FishXing is a unique software tool that models both culvert hydraulics and fish swimming and leaping performance through the predicted hydraulic environment. The topics covered in Calculations are intended to give you a general understanding of the computational methods used by FishXing as well as the assumptions and limitations associated with them. Detailed description and discussion are provided for computational methods that are unique to FishXing.
Most culvert hydraulic models are specifically intended for determining culvert capacity at specific headwater elevations. However, they often fail to adequately describe the hydraulic environment a fish encounters within the culvert. Additionally, standard methods for determining culvert capacity typically include a number of assumptions. Although valid for estimating headwater elevations, some of these assumptions may oversimplify our understanding of the hydraulic environment encountered by fish as they swim upstream through a culvert. Since FishXing is principally a tool for evaluating fish passage through culverts, the FishXing model attempts to compute a more realistic hydraulic environment by addressing certain hydraulic conditions differently than standard culvert models. Many of these differences are covered in the Inlet Contraction Velocity and Boundary Conditions topics.
Flow conditions in a culvert encompass a variety of hydraulic environments. Calculating depth of flow in a culvert involves a series of computational decisions.