In a study focusing on rainwater runoff in the Chaihe basin, researchers observed changes in nonpoint source pollutants like nitrogen and phosphorus during rainfall events. They found that the concentrations of these pollutants varied with the amount of rainfall, showing similar trends to the runoff itself. Notably, at different rainfall stages, the exit of the area had higher levels of total nitrogen and phosphorus compared to the entrance. This suggests that the flow of rainwater can impact the amount and type of pollutants carried in the runoff.