江西省宜春市城区暴雨统计特征及致涝分析

Statistical characteristics and waterlogging analysis of rainstorm in Yichun City,Jiangxi Province

文章基于宜春国家基准站1961-2020年日雨量资料、气象灾害风险普查资料、暴雨日天气形势场资料、江西WebGis雷达拼图产品和历史内涝信息等资料,对宜春城区暴雨日特征进行统计并开展致涝分析。结果表明:宜春市城区年平均暴雨日4.0天,年平均大暴雨日0.6天,2天以上连续暴雨占7.4%,有显著单波峰月、季分布特征,年代变化表现为20世纪70年代陡然减少之后缓慢增加;利用小波分析表明,暴雨日高频周期由2~4年增加到4~6年,2000年后出现14~16年低频周期变化特征,Mann-Kenddall检验表明2018年发生突变;宜春城区暴雨天气形势主要有槽前切变急流暴雨、梅雨锋暴雨、副高边缘暴雨、台风外围暴雨和冬季冷空气暴雨等;多普勒雷达回波表现为絮状、块状或短带状,中心强度经常达到50~55 dBZ;从历史洪水事件和近10年短时强降水致涝来看,36 h降雨量超过150 mm是出现大面积洪水内涝的基本条件,而对于短时强降水,连续2 h降水量超过45 mm时,则容易出现严重内涝,连续2 h降水量达到60 mm以上,内涝范围将显著增加。研究结果为宜春城区暴雨预报提供参考依据。

Based on the daily rainfall data of Yichun National Base Station from 1961 to 2020,meteorological disaster risk survey data,rainstorm daily weather situation field data,Jiangxi WebGis radar puzzle products,historical waterlogging information and other data.This paper makes statistics on the daily characteristics of rainstorm in Yichun urban area are counted and waterlogging analysis is carried out.The results indicate that:The annual average rainstorm days in Yichun urban area are 4.0 days,and the annual average heavy rainstorm days are 0.6 days.The continuous rainstorm for more than two days accounts for 7.4%.There are significant monthly and seasonal distribution characteristics of single wave peak.The annual change shows a sharp decrease in the 1970s and a slow increase in the 1970s.Using the wavelet analysis indicate that the daily high frequency periodic variation of rainstorm increases from 2~4 years to 4~6 years,and the low frequency periodic variation characteristics of 14~16 years appear after 2000.The MK test indicate that there is a sudden change in 2018.The weather situation of rainstorm in Yichun urban area mainly includes rainstorm of shear jet in front of trough,rainstorm of Meiyu front,rainstorm of subtropical high edge,rainstorm around typhoon and cold air rainstorm in winter.Doppler radar echoes appear as flocculent,blocky,or short bands,with center intensities often reaching 50~55 dBZ.From historical flood events and short term heavy rainfall in the past 10 years,it can be seen that rainfall exceeding 150 millimeters in 36 hours is the basic condition for large scale flood waterlogging.However,for short term heavy rainfall,the precipitation exceeds 45 millimeters for two consecutive hours,it is prone to serious waterlogging,reaching over 60 millimeters,and the scope of waterlogging will significantly increase.The research results provide a reference for rainstorm forecast in Yichun urban area.