Motivation
The sediment transport in large navigable and hydropower exploited rivers is an everlasting engineering challenge. For example, the German government spends more than 100 million euros every three years to dredge and clean the river pathways for the cargo boats to pass over. Thus, a proper sediment management is a crucial for good navigation of the ships and proper operation of the run-off hydropower plants. Take for example the stuck boat in Suez channel, or this sunk barge in Rheine river. In addition, the erosion of the banks and the riverbed should always be monitored, especially after large flood events.
Objectives
The objective of this study is to analyze the riverbed dynamics, shear stress and the sediment transport on river reach of Rheine river in Germany. The change of the active width of the bedload influences the deposition erosion patterns causing problems for ship tracks. Therefore, it is crucial to detect those variation and correlate with hydraulic variables. 2D Numerical model should be developed, and different scenarios should be processed. The input and calibration data should be taken from the data storage of the Hydrological Institute of Germany (BfG) and NTNU. The variations in the riverbed (i.e., erosion – deposition processes) should be analyzed numerically (using sediment transport modules of HEC RAS 6.0 or Riverflow 2D); and empirically by correlating the shear stress with observed changes and transport rates. The models should be validated and calibrated. The partition of shear stress related to the sediment transport is called grain-related shear stress, as opposite to the drag shear stress which is induced by the riverbed morphology (e.g., bedforms).
The final outputs would be mapping of the dynamic changes riverbed, changing of the active bedload width, defining the bedload pathways and establishing a correlation with the shear stress.
Outline of the thesis:
- Literature review over the existing reports and papers.
Data collection, analysis, and classification.
The data: grain size, bedload transport rates, suspended sediment transport, discharge (ADCP and hydrometric stations), water velocity, etc.- Numerical modelling of the reach using HEC RAS, Riveflow 2D or SIIM.
- Calibration and validation of the model using BfG data set and ADCP moving mode measurements.
- Mapping of the riverbed at different scenarios, mapping the shear stress of interest.
Desired capabilities:
- Handling large datasets.
- Good knowledge in open channel hydraulics.
- Knowledge in 2D numerical modeling.
- Basic statistics.
- Additional asset is knowledge of some programing language such as MATLAB or Python.
