Long Term Evolution Characteristics of Runoffs in the Tideway of the Changjiang River

Abstract

Abstract. Datong hydrological station is the last control station in the Changjiang River mainstream, and its runoffs have great significance on evolution of the tideway and the estuary of the Changjiang River. Therefore, this paper compiled long term series (1950~2010) of daily water discharges at Datong gauging station, and utilized the statistic methods to analyze the long term evolution characteristics of the Datong runoff. The results show that: (1) Inter-annual variability of runoffs was relatively stable, with average fluctuation range below 104m3/s, which may be caused by the location of the river basin and regulation of many large scale lakes; (2) The monthly runoffs have distinctly seasonal variation characteristics, wherein, the runoffs from June to September occupy 51% within a year, and the other months occupy the residual 49%, moreover, the runoff proportion of flood season within 2003~2010 has a slight decline of 2%, compared with that of 1995~2002.