雨涝指数在云南洪涝灾害监测中的应用

The Application of Flood-Waterlogging Index in Flood Disaster Monitoring in Yunnan Province

客观定量监测和评估雨涝灾害的强度,可为防御洪涝灾害提供技术支撑。基于极端降水事件中持续时间和强度关系理论,采用包含当日近5 d最强日相当降水量作为日降水强度指标,构建了雨涝指数和区域雨涝过程强度算法。利用1961—2018年云南省逐日降水资料,分析了云南雨涝过程特征。结果表明:①在云南地区确定25 mm日降水量作为雨涝过程出现的起始日降水量阈值是符合实际的,而非50 mm;②1961—2018年云南共发生320次雨涝过程,年均5.5次,其中特强34次、强60次、较强105次,一般121次。云南雨涝强度无明显趋势变化,但雨涝过程强度波动变化剧烈;③云南年均发生轻涝34.0站日,中涝6.4站日,重涝0.9站日,特涝0.1站日。云南雨涝发生月际变化大,全年除2—3月外,其余月份均可发生,主要集中在6—8月;④云南暴雨洪涝存在明显的年际和年代际变化特征,20世纪60—70年代、21世纪以来处于偏少期,20世纪80—90年代处于偏多期。总体来看,雨涝指数能更好地反映雨涝过程和区域雨涝强度,其结果与实际洪涝灾情较为吻合。

Objective monitoring and evaluation of the intensity of waterlogging disaster can provide technical support for flood prevention.Based on the intensity-duration theory for extreme rainfall event in the paper,the daily rainfall intensity index including the strongest daily precipitation in the last 5 days was adopted,the flood-waterlogging index and regional flood-waterlogging processes intensity algorithm are constructed.Using the daily precipitation dataset at 125 weather stations in Yunnan province from 1961 to 2018,the variation feature of the regional flood-waterlogging processes in Yunnan are analyzed.The results show that it is practical to determine 25 mm daily precipitation as the initial daily precipitation threshold for the occurrence of flood-waterlogging process in Yunnan,rather than 50 mm.From 1961 to 2018,a total of 320 flood-waterlogging events occurred in Yunnan,with an average annual rate of 5.5,including 34 extremely strong events,60 strong events,105 slightly strong events,and 121 general events.There was no obvious trend change in the intensity of flood-waterlogging in Yunnan,but the intensity of flood-waterlogging process fluctuated sharply.The average annual occurrence of light waterlogging in Yunnan is 34.0 station days,moderate waterlogging 6.4 station days,heavy waterlogging 0.9 station days and special waterlogging 0.1 station days.The occurrence of flood-waterlogging in Yunnan varies greatly from month to month,and it can occur in all months except February to March,mainly concentrated in June to August.There are obvious interannual and interdecadal variation characteristics of rainstorm and flood in Yunnan province,and it is in low stage from 1960 s to 1970 s and 21st century,and in high stage from 1980 s to 1990 s.On the whole,the flood-waterlogging index can better reflect the process of flood and regional flood intensity,and the result is consistent with the actual flood disaster.