中文摘要：

通过对鄂尔多斯高原西南部文献资料的搜集整理,研究了该区清代（1644~1911年）旱灾等级、年际变化、周期及成因等问题。结果表明：在清代（1644~1911年）的268年里,鄂尔多斯高原西南部共发生旱灾77次,平均3.48a发生1次。其中轻度旱灾、中度旱灾、大旱灾和特大旱灾各发生4次、65次、5次和3次,主要为中度旱灾,其他等级旱灾发生较少。研究区旱灾可分5个阶段,其中1644-1729年、1780-1809年、1860-1911年为旱灾少发阶段,1730-1779年、1810-1859年为旱灾多发阶段。总体来看,从清代早期到晚期,旱灾发生频次呈现增加的趋势。该区清代旱灾有4a、10a左右的短周期,30a左右的中周期和63a左右的长周期。研究区清代处于干冷气候期,年降水量减少和降水季节分配不均是发生旱灾的主要原因。研究区清代发生了3次干旱气候事件,分别在1757~1759年、1877~1878年和1908~1910年间,干旱气候事件对人们的生活和社会造成了严重危害。

英文摘要：

In this paper we studied the grades, annual variation of drought disasters and the causes in Southwest- ern Ordos Plateaus during the Qing Dynasty. The results showed that the drought disasters in the Qing Dynasty occurred 77 times and averagely occurred one time per 3.48 year. The light droughts were 4 times. Middle droughts were 65 times. The strong droughts were 5 times. The extreme droughts were 3 times. There were main- ly mild and moderate drought. It showed that the drought had spatial differences. The drought disasters in the Qing Dynasty could be divided into 5 phases according to the drought frequencies in this region. The phases of frequent drought occurrences include 1730 - 1779 and 1810 - 1859. The phases of seldom droughts occurrence include 1644 - 1729, 1780 - 1809 and 1860 - 1911. Overall, the drought occurrence frequency presented an in- creasing trend over time. In different time scales, the cycles of drought disaster occurrences were respectively 4a, 10a, 30a and 63a. The main cause of drought was annual precipitation decrease in study area, which in dry and cold climate period. We determined 3 draught events in the Qing dynasty, which were in 1757 -1759,1877 - 11878 and 1908 - 1910. The draught events had caused serious harm to the people＇s daily lives and the society.