What primarily causes erosion on construction sites?

Rainfall is the primary cause of erosion on construction sites due to its ability to displace soil particles and generate runoff. When it rains, especially in significant amounts, water can flow over exposed soil surfaces that have been disturbed during construction activities. This movement of water can lead to both surface erosion and rill erosion, causing soil to wash away into nearby areas, including storm drains and waterways.

Moreover, rainfall can exacerbate erosion on construction sites, particularly when the soil has been cleared or left bare, as there is less vegetation to stabilize the soil and absorb the water. Additionally, the compacted or disturbed nature of construction soil often exacerbates runoff, leading to greater erosion potential.

While wind and animal activity can contribute to erosion in general, they are typically not as impactful as rainfall in a construction context. Soil compaction, on the other hand, is usually a technique to reduce erosion potential rather than a cause of it. Therefore, the critical role that rainfall plays in the triggering and exacerbating erosion on construction sites underscores its designation as the primary cause.