The water surface profile within a culvert can be classified two different ways:

1.    Hydraulic Slope, which is based on the slope of the culvert bottom and

2.    Hydraulic Curve, which is based on the relationship of the water depth relative to critical depth and normal depth. 

FishXing uses these classifications to determine the appropriate inlet and outlet boundary conditions.

Hydraulic Slope Classifications

Note: Since FishXing does not model slope breaks within a culvert, therefore type 3 curves do not occur within the model.