Author(s): Luis Philipp Habersetzer; Luiz G. M. Silva; Roman Stocker; Jakob Brodersen

Linked Author(s): Luiz G Martins da Silva

Keywords: Catchment-scale; Riverbed; Deep rivers; Quantification of structure

Abstract: The regulation of large rivers by run-of-the-river hydropower plants (HPPs) creates contrasting reaches— impounded and non -impounded—which are hypothesized to reduce riverbed habitat heterogeneity. This study utilized low-cost, consumer-grade side-scan sonar and an object-detection model (YOLOv8n) to perform standardized, large-scale mapping of riverbed structure and quantify this impact across a river network in northern Switzerland. The methodology successfully assessed both fine-scale variability via a gray-level variance approach and larger structures (e.g., rocks >20 cm) via object detection, yielding a comprehensive map of riverbed heterogeneity. Preliminary results suggest that non-impounded sites exhibit higher median variance and a broader distribution of heterogeneity compared to impounded sites, indicating that flow regulation may lead to a reduction in the spatial variability of riverbed structure.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.294

Year: 2026