Hydraulic design of fish passes on the upstream Meuse subcatchment

Many obstacles to fish migration exist along non-navigable rivers, many of which in the form of weirs used by old mills or small hydroelectrical power plants. The goal of the project was to assist the Walloon authorities in the hydraulic design of fish passes to re-establish fish passage on such known obstacles.

Different methodologies were used to model the fish passes: analytical computation using specific approaches, and the use of 1D and 2D models built with HEC-RAS. The goal of the hydraulic analysis was to check the design in low and standard flows for fish migration (appropriate drops, speeds, energy), but also to evaluate the impact of the foreseen solution on water levels in high flows.

Studied sites were located along Meuse tributaries: the Lhomme, Samson and Bocq rivers.

Velocity distribution computation using a 2D HEC-RAS model on a fish pass
Computation of water levels using a 1D HEC-RAS model
Computation of water levels using analytical approaches


  • Client: SPW (Direction des Cours d’Eau Non Navigables)
  • Start date: 2016
  • Completion date: 2021