四川省汉源县大渡河干热河谷区清代洪涝灾害特征

目的]分析四川省汉源县清代洪涝灾害特征及成因,为防灾减灾等工作提供科学支持。方法]通过对大渡河干热河谷区汉源县清代洪灾等资料的搜集整理,运用数理统计分析等方法,探究了该地区清代洪灾的等级、频次、周期以及成因等问题。结果]清代汉源县洪涝灾害共计发生55次,平均4.87a发生1次。轻度洪灾、中度洪灾、大洪灾和特大洪灾各占洪灾总数的14.55%,60.00%,21.82%和3.64%,以中度洪灾为主。从清代早期到晚期,洪灾呈波动增加的趋势且有明显的阶段性,1644—1739年和1770—1809年是洪灾少发期,1740—1769年和1810—1911年是洪灾高发期,并出现了5次重大洪灾事件。清代汉源县洪灾存在约5a,10a的震荡周期。结论]在太阳黑子极值年、印度夏季风强盛期及南方涛动(ENSO)事件年前后出现洪灾的机率极大。清代中期以后的人口快速增长、农业垦殖、森林破坏等人为无序开发加剧了洪灾频次和严重程度。

Characteristics of Flood Disasters in Dry-Hot Valley of Dadu River in Hanyuan County, Sichuan Province in Qing Dynasty

Objective] To analyze the characteristics and causes of flood disasters in Hanyuan County, Sichuan Province in Qing Dynasty, in order to provide scientific support for disaster preventions and mitigations. Methods] The flood disaster data of Hanyuan County in Qing Dynasty was collected. Mathematical statistics analysis methods were used to study the level, frequency, period and causes of the flood disasters in Qing Dynasty. Results] There were 55 flood disasters with an average frequency of once per 4.87 years in Hanyuan County in the Qing Dynasty. Mild floods, moderate floods, major floods and catastrophic floods accounted for 14.55%, 60.00%, 21.82% and 3.64% of the total flood disasters, respectively, with moderate floods being the main events. Flood disasters showed a fluctuated increasing trend and obvious stages. The periods during 1644-1739 and 1770-1809 were the stage of frequent flood disasters, the periods during 1740-1769 and 1810-1911 were the stage of high-risk flood disasters, and there were five major flood events. The flood disasters in Hanyuan County in Qing Dynasty were marked by a shock period of about 5 years and 10 years, and the flood frequency was high. Conclusion] There is a high probability of flood disasters in the extreme years of the sunspot, the prosperity period of India summer monsoon and the year of the ENSO events. The rapid of population growth, agricultural reclamation, forest destruction and human-made disorderly development aggravated the frequency and severity of flood disasters.