【摘要】 通过对陕西省关中地区1850—1949年历史资料的统计,对该时期关中地区干旱灾害的时间变化、旱灾等级和成因等进行了分析.结果表明,关中地区这一时期共发生干旱灾害56次,平均1.78年1次,其中以1920—1934年干旱灾害为最频繁.该地区以中度旱灾为主,发生次数占旱灾总数的57.1%,大旱灾和特大旱灾发生频率分别占旱灾总数的10.7%和8.9%.旱灾具有明显的季节性特征,夏旱最多,春旱和秋旱次之,冬旱最少.典型的大陆性季风气候是旱灾发生的自然背景.关中地区特大旱灾和大旱灾一般是年均降水量减少200 mm以上造成的.轻度旱灾与中度旱灾主要是降水量分配不均造成的,有时伴随降水量减少.更多还原

【Abstract】 Through statistics and analysis of historical material from 1850 to 1949 in Guanzhong area,the paper studied the change,grades and causes of the droughts disaster.The result indicates that the droughts altogether had 56 times in the area,once average 1.78 years from 1850 to 1949,in which the droughts from 1920 to 1934 were the most frequent.In this area,the moderate droughts were main and accounts for 57.1% of the total number of droughts,and the serious droughts and worst droughts were 10.7% and 8.9% of the total number of droughts.The droughts had obvious seasonal difference and the droughts occurred in summer were the most,and that occurred in spring and autumn taken second place,and that occurred in winter was the least.The typical continental monsoon climate was the natural background for which the droughts occurred.In the Guanzhong area,the worst droughts and the serious droughts were created by the remarkable reduction of mean annual precipitation;The mild droughts and the moderate droughts mainly were created by the uneven precipitation assignment,sometimes following the certain reduction of precipitation.更多还原