Author(s): Sebastian Schwindt; Benjamin Kemmler; Federica Scolari; Gregory B. Pasternack

Linked Author(s): Sebastian Schwindt, Federica Scolari, Sebastian Schwindt, Gregory Pasternack

Keywords: Numerical simulations; WUA; HSI; Habitat suitability; FLIP; Unreal Engine; Niagara Fluids

Abstract: Ecohydraulic simulation has progressed from 1D weighted usable area calculations following Bovee and Stalnaker, in which reach -averaged hydraulics are mapped to species- and lifestage-specific suitability curves, to 2D depth and velocity fields that compute per-pixel habitat suitability indices, resolving spatial heterogeneity and connectivity. Yet many passage problems demand 3D because fish respond to vertical shear, turbulence intensity, and coherent structures. 3D models can clarify possible swimming routes, delay zones, and sensory thresholds tied to pressure and vorticity. In particular, agent -based methods couple Eulerian hydraulics with Lagrangian agents to predict movement decisions. However, widespread adoption still needs more calibration data, behavioral rules transferable across flows and species, and validation against trajectories and survival. Ultimately, we showcase parcel-based solvers integrated with Unreal Engine to render high- resolution flows, enabling exploration of aquatic environments from the perspective of fish and testing of virtual interventions before field deployment.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.113

Year: 2026