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Why is navigation difficult on the lower Vistula River?

Magnuszewski Artur

Gospodarka Wodna

2024

Nr 6

26--32

The lower Vistula River natural conditions limit the possibilities of river regulation. River regulation works performed at the end of the 19th c. did not take into account the massive transport of bed load that, in a wet year, can reach 1.5x106 tons of material. During low river stage periods, sandbars appear, forcing the river to strongly meander. The movement of sandbars was analysed based on the Sentinel-2 satellite images. The comparison of sandbars distribution on 04/09/2016 and 30/07/2017 indicated an average shift of 443 m. Sonar measurements performed in that period show that, during one year, the thalweg changes its position moving from one bank to another. In places where the thalweg alternates between the banks, the river depth over sandbars falls below 1 m.

Naturalne warunki dolnej Wisły stanowią ograniczenie dla regulacji rzeki. Wykonane w końcu XIX w. prace regulacyjne nie uwzględniały ogromnych mas rumowiska wleczonego, którego transport w warunkach roku mokrego może sięgać 1.5x106 t. Przy niskich stanach wody na powierzchni pojawiają się piaszczyste ławice, które wymuszają kręty układ nurtu. Do badania ruchu ławic wykorzystano analizę obrazów satelitarnych Sentinel-2. Porównanie położenia ławic na obrazach z 2016-09-04 i 2017-07-30 wykazało ich przesunięcie o średnio 433 m. Wykonane w tych latach pomiary echosondą pokazują, że w ciągu jednego roku nurt zmienia położenie, przemieszczając się spod jednego brzegu na przeciwległy brzeg. W miejscach, gdzie nurt przerzuca się między brzegami, głębokości nad ławicami spadają poniżej 1 m.

The Impact of Bridges on the Process of Water Turbidity on the Example of Large Lowland Rivers

Szatten Dawid, Habel Michał, Babiński Zygmunt, Obodovskyi Oleksandr

Journal of Ecological Engineering

2019

Vol. 20, nr 10

155--164

The transformations of river channels as a result of human activity may reflect the level of anthropogenic pressure. Recorded in macroscale, they are indicators of transformations for the larger part of the river basin, while in the microscale they usually refer to its fragment. The human activity that has the strongest influence on the fluvial processes, including suspended sediment transport, is the interference in the riverbed, such as hydrotechnical construction (create of water stages) or transformation of the river banks (concreting of the river banks). The aim of the research was to determine the impact of bridges on the process of water turbidity in the longitudinal profile of large lowland rivers. The research area was the lower reach of Vistula – bridge profiles: Torun, Bydgoszcz, Kiezmark (Poland) and bridge profile on Sukhona – a tributary of the Northern Dvina River near the city of Veliky Ustyug (Russia – Arkhangelsk Oblast). The research conducted in the years 2013–2017 included the measurements of water turbidity in the cross-sections of the above-mentioned rivers. The determinations of water turbidity were carried out using traditional (granulometry analysis) and nephelometric methods (devices: LISST-25X and turbidimeter). The impact of bridges on the variability of water turbidity was determined. The obtained results were related to the variability of depth conditions (bathymetric measurements) and hydrodynamics in the cross-section profile of the channel.