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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Transport and propagation of fine sediment at alpine rhine delta and lake constance during floods
Transport and propagation of fine sediment at alpine rhine delta and lake constance during floods
Author : DANIEL EHRBAR(1), MAGDALENA EDER(2), DAVID F. VETSCH(3) & ULRICH LANG(4)
ABSTRACT
The Alpine Rhine transports large quantities of fine sediment into Lake Constance each year. Embankments were built on
the original delta deposits to avoid further aggradation at the river mouth and to convey the sediment-laden water into
deeper parts of the lake. Because recent flood statistics indicate the potential of increased flood discharges, an upgrade of
protection measures upstream of the river mouth is planned. In addition, the impact of future floods and sediment
discharges on the river mouth and Lake Constance are investigated by numerical simulations. The mainly fluvial transport
processes in the channel and the interaction with the lake are simulated using a 2D Saint-Venant-Exner model. The
incorporated sediment transport model includes both bed-load and suspended-load and the exchange between both
modes. A Reynolds-averaged 3D model is applied for fine sediment propagation in the lake, thereby considering density
as well as temperature gradients and thus allowing for the simulation of turbidity currents and lake stratification. The fluvial
and lake models are coupled by exchange of water and sediment discharge. For model calibration and validation, two past
floods were simulated and compared with measurements, i.e. estuarine and lake topography as well as data of
temperature and turbidity loggers. These simulations indicate that morphological patterns in the channel are sensitive to
configuration of transport model exchange terms. In the lake, the sediments may be transported over large distances.
Depending on the processes, interflow and underflow form and turbidity currents may occur reaching nearly the German
shore. These underflows are strongly linked to resuspension processes. Based on the validated model, scenarios of future
floods at different combinations of discharge and lake level are investigated. The results to be presented in the paper
submitted indicate the fitness of the existing estuarine works. Furthermore, depositions and propagation of fines in the lake
are also discussed.
File Size : 1,442,415 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 28/08/2015
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