Rills are small, narrow channels that form in the soil or on the surface of the land due to the flow of water. They often develop during heavy rainfall or when snow melts, as water runs off the surface and begins to erode the soil. Rills can vary in depth and width, but they are typically less than 30 centimeters deep. Over time, if not managed, rills can grow larger and evolve into more significant features like gullies. They play a role in the natural drainage of landscapes and can affect soil erosion and water quality in nearby streams and rivers.