明清时期嘉陵江流域水旱灾害时空分布特征

Spatial and temporal distributions of floods and droughts in Jialing river basin in the Ming and Qing dynasties

在系统搜集、整理明清时期嘉陵江流域水旱灾害历史资料并对其进行量化统计分析的基础上,揭示了明清时期的500多年间嘉陵江流域水旱灾害存在如下特征:①水灾和旱灾频繁,而水灾略多于旱灾。两种灾害的发生频率分别为2.56年/次和3.03年/次;②水旱灾害主要发生在农历五、六、七月。在发生月份可考的灾害中,农历五、六、七月发生的旱灾超过了总数之半,水灾也达到水灾总数的69.5%;③涪江流域是水旱灾害发生最频繁的区域。涪江流域的水灾次数占嘉陵江流域水灾总数的31%,旱灾占嘉陵江流域的38%;④水旱灾害等级以一般性灾害和大灾害为主,特大灾害较少。明清时期嘉陵江流域的212次水灾中,一般性水灾147次,大水灾42次,特大水灾23次;所发生的179次旱灾中,一般性旱灾115次,大旱灾42次,特大旱灾22次;⑤森林覆盖率与水旱灾害的发生次数成反比例关系。本文所探讨的明清时期嘉陵江流域水旱灾害的时空分布特征对当前该区域的防灾减灾工作有重要的借鉴意义。

Based on the systematical collection of historical data, and quantitative statistics and analysis, this paper examines the characteristics and rules of floods and droughts of Jialing River in the Ming and Qing dynasties. Five main conclusions can be drawn as follows. （1） The disasters occurred frequently, with floods a bit more than droughts. The frequency of the former is 3.03 times per year while the latter is 2.56 times. （2） Most of the disasters occurred in May, June and July in the Chinese lunar calendar. Specifically, over half of the flood events occurred in these months, accounting for 69.5% of the total, and more than half of the drought events were observed in this period. （3） The Fujiang River basin suffered far more disasters than other areas. It witnessed 31% of flood events and 38% of drought events of Jialing River basin. （4） There are more normal and major disasters than extremely serious disasters. Extremely serious floods accounted for 10.85% of all the floods in this basin during this period, and extremely serious droughts accounted for 12.29% of the total. （5） The forest coverage is inversely proportional to the frequency of floods and droughts in this area. We believe that the results will provide reference for disaster mitigation and prevention in this basin.