SPATIAL AND TEMPORAL VARIABILITY CHARACTERISTICS OF PRECIPITATION IN HUAI RIVER BASIN DURING 1961~2005

Surfaces of precipitation at resolution of 1 km×1 km were generated by the series data from 170 observation stations in Huai River basin from 1961 to 2005,using Kriging interpolation method.Based on the grid data series,the spatial and temporal variability characteristics of precipitation in Huai River basin were analyzed.Results showed that the higher precipitation occurred in the south of the basin,and lower precipitation occurred in the north of the basin,and lower precipitation occurred in the north of the basin.There was no significant trend with large inter-annual variabilities of annual precipitation in recent 45 years,and the rainfall of various season had different change patterns.The linear trend analyses and Mann-Kendall trend test indicated that the changing trends of precipitation did not arrive at the significant level in Huai River basin.Nevertheless,the inter-decadal variabilities of annual and flood season precipitation had obvious phase characteristics.The precipitation present decline trend before 1990s,while an apparent increasing trend after 2000.At present,the precipitation of Huai River basin is in a phase of high climate variability.During recent 45 years,there was an evident variation in the spatial distribution of precipitation in Huai River basin,which was represented by an increase trend of precipitation in the upper and middle Huai River,and a decline trend in the northeast of basin.