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通过对甘肃省 5 2 5年旱涝等级资料累积等级及跃变分析表明 ,甘肃日趋干旱化。其中 ,中部和河西地区最严重 ,陇东次之 ,渭水流域最小。河西、中部、陇东和渭水流域气候变化具有明显的差异性 ,近 5 2 5年来中部地区气候跃变不明显。近 2 0 0年来河西地区气候跃变系数具有与陇东、渭水流域相反的变化趋势。近百年来旱涝等级资料的第一主成分有显著的 3年、8年、1 1年周期 ,第二主成分有 1 4年、2 9年的周期。通过对主成分与近 5 0年产量波动关系的研究 ,第一和第二主成分在 7～ 9年和 2～ 2 .44年、2 2年以上周期时影响夏粮产量 ,但二者对夏粮产量均为负贡献 ,它们与产量波动关系极其密切。除超短波外 ,旱涝对产量的影响滞后约半年时间。并通过对干旱累积效应的分析 ,确定了近 5 2 5年发生特大旱的次数、持续时间、等级及其对夏粮的影响。
Based on the cumulative grade and grade change of drought and flood data in 525 years in Gansu Province, it shows that Gansu is becoming more and more arid. Among them, the Central and Hexi area is the worst, followed by Longdong and Wei River. The climate change in Hexi, Central, Longdong and Weishui watersheds is obviously different. In the recent 52 years, the climate change in Central China is not obvious. In the recent 200 years, the climatic jump coefficient of Hexi area has the opposite tendency with Longdong and Weishui watersheds. The first principal component of drought and waterlogging data over the past century has a significant period of 3 years, 8 years and 11 years, and the second principal component has periods of 14 years and 29 years. Through the research on the relationship between the principal component and the fluctuation of output in the recent 50 years, the first and second principal components affect the summer grain yield during the period of 7-9 years, 2-2.44 years and 22 years. However, Production is a negative contribution, and their relationship with the yield fluctuations are extremely close. In addition to ultrashort wave, the impact of drought and flood on the output lag about six months. And by analyzing the cumulative effect of drought, the number of severe drought, duration, grade and its impact on summer grain in the past 525 years have been determined.