Monitoring Of Drought In Inner Mongolia Based On MODIS

Drought is one of major natural disasters that happens frequently in world-wide in recent decades, they not only threaten the natural environment where mankind to survive, but also affected social and economic sustainable development seriously. The regions where are affected by drought almost all over the world, especially in the monsoon regions and arid regions. Inner Mongolia is located in arid and semi-arid continental monsoon climate regions, the drought is the major natural disasters that affected the agricultural and livestock production. Therefore, through monitoring drought that has occurred in the Inner Mongolia, and discusses its law of development and the influence factor relations, provides the scientific basis for the disaster prevention disaster reduction policy-making.In this paper, using MOD11A2 data and MOD13A3data between April and September in 2007 and 2008 to retrieved TVDI in Inner Mongolia, and analyze its spatial variability,inter-month, inter-annual change and relations between their main impacted factors (evaporation, precipitation, vegetation type , soil type and landform type).the conclusions are as follows:1) According to the scatter that includes the meteorological site, samples of soil moisture and TVDI, we can conclude that temperature vegetation drought index is reasonable to indicate the evaluation of drought. But TVDI of few points is deviated, this may be related to relatively low surface temperature and vegetation in mountainous areas, it is also related to the authenticated methods simultaneously.2) The type of droughts in vegetation growing in Inner Mongolia mainly is light dry, the area of this type is accounted for more than 70 percent; the proportion of wet, normal and re-dry area is small, and the type of wet and normal are mainly distributed in Daxinganling forest area in the eastern part of Inner Mongolia, Light dry and middle dry are distributed in grassland in the central and western areas of Inner Mongolia, re-dry are mainly distributed in desert area in Alashan. 3)From month change of the Inner Mongolia region in 2007and 2008 , we can find that at temporal scales, the drought is serious in Inner Mongolia at April,May and June, and it eased at July and August, and it is lightest drought of the whole year, but it gradually increased when entered to September; at spatial scales, the least drought is in Northeast of Inner Mongolia, the type of drought mainly is wet and normal; the drought in other regions is relatively eased at July and August, the type of drought is light dry and middle dry; but the drought in western desert region between April and September is very seriously.The drought is wholly less in 2008 than 2007 at inter annual variability, except in July 2008 in the central and western regions of the Inner Mongolia and in April in the eastern region. The area of re-dry and middle dry is accounted for 70 percent in 2007, while in 2008, the area of their is accounted for 56 percent; the area of light dry is accounted for 30 percent in 2008,it is increased by 13 percent.From the drought of League, we can conclude that the lightest rate of drought is in Hulunbeier, and the type of it is wet and normal, the area of it is accounted for 53 percent, the rate is below 10 percent in other regions. The middle dry in Ordos, middle dry and re-dry in Alashan, and light dry and middle dry in other leagues and cities.4) There is good correlation between precipitation and TVDI, with precipitation increased, the trend of TVDI has increased. But there is no apparent linear relationship between the evaporation and TVDI, which may be related to deviations between measured and actual evaporation, and evaporation data is measured by pan in meteorological site in Inner Mongolia, which can only be shown that the ability to evaporate, rather than actual evaporation in the region. Therefore, I think this will be the main reason that impacted evaporation and TVDI, it is necessary to certify by other means.5) From the relations between drought and vegetation types, we can conclude that the type of vegetation varied from forest in the north-east to desert-steppe in the west of Inner Mongolia, the average drought index of the vegetation type is increased, it indicated that with the change of vegetation coverage and water absorption and evaporation, the drought index has corresponding changes. and in the type of wet and normal areas are mainly cold and warm coniferous forest and deciduous broad-leaved forest; in light dry and middle dry areas are dominated by grassland vegetation; re-dry areas are dominated by desert vegetation of western desert and sandlot areas.From the relationship between soil type and drought index, we can conclude that with organic matter content of soil and the viscosity of soil texture is weakened, the trend of drought index has increased.From the relations between landform types and drought index, we can conclude that the drought index has the law of change because of the different types of terrain , different site of topography and the redistribution of hydro-thermal conditions, drought index from small to large followed by mountains, plains, hills, mesa, high plains, sand and desert.