Author(s): Aude Lecrivain; Giovanni De Cesare; Christine Weber; Nico Batz

Linked Author(s):

Keywords: Habitat assessment; Macroinvertebrates; Hydropeaking; Hydrodynamic modelling; Flow alteration; River restoration

Abstract: Understanding how flow variability and morphological change affect aquatic habitats is central to managing riverine ecosystems. Macroinvertebrates, are highly sensitive to changes in flow regime and river morphology, requiring a spatially and temporally resolved assessments that reflect ecologically meaningfull habitat conditions. To address this need, we present a modular Python -based toolbox developed to quantify macroinvertebrate- relevant habitat dynamics at the patch scale – defined here as a geographically fixed area (~0.25 m²) that reflects the scale at which macroinvertebrate larvae interact with and respond to their environment. The toolbox integrates high-resolution 2D hydrodynamic models (0.5 m spatial, 10 min temporal resolution), a generalized habitat classification, and ecologicallyderived criteria to generate a habitat time-series. From this, four patch-scale metrics are derived: habitat probability, habitat shifts, drift risk, and desiccation risk. Together, these metrics capture habitat dynamics, persistence and exposure to stress, key drivers of macroinvertebrate spatial distribution within a reach. While broadly applicable across taxa, flow regimes , and river morphologies, we demonstrate the toolbox's functionality using a nalpine river affected by hydropeaking (i.e., sub -daily flow fluctuations caused by on-demand hydropower production). The toolbox identifies ecological hotspots, reveals trade-offs linked to structural complexity, and visualizes cumulative stressors exposure across time and space. By making patch-scale habitat dynamics both visible and quantifiable, the toolbox bridges the gap between process-based hydrodynamic modelling and ecological risk assessment. It offers a transferable, open-source approach that supports more spatially targeted river management, adaptive flow designs, and stratified long-term monitoring approaches in regulated river systems .

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.154

Year: 2026