Projects

Outcome

In this project we gain insight on the large-scale river response to human intervention and climate change. We see that the river is still adjusting to past river normalizations (18th-20th) through changes in the channel slope, which lead to bed incision. This response is more prominent than the response to climate change scenarios.

Research Challenge

We have three main questions:

1. How has the lower Rhine River responded to past human intervention, in terms of bed level change and bed surface grain size change?
2. How does the lower Rhine River respond to different climate change scenarios, and how does this response compare to the response to past human intervention?
3. How does the lower Rhine River respond to future scenarios of human intervention, and how does this add up to the ongoing response?

Relevant for Whom and Where

This research is relevant for the following user groups:

• River managers and engineers — at initial stages of intervention/river management strategy planning, and to evaluate how local problems (e.g., around fixed layers), are part of larger scale dynamics.
• Researchers – to better understand large-scale channel response in engineered rivers.

Findings and Practical Application

• While river bed erosion is particularly challenging at specific locations (e.g. around fixed beds), it is crucial to understand that it follows much larger scale dynamics.
• River response to human intervention is dominant, more so than river response to climate change.
• Highly schematized, calibrated 1D numerical models are a fast and very useful tool to assess large-scale channel response to climate change and human intervention.
• Different management policies across regions or countries can lead to large differences in channel response. Transboundary river studies are therefore essential.
• Frequent monitoring of the river bed is crucial to understand river dynamics.

Status for Day to Day Practice

Potential users should consider large-scale dynamics even for local intervention/management strategy planning, and keep in mind that  it is possible to follow the same modeling framework developed in this project and apply it to any river

Next Steps

Some types of river intervention are inherently two or three-dimensional. While schematized 1D numerical models can provide insight on their effects, 2D studies would help us understand some features such as fixed beds, or bifurcations.

In addition, while some characteristics of the river are intensely and accurately monitored (e.g., water levels), sediment-related measurements (like sediment fluxes or bed surface composition) are much scarcer and uncertain. More sediment-related data collection would help reduce the uncertainty of these studies.