The historical data about flood disaster was collected

reorganized and analyzed in upper reaches of Hanjiang River during the historical period(208BC-2010AD).By using least squares method

wavelet analysis

and the Kriging interpolation

the times when flood disaster occurred(stage

seasons

cycles

etc.)

the spatial variation and the causes of flood disaster were studied.The results showed that

during the past 2 220years

the flood disaster mainly occurred in the summer and Autumn(May to September)by 336times with a frequency of once every 6.6years in the upper reaches of Hanjiang River.The flood disaster could be divided into 4classes

mild

middle

great and serious floods

and each class accounted for 24.7%

29.5%

40.5% and 5.3%in the total numbers of floods

respectively.Wavelet analysis showed that

the period of each class was 2~5a

38~40a

120a

and 160a

respectively.The floods showed an increasing trend

and could be broadly divided into three stages.There were three flood-prone periods

the early Qing Dynasty of Emperor Daoguang's Reign

Qing Dynasty of Emperor Guangxu's Reign

and the Late Republic to the end of the 20th century.Flood disasters varied significantly at spatial scale

which were declined from Ankang Basin to periphery

and there are two high-frequency centers and two low-frequency centers.Atmospheric circulation anomalies

special terrain conditions

the river's water system characteristics

the degree of bending of the river and the impact of human activities are the main causes of flood disasters in this region.