I am attempting to model a few road crossings in HY-8. When analyzing the results for a few of the crossings I noticed the water surface profile inside the culvert seems a little odd. For example, I have a headwater that rises above the top of the culvert, yet the culvert is only running about 3/4 full. Maybe I'm imputing incorrect data somewhere or maybe it is just how HY-8 calculates the water surface profiles. Can someone explain to me why this might be the case? Attached is a picture as an example. Thanks for the help!
HY8 Example Pic.tif