明清时期陕北自然灾害的时空分布研究

Spatial-temporal variations in natural disasters of northern Shaanxi Province during Ming and Qing Dynasty

通过对历史文献资料的整理和分析,利用最小二乘法、小波分析法、空间插值法等,对明清时期陕北自然灾害的种类、等级、时空特征及原因进行研究.结果表明:明清时期陕北自然灾害频发,共发生645次,主要灾害类型为旱灾、水灾、雹灾和寒冻低温灾害,将自然灾害划分为轻、中、重度3个等级,各占灾害总频次的27.4%、66.4%和6.2%.自然灾害10 a频次呈显著波动增加趋势,最大值发生在1830—1839年,分为频次最少-频次较高-快速上升3个阶段,单一季节灾害多在秋季和夏季,跨季节灾害多为夏秋连发、春夏连发且灾害等级较高.灾害发生具有2~3 a,5~8 a,10~13 a的周期.空间分布差异明显,榆林、绥德、延安为3个高频中心,黄陵、吴起则为低频中心.不同自然灾害类型空间分布差异表现为旱灾在米脂、绥德频繁,水灾、雹灾、寒冻低温及风灾以榆林为最突出,虫灾和地质灾害主要发生在黄陵.气候的寒冷干旱,以及由于屯垦、砍伐等人类活动造成了生态环境恶化,是灾害发生的主要原因.

Based on the statistics and analysis of disasters in historical documents in northern Shaanxi Province during Ming and Qing Dynasties,the temporal-spatial distribution and cause analysis have been analyzed by methods of least squares,wavelet analysis and Kriging method.The results show that there were 645 recorded disasters,and the main disasters were drought disaster,flood disaster,hail disaster and freeze disaster. The mind,moderate and severe disasters accounted for 27.4% ,66.4% and 6.2% ,respectively.Changes in occurring frequency on the decade intervals show the volatility rising trend and the maximum appeared in the years from 1830 to 1839,and the frequency experienced three stages,namely the lowest frequency,higher frequency,and rapid increase.The disaster occurred mainly in summer and autumn,and often occurred across the season,include summer and autumn,and spring and summer,in relatively high grade.Wavelet analysis shows that historical flood disaster cycle patterns are 2—3 a,5—8 a,10—13 a.The spatial distribution of disaster varied distinctly.Yulin,Suide and Yan-an were the three high-frequency centers,and Huangling and Wuqi were the two low-frequency centers.Different disasters had different spatial distributions. Drought occurred frequently in Mizhi and Suide. Flood,hail and freeze mainly occurred in Yulin,and pest and geological hazard mainly occurred in Huangling. The findings are that there was a close relationship between the disaster frequency and the climate,and the deterioration of the ecological.