Fish stranding in relation to river bar morphology and baseflow magnitude: Combining field surveys and hydrodynamic–numerical modelling

• DOI: 10.1002/eco.2616
• Publication Date: 2024-01-26T12:20:20Z
• Authors: Daniel S. Hayes; Christoph Hauer; Günther Unfer
• Keywords: Base flow; Bar (unit)

Abstract Hydropeaking mitigation based on down‐ramping thresholds is crucial to avoid stranding of fish and ensure sustainable hydropower production. However, the risk influenced by several biotic abiotic factors that interact with ramping rate, including river morphology baseflow magnitude. Also, at bar scale, lateral or horizontal velocity may be even greater importance than vertical one as prior integrates morphology. This study investigates connection between ecologically relevant hydraulic parameters (vertical velocity, dewatered width) young‐of‐the‐year European grayling ( Thymallus thymallus ) due down‐ramping, field observations stranded hydropeaked Drava River in Austria combined hydrodynamic–numerical modelling. We also examine interplay conditions topography areas. Stranding spring summer found a median rate 90 individuals per 100 m, ranging from 50 500 m shoreline. rates were three times higher night during day. Our data revealed positive relationship hydraulics, intensity resulting more fish. association was stronger for presumably because former accounts morphology, suggesting dewatering better indicator assess scale velocity. negative extent area magnitude, indicating low flow conditions.