Risk Assessment And Regionalization Study On Winter Wheat Drought In He Nan Province

On the background of soil humidity to influence on the winter wheatgrowing, the soil drought index was built and the spatical-temporal variation ofthe winter wheat drought disasters in henan province was analyzed on the basisof previous researches by EOF. The results show: the heavy drought locality isin the north of northern Henan, in the east and west, as well as partial regions ofthe middle; large parts of the south and southwest are light degree. Waveletanalysis show that the winter wheat drought in henan exists 3-5a and 8-9aperiods, High frequency surge is unconspicuous before 1990 year and fortifiedafter 1990 year.Based on the different need of winter wheat to soil moisture, thedevelopment phases of the winter wheat were divided into four periods for thesake of studying the drought influence on the winter wheat growth andyield. The outcome indicated: drought from tassel to mature of the winterwheat is the heaviest in the four phases. The impact of drought to the wheatyield is negative, but it is positive sometimes in especial periods because of thedrought degree is diverse. There are not severe corresponding connectionbetween drought and wheat yield. In drought year, the wheat yield is not cutdefinitely. In the heaviest drought year, the wheat yield degressive rate is notgreat affirmatively.Based above research, from view of risk, a index system of risk assessmentof the winter wheat losses caused by drought was established, including thedrought year probability, yield losses by drought disaster, variation coefficient,disaster resistance capability, then on the base of these indices, thecomprehensive risk index model of losses caused by drought was established and regionalized. The results show: the higher risk areas include san men-xia,gongyi in the west, linzhou in the north, zhengzhou in the middle and fangchengin the southwest. The middle risk degree areas include xinxiang in the north,xuchang in the middle, zhumadian and nanyang in the south. The west regionson the Jingguan railway and the southwest in Henan are low risk degree.