清代时期都江堰地区洪涝灾害与气候特征研究

Flood Disasters Events and Associated Climate in Dujiangyan City during Qing Dynasty

分析历史时期洪涝灾害对揭示古气候环境有重要科学价值。本研究通过对都江堰地区历史资料的整理分析,运用数理统计和小波分析等研究方法,探讨了该地区清代洪涝灾害的等级、频次、周期以及历史气候特征。结果表明,在清代268年中共发生洪灾62次,平均每4.3年发生一次,从清代早期到晚期洪灾呈现波动增加趋势且有明显的阶段性:1644—1679年和1790—1839年是洪灾少发期,1680—1789年和1840—1911年是洪灾高发期。小波分析结果显示清代都江堰地区的洪灾明显地存在4 a左右短期振荡周期、23 a左右的长期振荡周期,清中晚期还存在一个约8 a的中振荡周期。清代该地区出现了6次降水增多事件,分别发生于1744—1746年、1863—1868年、1873—1875年、1878—1881年、1897—1902年和1906—1908年,集中于清代中后期。厄尔尼诺事件也是诱发本地区洪灾发生的一大因子。推断本地区发生特大洪灾和大洪灾年份的降水量显著增多,年降水量约1510 mm或更多。

By examining historical data of Dujiangyan region,this research conducted statistical analysis and wavelet transform to retrieve the ancient flood information in Qing Dynasty,including the grading,frequency and periodicity of flooding as well as climate pattern. Results showed that flooding occurrences amounted to 62 for the whole 268 years of the Qing dynasty,once every 4. 3 years,and from early Qing dynasty to the late,flooding occurred with a fluctuated increase trend and obvious periodic pattern： a period of less flooding during 1644-1679 and 1790-1839,and at high risk of flooding for 1680-1789 and 1840-1911. Flooding in Dujiangyan region in Qing dynasty obviously existed a short period of 4 a and long-term oscillated period of 23 a. Besides,there was an 8 a in the middle and late Qing dynasty. There were 6 incremental precipitation period in the region during Qing dynasty,occurred in 1744-1746,1863-1868,1873-1875,1878-1881,1897-1902 and 1906-1908 years,respectively,concentrated in the middle and late Qing dynasty. El Nino event was also a major factor inducing flood disasters. It referred to a significant increment of rainfall in the year of catastrophic flood and great flood,with an estimation of precipitation about 1510 mm or more.