Abstract:

Using the precipitation data of 51 meteorological stations in the upper basin of the Changiiang River from 1961 to 2009,the Z index of years and four seasons were computed and inspected. Based on defining the regional drought and flood indices,the characteristic of drought and flood indices were analyzed during the past 48 years,and then the method of choosing typical drought or flood years was discussed.The study showed that the 〖WTBX〗Z〖WTBZ〗 index and regional flood and drought indices depicted obviously the variation features of flood and drought of years and four seasons in the upper basin of the Changjiang River.The drought/flood variation was characterized by obvious interdecadal changes in the upper basin of the Changjiang River.The drought index and the flood index time series have almost antiphase variations on the annual and seasonal time scales. Drought and flood in four seasons had close relationship with 500 hPa circulation pattern at same time.Except winter,dought and flood in other seasons were related with SSTA Field.The conclusion is useful to the development of the upper basin of the Changjiang River;it will provide technical support to scientific management of the Three Gorges Reservoir