Evaluation of Wanapum Dam Bypass Configurations for Outmigrating Juvenile Salmon Using Virtual Fish: Numerical Fish Surrogate (NFS) Analysis

摘要

As part of the Federal Energy Regulatory Commission (FERC) relicensing process, Public Utility District No. 2 of Grant County (the District) wishes to improve performance of fish bypass at Wanapum Dam. The Numerical Fish Surrogate (NFS) is a Eulerian-Lagrangian-agent model (ELAM) developed for analyzing, decoding, and forecasting the movement and passage behavior response of outmigrating juvenile salmon (migrants) in complex 3-D hydrodynamic fields near fish bypass systems in hydropower dam forebays. The NFS (and ELAMs, in general) uses a mechanistic plug-and-play behavior algorithm embodying a biological hypothesis of how an individual responds to biotic and/or abiotic stimuli. The University of Iowa IIHR - Hydroscience and Engineering developed a computational fluid dynamics (CFD) model to describe the 3-D steady-state hydrodynamic fields associated with 12 different structural and operational fish bypass system configurations (cases) at Wanapum Dam. In Phase 1 of the study, forecast (virtual fish) and observed (radio- tagged fish) passage proportions were compared for five different cases from years 1997, 2001, and 2002. Comparison of forecast and observed passage for four out of the five cases were done blindly (i.e., independently reviewed and evaluated) and within the expected limits of about 5 to 10 percent for the bypass systems and considerably better than forecasts of passage from passive particles (i.e., behavior rules turned off). This indicates migrant movement behavior in the flow field is likely an integral part of bypass success. In Phase 2 of the study, the NFS was used to forecast the passage response of migrants to seven different structural and operational design alternatives under consideration for Wanapum Dam prior to construction and installation.