Rearranging the drainage of land has an old history. It was one of the hallmarks of the High Medieval period in northern Europe, opening up hundreds of thousands of acres of former wetlands for cultivation across France, the Netherlands, and Great Britain. Creating drainage varies from the reclamation of land, taking impassable swamp, as it might be in the fens of England, and turning it into land that is consistently workable surrounded by ditches and dykes or it might be a matter of carefully choosing how to plough so that over time the land drains faster.
North America also has seen the wholesale rearrangement of drainage. One of the problems with New England was the combination of rock and water. The Berkshire hills are a mixture of bedrock outcroppings, glacial debris, swamp, and the occasional hillside and valley of extremely fertile soil. There is a reason why Connecticut farmers left in droves for the mid-western region in the 1800’s. The Connecticut valley may have some of the best soil on the continent (now mostly buried under shopping malls) but it isn’t a large area, and the land in the hills requires hard work to even get a usable field.
You can, of course, find those fields. We have an extremely good small hayfield of about 15 acres. A west-facing, stepped hillside, the bedrock outcropping is some way from the surface and two centuries of cultivation have reduced the rocks (reduced only, if you plough it the average is about one fist sized or bigger rock per yard…every year). But, it is also a good field because a big tile drain angles across the middle, draining the upper half. The lower half has no such drain, and the lowest corner is permanently wet to the point where it cannot always be mown. Head down the hill another hundred feet or so and the bedrock comes nearly to the surface.
This drain was put in place sometime in the late 1800’s and takes mostly subsurface water, which would otherwise collect and stand at the bottom of the first steep section of the slope. This would make about a third of the flattest section of the field unusable. It is a tile drain, sections of terracotta pipe with open joints, beginning on the neighbouring property and daylighting on the lane where it joins the lane’s ditch. Unfortunately, the joints have gradually shifted farther apart. So, I spent today filling the gaps with rocks. Why? Not for the tractor I assure you. Rather, for the horse. A depression might cause a stumble, a hoof-sized hole dropping down six inches to two feet…well, better not to consider it. It isn’t a permanent fix, but it is better than it was!
Acair Fearann 
To know where the water goes, and where it comes from; that is to know a piece of land truly intimately. No dowser needed; but chances are dowsers were exceptionally good at acquiring that kind of familiarity rapidly on a new piece of land.
I could, in actuality, trace water falling on the roof, into the tile drain, under the wall, down the lane, through the woods, down the brook, into the Nepaug, and thence to someone’s tap in Hartford. If nothing else such knowledge makes one more careful about what one dumps on the ground.