The study looked at how rainfall and slope characteristics affect runoff on hilly surfaces in a loess region. By analyzing nine years of data from seven runoff plots, researchers found that areas with high-intensity rainfall had the highest runoff coefficients, while areas with low-intensity rainfall had the lowest. Runoff coefficients first increased and then decreased with slope degree, reaching a peak for certain slope surfaces. Runoff also increased with slope length for medium and low-intensity rainfall. Additionally, runoff increased with slope gradient for specific plots. Overall, the study shows how different rainfall patterns and slope features impact runoff generation on hilly surfaces in the region.