Abstract: In the hope of understanding the water cycle and ecosystem features of Lixia River in Jiangsu Province, we examined the trend and variation regularities of runoff coefficient over years (1961-2018) based on precipitation and runoff data via accumulated anomaly analysis, correlation analysis, Mann-Kendall test, moving-t test, as well as Morlet wavelet analysis. Results revealed that: 1) Runoff coefficient changed with precipitation, and the change was consistent with primary and secondary cycles; but the unevenness of annual and interannual runoff is much greater than that of precipitation. The annual variation of runoff coefficient is not only related to the annual distribution of precipitation, but also closely related to regional geomorphological characteristics and agricultural production. 2) In recent years, precipitation has not increased significantly, while runoff coefficient changed abruptly in 1966 and 1982. In the process of changing with precipitation, runoff coefficient increased the most in 1980s, and the smallest after 2012. The change of runoff coefficient in different periods reflects the change of water cycle and the adjustment and balance ability of natural ecosystem. The research findings are of practical significance for regional flood control and drought relief as well as the development and utilization of water resources.

Key words: runoff coefficient, precipitation, evolution trend, change characteristics, hinterland area of Lixia River