Ditch to pipe transition - How to go from an open ditch to a piped

[Special Circumstances]

My back garden is bordered by a ditch. A previous owner has piped (4" clay) this but 'uphill' my next dorr neighbour's ditch is open. Currently I regularly clear the transition from open ditch to pipe. I would like to make the 'reverse' of an out flow to at least make clearing the end of the pipe easier or ideally reducing the regularity of clearing.
I assume a solid block where the pipe leaves the ditch and three 'slabs' to make a floor to the ditch and sides to the entrance to the pipe. This would make it much easier to dig out when blocked.
What thoughts about gratings, bars etc to try and keep the pipe clear of trees leaves etc. BTW the ditch has a hedge behind it and some very mature oak trees (many tons of leaves come autumn)

[GB_Groundworks]

On our lane we have silt traps before every pipe transition. Generally formed in concrete with a grate stuck in it, have to do it when it's dry. Grate has to be fairly strong though not just chicken wire hehe.

You can just lay a small ledge across that'll slow water and gather the silt or leaves but an in situ cast concrete and steel one is better