Wyniki wyszukiwania - BazTech

1

Preliminary evidence on laboratory experiments to detect the impact of transient flow on bedload transport

Przyborowski Łukasz, Nones Michael, Mrokowska Magdalena, Książek Leszek, Phan Cong Ngoc, Strużyński Andrzej, Wyrębek Maciej, Mitka Bartosz, Wojak Szymon

Acta Geophysica

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2022

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Vol. 70, no 5

2311--2324

EN

Trapezoidal-shaped hydrographs are typical of anthropized rivers, as this form is generally associated with the release of water from hydropower dams. To investigate how such unnatural waves can affect bedload rate, preliminary fume experiments were performed in Krakow, Poland, looking at bedload transport rate, bed shear stress and bed morphology. In addition, close-range bed surface photogrammetry was used to investigate bed changes due to the passage of the food wave. Three scenarios, having the same water volume but different wave magnitudes, were tested. The lowest wave showed almost no sediment transport and no visible changes in bed morphology, while higher waves changed the bed morphology, creating erosion and accumulation zones. The highest wave was characterized by an 8-shaped hysteresis of the bedload rate with a peak during the wave maximum. The lag time between the maximum bedload rate and the wave plateau was longer than expected due to zero-slope conditions.

2

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large foods

Balouchi Behnam, Shafai Bejestan Mahmood, Ruther Nils, Rahmanshahi Mostafa

Acta Geophysica

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2022

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Vol. 70, no 5

2283--2296

EN

River confluences have a complex flow and sedimentation pattern that have vital influences on the hydraulic and bed morphology of river reach and the surrounding area. Confluences can be observed in waterways with various situations such as live bed conditions. This condition is a hydro-morphological situation with a high densiometric Froude number, i.e., bed load transport is supplied from upstream. According to the literature review, most of the experimental studies investigate the flow pattern on the flatbed and not on the developed riverbed, or/and in the low densiometric Froude number, or/and without supplying the sediment from upstream. Therefore, in the present study for the quantification of the flow pattern under these conditions, each developed bed was fixed with the cement blanket method in the laboratory. Then, the 3D velocity was measured at specific points at the confluence. The current study was designed to understand the flow pattern corresponding to the river bed behavior in the case of large foods. It is expected that the morphological features downstream of the confluence have a different pattern than the ones in the condition described in other literature. Thus, this paper describes briefly what are the different bed features and investigates the corresponding flow pattern. The results of the flow pattern on the developed bed show that all zones at the river confluence can be observed except the point bar due to the approximate equality of the mean longitudinal velocity of the separation zone and the main channel upstream of the confluence. Moreover, results show that by increasing the bedload ratio (sediment discharge to water discharge of the main channel of upstream of the confluence) from 0 to 3× 10−4, for defection to the outer bank of the channel decreased down to 45%, the stagnation equivalent area decreased down to 2.5 times, and bed shear stress decreased down to 40%. Hence, the momentum of lateral flow decreased with increasing bedload. Besides, the recovery zone occurred at a longer distance after the confluence compared to the case without bedload. Hence, the location of the maximum velocity zone, vortices, and secondary flows changed downstream of the confluence, by changing the bed load value.

3

Problem odnowy rumowiska wleczonego poniżej zapór. Ocena możliwości sztucznego uzupełniania rumowiska poniżej stopnia wodnego we Włocławku

Habel M., Babiński Z., Szatten D.

Gospodarka Wodna

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2017

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Nr 11

360--363

PL

Artykuł stanowi pierwszą część z cyklu poświęconego projektowi sztucznego uzupełniania rumowiska wleczonego w odcinkach, gdzie występuje jego deficyt. Podjęto próbę wyznaczenia warunków brzegowych dla trwałego ustabilizowania procesów erozyjno-akumulacyjnych koryta dolnej Wisły. Ustalono, że powstanie sztucznego zbiornika wodnego skutkuje zmianą reżimu hydrologicznego rzeki, w tym następuje ograniczenie przepływu rumowiska rzecznego. Przeciętna roczna wielkość transportu osadów piaszczysto-żwirowych na dolnej Wiśle to ok. 2,2 mln ton i tyle jego dociera do cofki zbiornika włocławskiego. Deficyt w transporcie rumowiska poniżej zapory jest uzupełniany w wyniku erozji wgłębnej, często też bocznej, jednak tylko do przeciętnej rocznej wartości 1,1 mln ton. Wskazuje to na fakt, że Wisła samodzielnie nie jest w stanie odbudować transportu swoich osadów. W rezultacie rozważań proponuje się potrzebę „dokarmiania” koryta osadami piaszczysto-żwirowymi w odcinku erozyjnym w ilości mniejszej niż 0,5 mln ton rocznie.

EN

The article is the first of a cycle devoted to the project of artificial reconstruction of the bed load in sections where its shortage occurs. It attempts to determine the framework conditions for permanent stabilization of the erosion and accumulation processes in the Lower Vistula riverbed. It was found that creation of an artificial reservoir results in modification of the river’s hydrological regime, including limitation of the bed load flow. The average annual value of the sand and gravel deposits transport in Lower Vistula amounts to approx. 2.2 million tons and this is the amount that reaches the backwater part of the Włocławek reservoir. The deficit in the bed load transport downstream of the dam is completed mainly as a result of bottom erosion and, frequently, lateral erosion, but no more than to the average annual value of 1.1 million tons. It indicates that Vistula is not able to autonomously recreate the transport of its deposits. As a result of these considerations, the authors propose to “feed” the riverbed with sand and gravel deposits in the erosion section, in the amount of not less than 0.5 million tons per year.

