I live in an area where the soil and land is very level and very low. Low as in, we are very near sea levels, in fact in some areas, they are below sea level. I am not an expert, but having lived in the area all my life, I have seen a little of what goes on. To drain land, the old method was to lay clay pipes. These pipes were I guess a foot long, and most about 4 or so inches wide. A special spade called a `gauge` was used to dig a trench by hand, and a `fall` or slight angle was given in the trench so ending in a `dyke` at the ending of the field. The `gauge` was a spade that was the width of the clay pipe, plus a bit, but the blade was a semi circle, like a rain gutter, but made of steel. Years ago the young men, my dad was one of them, would lay these pipes and were paid per the amount they laid. The pipes in the `top` of the field would be at least the depth of a plough, and simply recovered with the soil dug out. The pipes were simply laid end to end and the water crept through the gap/join. Many of these pipes have been down many years and still give good service. Today things have moved on, and today a machine is used that has a very large turning wheel with buckets on. This digs the trench and immediately behind the wheel, a continuous plastic pipe is fed into the trench. This pipe comes in various sizes and has small holes all over it. I have stood and watched both of these pipe outlets as they discharge into the dykes, or creek or river or what ever we all call them, and after a rain, the flow is fast and clean, so little soil is eroding.
