Interactive engineering model
HEC-14 culvert outlet scour geometry
Apply FHWA HEC-14 Equation 5.1 to a circular outlet using full-flow hydraulic radius, material gradation, peak duration, slope, and outlet drop-height corrections.
Preparing the 3D model...
A cutaway circular culvert carries its solved outlet flow depth and sits exactly the drop height above a closed soil block, with a dimensioned drop between the invert and the bed. The jet plunges into an asymmetric scour hole that is deepest at 0.4 Ls, closes at Ls, and is followed by a low deposition mound; depth contours are traced on the hole and dimension lines mark hs, Ls, Ws, and the maximum-scour location. The slope control offers the four published HEC-14 bands and tilts the barrel, and the tailwater floods the hole against a labelled 0.5D applicability marker.
Focus the 3D view and use the arrow keys to orbit, plus or minus to zoom, and Home to reset the view.
Text explanation and non-WebGL fallback
A cutaway circular culvert carries its solved outlet flow depth and sits exactly the drop height above a closed soil block, with a dimensioned drop between the invert and the bed. The jet plunges into an asymmetric scour hole that is deepest at 0.4 Ls, closes at Ls, and is followed by a low deposition mound; depth contours are traced on the hole and dimension lines mark hs, Ls, Ws, and the maximum-scour location. The slope control offers the four published HEC-14 bands and tilts the barrel, and the tailwater floods the hole against a labelled 0.5D applicability marker.
Important: Equation 5.1 is for cohesionless soil and peak duration of at least 30 minutes. Maximum scour was observed below about 0.5D tailwater; the equation has no continuous tailwater correction, and cohesive soils require HEC-14 Equations 5.2-5.4.
The numeric controls and readouts remain usable if WebGL is unavailable. Drag or swipe the 3D view to orbit and use a wheel or pinch gesture to zoom. With the 3D view focused, use the arrow keys to orbit, plus or minus to zoom, and Home to reset. The complete numeric lesson is also keyboard-accessible in the adjacent controls and readouts. This model is an educational aid and does not replace applicable design standards or professional review.