Is Contour Plowing Necessary Before Installing Swales?

Understanding Contour Lines and Swales

Contour lines, often marked on topographic maps, represent the elevation of the land at regular intervals. Installing swales along these lines can help direct water flow and collect runoff. However, contour plowing, which involves plowing parallel to the contour lines, is typically used for slope stabilization and erosion control rather than swale installation.

Designing Swales without Contour Plowing

To design swales without contour plowing, identify a suitable location with a gentle slope, typically 1-2% grade. Mark the swale’s location with stakes and twine, then dig a shallow trench, about 6-8 inches deep, to create the swale’s depression. The soil excavated from the swale can be used to create a berm, which helps to filter and slow down water flow, preventing erosion and allowing for efficient water harvesting.

Installing Swales in Sloping Terrain

When installing swales in sloping terrain, consider creating a series of swales, or “steps,” to gradually decrease the slope and prevent erosion. This approach involves digging a series of swales, each connected to the next, to create a gentle slope that allows for smooth water flow. The distance between each swale, or “step,” can vary depending on the slope and terrain, but a general rule of thumb is to space them 10-20 feet apart.