The Time-sharing And Zoning Research Of Winter Wheat’s Drought Risk

Drought poses major agricultural disaster for the growth of winter wheat in North Chinaand has made huge impact on its growth and yield formation. By selecting the typicalirrigated agricultural area of North China, Xingtai City as the basic research area, this paperbuilds the index system of winter wheat hazard risk, pregnant disaster environmentalsensitivity as well as vulnerability of hazard-bearing body and analyzes the hazard risk andpregnant disaster environmental sensitivity for each growth stage of winter wheat in XingtaiCity respectively in the years of2002-2003,2004-2006,2008-2009,2010-2011. Besides, thispaper also explores the comprehensive drought risk degree in whole growth period of winterwheat and classifies different risk scenarios, and further proposes preventive measurespartition of winter wheat drought risk by combining with vulnerability of hazard-bearing body.Preliminary understandings and conclusions in this paper are as follows:（1） The drought hazard risk assessment of winter wheat shows: five winter wheatgrowth stages of drought hazard risk are wintering stage, seedling growth stage, turning green-jointing stage, heading jointing stage, and heading mature stage in succession from small tolarge. In terms of various growth stages the drought hazard is different in different years. Inspace, various growth stages all have low-risk centers, and low risk centers transfer over time.In the wintering period there is only one Ren County-centered low-risk area. Low-risk centerof green-jointing stage transfers from Ren county to the region of Xingtai and Linxi-centered.In terms of jointing stage low hazard risk has three centers, namely, central to Ren county inthe middle, Qinghe in the east and Linxi in the southeast. The low-risk center transfers toXingtai city in heading mature stage. From the risk level of whole growth period one can seethat drought hazard risk differs in different years, particularly the notable regional differences.More specifically, the low-risk center mainly locates in the Ren county-centered middle areaand high-risk center mainly locates in western mountains and eastern plains.（2）The results of the evaluation of winter wheat disaster sensitivity show: the stage hasa low sensitivity of winter wheat during the period of pregnancy environmental disaster toseedling stage; the stage has a strong sensitivity to the mature stage. Turning green-jointingstage and heading jointing stage are the most sensitive stage which identify with the winterwheat hazard risk analysis. The whole region is mild sensitive in2004-2006, and moderatesensitive in2010-2011. Regional differences in the sensitivity of the whole growth period issignificant in the years of2002-2003,2006-2007and2008-2009: highly sensitive zone ismainly distributed in western mountainous areas and in most parts of the eastern plains, therelatively low sensitivity of the zone is mainly distributed in NingJin, Baixiang, Lngyao, Juluand Nanhe, east of Neiqiu and downtown area of Xingtai city in front of Taihang Mountains.Highly sensitivity values are different in various growth stages. Seeding stage is mainlydistributed in the eastern plains area, forming the highly sensitivity area which is centeredwith Qinghe including Linxi, Nangong and Guangzong. Highly sensitive region of winteringis mainly located in western mountains and eastern plains, and the relatively low sensitivity ofthe area is mainly distributed in eastern Ningjin, Baixiang, Longyao, Julu, Nanhe, east ofNeiqiu and downtown area of Xingtai city in front of Taihang Mountains. In green-jointingstage,the relatively highly sensitivity area is mainly located in western mountain region including Xingtai, Neiqiu, Lincheng and baixiang, eastern plains including Qinghe,Linxi,Weixian and Pingxiang, etc. In heading jointing stage, the winter wheat sensitivity pregnantenvironment disaster is lower, the higher sensitivity level of rural areas are Pingxiang, Shahein the east and Xingtai, Lincheng, Ningjin, Baixiang, Julu in the west.（3）The results of the evaluation of vulnerability of winter wheat manifest: The extentwinter wheat is reduced due to drought in recent years is lower, less than twenty percent. In2002-2003the overall reduction in Xingtai is small, and winter yield of Lincheng, theRenxian in central western, Nanhe, Pingxiang, and Guangzong, Weixian in the east decreasesover10percent. From2004to2008, the area of production-reduced expanded and onlyNingjin, Longyao, Guangzong and Linxi areas received no reduction. In most parts of thewestern region, south-central and eastern parts the winter wheat yield decreased, and wheatfragile degree was large. In2006-2007, Shahe in the west, Ningjin in the north-central,Guangzong in the east, Weixian and Linxi were not reduced, and wheat fragile degree wassmall. In2010-2011, the occurrence of severe drought affected the winter wheat, exceptdowntown area and Guangzong, the phenomenon of reduction of output is common inlarge-scale of Xingtai, and the overall vulnerability was large.（4）The results of annual drought comprehensive risk figure prove: there are differencesin the space with the risk level. There exists a low risk area in the middle, to the centeroutward radiation of Renxian, including Renxian, Longyao, Julu, some areas of the Nanhe.Linxi in the east, Longyao in the middle and Pingxiang, Julu, some regions of Ningjin and thewestern parts of Neiqiu, Shahe, Xingtai, Baixiang are moderate risk of drought. Xingtai,Neiqiu and western Lincheng are high risk areas. Other areas belongto severe risk areas. Fromthe time sequence, the area for the high risk periods of winter wheat growth were increasingfrom2002-2003to2010-2011. When severe drought occurred in2010-2011, winter wheatgrowing areas have reached severe risk in the whole area.（5）This study that relates to winter wheat risk prevention, on the basis of division ofrisk scenarios, divides into the western high-risk areas, low-risk areas in the central andeastern high-risk areas in terms of risk intensity; From the time sequence, this paper dividesthe winter wheat drought risk scenarios of Xingtai into wheat yield formation rate, Seedlinggrowth stage, spring-jointing stage and heading to the mature stage. There are threecategories and9subcategories in total, and the study discusses appropriate risk preventivemeasures to different regions combining regions and time frame.