4

Transport rumowiska wleczonego ze zlewni źródliskowej (przykład źródlisk Łyny)

Afelt A

Inżynieria Ekologiczna

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2012

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Nr 31

5--16

PL

Wstępne wyniki badań źródliska Łyny wskazują na proces intensywnego odprowadzania substancji mineralnej w postaci stałej – jako składowej erozji wodnej zachodzącej w krajobrazie młodoglacjalnym na styku wód podziemnych i powierzchniowych. Pomiary polowe eksportu substancji mineralnej w formie rumowiska wleczonego wykazały, iż sumarycznie w roku erozyjnie ze zlewni odprowadzane jest w przybliżeniu 840 kg materiału (okres badań lata 2008-2009). Oznacza to średnio ubytek masy rzędu 580 kg z 1 km2 powierzchni jednostkowej zlewni rocznie. Woda źródlana pełni bardzo ważną rolę w odprowadzaniu substancji nierozpuszczonej ze zlewni topograficznej. Erozja wodna – sterując intensywnością transportu rumowiska, stymuluje w źródlisku Łyny proces odgrzebywania lokalnej rynny polodowcowej.

EN

The spring area of the Łyna river is a geological reserve, where naturally occurring retrogressive erosion is protected. Intensity of removal of solid and dissolved mineral material from the spring area of the river is the study aim. The study area is exceptional for Polish lowlands due to its complexity, as it includes 9 spring niches and 4 effluents. Geological setting plays here a decisive role, because all springs are situated in a head of a deep, buried tunnel valley which is developed in older sediments. The tunnel valley is filled with sands and gravels deposited during the last phase of the Vistulian glaciation. Removal of solid and dissolved material by retrogressive erosion leads to enlargement of the spring area and to uncovering of the buried tunnel valley. Intensive increase of the flow rate occurs downstream as tributary streams join the main river. Data from 3 gouge profiles covering 850 m downstream are as follows; 8,5; 22,8 and 48,8 dm3/s on average (based on a period 2004-2010). Intensity of the dragged material increases from 0,01 up to 0,08 g/s (measured in 2007-2008), 0,027 g/s on average. Mineralization of river water ranges between 150 and 234 mg/dm3 (178 mg/dm3 on average). It is assessed that the dissolved material removed from the area equals to 630 kg per day (230 tons per annum). On the other hand, the solid dragged material equals to 2,3 kg per day (0,84 tons per annum) for 34,8 dm3/s discharge measured at the lowermost gouge profile and for average mineralization of spring waters. Springs of the Łyna river have a high and stabilized outflow leading to the dynamic removal of mineral material. Removal of the dissolved material by the spring waters represents denudational potential of the regional aquifers which feed the springs. On the other hand, removal of the dragged material represents only erosion occurring within the uppermost part of the topographic catchment adjacent to the spring area which supplies the river channel with the solid material.

5

Określanie prędkości granicznych dla ruchu drobnoziarnistego rumowiska dennego w korycie laboratoryjnym z płaskim dnem

Popek Z.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2004

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Vol. 13, No. 2

21--31

EN

In this paper the results of laboratory investigation on the critical velocities for beginning of grain’s movement of sandy materials are presented. Critical velocities have been determined for seven kinds of alluvial sand with different uniformity and regularity of granulation and mean grain diameter d50 = 0.20-1.7 mm. The measurements, in steady uniform flow conditions in laboratory flume with rectangular cross-section and sandy bottom were carried out at variable bottom slopes and water depths. Measurements were carried out in range Re = 3-55, relative roughness Rd/d50 = 14-250 and cross-section concentration B/h = 1.7-7.3. Results of author’s investigation shows similar relations to that one presented by Yalin (1977) and Bartnik (1992), as well as some differences in case of Yung’s (1996) results.

6

Transport rumowiska wleczonego i skład jakościowy osadów dennych Potoku Jałowieckiego w Beskidzie Makowskim (Karpaty polskie)

Radecki-Pawlik A., Florencka N.

Inżynieria Środowiska / Akademia Górniczo-Hutnicza im. S. Staszica w Krakowie

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2001

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T. 6, z. 2

385-397

PL

W pracy przedstawiono wyniki badań chemicznych rumowiska dennego zgromadzonego w łachach korytowych potoku górskiego płynącego przez zlewnię położoną na obszarze wiejskim pod kątem ewentualnej akumulacji metali ciężkich w występujących w korycie potoku utworach aluwialnych. Stwierdzono, że największa ilość akumulowanych pierwiastków chemicznych odkłada się w rumowisku najdrobniejszym, w miejscach ocienionych naturalnymi wychodniami skalnymi, gdzie wymiana materiału następuje wyłącznie podczas przepływów ponadkorytowych i jest to Pb oraz Cd. Dodatkowo wykonano obliczenia transportu rumowiska wleczonego metodą Parkera oraz unoszonego metodą DRUSLE.

EN

The paper presents the field research of heavy metals accumulation in point bars and sediments. The research was undertaken in Jałowiecki mountain stream - Polish Carpathian mountainous region. It was found that in some tiny sediments situated within shadow of mega-clusters or rocks there is a tendency to accumulate heavy metals, especially Pb and Cd. Additionally bed load transport was calculated using Parker method and suspended load using DR-Usle concept.