In message , Tony Williams
writes
I wonder if the chap was trying to create a reedbed?
Reedbeds do have some respectability now. Might be
worth some research on plantings to improve it.

I thought of that, could be an interesting idea, it was not his original
idea though. He took the pipe as far as he thought necessary at the time
and then stopped and let it run in a small ditch to the stream.
Unfortunately as it is well away from where people normally go, only a
rather adventurous Welsh Cob dares go there, it has become over grown
and well trodden over by the horse and his predecessors.

--
Bill