摘要
干旱作为一种气象灾害,系以降水缺少并造成减产为特征。用三次多项式对历史产量序列进行处理,求出趋势产量和气象产量,然后对气象产量和降水距平的关系进行了相关分析。结果发现,气象产量与冬小麦全生育期和拔节期的降水距平有着十分密切的关系,尤其是前者。通过统计分析,建立了它们之间的回归方程,并与农业干旱划分标准相结合,确定了两套与轻旱、中旱、重旱和极端干旱相对应的干旱指标,即冬小麦全生育期降水负距平分别为小于15%,15%～35%,35%～55%和大于55%时,出现轻旱、中旱、重旱和极端干旱,产量分别减少小于10%,10%～20%,20%～30%和大于30%;拔节期降水负距平为小于30%,30%～65%和65%～100%时,分别出现轻旱、中旱和重旱,分别减产小于10%,10%～20%和20%～30%。可以看出,拔节期降水缺少对产量的影响,远远不如全生育期的降水影响大,因此评估中应以前者为主,后者为辅,相互配合使用。
As a natural disaster, drought is characterized by short of precipitation and reduction of crop yield. In this paper, the sequence of historic yield of winter wheat is processed with cubic polynomial and thus the yield can be divided into two parts—— tendency yield and meteorological yield which is mainly affected by meteorological factors. Then the correlation between meteorological yield and precipitation anomaly was analyzed. It was found that there are close relationship between meteorological yield and precipitation anomaly in whole growing season and in jointing stage, especially in the first period. The regression equations between them were established. Considering the drought is classified in light, moderate, heavy and severe grades in agriculture, two sets of drought indices were determined. The negative anomaly of precipitation of less than 15%, 15%～35%, 35%～55% and more than 55% in whole growing season of winter wheat correspond to light, moderate, heavy and severe drought respectively and the yield was reduced by less than 10%, 10%～20%, 20%～30% and more than 30%. But in period of jointing stage, the drought indices are less than 30%, 30%～65% and 65%～100% of negative anomaly of precipitation, which corresponds to light, moderate and heavy drought. The yield was reduced by less than 10%, 10%～20% and 20%～30%. Therefore the affection of short of precipitation in jointing stage on yield is not as much as that in whole growing season. The drought indices in whole growing season should be in priority compared with that in jointing stage when evaluating drought status.
出处
《自然灾害学报》
CSCD
北大核心
2003年第1期145-150,共6页
Journal of Natural Disasters
基金
国家"十五"科技攻关项目"农林重大病虫害和农业气象灾害的预警及控制技术研究"(2001BA509B14)
关键词
华北
冬小麦
干旱指标
North China
winter wheat
drought indices
