Hydropeaking impact on a riparian ground beetle community

The Common Meuse reach is strongly influenced by the operation of a hydropower plant at the upstream weir of Lixhe, especially during periods of low flow. Ecologically-based in-stream flow requirements and fluctuation thresholds have already been determined for this reach by reconstruction of the natural discharge course from historic and actual reference conditions. Nevertheless, more evidence from the present biota at risk has been demanded. This study therefore attempts to define boundary conditions for the low flow regime from the analysis of riparian ground beetles in this river reach. To achieve this, reference conditions for the hydroregime aspects of flow variation were determined. Then, using the habitat templet approach, the hydropeaking pressure was related to biological quality elements. Finally, after detecting the impact on the specific gravel bar ground beetles, thresholds and boundary conditions were determined for the hydropeaking pressure in peak velocity.