Contour trenching is a technique used to create a trench in the earth that follows the contours of the terrain. It is used to create drainage channels, irrigation systems, and other features on a sloped or uneven surface. It involves digging a trench along the contours of the land, and filling it with soil to create a level bottom. This method of trenching is sometimes used instead of more traditional methods, such as trenching straight down, as it is often more cost-effective and less disruptive to the environment.