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  2. Dyle Catchment

Dyle Catchment​

The Dyle catchment forms part of the wider Scheldt river basin and joins the Demer River. It rises in Wallonia and flows northwards into Flanders. The non-navigable part of the Dyleriver in this pilot has a catchment area of around 1,250 square kilometres.

The southern part of the catchment is hilly, further north, the landscape becomes flatter and more urbanised. Agriculture is the dominant land use of the catchment, then urban areas and lastly some forests, moors and heathland. The upper Dyle still follows a relatively natural course, whereas downstream from Leuven, the river is more strongly regulated through flood-control structures and constrained river channels.

photo: landscape of the Dyle valley - copyright: Alex Van Mol (Aminal)

Why was this pilot site selected?

The Dyle flows through the Belgian Loess Belt, an area with highly productive but very erosion-sensitive soils. Intensive agriculture can cause large quantities of sediment to enter rivers. This affects water quality and aquatic ecosystems and creates a need to manage sediment throughout the river system. The scale of the challenge became particularly clear during the floods of July 2021 when more than 30,000 tonnes of sediment were transported over just a few days. The catchment crosses Flanders, Wallonia and Brussels, which makes cooperation and catchment-wide sediment management especially important.

What do we want to achieve?

The pilot wants to understand where erosion occurs, how much sediment enters the river, and how that sediment is transported and deposited throughout the catchment. It examines how changes in land use, mitigation measures and climate conditions could influence erosion and sediment movement. The goals is more coordinated and effective sediment management.

How will we do this?

The project develops scientifically robust models to:

  • identify erosion hotspots
  • estimate sediment loads entering the river
  • simulate sediment transport and deposition
  • assess different land-use and mitigation scenarios
  • evaluate how climate change may affect erosion and sediment-related risks

Monitoring data will help support this work, as well as a regional working group. The modelling and planning framework should be transferable to other erosion-prone rivers with similar challenges.