2021年6月大兴安岭地区暴雨洪涝灾害成因分析

Cause Analysis of Rainstorm and Flood Disaster in Daxinganling Region in June 2021

2021年6月黑龙江上游大兴安岭地区发生特大洪水,出现历史上罕见的洪涝灾害。利用大兴安岭地区国家地面气象观测站、区域气象自动站、水文和水位站资料,采用统计方法,分析降水变化和主要江河洪水的特征。同时,通过欧亚500 hPa高度和距平场、EC模式500 hPa高度和850 hPa风场、物理量场,采用天气学原理及诊断分析方法,分析了暴雨形成的机制,对2021年洪水与历史洪水年进行了对比。结果表明:(1)大兴安岭地区秋、冬、春季降水量均偏多,使黑龙江上游江段水位偏高,土壤底墒含水率多,增加黑龙江上游河槽蓄水量,使黑龙江上游江河底水高,超警戒水位;(2)汛期雨季来临早,受东北冷涡影响,6月中旬两次暴雨叠加,低层高温高湿的不稳定能量与中高层向南渗透的冷空气结合,导致中低层位势不稳定的建立,为暴雨过程提供动力、热力和水汽条件;(3)强降水集中,加之上游来水比重大,形成暴雨洪水,导致洪峰水位高,超警幅度大,造成2021年6月大兴安岭地区发生暴雨洪涝灾害。

In June 2021,a major flood occurred in Daxinganling region in the upper reaches of Heilongjiang Province,resulting in a rare flood disaster in history.Based on the data of national meteorological station,regional station,hydrology and water level station in Daxinganling region,the characteristics of precipitation changes and floods of major rivers are analyzed by statistical methods.At the same time,through Eurasia 500 hPa height and anomaly,EC Model 500 hPa height and 850 hPa wind,Physical quantity data and by using synoptic principles and diagnostic analysis methods,mechanism of rainstorm formation are analyzed;The comparison method is used to analyze the flood in 2021 and the historical flood year.The results show that:(1)more precipitation in autumn,winter and spring in Daxinganling region resulted in higher water level in the upper reaches of Heilongjiang,higher soil moisture content,higher water storage in the upper reaches of Heilongjiang River channel,and higher bottom water in the upper reaches of Heilongjiang river,exceeding the warning level;(2)The rainy season came early in the flood season,Influenced by the Northeast cold Vortex,two heavy rains were superimposed in mid-June.The unstable energy of high temperature and high humidity in the lower layer combined with the cold air penetrating southward in the middle and upper layers,leading to the establishment of the unstable potential in the middle and lower layers,which provided power,heat and water vapor conditions for the rainstorm process;(3)The heavy precipitation concentration,coupled with the significant inflow ratio in the upstream,resulted in rainstorm and flood,resulting in high flood peak water level and large over-alarm range,resulting in the rainstorm and flood disaster in Daxinganling region in June 2021.