长沙县近10年暴雨内涝雨量阈值统计分析

Statistical Analysis of Rainfall Threshold of Rainstorm Waterlogging in Changsha County in Recent 10 Years

摘要: 利用2011~2021年长沙县自动气象站逐小时降雨量数据，分析该地区近10年来发生的21次内涝过程主要特点，并统计对应乡镇(街道)范围内自动气象站1小时、3小时雨量数据：1) 2011~2021年的21次内涝过程以6月份发生次数最多，时间主要集中在下午至夜间，这与本地强降雨主要出现下午至夜间的特点基本一致；从乡镇分布看，主要集中在城区和中部乡镇，其中星沙街道和黄花镇发生次数最多。2) 发生内涝时，自动气象站1小时降雨量在18.4~52.8 mm之间，3小时累积雨量在27.4~73.3 mm之间；根据统计结果及日常业务应用，将25 mm、45 mm定为长沙县城市内涝1小时、3小时雨量阈值，即当1小时降雨量 ≥ 25 mm或3小时累积雨量 ≥ 45 mm时，长沙县城区范围内极大可能出现城市内涝。

Abstract: The main characteristics of 21 urban floods and its 1-hour, 3-hour rainfall data in recent 10 years is analyzed based on the hourly rainfall data of Changsha automatic weather station from 2011 to 2021: 1) The 21 urban floods from 2011 to 2021 occurred most frequently in June, mainly from afternoon to night, which is basically consistent with the characteristics of local heavy rainfall; from the perspective of township distribution, it is mainly concentrated in urban areas and central towns, of which Xingsha street and Huanghua town have the most occurrences. 2) In case of urban flood, the 1-hour rainfall of the automatic weather station is 18.4~52.8 mm, and the 3-hour cumulative rainfall is 27.4~73.3 mm. According to the statistical results and daily business applications, 25 mm and 45 mm are defined as the 1-hour and 3-hour rainfall thresholds of urban floods in Changsha County, that is, when the 1-hour rainfall is greater than or equal to 25 mm or the 3-hour cumulative rainfall is greater than or equal to 45 mm, urban flood is most likely to occur in Changsha County.