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Comparison Of Drought Hazard During Growth Period Between The Corn Belts Of China And The United States

Posted on:2019-02-03Degree:MasterType:Thesis
Country:ChinaCandidate:F WangFull Text:PDF
GTID:2333330545466646Subject:Science of meteorology
Abstract/Summary:PDF Full Text Request
Northeast China(NEC)and the Great Plains of the United States(US),which are located in the same latitude zone(35-55°N),are known as the two famous “Gold corn belts” in the world.In recent years,maize planting in two areas has been affected by frequent drought disasters,and the drought risk is still high in the future climatic background.As the most developed agriculture country in the world,the US has accumulated rich experience in drought mitigation and disaster reduction of maize.In order to improve the ability of domestic drought mitigation and draw lessons from the US,it is necessary to understand the differences of climatic background,yield fluctuation and drought hazard between the corn belts of NEC and the US.This paper collected the meteorological data,corn yield data,planting data and related social statistics of two study areas from 1986 to 2015.Based on the difference analysis on characteristics of climatic resources and corn yield fluctuation during the corn growth period(GP,April-October)in two areas,the standardized precipitation evapotranspiration index(SPEI)was selected to quantify the me teorological drought intensity during the GP.Comparing drought characteristics between the two areas and analyzing the causes of the difference,through calculating the correlation between SPEI and yield fluctuation,this paper explored the effects of different time scale dry-wet conditions on corn yield,and chose the optimal month-scale SPEI to construct monthly and GP-scale drought hazard index(DHI)in the second-level administrative divisions(prefecture/County),and then drought hazard degree and its effect on corn yield were evaluated and compared.The main results were as follows:(1)Compared with the US,in the last 30 years,corn belt of NEC had higher solar radiation,lower mean temperature,less precipitation and concentrated in the late growth stage of corn,and the precipitation in the early(EGS,April-June)and late growth stages(LGS,July-October)of corn belt in the US was more balanced.(2)The frequency of abnormal high temperature,less precipitation and high radiation weather in corn belt of NEC was higher than that of the US,so that the drought frequency and intensity of EGS and LGS was higher,especially in LGS of the US,due to the lower frequency of abnormal weather,the difference between two areas was more significant.Consistency of the evolution of solar radiation,temperature and precipitation,resulted in the similar change trend of dry-wet conditions in the GP between two areas,that is,wetting in EGS and drying in LGS.But only wetting trend in LGS of the US was significant,the main reason was that the precipitation significantly increased and the solar radiation significantly reduced in this growth stage.(3)The average corn yield from 2001 to 2015 in corn belt of the US was about 1.4 times than that of NEC,and the corn yield in two areas showed obvious fluctuation affected by meteorological factors.In most parts,corn yield was more positively correlated with the 1–3 month-scale SPEI from July to October,that is,the effects of short-term dry-wet changes occurred in the LGS on yield were more significant.(4)Monthly variation of DHI was fell first and then rose,which reached the low value in the dry-wet sensitive period(LGS).DHI of April-September and different growth stage in corn belt of NEC were higher than that of the US,especially in EGS the difference between two areas was bigger.In most parts of corn belt in NEC,DHI of different growth stage had increased in recent 15 years(2001–2015)compared to the previous 15 years(1986–2000),DHI of LGS in the US also had similar performance,but only a small part with decreasing DHI in EGS and GP.The yield loss rate of recent 15 years in two areas was positively correlated with the DHI of GP,with higher sensitive to the DHI of GP in NEC compared with the US.On the basis of this,the suggestion of referencing the experience of American drought management in NEC was proposed.
Keywords/Search Tags:Corn belt, meteorological drought, meteorological yield, yield loss rate, drought hazard index
PDF Full Text Request
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