Rainfall Simulator At the Kansas State Agronomy field day, kids were able to see the mini-rainfall simulator in action. Real rainfall is highly variable, and results from simulators shouldn't be directly compared to actual rainfall. But the principles of erosion and lessons for controlling erosion can be shown using these tools.
Soil erosion begins with the first raindrop.
The collision of the raindrop with the aggregates at the soil surface starts the erosion process. Raindrops travel at about 20 mph. At first, water moves down into the rest of the soil, carrying these finer particles along. Smaller particles, especially the silt and clay fractions, are suspended in the water creating puddles on the soil surface. When the infiltration rate is less than the rainfall rate, runoff begins to occur.