Forecast simulations of 3-D fish response to hydraulic structures

Utility of a theoretically- and computationally-robust mathematical model for decoding the movement patterns of individual fish in 3-D space-time is described. Hydrodynamic stimuli queried from a 3-D CFD model (U2RANS) are used to elicit spatially-explicit virtual fish behavior. The modeling scheme, coupled Eulerian-Lagrangian agent individual-based modeling (CEL Agent IBM), is intuitive and based on well-established principles in computer science, fluid and water quality dynamics, computational fluid dynamics (CFD) modeling, and game and foraging theories. We demonstrate the utility of a prototype CEL Agent IBM (the Numerical Fish Surrogate) developed for outmigrating juvenile salmon in the Pacific Northwest. The Numerical Fish Surrogate is used by the US Army Corps of Engineers to decode behavior and then, using results from back-casting analysis, forecast the response of salmon to virtual designs of proposed alternative bypass structures to aid project selection and design. CEL Agent IBMs and the Numerical Fish Surrogate provide the means to integrate high fidelity CFD and water quality modeling and individual-based modeling to improve biological simulation of aquatic wildlife for water resource decision-support and reduce reliance on the build-and-test paradigm.