| Drought is a major natural disaster faced by humanity, agricultural droughtis one of the worst disasters impacting on the agricultural production, each yearthe damage and loss from agriculture drought are far more than that from theother meteorological disasters, and it brought a very serious harm to our foodsecurity and social stability.Shanxi province, as a arid and semi-arid region, is called "the drought ofnine in ten years". According to historical records, drought caused greatdifficulties on agricultural production and severe losses in Shanxi. Timely andaccurately monitoring the temporal evolution of agricultural drought in Shanxi,may provide a scientific basis for formulating the measures and countermeasuresof preventing drought, fighting drought and reducing drought, and providetechnical support for food security. Remote sensing technology, due to itscharacteristic of real-time, dynamic, fast, wide coverage and othercharacteristics, overcomes the shortcomings of traditional monitoring methodsand is widely used for monitoring drought.Based on a systematic analysis of the advantages and disadvantages of theexisting crop drought monitoring methods and models, this paper choosessurface temperature (MOD11A2) and vegetation index (MOD13A2) data fromMODIS, gets temperature vegetation drought index (TVDI) in2001-2014inShanxi Province through the establishment of Ts-EVI feature space, andestablishes agricultural drought monitoring model; The reliability of the TVDI model is verified through analyzing the relationship between TVDI with theprecipitation, EVI, Ts, and by which the monitoring results of agriculturaldrought are got in2001-2014year. On this basis, the time-varyingcharacteristics of agricultural drought are analyzed respectively in the month andinter annual scale; according to TVDI distribution, the evolution characteristicsof province’s agricultural drought are obtained in space. Finally, thespatial-temporal distribution and evolution of agricultural drought are got in2001-2014in Shanxi province.The following main conclusions are made through the research:(1) In the Ts-EVI feature space, each year most of the slopes of fittingequation of dry side are negative, while the slopes of the wet edge aresubstantially negative in the5th-9th month and the others are positive value inother months.(2) TVDI and EVI have a negatively correlation, as well as average annualprecipitation anomalies of the meteorological stations and TVDI and Ts have apositive correlation.(3) The space distribution of agricultural drought in Shanxi province: Mostof Shanxi province belong the drought regions, as a whole, the drought isslightly severe in the south-central and southern regions, and the drought in themountain is better than in the basin. The wetter areas are mainly located inLuliangshan in the western, Hengshan and Wutai mountain in the northeast, etc;and the more serious regions are mainly located in Datong Basin in the northern,Taiyuan Basin in central, Yangquan City in the east, Changzhi basin in thesoutheast and Linfen basin and Yuncheng Basin in the southwest, especiallyYuncheng, Linfen belong to severe drought regions.(4) The time variation of agricultural drought in Shanxi province: monthly,the drought is becoming serious in1-3months, mitigation in3-7month, seriousagain in7-12month, the drought of March is worst and the drought of July is lightest; On the season, the drought variation from the seriousness to themitigation is spring> winter> autumn> summer; Interannually, the overalldrought situation has eased in Shanxi Province. Especially in the five years from2003to2007, the trend of drought mitigation was significant (decreasing trendof TVDI value0.03466/5a). |
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