公元1400年以来陇中地区干旱灾害特征

Research on Drought Disasters in Central Gansu Province during the Period from 1400 to 1999

通过对历史文献资料的整理与统计分析,对甘肃陇中公元1400-1999年干旱灾害的等级序列特征、年代际变化、季节变化、空间变化及气候背景进行研究。结果表明:陇中公元1400-1999年共发生旱灾280次,平均每2.14年发生1次。干旱灾害以中度旱灾为主,占旱灾总次数的45.4%,其次是大旱灾,占旱灾总次数的32.1%,特大旱灾和轻度旱灾发生频率较低,各占旱灾总次数的10%和12.5%。旱灾可划分为3个阶段,第1阶段在1480年代之前,为旱灾持续增加的高发阶段;第2阶段在1490-1700年代,旱灾持续减少,是旱灾低发阶段;第3阶段在1710年代之后,旱灾波动增加,是旱灾高发阶段。旱灾在季节上以夏旱次数最多,其次为春旱和多季节连旱。旱灾严重程度在空间上呈现由西南到东北增强的特点。在15-17世纪,陇中气温冷暖波动性较强,旱灾发生频次变化较大;在18-19世纪,随着气温的持续走低,旱灾发生频次有不断增大的趋势。20世纪暖期,旱灾发生频次居近600年之首。

In this paper,the historical documents of drought disasters in central Gansu Province during the period from 1400 to 1999 were collected and analyzed. The ranks,decadal change,seasonal change,regional variation and climatic background of drought disasters in central Gansu Province during this period were focused on. It was found that 280 times of drought disasters occurred in central Gansu Province during this period,approximately once every 2.14 years in average. Drought disasters were mainly the moderate ones and accounted for 45.4% of the total,followed by severe ones and accounted for 32.1% of the total,and the occurring frequency of tremendous and slight ones accounted for 10% and 12.5% of the total respectively. Occurrence of drought disasters in central Gansu during the period from 1400 to 1999 could be divided into three stages. The first stage was before the 1480s,and it was characterized by high occurring frequency and continuous increase of drought disasters; the second stage was between the 1490s and the 1700s,and it was characterized by low occurring frequency and continuous decrease of drought disasters; the third stage was after the 1710s,and it was characterized by high occurring frequency and fluctuated increase of drought disasters. Seasonally,drought disasters occurred mainly in summer,and followed by spring drought and successive two-or three-season drought. Spatially,severity of drought disasters was increased from southwest to northeast of central Gansu Province. Occurring frequency of drought disasters fluctuated sharply in central Gansu Province during the period from 15th century to 17th century due to climate fluctuation; occurring frequency of drought disasters was continuously increased with temperature decrease during the period from 18th century to 19th century. Occurring frequency of drought disasters was the highest during the warm period in the 20th century in recent 600 years.