Spatio-temporal characteristics of extreme precipitation event in Yellow River basin in recent 53 a

Based on daily precipitation data of 76 meteorological stations in Yellow River basin from 1960 to 2012,four precipitation indices were calculated,the inter-annual change trends were studied by methods of regression analysis and five years moving average,and spatial distribution characteristics of the precipitation indices were analyzed by radial base interpolation.The results show:(1) In time,In the period of 1960~2012,average annual rainfall were significant descend with the rate of-7.2/10a,extreme precipitation was the same descend trend with the rate of-0.64/10a as intensity of extreme precipitation with the rate of-0.07827/10a,extreme precipitation concentration ratio has increased weakly by the rate of 0.49/10a.(2) In space,the spatial distribution of extreme precipitation indices exhibited notable spatial disparity.Rainfall increased significantly from north to south,and the area with the least rainfall is located in the peripheral region of Yinchuan,the most rainfall in the southern Yellow River Basin.Extreme precipitation showed an increasing trend and the same spatial distribution characteristics as rainfall,and the more extreme precipitation,the more rainfall.Intensity of extreme precipitation had an increasing trend from west to east,and the minimum value of less than 20mm/d in west,maximum value of more than 76mm/d in the east.Extreme precipitation concentration ratio has a decreasing trend from north to south with a maximum value centering on Yinchuan,a minimum value centering on Xi'an city.