Soil erosion is a problem in watersheds when soil particles are washed away by rain and runoff. To better understand and manage this issue, researchers in South Korea studied monthly factors that affect soil erosion in four major watersheds. They looked at soil type, crop management, and rainfall patterns over 15 years. By using these monthly factors, they found that soil loss estimates were more accurate compared to traditional yearly estimates. This approach helps to identify when and where soil erosion is most likely to occur, allowing for better planning and prevention strategies.