Abstract: Quantitative evaluation of the effects of precipitation variation and human activities on runoff in Liuyang River watershed is conducive to a more rational utilization of water resource. In this paper we analyzed the evolution law of and the relationship between runoff and precipitation in 1969—2013 in Liuyang River basin by means of linear fitting, moving average and accumulative anomaly. We also estimated the contribution rates of precipitation variation and human activities to runoff variation in different periods quantitatively by comparing cumulative slope variance ratio. Results indicated that precipitation displayed an increasing trend in a rate of 3 mm/(10 a), while runoff represented a decreasing trend in a rate of 2.7 (m³·s^-1)/(10 a). Precipitation and runoff both witnessed an abrupt change in 1989 and 1999 in a trend of “decrease-increase-decrease”. Compared with the baseline period from 1969 to 1988, the contribution rates of precipitation variation to runoff variation in 1989—1998 and 1999—2013 were 56.8% and 7.62%, while the contribution rates of human activities in 1989—1998 and 1999—2013 were 43.2% and 92.38%, indicating that human activity has become the main factor which affects the runoff variation in Liuyang River watershed.

Key words: Liuyang River watershed, runoff variation, method of comparing cumulative slope variance ratio, precipitation variation, human activities