Influence of river channel deflector hydraulic structures on lowland river roughness coefficient values: the Flinta river, Wielkopolska Province, Poland

Zaborowski, Stanisław; Kałuża, Tomasz; Rybacki, Maksymilian; Radecki‐Pawlik, Artur

doi:10.1016/j.ecohyd.2022.10.002

Cited by 7 publications

(5 citation statements)

References 56 publications

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“…In the analysis of the distribution of the degree of turbulence Tu relative to successive Xprofiles (lengthwise), it is apparent that there is a very clear difference in the values of the Tuparameter determined for flow in a channel with plant zones compared to flow conditions in a channel without plants (Figure 8A,B). In this case, the hydraulic impact of plants is particularly significant, which is also confirmed by literature reports [15,19,44,[48][49][50][51].…”

Section: Intensity Of Turbulencesupporting

confidence: 86%

“…On the other hand, in the analysis against Y-profiles (Figure 7D), the fluctuation of the transverse velocity v y along the length of the channel caused by the hydraulic influence of alternating vegetation zones is most clearly visible (Figures 3 and 4). This hydraulic phenomenon has also been observed by several other research teams [44][45][46][47][48].…”

Section: Spatial Distribution Of the V Y Velocity (The Lateral Compon...supporting

confidence: 82%

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Hydraulic Effect of Vegetation Zones in Open Channels: An Experimental Study of the Distribution of Turbulence

Tymiński,

Wolski

2023

Sustainability

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The development of vegetation in riverbeds is an important part of river engineering, and an in-depth understanding of its hydraulic influence is greatly needed. Our research focuses primarily on common reed (Phragmites australis) in riverbeds. To date, little is known about the hydraulic impact of the Phragmites australis reed and both field and laboratory data are still very scarce. Consequently, the main goal of our study was to evaluate the effect of vegetation zones on the spatial distribution of turbulence. Based on laboratory measurements of local instantaneous velocities, the values of the turbulence intensity (degree) Tu were determined, and its spatial distribution was illustrated. Analysis of the results showed that the relatively dense clusters of plants (reeds) act as “openwork deflectors” of the current and very clearly shape its spatial distribution. This can also be observed in the case of the distribution of the turbulence parameter Tu. For example, in the case of the development of riparian vegetation in the form of quasi-triangular communities of common reed (Phragmites australis) located alternately, there is a channelization of the flow, but also spatial changes in its character that occur. This work only presents results for preliminary hydraulic tests for Phragmites reed. These experiments should also be continued for other species of flexible riparian vegetation such as wicker. In the laboratory, the hydraulic influence of only triangle-shaped vegetation zones has been studied. Therefore, there is also a need for further hydraulic studies on vegetation zones of shapes other than triangular, e.g., rectangular, as well as vegetation zones with irregular shapes The authors see the need for such research and have already planned its continuation. Research on the interactions between vegetation and the structure of water flow in the riverbed is a very important aspect of contemporary trends in river environment management. Conscious, planned, and model-tested locating (or removing) of vegetation in a stream allows for shaping hydraulic and morphological conditions, thus controlling the processes of erosion, transport, and accumulation of debris.

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Section: Intensity Of Turbulencesupporting

confidence: 86%

Section: Spatial Distribution Of the V Y Velocity (The Lateral Compon...supporting

confidence: 82%

Hydraulic Effect of Vegetation Zones in Open Channels: An Experimental Study of the Distribution of Turbulence

Tymiński,

Wolski

2023

Sustainability

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“…Based on the results obtained, as well as on the research published in earlier articles [12,46], this study succeeded in confirming the hypothesis put forward in this paper that the use of semi-natural structures, such as deflectors, improves the hydromorphological conditions of anthropogenically transformed watercourses. These structures show great potential to initiate and accelerate renaturalisation processes in small lowland watercourses.…”

Section: The Impact Of Deflectors On the Ecological Conditions Of Ren...supporting

confidence: 81%

“…By comparing the simulation results to the calculation in the 1D modelling and measurement results described in [46] by Zaborowski et al, the roughness coefficients had small values. Depending on how the deflectors were represented in the numerical model, the values of the tared coefficients ranged from 0.060 s•m −1/3 to 0.075 s•m −1/3 in the vicinity of the deflectors themselves and 0.055 s•m −1/3 to 0.065 s•m −1/3 in areas beyond their influence.…”

Section: Results Of Hydraulic Simulations In Hec-rasmentioning

confidence: 93%

“…In this way, PBHS had a positive impact on the hydromorphology of the river's reach and may have enhanced its settlement by enabling a greater variety of animals to live in the river. The adverse consequences of the introduction of PBHS for engineering constructions and river maintenance are very limited, and due to the low impact of the structures on high-flow levels, they do not increase the risk of inundation [46].…”

