpowicz D., Jianxin X.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2017

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Vol. 5, Iss. 2

35--42

EN

such structures has resulted in a more and more conventional approach to their design. However, every single hydraulic engineering structure with a negative impact on the possibility of a watercourse in fact requires an individual approach. Often, the solutions which are the most convenient and the easiest for a designer are not in the least the best ones for migratory fish. Semi-natural fishways in particular pose a technical challenge that requires an interdisciplinary approach. Designing and constructing them correctly is not an easy task, but once it is achieved, the structure is highly effective in terms of fish migration and the formation of new habitats. Another, equally important issue related to fishways of this type is their long-term usage and proper maintenance. In this case, it is crucial to consider the transport of load through the fishway channel, and more particularly its sedimentation in zones of lower flow velocities. This paper presents a qualitative analysis of the sedimentation of load based on laboratory research carried out on a model of a vegetated fishway. This research was performed to investigate and confirm the expected locations of accumulation of load in a semi-natural vegetated step-pool rock ramp fishway. Experiments show that the sedimentation of load in fish passes may be a highly problematic issue and may require that more attention be given to the proper upkeep of fishways. It may be necessary to address the problem of fishway maintenance and deal with fishways as structures that change over time not only because of hydrological conditions, but also due to the yearly growth cycle of vegetation.

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Badania modelowe hydraulicznych warunków przepływu w przepławce z zabudową roślinną

Tymiński T., Mumot J.

Inżynieria Ekologiczna

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2015

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Nr 44

227--234

PL

Działania mające na celu zachowanie „korytarzy ekologicznych” w rzekach są zagadnieniem trudnym i złożonym, które wymaga wiedzy specjalistycznej z wielu dyscyplin nauki. Jednym z ważniejszych rozwiązań zapewniających ciągłość ekologiczną rzek są przepławki dla ryb, zwłaszcza te o charakterze naturopodobnym. Cechą charakterystyczną ich budowy jest zastosowanie naturalnego budulca (kamienie, pnie drzew, żwir, roślinność) w taki sposób, by swoim wyglądem przypominały małe cieki naturalne. Projektowanie hydrauliczne przepławek oparte wyłącznie na kryteriach prędkości dopuszczalnych v oraz parametru jednostkowej energii wody E, nie daje pełnej informacji o skuteczności działania tych urządzeń. W celu wytworzenia w przepławce optymalnych dla ichtiofauny warunków przepływu przydatne są badania struktury przestrzennej parametrów hydraulicznych np. zaburzeń pola prędkości lub rozkładów stopnia turbulencji Tu. W pracy zaprezentowano przykład takich badań, które autorzy przeprowadzili na modelu przepławki seminaturalnej w laboratorium wodnym IIŚ UP we Wrocławiu. Otrzymane wyniki posłużyły do oceny poprawności funkcjonowania przepławki. Badana przepławka z zabudową roślinną w formie rygli i komór spełnia wymogi hydrauliczne dla migrującej ichtiofauny i stanowi ciekawą, proekologiczna alternatywę do „ciężkiej” zabudowy technicznej.

EN

Our engineering activity aiming at keeping ecological corridors in rivers are a difficult and complex issue that requires specialist knowledge in many disciplines. One of the installations for ensuring ecological continuum river are fishways, particularly their “near-natural” designs. They resemble mountain streams and creeks. Natural materials, such as wood, vegetation, gravel, stones and rocks are used for their construction. Design of hydraulic fishways based solely on the criteria of maximum speed v max and parameter of unitary energy of water E, it does not give complete information about the effectiveness of these devices. In order to produce the optimal flow conditions for ichthyofauna, very useful are spatial structure research of hydraulic parameters, such as disorders of flow velocity field or distributions of the turbulence number Tu. The article presents an example of such a study, which the authors carried out on the model seminatural fishway in the water laboratory in Institute of Environmental Engineering in Wrocław. The results were used to assess the accuracy of the functioning of the fishway. The tested combination of “vegetated baffles” and “pools” in the fishway model was found to be optimal for the ichthyofauna. Vegetation build-up in fishways is an interesting and proecological alternative for “heavy” technical build-up.