Abstract: The trends and abrupt changes of runoff at major control stations in the upstream of Zhengyangguan were investigated by using Mann-Kendall trend analysis method,Mann-Kendall abrupt change test method,and moving-t test method based on monthly measured runoff data and the monthly precipitation data since the 1950s. Factors affecting the abrupt change of runoff were also analyzed. Results demonstrated that the runoff of main control stations upstream of Zhengyangguan has been on a downward trend since the 1950s, and that of the tributary control stations more obvious. In the late 1950s, the Jiangjiaji station and Hengpaitou station in the southern tributary of Huaihe River witnessed abrupt changes in runoff because the reservoirs in the upstream of control station was built and put into operation, which led to the abrupt reduction of runoff. The annual runoff of Fuyangzha station in Huaibei tributary declined abruptly in 1971 possibly because of both the small precipitation in the 1970s and the regulation effect of sluice and dam. During the abrupt changes, the runoff of Jiangjiaji station, Hengpaitou station and Fuyangzha station affected by human activities were 116.0 billion,104.3 billion,130.3 billion m³ respectively, and the runoff reduction rates were 49.5%, 61.8% and 42.3%, respectively.The research results can provide technical support for flood and drought disaster prevention and water resources management for the Huaihe River Basin.

Key words: runoff change, trend analysis, abrupt change test, Huaihe River, reaches upstream of Zhengyangguan