The study used a model to simulate how nitrogen and phosphorus pollution in farmland changes with different rainfall levels. They found that rainfall is the main factor affecting the loss of nitrogen and phosphorus, with more loss during heavy rainfall. To reduce pollution, better water and fertilizer management is needed during flood season. The study also showed that pollution loss is higher in upstream areas compared to downstream areas. To control pollution, ecological ditches and wetlands can help purify and reduce pollution in farmland.