Trend and control strategies of short-term heavy rainfall in typical watersheds of Zhejiang Province under climate change

CHEN Yuting; CHEN Xiaofei; ZHU Xinchao

doi:10.3969/j.issn.1000-1123.2025.17.009

Abstract：To investigate the evolution patterns and prevention pathways of short-term heavy rainfall in small and medium-sized watersheds of Zhejiang Province under climate change,the Jiaojiang River basin was selected as the study area.Long-term series of daily precipitation and flow data from the Baizhi'ao and Shaduan stations were used,along with characteristic values of maximum 1-day,3-day,5-day,and 7-day rainfall and runoff.Linear trend analysis,the Kendall test,and the Pettitt mutation test were applied.Results indicate that short-term heavy rainfall exhibits significant interannual variability at both stations,with smaller time scales corresponding to higher coefficients of variation and extreme ratios.The frequency of heavy rainfall has notably increased at Baizhi'ao Station over the past 20 years and at Shaduan Station over the past 10 years,although the overall trends of most characteristic series are not statistically significant.A sudden change occurred in short-term heavy rainfall at Baizhi'ao Station in the early 21st century,with post-change mean values increasing by more than 20%compared with the prior period.However,no significant mutation was observed in annual total precipitation,reflecting greater intra-annual unevenness.Regarding runoff,peak discharge shows a significant upward trend,whereas mean discharge increases more slowly than precipitation,suggesting the positive effect of flood control projects.Based on these findings,it is recommended that Zhejiang Province improve its flood control system through measures of"increasing storage,diverting floods,accelerating drainage,and strengthening defense",establish digital twin watersheds,and enhance flood risk management to support resilience in small and medium-sized watersheds facing short-term heavy rainfall.