This research is a part of the project "Sedimentmanagement of the Upper Rhine" and carried out in cooperation with BfG.
The sediment management in the Upper Rhine River can be affected in the long-term by various natural or anthropogenic activities, e.g. the climate change and land use changes, restoration and engineering measures. To investigate such impacts, a long-term simulation of such scenarios is necessary.
In this research, the long-term dynamics of the fine sediment budget in the Upper Rhine will be determined (i.e. how long does it take to refresh the top layer of the deposition?).
Furthermore, morphodynamic processes in the Iffezheim reservoir with non-uniform bed composition will also be investigated using SSIIM 3D modeling system. High-resolution numerical models combined with other suitable methods will be chosen for the scenario analyse. The results will serve as the basis for a much coarser sediment budget model of the Upper Rhine.
The research will include:
The Iffezheim reservoir consists of a weir, a hydropower plant, a ship lock and a fish passage.
The focus area of the investigation is based on the weir channel where more than 115.000 m³ of suspended sediments are depositecd every year (WSA,2011). With regard to flood protection requirements, the responsible water and shipping authority has to complete regular dredging of the area. The river bed evolution is presented in the figure from 2005 December to 2007 April. WSA, Wasser- und Schifffahrtsamt, Freiburg, 2011. Sachstandbericht oberer Wehrkannal Staustufe Iffezheim 2011.
A high-resolution model was set up for investigations of river morphodynamic processes in the Iffezheim Reservoir. For the long-term simulation the coarsening of the spatial grid resolution was carried out. The impact of this coarsening on the accuracy of the hydraulic and morphodynamic parameters with further consideration of the processing time was investigated.
The simulation of sediment transport consists of three steps in the SSIIM programme:
Since the results from the first step affect the subsequent sediment simulations, the water flow calculation must be performed accurately to ensure correct results for further steps.
Since the sediment concentration is distributed inhomogenously in the river bed, the fitting method polynomial regression is used to define a concentration profile of suspended sediment at the model boundary.
Speckter, T.F.: Auswirkungen vergröberter räumlicher und zeitlicher Gitternetzauflösungen bei der hoch aufgelösten Modellierung von Hydraulik und Sedimenttransport an der Staustufe Iffezheim, Master thesis (Civil engineering).
Zhang, Q., Speckter, T.F., R. Hinkelmann: Auswirkungen vergröberter räumlicher und zeitlicher Gitternetzauflösungen bei der hoch aufgelösten Modellierung von Hydraulik und Sedimenttransport an der Staustufe Iffezheim, Presentation, GESINUS Meeting, Aachen.
Brandolini, A.: Grouping upstream boundary conditions - river discharges and suspended sediment concentrations from 1978-2009, student research project.
Truong, T.M.: Bestimmung eines ARIMA-Modells zum Erstellen einer Vorhersage der monatlichen Abflüsse der Staustufe Iffzheim, student research project.
Scheer, C.L.: Literature Research on the application of artificial neural networks (ANNs) in river morphology, student research project.
Qing Zhang M.Sc.
April 2015 - March 2017
BfG Federal Institute of Hydrology