Certified Storm Water Operator Practice Exam

Which climatic factors are known to influence erosion and runoff?

1. Humidity, seasonality, and wind speed

2. Rainfall amount, frequency, and intensity

3. Temperature, sunlight, and storm duration

4. Soil moisture, evaporation, and frost occurrence

The correct answer is: Rainfall amount, frequency, and intensity

The choice indicating rainfall amount, frequency, and intensity is recognized as the most significant climatic factors influencing erosion and runoff. Rainfall plays a critical role in determining how much water enters the soil and how much runs off the surface. The amount of rainfall directly affects the volume of water available to cause erosion; in higher amounts, there is a greater potential for runoff. The frequency of rainfall events can influence the saturation of the soil, where frequent rains may prevent soil from absorbing water effectively, leading to increased surface runoff. Intensity is equally important, as heavy rainfall can lead to rapid runoff and soil erosion because the soil does not have enough time to absorb the water, leading to ineffective infiltration and increased surface flow. While the other factors mentioned in the other options—such as humidity, seasonality, temperature, sunlight, and soil moisture—can impact erosion and runoff indirectly, they do not have the same level of direct influence as the characteristics of rainfall. For example, while temperature can affect the soil moisture content and thus influence erosive conditions, it does not create runoff in the same immediate manner as rainfall does. Similarly, aspects like wind speed or evaporation can alter surface conditions but do not directly drive the processes of erosion and runoff.