华北地区冬小麦干旱危险性分析

Hazard analysis of drought disaster for winter wheat in north China

利用华北地区48个农气站冬小麦发育期资料(1981-2010年)和气象资料(1961-2010年)以及近50 a产量资料,将冬小麦全生育期划分为前期(播种期—起身期)、中期(拔节期—开花期)、后期(灌浆期—成熟期)3个阶段,并考虑了底墒形成期(播种当年7-9月)内的降水。通过构建干旱指数,分析不同发育阶段干旱灾害的时空分布规律。根据典型灾害年份的减产率数据,将不同发育阶段干旱灾害造成的灾损情况进行了量化,并以权重系数的形式来反映干旱危险性的贡献大小。最后利用GIS技术绘制了华北地区干旱危险性区划图。结果表明:(1)华北地区冬小麦各发育阶段均受到干旱威胁,其中中期水分亏缺最为严重。(2)冬小麦平均干旱指数空间分布在前期和后期由东南向西北递增,在中期由南向北递增。(3)华北地区冬小麦前期危险性权重系数由南向北逐渐增大,而中期危险性权重系数由北向南逐渐增大。

Using the data of winter wheat growth and development( 1981- 2010) and meteorology( 1961- 2010)from 48 agro-meteorological observatories and data on yield in recent 50 years,the whole growing period of winter wheat was divided into three stages,i. e. early stage( from sowing to standing stage),medium stage( from jointing to flowering stage) and later stag( from filling to mature stage),and the precipitation in the period before sowing was taken into account. Through construction of drought index,the spatiotemporal distribution law of drought disaster in different developmental stages was analyzed. The degree of damage in each development stage was quantified by applying the yield reduction rate data in typical drought years,and its contribution to the whole damage was shown in the form of risk weight. Then,a map for drought hazard to wheat production in North China based on GIS was presented. The results show that:( 1) Water deficiency exists in each developmental stage of winter wheat in North China,and the medium stage suffers the most.( 2) The drought index of winter wheat in early and late stages increase gradually from southeast to northwest,in medium stage it increases from south to north.( 3) The risk weight in early stage increases from south to north in North China. On the contrary,risk weight in medium stage decreases from south to north.