The study analyzed 53 years of runoff data from the Huaihe River. They found that the annual runoff varied greatly, with most occurring during the flood season. Since the 1980s, runoff distribution has become more uneven and concentrated, with a delay in the peak period. Downstream areas showed a significant decrease in annual runoff, especially in the dry season. The researchers identified two wet stages and three dry stages in the annual runoff pattern, with frequent changes between 1996-2008 due to alternating drought and flood periods.