Research Idea Details

Research Idea Scope

An overall assessment of fish passage conditions from headwaters to estuaries requires the analysis of the entire channel network connecting those habitats. Such an analysis should not be performed in a single time snapshot, but rather over an extended period corresponding to the migration seasons of target fish species. With the exception of few packages such as HEC-RAS, most models consider discrete rates (e.g., 7-day low flow event) in the analysis, thus neglecting broader spatial and temporal interactions within stream networks (e.g., backwater effects). A model that integrates the hydraulics of this complex system along with the fish passage characteristics doesn’t exist at present and, hence, the upstream and downstream migration of fish within the watershed context cannot be properly assessed.

A watershed-based computer program will be developed and made publicly available. This program is a post-processing tool to HEC-RAS that will enable the assessment of fish passage conditions throughout the entire watershed. The program will use the results from HEC-RAS to select the data gathered in experiments and Computational Fluid Dynamics (CFD) results to reconstruct the velocity map at the cross sections of the culverts of interest, at each time step of the extended period simulation. These velocity results will be compared with fish species’ swimming performance, and an assessment of whether individual reaches, geologic formations, and culverts are blocking fish passage at that given time step can be made. The fish performance data will come from integrating the post-processing tool with the fish database available in FishXing model. This post-processing tool will have an intuitive user interface, suitable to be applied by engineers, scientists, and/or technicians in charge of the assessment of fish passage conditions.  Finally, the code will be made open-source, and will be readily available for the interested community, which can expand and improve it according to particular needs.

Urgency and Payoff

The outcome of this research will result in an open source (free and open access) predictive tool that can be used by stakeholders (planners, watershed councils, citizen groups, policy makers, managers) for better assessing fish passage conditions in an entire watershed system and hence conceiving remediating plans aiming to minimize the impacts of those dispersed barriers in a watershed-integrated fashion. The resulting program will provide policymakers with a tool that accounts for the entire inland migratory route of a fish stock. Once policymakers have applied the model to their watershed and fish species of interest they will be able to identify locations in the watershed that are acting as migratory barriers or inducing migratory delay. Further, the percentage of time during a migration season that a reach or structure acts as a migratory barrier will be apparent. The watershed can also be modified within the model to predict changes in population level passage efficiencies upon implementation of various proposed modifications. The resulting predictive tool will be usable under present and climate change scenarios.