"MNRebecca" wrote in message

But would there
have been ditches WITHOUT such bridges in the first place? How did
you get the water out of the ditch and onto the field without the
bridge/pump system?

Of course there would have been. Watering can be moved out of the ditch by
hand very easily using a simple syphon method and that is common enough even
today. See pic on this cite:
http://www.pump-zone.com/piping/pipi...ing-sound.html