Which factor is used to describe rainfall erosivity in erosion risk assessment?

• A. Rainfall infiltration
• B. Soil color
• C. Rainfall erosivity
• D. Bulk density

Answer: (C)

The main idea here is that rainfall erosivity measures the actual potential of rainfall to cause erosion, based on how energetic the rain is and how intense the events are. Erosion gets driven by the energy of raindrop impact and the rate at which rain falls; when storms are intense and deliver a lot of energy in a short time, they detach and move more soil. That erosive potential is captured by the rainfall erosivity factor, which in widely used models (like USLE or RUSLE) is the R factor. It summarizes how severe rainfall is for erosion, independent of soil properties or land conditions.

That’s why this option is the best answer: it directly quantifies the rainfall’s capability to cause erosion. In contrast, infiltration describes how water enters the soil (affecting moisture and runoff, but not the rainfall’s erosive power by itself); soil color and bulk density describe soil characteristics rather than the rainfall’s energy or intensity.