The researchers studied how water runoff works in croplands on hilly purple soil. They used field experiments and mimicked rainfall to investigate. They found that surface runoff had peaks influenced by rain intensity, while subsurface runoff had only one peak that lasted longer than surface runoff. Runoff was highest from the late growth to harvest period, with most runoff coming from subsurface sources. Rainfall and runoff were linked, with surface runoff increasing with slope angle but subsurface runoff decreasing. In a year, surface runoff was 95.78 mm and subsurface runoff was 108.19 mm, making up the total runoff.