Example of a side channel that was built along the Dutch river Lek at the east of Schoonhoven (Source: Rijkswaterstaat / Bart van Eyck).
Three side channel categories and a modelling framework to estimate the side channel development over time as input for their design and maintenance.
Side channels are common in natural rivers but they disappeared due to human interventions. In several European and North-American rivers, side channels are restored to reduce flood risk while increasing the ecological value of the river. For example in the Netherlands, over 20 side channels have been constructed since 1996. As on the image on the right, many of these channels show aggradation and/or deposition of sediment. Thereby, these channels may loose their function over time. Maintenance is then required, but this is costly and disturbs the ecosystem. To improve the design and maintenance of side channels, we need to better understand the mechanisms that influence the time scale of the side channel development.
Key goals: Fundamental understanding Innovative monitoring
Modelling framework that combines available or collected measurements with 1D and 2D numerical modelling to define three side channel categories.
Many side channels are built or restored without knowing how they will develop. By combining model results with available measurements (left side of the figure), we proposed a modelling framework to define three typical channel categories (right side of the figure). These side channel categories are based on how the sediment that is deposited in the side channnel is predominantly transported in the main channel (bed load, suspended bed-material load or wash load). Multi-temporal images back to 40 years show the changes of a natural side channel system abroad (top left of the figure). For the Dutch man-made side channels, the Gameren in the river Waal was the only side channel where frequent measurements were available. Bed level measurements over a period of about twenty years gave insight into the side channel changes. In addition, we collected soil samples at different locations (center left of the figure). We modelled the natural channels by using a 1D numerical model and looked in detail into the Dutch case with 2D numerical models to gradually increase the complexity of the mechanisms studied. The 2D model also included varying hydrodynamic conditions (left bottom of the figure).
For whom and where?
- Regions around the world that are interested to build side channels or to better understand the dynamics of natural ones;
- River managers that need to minimize maintenance efforts of future side channel designs.
Data-collection methods: Field survey measurements Numerical modeling Remote sensing
Temporal scale: 1-10years 10-50 years
Application development and findings
We proposed a framework to predict the development of side channels over time as follows (see the outputs list for further details):
- There are three categories of side channels which are defined by how the sediment deposited in the side channel is transported in the main channel.
- Using the bed level measurements and soil samples, the side channel category can be determined. This gives an indication of which mechanisms are important for the side channel development.
- Furthermore, by using the side channel category, we can give a first estimate for the development time scale of the side channel. This estimate can be verified using aerial images or bed level measurements.
- Measurements from Gameren show that the sedimentation rate is related to the varying hydrodynamic conditions. In addition, an initial bed level adjustment was observed up to 1 meter within 5 years of the side channel construction.
- A more sophisticated numerical model (using mixed-sediment morphodynamics) is needed to study the side channel development in more detail and to include the effect of varying hydrodynamic conditions.
Status for day-to-day practice
Advisors in consultancies or government organizations can use the above framework to identify the mechanisms that affect the side channel development and estimate their evolution in years according to the side channel category.
For our modelling framework, we used the available multi-temporal images at all locations. Moreover, we collected soil samples at the Dutch location in Gameren.
Spatial scale: Channel
Key locations: Ain River (FR) Nederrijn-Lek River (NL) Rhine River (NL) Sacramento River (USA) Waal River (NL) Wabash River (USA)
The three side channel categories and the modelling framework give a first indication of side channel development (in years), as input to improve the design and planning of maintenance efforts.
Last updated: 10/02/2020
Explore the contact details to get to know more about the researchers, the supervisory team and the organizations that contribute to this project.
Pepijn van Denderen
University of Twente
As soon as available, explore the storyline to get to know more about the main methods or prototype tools that were developed within this project.
How do side channels develop?
We assess several side channel systems and propose a method to estimate their development.
Pepijn van Denderen
University of Twente
Explore the output details for available publications to get a glance of the innovative components and implications to practice as well as the links to supporting datasets.
A characterization of side channel development
Side channel generally aggrade. The rate at this occurs depends on the design of the side channel. We propose three categeories of side channels which can be used to estimate the time scale of side channel development
01/11/2019 by Pepijn van Denderen et al.View details View publication
Contains: Publication open access
Explaining artificial side channel dynamics using data analysis and model calculations
Morphodynamic assessment of side channel systems using a simple one-dimensional bifurcation model and a comparison with aerial images
To aid the future design and maintenance, a set of diagrams allow to estimate both the equilibrium state and the time that takes for the bed load of the main channel to aggrade or deposit in the side channel.
05/12/2017 by Pepijn van Denderen et al.View details View publication
Contains: Dataset upon request Storyline for practice
Take a look to the dissemination efforts and application experiences which are available in the news items and blogs.
Side channel dynamics from the perspective of four-years research
17/06/2019 by Pepijn van Denderen
Side channels are common river interventions, but how do they develop and how fast do they fill with sediment?
Sharing knowledge with HKV, one of the project partners.
For RiverCare, it is very important to have face to face meetings to exchange the knowledge, and make sure to discuss with interested parties the results of the researchers.
Knowledge sharing meeting in Witteveen+Bos, Rotterdam
How can we apply the researchers’ findings to improve our designs and environmental impact assessments? How can we share lessons learned from RiverCare within our team of engineers and consultants?
RiverCare was featured on the DeltaLink edition about rivers
01/10/2016 by dr. ir. Astrid Blom
The Room for the River programme aimed at increasing flood safety by creating space for water. However, when considering integrated management, there are other...
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