The discharge bed of the culvert is in that position of the culvert. ! thank you

after the water from the culvert flows out of the culvert, it usually flows out at the bottom of the hole between two splayed walls. However, the outlet of some culverts is still relatively high and far from the foot of subgrade slope, so it is necessary to design a ditch similar to the rapids between the hole and the foot of slope. It's called a leaky bed. It is generally used when the cross slope of the original ground at the culvert is too large and the slope of the culvert water surface cannot be set.