Temporal and spatial characteristics of annual and main flood season precipitation in the upper and middle reaches of Huaihe River Basin between 1960 and 2014
In order to understand the temporal and spatial distribution characteristics of annual and main flood season precipitation in the upper and middle reaches of Huaihe River basin,we analyzed the monthly precipitation data in 19 meteorological stations during 1960-2014 by using the climate tendency rate,Mann-Kendall analysis,coefficient of variation,non-uniform coefficient of annual distribution,wavelet analysis,and Kriging method.The results were as follows:(1)The main flood season precipitation accounted for more than 50%of the annual precipitation,and it tended to concentrate in the southwest and southeast. The annual precipitation showed" wet/dry " alternations on the 21~32 a,8~19 a,and 3~7 atime scales,while the main flood season precipitation showed such alternations on the 24~32 a,8~21 a,and 3~7 atime scales.The" wet/dry " alternations on the same time scale were basically identical.(2)The coefficient of variation(C_v)of main flood season precipitation was generally greater than that of annual precipitation,yet their spatial distributions were different.The larger C_v values of annual precipitation were mainly distributed in the western and northern basin,while the smaller values were in the east and southeast.The larger C_v values of main flood season precipitation were distributed in the western basin,while the smaller values were in the northeast and Bengbu area.The non-uniformity of annual distribution of precipitation in the north was slightly larger than that in the south.(3)The variation trends of both annual and main flood season precipitation were not significant,failing the 95% confidence test.But the main flood season precipitation showed a slight increasing trend whereas the annual precipitation showed a slight decreasing trend.The annual precipitation tended to decline in the north,west,and southwest,but it tended to increase in the middle,south and southeast.The main flood season precipitation tended to increase in a striped manner from north to south.