Hydraulic Criteria Tab:

In many cases fish passage conditions may be evaluated based on established hydraulic criteria rather than entering swimming abilities. In the Hydraulic Criteria tab you enter specific hydraulic requirements that must be satisfied to meet desired fish passage conditions.

Maximum Water Velocity:

Fastest water velocity in the culvert that still allows for fish passage.  A velocity barrier is identified if water velocity (reduced by the velocity reduction factors, if applicable) within any portion of the culvert is above the entered Maximum Water Velocity.

Max Outlet Drop:

The maximum allowable water surface drop at the outlet that the fish will be able to enter the culvert.  The drop is calculated as the difference between the water surface in the outlet and the tailwater surface.  FishXing will identify a drop barrier when the calculated outlet drop is greater than the specified Max Outlet Drop.  Unlike the leaping calculations, the outlet drop criteria apply even when the tailwater surface is above the culvert bottom.  See Outlet Drop Criteria for a discussion on how and when the drop is calculated.

Min Water Depth:

The depth of flow within the culvert required for successful fish passage.  A depth barrier is reported if the calculated water depth is below the specified Min Depth at any location within the culvert. The shallowest depth that allows fish passage is usually the depth required to completely submerge the species of interest. See Water Depth for Swimming for a discussion on the limitations of swim speed equations when a fish is not fully submerged.

Notes and References:

Notes area is a text box available for entering comments or referencing the source of the inputted hydraulic criteria.