Eliot Mason wrote:Well, sort of. If you build perfectly on contour then you are really building a series of dams on the hillside. In a rain event, that water has no place to go except through the swale ... and if does that you've got a problem! Also, its possible that the highest swale captures all of the water coming down the slope and holds it - and although "stacking" water up high isn't a bad idea the swales further down the slope are deprived of that water.
So you can instead build the swale slightly off contour, and have them zig-zag down the slope. Water coming down is then allowed to slowly wander along each swale before spilling into the next and changing direction.