Optimizing fish pass design: Utilisation of photogrammetry in hydraulic modeling

Photogrammetric scanning is a technique used to create 3D models by capturing the dimensions and textures of objects or areas. This study applies photogrammetry to scan a fish pass, focusing on capturing the channel's micro-relief at optimal resolution. A drone was used for measurements, supplemented by terrestrial images to generate a dense point cloud. The point cloud was processed for various applications, including hydraulic flow modeling. In HEC-RAS simulation software, the point cloud, as a raster file, serves as the terrain base for defining the channel's geometry. The raster resolution directly affects the quality and precision of the model's geometry. The study explores how geometry settings, such as the number of defined cross-sections and terrain detail, influence flow simulations in fish passes. Special attention is given to perturbation boulders, which affect flow dynamics and help meet the required parameters for different fish pass types and target fish species. By analyzing the interaction of geometric inputs, an understanding of their effectiveness in accurately representing the river bed and their impact on the results of simulated water levels was sought. This research provides insights into effective flow modeling based on data from photogrammetric scanning, contributing to the design and monitoring of fish passes.