Abstract

The Mann-Kendall test was applied to analyzingthe shift points and defining the hydrologic series of the riverstream flow from 1963 to 2011. The Tennant method wassubsequently used to evaluate the ecological flow and themonthly guaranteed frequency method was applied tocalculating the monthly ecological water requirements in twodifferent hydrologic series. The results were as follows. 1) Theyears during 1963 - 1985 and the years during 1986 - 2011 weredistinguished as two hydrologic series. 2) The ecological flowwas generally in better condition in other season than that inspawning season. During the spawning season, 87.0% of streamflow was not at the appropriate level before 1985 and 72.4%after 1986, which indicated a worse condition for thereproduction and breeding of aquatic organisms. 3) Themonthly ecological water requirement varied and showed adecreased trend, consistent with the stream flow regime. Thisresearch helps to deepen understanding of the evaluation of theecological flow and to provide a basis for decision making andreservoir regulations with hydrological alterations.