Water runoff from construction sites is typically how many times greater than that from agricultural land?

The correct answer is that water runoff from construction sites is typically 10-20 times greater than that from agricultural land. This significant increase can be attributed to several key factors related to land disturbance and impervious surfaces.

When construction activities take place, they often involve clearing vegetation, grading land, and creating hard surfaces such as concrete and asphalt. These alterations reduce the land’s natural ability to absorb rainfall, leading to increased surface runoff. In contrast, agricultural land, while also prone to runoff, often retains some vegetation that can help absorb rainwater and reduce the speed and quantity of stormwater runoff.

Additionally, construction sites are often characterized by exposed soil, which can lead to erosion and further increase the amount of runoff as well as sediment flowing into nearby water bodies. Such impacts on natural hydrology are considerably more significant compared to agricultural operations that might employ practices aimed at managing water flow and minimizing runoff.

Thus, the estimation that runoff from construction activities is 10-20 times greater aligns with the observed data, emphasizing the need for effective stormwater management practices on construction sites to mitigate these impacts.