1961~2015年西南地区降水及洪涝指数空间分布特征

利用西南地区98个气象站连续完整的日降水序列数据，整合降水强度、持续性指数及等级指数形成降水指数体系并研究该区域降水及洪涝指数的空间分布特征，得到以下主要结论：（1） 1961~2015年，西南地区年降水量（PRCPTOT）与极端降水量（R95PTOT）都呈现出“东多西少、南多北少”的分布形态；持续降水日数（CWD）则表现为“南高北低、西高东低”的分布格局。区域多年平 均PRCPTOT、R95PTOT、CWD分别以-13.12 mm/10 a、1.34 mm/10 a、-0.29 d/10 a的速率变化。（2）西南地区不同等级降水日数具有相似的空间分布特征，均呈现出“南高北低、东高西低”的分布形态。（3）西南地区洪涝强度指数呈由东北向西南递减的分布特征；降水总量越多的地区，洪涝强度反而越低，主要由于单站洪涝强度表征的是降水的波动情况，降水量越多波动越不明显。21世纪以来，该 地区洪涝等级以重级为主，2010年以来连续多年出现特重级洪涝。此外，洪涝强度越大，区域性年度灾害等级越高。该研究对于掌握西南地区极端气候变化规律，从而服务于防灾减灾具有一定的理论意义。

SPATIAL DISTRIBUTION CHARACTERISTICS OF PRECIPITATION AND FLOOD INDEX IN SOUTHWESTERN CHINA DURING 1961-2015

With the advent of rapid industrialization process induces climate change and variability,flooding has become one of the most common natural hazards in the world,there by attracting growing public concern.To understand the spatiotemporal variation of precipitation and flooding in southwest China better,this study used 98 meteorological stations in the region during 1961-2015 to calculate precipitation intensity,precipitation persistence and precipitation degree,and further analyzed their spatiotemporal change.The main conclusions reached are:(1) The spatial patterns of Index of total annual precipitation (PRCPTOT) and extreme precipitation indicator (R95PTOT) in southwestern China were ‘ high in the southeast and low in the northwest'However,the spatial pattern of the CWD (Consecutive wet days) was shown to be ‘ high in the southwest and low in the northeast'.Also,the PRCPTOT decreased at the rate of 13.12 mm/10 a,and the CWD decreased at the rate of 0.29 mm/10 a while the R95PTOT increased at the rate of 1.34 mm/10 a.(2) The spatial pattern of precipitation at different level were similar,showing that ‘ higher values in the southeast and lower values in the northwest',Besides,most high-value concentrated in the south Yunnan,south Guizhou and near the southwest of Sichuan basin.Nevertheless,the tendency of several indices showed different trends,the R25 (Heaviest rain days) and HD (Continuous heavy rain days) in most regions increased,while the RD (Continuous rain storm days) reduced in most of the region.Specifically,the spatial pattern of continuous heavy rain days and rainstorm days were ‘high in the southeast,while low in the northwest'(3)The flood intensity index in the region decreased from northeast to southwest,and for most of the study area,the rate of flood intensity tended to increase.Evidently,the area saw a negative correlation between the flood intensity and precipitation.From the beginning of the 21 st century,particularly since 2010,this region was experiencing heavy flooding.In addition,precipitation in the southwest China declined,but the intensity of flooding was still severe.This work may help to understand regional climate change,and provide suggestions for mitigating regional disaster.