The correct option is (a).
Explanation
Contour Barriers are a specific soil conservation technique employed on sloping terrains to manage water runoff and prevent soil erosion.
- Option (a) is correct: The defining feature of contour barriers is the construction of barriers along the contour lines of a slope using materials like stones, grass, or soil. Trenches are made in front of these barriers to collect water. This slows down the flow of water, allowing it to percolate into the soil rather than washing away the topsoil.
- Option (b) is incorrect: This method is not exclusive to coastal regions. It is primarily used in hilly areas and agricultural lands with slopes where soil erosion due to water runoff is a concern.
- Option (c) is incorrect: The process of cutting steps into a slope to create flat land for cultivation is known as Terrace Farming, not contour barriers.
- Option (d) is incorrect: Contour barriers utilize a variety of materials available on the land, including stones, grass, and soil, rather than relying solely on rocks.
Key Takeaway: Contour barriers conserve soil and water by placing physical obstructions along contour lines, supplemented by trenches to trap runoff and enhance infiltration.