Nature-like Fishway Modeling and Design

Elaine Langone, Forum

Worldwide, millions of dams can have adverse impact on the connectivity of rivers and streams, hindering fish migration and proliferation. Efforts to re-establish connectivity traditionally involve providing a fish passage structure near a dam. Traditional fish passage structures, such as fish ladders, have historically performed suboptimally. Additionally, certain fish species may have difficulty finding the entrance to the structures or may be unable to navigate through the structures. Efforts to increase passage rates have shifted to design passages which mimic natural settings by considering fish behavior and natural habitat in the design process. These “nature-like fishways” (NLF) require site-specific modeling for a given dam and target species. This study uses one hydroelectric dams on the lower Susquehanna River as an example to show how state-of-theart science and technology can be used to better design NLF. Here, we will test the preliminary engineering design with detailed computer modeling and laboratory experiments. Both two-dimensional and threedimensional computer models will be used to examine the river flow at the site and the hydraulics within the fish passage. Additionally, we will build and run a laboratory model of the proposed NLF. The laboratory measurements will provide validation of the simulation results and help designers engage key stake holders in the design process. The flow field (velocity, depth, and turbulence) obtained from the computer and physical models will be further used in a Lagrangian-based fish behavior model to simulate the passing process of target fish species. Success, remaining technical issues, and future research directions will be discussed.