One way to mark out swales is using an A-frame. It shows you where to dig so the bottom of the swales are level with your contour line. They really help with rainwater collection and I'm sure in conjecture with the drip irrigation our crops water needs will be well taken care of without having to use a petrol pump. We're a long way off from town so I'll need to plan a supply run where I can get other material we need for the farm along with the pots. Really looking forward to trying this out!