Millions of dams in the world interrupt the longitudinal connectivity of rivers, posing as major threats to fish migration and proliferation. As a remedy, fish passage structures are often constructed near dams to re-establish stream connectivity. However, due to the oversimplified design methods, numerous existing fishways achieved only limited success – poor attraction to passage entrance and low pass rate in the passage. Efforts have shifted to design passages by considering target fish behavior and site-specific conditions in the design process. 

To this end, this study implements an individual-based model (IBM) in conjunction with a biased random walk model in the open source computational fluid dynamics (CFD) platform OpenFOAM. IBM is used to represent fish individuals whose movement follows the rules of fish behavior. The fish behavior is programmed in response to hydrodynamic cues and other stimuli such as certain sounds frequency, water temperature, and illumination intensity which are too complicated and beyond the state-of-the-art of science. Therefore, to model the fish direction choice affected by other stimuli, a biased random walk model is used. The details of the model implementation in the OpenFOAM will be presented. Then, a preliminary application run will be shown for estimating the attraction of fish passage entrance and pass rate in the passage.

An Implementation of Individual-Based Model for Fish Passage Design

Created in 1999, the Environmental & Water Resources Institute (EWRI) is the recognized leader within ASCE for the integration of technical expertise and public policy in the planning, design, construction, and operation of environmentally sound and sustainable infrastructure impacting air, land and water resources.

[Paper Proceedings](https://doi.org/10.1061/9780784483466)

Conference DOI: https://doi.org/10.26226/m.6329c39b68fb0e00131f77d2