Sediment Sampling and Analysis in Rönne å at Ängelholm

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Abstract

This report presents the results of sediment sampling in Rönne å (river) at Ängelholm, located in the north-western part of Scania, which is the southern-most province in Sweden. The sampling and subsequent grain-size analysis were performed primarily to verify hypotheses about main mechanisms controlling local scour at a number of sites where scour holes had been observed in the river during detailed bathymetric surveys. Thus, this study is expected (1) to complement the results from the bathymetric survey where bottom erosion (local scour) was detected in order to establish the main causes of the erosion, and (2) to subsequently employ the information on bottom sediment (grain size) conditions into an existing hydrodynamic model, improving model predictability regarding scour.

Sampling were performed at 8 locations encompassing in total 19 samples that represented parts of the Rönneå river bottom experiencing scour in the city of Ängelholm, covering a stretch from the river mouth to about 8 km upstream. These locations comprised bottom areas with pronounced scour holes due to the presence of bends, bridges, and hard bottom. The samples were subjected to analysis, including sieving and visual inspection and classification, depending on the material composition. A few samples consisted mainly of cohesive material and they have not been analysed yet.

Overall, the sampling and related analysis verified the hypotheses about the mechanisms governing the evolution of the scour holes at the investigated locations. The main causes of the scour were bend scour (locations SH1, SH4, SH9, SH10, and, SH12; see figure 1), bridge scour (SH8), and hard bottom scour (SH5 and SH6). However, at SH8, SH9, and SH10, hard bottom also contributed to the scour. The sediment parameters determined in the grain-size analysis will be useful for calculating the development and equilibrium properties of the scour holes using appropriate formulas from the literature. For the samples where grain-size analysis could be carried out the median grain size approximately varied between 0.6 mm and 15 mm, but larger-sized substrate (e.g., gravel) was observed in the field at hard bottom locations, where no samples could be retrieved by the applied sampling technique.

Detaljer

Författare
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Vattenteknik
Originalspråkengelska
UtgivningsortLund
FörlagLund University
Antal sidor37
StatusPublished - 2021 maj 21
PublikationskategoriForskning

Publikationsserier

NamnTVRL
Nr.3243
ISSN (elektroniskt)1101-9824

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