| Drought is one of major natural disasters that happens frequently inworld-wide in recent years, they not only disturbed social and economicsustainable development seriously, but also affected agriculture especially.The western region of Jilin Province where is the major agriculture andlivestock production in Jilin province is affected by drought frequently,because of the natural geographic and climate. Compare with thetraditional agricultural drought monitoring, remote sensing is more andmore applied in agricultural drought monitoring for its fast, efficient, lowcost and other characteristics. Land surface temperature and vegetationindex has the close relationship with the vegetation physiology andgrowth, so they have become the important indexes of agriculturaldrought monitoring. But only one index for drought monitoring willcause a problem which reduces the accuracy and usefulness of thedrought monitoring because short-term vegetation subjected to waterstress can maintain the original green time. So the methods which use twoindexes become an important direction of current drought monitoring.In this paper, using MODIS land surface temperature data andsurface reflectivity data between May and September from2000to2008with GIS, RS and GPS technology to retrieved TVDI in the westernregion of Jilin Province, and analyze the relationship between TVDI with Ts, NDVI, surface soil moisture and meteorological data as well as itsspatial variability inter-month, inter-annual change. The conclusions areas follows:1) The study area of Ts-NDVI feature space dry and wet edge arenot a straight line at all, and there are similar shapes of dry or wet edge indifferent feature space; the slope of dry and wet edge changes with theNDVI values.2) There are some relationships between TVDI with Ts, NDVI,samples of soil moisture and precipitation; we can conclude thattemperature vegetation drought index is reasonable to indicate theevaluation of drought. From the correlation of TVDI and Ts, NDVI andthe samples of soil moisture showed that TVDI and Ts has a significantpositive correlation, TVDI and NDVI has a negatively correlation, TVDIand soil moisture has a significant negative correlation. TVDI with theprecipitation showed that the data change trend has a contrary trend withthe increase of TVDI values.3) From month change of the western region of Jilin Province from2000to2008, we can find that there was little change in the wet areas ofnorthern of region; the drought was middle dry and severe dry in thewestern region of Jilin Province at May and June and it was easy to causethe spring drought, especially in Baicheng, Taonan, Tongyu. With thedevelopment, the middle dry and severe dry reduced at July and August, and the normal and light dry increased at the same time, the drought ofSongyuan, Qianguo and Changling eased particularly; The droughtconditions can be roughly divided into two parts when entered toSeptember. One part was the west of Da’an (include Da’an), the type ofdrought was still middle dry and severe dry, another part was the eastregion of Da’an, the drought dominated normal and light drought.4) The inter-annual variability from2000to2008analysis showedthat, the region was mainly in light drought and middle drought. And thedrought changed with middle drought to severe drought from east to west,especially the southwest Tongyu had the most years of the severe drought.There were the biggest areas of the middle drought and the severedrought in2007, two areas were accounted for71.5percent of the region,and the drought is the most serious in this year. The areas of middledrought and severe drought were the least areas in2005, they wereaccounted for38.7percent, and this year is the lightest drought than otheryears. |
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