In addition to controlling water, it’s important to stabilize the land, including the bottom of a gully, to keep it from getting any deeper. To do that, build a check dam, which is a small series of dikes that slow water flow so that the ground can recover.
Choose your dam material. You can use rocks, poles, planks, or another sturdy material. You can pack holes with straw or brush. Each dam will be about 2 feet (0.6 m) high. Dig the first dam into the sides of the gully. Construct your dam by placing material across the gully so that it touches the bottom and digs into the walls on either side, so that the water can’t flow around it. Make a notch in the middle. The middle of the dam should have a space where water can get through; otherwise it’ll just find a way around the dam. Make a rock apron on the other side. The water needs a place to land on the other side so that its impact is reduced. Put a bed of rocks in front of the dam. Construct more small dams or dikes to form a series. Depending on the size of the gully, put in several more dams. The system works most effectively if the dams are close together, so the water can’t pick up much speed in between them.