1961~2018年海河流域极端降水时空演变特征

Temporal and Spatial Variation of Extreme Precipitation in Haihe River Basin During 1961-2018

基于海河流域35个气象站1961~2018年的逐日降水数据,选取9个具有代表性的极端降水指数,采用Mann-Kendall非参数检验、R/S分析、Morlet小波分析和相关性分析等方法探究海河流域极端降水的时空演变特征。结果表明,1961~2018年流域多数极端降水指数呈减少趋势,其中rx1day、rx5day、R99pTOT指数分别以1.40、2.50、3.12 mm/10a的速率减小;极端降水指数存在较大的空间差异性,东部平原地带的极端降水强度大于西部山区,北京市及其周边地区的极端降水呈较显著的下降趋势;基于R/S分析可得流域极端降水指数未来呈下降趋势,极端降水强度、频率下降;不同极端降水指数序列的周期性存在差异,以5~10、15~18、25~30年为主;除CDD指数外,各极端降水指数与年降水量、汛期降水总量之间均具有较好的相关性。

Based on the daily precipitation data of 35 meteorological stations from 1961 to 2018 in the Haihe River Basin, nine extreme precipitation indicators were selected, and Mann-Kendall non-parametric test, R/S analysis, correlation analysis, Morlet wavelet analysis were used to analyze the temporal and spatial characteristics of extreme precipitation in the Haihe River Basin. The results showed that the most extreme precipitation indicators appeared downward trend during 1961-2018. In particular, the rx1 day, rx5 day, and R99 pTOT indicators decreased by 1.40 mm/10 a, 2.50 mm/10 a, 3.12 mm/10 a, respectively. There were large spatial differences in extreme precipitation. The intensity of extreme precipitation in the eastern plains was greater than that in the western mountainous areas. Meteorological stations with obvious trends of extreme precipitation were mainly concentrated in Beijing and surrounding areas. According to the results of R/S analysis, the extreme precipitation indicators of the Haihe River Basin may show a general downward trend in the future, indicating that the intensity and frequency of extreme precipitation will decrease. There were differences in the periodicity of different extreme precipitation indices, with periodic changes of 5-10 a, 15-18 a, and 25-30 a being the main ones. Except for CDD, each extreme precipitation index had a good correlation with the annual precipitation or the total precipitation in the flood season.