Detecting evolution trends in the recorded runoffs from the major rivers in China during 1950–2010
Evolution trends as well as abrupt changes in recorded runoffs from the major rivers in China during 1950–2010 were investigated using the Mann–Kendall test and ordered clustering analysis. Results show that the recorded runoff series at ten key hydrometric stations on the major rivers in China are characterized by a general decreasing trend. A significant decrease has occurred at six stations: Yichang, Huayuankou, Guantai, Shixiali, Tieling and Haerbin stations, which are located on the northern major rivers. Abrupt changes in runoff series are detectable for the Yellow River (1986), the Hai River (1965 at Guantai station, 1970 at Shixiali station) and the Liao River (1965). The relationship between runoff and precipitation at these stations is different before and after the abrupt change. Intensive human activities, such as land use change, water conservation projects, water diversion projects and rapid increases in agricultural irrigation, are likely to be among the main causes of the abrupt changes in runoff. Effective strategies for water conservation and adaptation to climate change will be needed to ensure sustainable use of water resources and safeguard economic growth under China's 12th 5-year plan.