近200年来渭河流域干旱洪涝事件特征

通过对渭河流域1813—2017年旱涝灾害资料的收集整理，重建旱涝等级以及指数序列，采用滑动t检验及小波分析等方法，分析了渭河流域近200年来旱涝变化规律。结果表明:近200年来渭河流域发生水旱灾害共111次，水灾和旱灾分别发生了55次和36次，同年水旱灾害交替出现20次，发生频率由高到低依次为:轻度旱灾 > 中度旱灾 > 轻度涝灾 > 旱涝交替 > 中度涝灾 > 重大涝灾及重大旱灾。旱涝灾害的发生具有明显的阶段性:1833—1880年、1914—1933年为中度和重大旱灾的多发期，1894—1910年、1933—1939年为中度和重大涝灾多发阶段。旱涝演变存在5~7年、10~11年、18~20年、60年和105~110年周期震荡。110年左右的周期震荡最强，为第一主周期，第二主周期为60年，第三主周期为20年，同时检验出旱涝有5个突变年，分别为1825年、1881年、1914年、1933年及1981年。空间分布上，渭南地区旱灾发生频率最高，天水和铜川次之，渭河源头处发生频率最低。西安、渭南涝灾发生频率最高，天水、宝鸡、咸阳次之，渭源和铜川涝灾发生频率最低。

Characteristics of Drought and Flood Events in the Weihe River Basin in the Past 200 Years

By collecting and sorting out the data of drought and flood disasters in Weihe River Basin from 1813 to 2017, and reconstructing the drought and flood index and exponential sequences, this paper uses the methods of indexing, moving average, moving t test and wavelet analysis to analyze the variation of drought and flood in Weihe River Basin in recent 200 years. The results showed that there were 111 events of floods and droughts in Weihe River Basin in the past 200 years, 55 events of floods and 36 events of droughts, respectively, and 20 events of floods and droughts occurred alternately in the same year. The frequency of floods and droughts decreased in the order: mild drought > moderate drought > mild flood > alternation of droughts and floods > moderate floods > major floods and droughts. The occurrence of drought and flood disasters had obvious stages, moderate and severe drought-prone periods occurred in the period of 1833—1880 and 1914—1933, moderate and severe flood-prone periods occurred in the period of 1894—1910 and 1933—1939. There were periodic shocks of 5~7 years, 10~11 years, 18~20 years, 60 years and 105~110 years in the evolution of drought and flood. The period oscillation around 110 years was the strongest, which was the first main period, the second main period was 60 years, and the third main period was 20 years. At the same time, five mutation years of drought and flood were detected, which occurred in 1825, 1881, 1914, 1933 and 1981, respectively. With respect to spatial distribution, the highest drought frequency was found in Guanzhong Basin, followed by Tianshui and Tongchuan, and the lowest on was found in the source of Weihe River. The highest frequency of floods was observed in Xi’an and Weinan, followed by Tianshui, Baoji and Xianyang, and the lowest frequency was found in Weiyuan and Tongchuan.