基于灾害指数的芮城县连阴雨分析

利用芮城县1961—2014年3—11月份的逐日降水量,找出近54年芮城县的连阴雨过程,计算出每次连阴雨过程的灾害指数,依据指数等级,同时对照同期灾情普查数据,对连阴雨过程进行分析。结果表明,近54年芮城县共出现了158次连阴雨天气过程,呈逐年下降的趋势,变化倾向率为-0.35次/10 a;9月份出现连阴雨天气的次数最多,3和11月份出现连阴雨次数最少。近54年来连阴雨灾害指数最大为12,最小为1.2;连阴雨灾害指数(LYRI)主要集中在LYRI3.0(V级,占比74.7%);其次是Ⅳ级(轻度),占比13.9%;Ⅲ级占比9.5%;而严重(Ⅱ级)和特别严重(Ⅰ级)的占比不到2%。近54年芮城县Ⅳ级以上连阴雨灾害等级主要出现在秋季,占比50%;其次是夏季,占比35%;而春季出现很少,仅占15%。在芮城县只有8.3%的连阴雨过程会造成灾害,且发生在秋季的连阴雨更易发生灾害。

Analysis of Continuous Rain in Ruicheng County Based on Disaster Index

Using the daily rainfall data of Ruicheng County from March to November during 1961-2014,the continuous rainy process of Ruicheng County in the past 54 years was found out,and the disaster index of each continuous rainy process was calculated.According to the index level and the census data of the same period,the continuous rainy process was analyzed.The results showed that a total of 158 consecutive rainy weather processes occurred in Ruicheng County in the past 54 years,showing a trend of declining year by year with a rate of change tendency of-0.35 times/10 a.The highest number of consecutive rainy weather occurred in September and the lowest number of consecutive rainy days in March and November.The maximum disaster index of continuous rainy was 12 and the minimum was 1.2 in the past 54 years.The LYRI was mainly concentrated in LYRI ＜ 3.0 (Grade Ⅴ,accounted for 74.7％);followed by Grade Ⅳ (mild),accounting for 13.9％;Grade Ⅲ accounted for 9.5％;while severe (Grade Ⅱ) and especially severe (Grade Ⅰ) accounted for less than 2％.In the past 54 years,the grade of continuous rainy disaster above grade Ⅳ in Ruicheng County mainly occurs in autumn,accounting for 50％;followed by summer,accounting for 35％;while the spring was rare,accounting for only 15％.Only 8.3％ of the continuous rainy process in Ruicheng County could cause disasters,and the rainy season in autumn was more prone to disaster.