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

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

doi:10.1007/s11600-022-00743-5

Cited by 5 publications

(3 citation statements)

References 44 publications

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“…The intensity of fluvial processes was described here with critical stresses on multifraction bed material (Bartnik, 1992;Michalik 1990;Shields, 1936;Wang, 1977;Strużyński et al, 2013a;Przyborowski et al, 2022) and compared to the change in unit stream power (Knighton, 1998;Bojarski et al, 2005).…”

Section: Hydrodynamic Parametersmentioning

confidence: 99%

Causes and mechanisms of the disappearance of braided channel patterns (the example of the Białka River, Western Carpathians)

et al. 2023

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The channels of multi-threaded (braided) rivers occur commonly in areas that fulfill certain conditions such as substantial influx of bed material and gradients large enough to create significant energy of flowing water. Natural conditions favoring the formation of multithreaded channels are present in the Carpathians in Poland in Podhale – a large basin located in the piedmont area of the high-mountain Tatra massif. The area had experienced glaciation in the Pleistocene. Yet the 20th century – and especially its second half – was a period of rapid and irreversible elimination of braided channels across the region. The Białka is considered to be the last braided river in the Carpathians in Poland. Many parameters like: structure (morphologic reach sequence), degree of braiding (BI index, W/D) and also a number of hydrodynamic ones (unit stream power, critical stress, shear stress, others) were investigated in order to assess a current stage of development of the Białka river channel. The Białka river channel appears to be a complex system with a differentiated structure. Its channel system is a mosaic of different types described by the following sequence: straight-sinuous-braided. It represents an intermediate type that is somewhere between a single- and a multi-threaded channel. Future evolution of the Białka river channel appears to include further degradation and transformation into a poorer channel ecosystem.

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Section: Hydrodynamic Parametersmentioning

confidence: 99%

Causes and mechanisms of the disappearance of braided channel patterns (the example of the Białka River, Western Carpathians)

et al. 2023

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“…,Qu (2002),Wang et al (2021) andPrzyborowski et al (2022). The coefficients of determination were very low, particularly for P mod , which imply that their interrelation was not significant.…”

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confidence: 94%

Effects of Flow Unsteadiness on the Transport of Bimodal Bed Material

BOMBAR,

OZGENC AKSOY,

GÜNEY

2023

Turkish Journal of Civil Engineering

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The grain size distribution of the transported bed load was experimentally investigated under unsteady flow conditions with bimodal mixture of sand and gravel in a laboratory flume. Five various triangular hydrographs were generated. A clockwise behavior for the total bed load versus shear velocity was observed meaning that the bed load during rising limb was higher than that of falling limb. It was found that the percent finer at the plateau of bimodal sediment size distribution curve had higher values during the initial and final phases compared to those obtained during the peak time. At all plateaus, the percent finer values related to the hydrograph peak discharge were in the same order of magnitude with that of the bed material. The sand content of the transported bed material initially decreased, then maintained a constant value during a certain time interval and finally returned to its original value. The sand percent of the bed load decreased in the falling limb showing a counterclockwise loop and the duration of the hydrograph did not affect the results considerably. The greater the peak flow rate of the hydrograph, the greater was the hysteresis. The bimodality index was calculated for all transported sediment samples and it was revealed that its initial and final values were less than that of the bed material but it was approximately the same elsewhere. The 5% finer sediment amount was nearly equal during rising and falling limbs. It was revealed that D50 value of the bed load decreased in the rising limb showing a clockwise loop. The hysteresis was not considerably changed according to the hydrograph characteristics. The clockwise type hysteresis was also observed for the size group of D95. The lag increased as the peak flow rate increased. A strong relation was found between the dimensionless total bed load Wt* and the total work index Wk as well as Wk and the ratio WR/WF. The correlations between the dimensionless total bed load and the unsteadiness parameters P, and Pmod were very weak, whereas a high value of determination coefficient was obtained with the unsteadiness parameter Pgt, implying an appreciable interdependence.

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“…This required fixing the instrumental parameters to the expected velocity magnitude along the entire profile from almost zero very close to the wall to flow core velocity outside the boundary layer (Liu et al 2022). The transient flow effect on bedload transport was successfully investigated by image and ultrasound-based techniques (Przyborowski et al 2022) that again bore out the capability of advanced techniques in observing challenging processes in terms of spatial and time resolution required. The river's hydro-morphology is driven by both bedload and suspended load, which is especially impactful for engineers.…”

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confidence: 99%