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干旱,是陕北农业生产的主要灾害。据1368～1976共607年的资料记载,在247次旱年中,共发生56次大旱年(即一个旱期的最高峰)。早期和大旱年的出现,往往是连续二年以上较大范围的干旱,对农业生产危害最大。本区平均年雨量500～600毫米,分布极不均衡。延安在1952～71的20年中,1964年871.2毫米,1965年仅380.3毫米。延长、延安、志丹和吴旗多年平均依次为579.2、570.3、557.2和512.8毫米,1972
Drought is the major agricultural disaster in northern Shaanxi. According to the data of 607 from 1368 to 1976, 56 major drought years (ie the peak of a dry season) occurred in 247 dry years. The emergence of early and severe dry years is often the result of a large area of drought lasting more than two years, which is the hardest hit by agricultural production. The average annual rainfall of 500 ~ 600 mm, the distribution is extremely uneven. In the two decades 1952-71, Yan’an was 871.2 millimeters in 1964 and 380.3 millimeters in 1965. Yan’an, Zhidan and Wu flags averaged 579.2, 570.3, 557.2 and 512.8 millimeters in succession in 1972, 1972