Artificial rainfall was used to study how phosphorus moves in purple soil on sloping land. The study found that as rainfall intensity and slope increased, more bio-available phosphorus was carried away. Subsurface flow carried about 30-45% of the phosphorus compared to overland runoff. Sediment in the runoff was a key way phosphorus was transported. High-intensity rainfall caused more phosphorus and sediment to be carried away, which can harm water quality.