Title of the project
Understanding the behaviour of scour holes and developing mitigation measures
Type
PhD Research
Duration
November 2023 – November 2027
Persons involved
M. Oldenhof (PhD candidate)
Dr. A. Bomers (Daily supervisor)
Dr. J.J. Warmink (Co-supervisor)
Prof. dr. S.J.M.H. Hulscher (promoter)
Funding of the project
Part of the NWO-funded project Future food risk management technologies for rivers and coasts
Summary of the research
The bed of river deltas commonly consists of an erosion resistant top layer and an underlying layer with higher erodibility. Due to extreme rainfall and floods, the erosion resistant top layer can break up and the underlying layer easily erodes. This results in the formation of large scour holes, with a depth of at least three meters, within a short amount of time. The scour holes can threaten the stability of structures such as bridge piers, pipelines and dike foundations. For this reason, the scour holes are often artificially filled after the flood while this disturbs the positive effects on natural river bed dynamics on habitat restoration. Room for the river and nature-based solution projects aim to improve the river system’s natural conditions, and therefore it might be desirable to leave these scour holes open after formation.
This research aims to provide a better understanding of the long-term evolution of scour holes in a heterogeneous subsurface. The research consists of a data analysis of available field measurements of the Meuse delta. The data is used to evaluate how scour holes mitigate over time, become stable, further erode or fill over time. Secondly, a numerical model study will be performed in which an idealised model will be developed to study the dynamics of scour holes under varying conditions.
The results of the data analysis and the model study are used to draw a conclusion if the scour holes need to be filled after the occurrence of a flood for safety reasons or if they can remain open to improve the ecological condition in the river system.
Keywords
Lowland river, scour holes, morphological changes, floods, numerical modelling
More information
Marthe Oldenhof
HR W-207
m.oldenhof@utwente.nl