Which condition MOST increases runoff and erosion?

• A. High infiltration
• B. Vegetation cover
• C. Low infiltration
• D. Soil aggregation

Answer: (C)

The key idea is infiltration capacity—the soil’s ability to absorb water. When infiltration is high, rainfall mostly enters the soil, so surface runoff stays low. When infiltration is low, water can’t soak in quickly enough, so more of the rainfall becomes surface runoff. That overland flow has the energy to detach and transport soil particles, leading to more erosion. In rangelands, vegetation and good soil structure typically boost infiltration and protect the soil, reducing runoff and erosion, while a condition of low infiltration does the opposite. So the factor that MOST increases runoff and erosion is low infiltration.