This is an unusual loophole in real property law- where water accumulates on land, the owner of that land has the right to drain it off- however, as the land owner of the lower 'field', you are under no obligation to accept the water that drains.
This comes from a well known text calleg "Land Law" by Gray & Gray, who make the point that there has not yet been any case law on the subject. My knowledge of property is a bit stale though, so if anyone else knows more I'm sure they'll tell you.