Section: Influence Of Deflectors On the Hydromorphological Changesmentioning

confidence: 99%

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Environmental Restoration and Changes of Sediment and Hydrodynamic Parameters in a Section of a Renaturalised Lowland Watercourse

Zaborowski,

Kałuża,

Jusik

et al. 2024

Sustainability

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In Europe, the routes of most watercourses were straightened and shortened, leading to the destruction and degradation of many natural environments. Currently, in places where it is possible, as part of the implementation of the Water Framework Directive, efforts are made to improve environmental sustainability, including improving the ecological condition of rivers. This paper presents the impact of three in-stream deflectors on changes in the section of a small lowland river—the Flinta (Poland)—where (from 2018 to 2023) detailed, systematic geodetic, and hydrometric research and an assessment of the ecological conditions were carried out. The presented results show the influence of deflectors on the initiation of fluvial processes in the transverse and longitudinal layouts of the channel. The river channel was narrowed from 6 to 5 m, and the current line shifted by almost 3 m. Changes were observed in the distribution of velocities and shear stresses, varying along the surveyed section of the river. In the first year after their application, an increase in velocity at the deflectors can be observed (from 0.2 m∙s−1 to 0.6 m∙s−1 in the deflector cross-section). In the following years, on the other hand, a clear decrease in velocity was observed in the sections between the deflectors (to 0.3 m∙s−1). The introduction of deflectors resulted in a significant increase in the values of shear stresses (from an average value of 0.0241 N∙m−2 in 2018 to 0.2761 N∙m−2 in 2023) and local roughness coefficients (from 0.045 s∙m−1/3 before the introduction of the deflectors to 0.070 s∙m−1/3 in 2023). Based on analyses of sediment samples, erosion and accumulation of bottom material were initially observed, followed by a subsequent stabilisation of particle size. Differences in grain size were observed, especially in the cross-section of the deflectors (increase in granularity d50% downstream of the deflector from 0.31 mm to 3.9 mm already 2 years after the introduction of deflectors). This study confirmed the positive impact of using deflectors on hydromorphological processes as deflectors facilitate the achievement of a good ecological status, as required by the WFD. The innovation of this paper lies in demonstrating the possibility of using small, simple structures to initiate and intensify fluvial processes, which may contribute to improving the ecological conditions of watercourses.

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The Effects of Meander Reconnection and Deflector Installation on the Physicochemical Water Quality

Hons,

Maris,

Schoelynck

2024

River Research & Apps

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River restoration efforts are gaining momentum in response to the pressing need for resilient river systems, in light of escalating climate change impacts. However, achieving predefined restoration goals remains challenging due to insufficient understanding of river system responses. Of particular complexity is assessing the success of restoration measures on water quality, a critical abiotic factor in freshwater ecosystems. This study examined the impact of meander reconnection and deflector placement on water quality. Two distinct meander sections and a degraded section were meticulously sampled both upstream and downstream to assess impacts. The meander sections were reconnected using different approaches: one fully reconnected, receiving all discharge, and the other partially reconnected, receiving part of the discharge while maintaining the channelized trench. The results showed promising potential of reconnected meanders for mitigating phosphorus and carbon levels. However, the effectiveness of these improvements was compromised by deflector placement, which led to increased erosion and release of phosphorus bound to organic soil particles. Conversely, dissolved nutrients (e.g. nitrate, orthophosphate, DOC) exhibited no significant alterations, likely attributed to the absence of macrophytes and the limited extent of restorative actions, which currently do not increase water residence time sufficiently. Temporal trends revealed progressive reductions in carbon, phosphorus, and nitrogen levels suggesting that time is a crucial factor in restoration success, possibly due to soil stabilization. Seasonal dynamics also played a significant role, with discernible effects observed primarily during summer. This study underscores the importance of long‐term, watershed‐scale investigations that account for seasonal variability to fully understand the impacts of river restoration.

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Influence of river channel deflector hydraulic structures on lowland river roughness coefficient values: the Flinta river, Wielkopolska Province, Poland

Cited by 7 publications

References 56 publications

Hydraulic Effect of Vegetation Zones in Open Channels: An Experimental Study of the Distribution of Turbulence

Hydraulic Effect of Vegetation Zones in Open Channels: An Experimental Study of the Distribution of Turbulence

Environmental Restoration and Changes of Sediment and Hydrodynamic Parameters in a Section of a Renaturalised Lowland Watercourse

The Effects of Meander Reconnection and Deflector Installation on the Physicochemical Water Quality

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