What is the maximum allowable slope in an area to be planted with ground cover and shrubs?

What is the maximum allowable slope in an area to be planted with ground cover and shrubs?

• A. 50 percent
• B. 60 percent
• C. 40 percent
• D. 30 percent

Answer: (A)

Ground cover and shrubs are used on slopes to slow erosion and hold soil, but their effectiveness drops as the slope gets steeper. The practical upper limit for planting with these vegetation types is 50 percent. At this slope, many ground covers and shrubs can establish roots that grip the soil well enough to reduce erosion, while still allowing irrigation, maintenance, and establishment to be feasible. Steeper slopes, like 60 percent, pose too much runoff and instability for reliable establishment, so other erosion-control methods such as terraces or retaining features are typically needed. While 40 percent or 30 percent are certainly manageable, the question asks for the maximum allowable slope, which is 50 percent.

Ground cover and shrubs are used on slopes to slow erosion and hold soil, but their effectiveness drops as the slope gets steeper. The practical upper limit for planting with these vegetation types is 50 percent. At this slope, many ground covers and shrubs can establish roots that grip the soil well enough to reduce erosion, while still allowing irrigation, maintenance, and establishment to be feasible. Steeper slopes, like 60 percent, pose too much runoff and instability for reliable establishment, so other erosion-control methods such as terraces or retaining features are typically needed. While 40 percent or 30 percent are certainly manageable, the question asks for the maximum allowable slope, which is 50 percent.