What are contour ditches?
Contour ditches are horizontal ditches dug on the slope of a hill to catch the rainwater running down the hill. Because the ditch is on the contour of the hill or horizontal, the rainwater fills it evenly. The concept is that when it rains, water will run down the hill and fill the ditch and, because the soil is chiefly clay, the water will sit in the ditch for several days and be available for the roots of the fruit trees. Thus water is retained which would otherwise have run off and, although there will be evaporation, there will also be infiltration into the ground.
Contour ditches examples
In this example, I leveled the side of the hill to provide the base for a new orchard of 14 fruit tree saplings. Space constraints prevented the leveled area following the contour – it wasn’t exactly horizontal. A ditch was excavated down the middle of the leveled area and on either side of it, the fruit tree saplings were planted. Because the ditch could not be established on the contour it was constructed on 3 levels with the highest level (furthest in ‘photo), when filled, draining into the lower levels. I used a transit level to determine the horizontal planes.
Since bermuda grass is invasive, and in order to minimize evaporation, cosmos and other wildflower seeds were sown. The ‘photo top right shows the ditch in spring 2011 and the adjacent ‘photo shows the same area a few months later.
I also excavated contour ditches near the top of the hill for berry trees (bottom) and vegetables (bottom right). I recycled sections of tree trunks to provide the posts for the cables supporting the berries and tomato and cucumber plantings.
I have dug several other contour ditches – fortunately not manually, but with the help of a trenching tool attached to my tracked bobcat.