Abstract:

Using daily precipitation data from 1960 to 2018 over the Liaohe River Basin, the spatiotemporal characteristics of daily precipitation concentration in this region were analyzed after calculating the precipitation concentration index (CI).The results indicated that CI can reflect the degree of precipitation concentration in the Liaohe River Basin, with an annual mean value of 0.67.The precipitation CI is smaller in the eastern and western regions of Liaohe River Basin and higher in the southern and northern regions, exhibiting a saddle pattern.The precipitation concentration is higher in summer, with the seasonal mean CI value at each station being 0.65.The seasonal mean distribution of CI is similar to the annual mean distribution.The smallest seasonal mean CI value of 0.60 occurs in winter, and the CI values decrease from the southeast to the northwest.During the study period, the annual mean CI values exhibit an insignificant decreasing trend, with the largest decreasing rate occurring in the eastern region.The mean variation cycle of CI in each sub-regions is about 3 years.Before 1985, the variation cycle of CI is relative short, about 2 years, while after 1985, it increases to more than 3 years.

Key words: Liaohe River basin, Precipitation concentration index (CI), Wavelet analysis