| Drought is a frequent occurrence natural phenomenon, lasted for a long time, influence on sustainability and widely so that it is involving many fields. It not only brings harm to the industrial production, urban and rural residents and the surface of the earth ecological environment system, and caused great loss to agricultural production. Yunnan is located in low latitude plateau, with its unique geographical environment and climate characteristics, prone to drought disaster. To explore a kind of objective, dynamic and real-time remote sensing drought monitoring method, timely and accurately reflect the drought occurred scope, the degree and its change trend in yunnan province,which has a great guiding significance to take positive and effective of drought-resisting and drought-resistance.The comprehensive application of 3S technology, select January-June 2012 ETM data and MODIS data, using the single window algorithm inversion of surface temperature, Land Surface Temperature, Construction of land surface temperature(TS)- vegetation index(NDVI) feature space, simulation of dry and wet edge equation by using the TS-NDVI feature space, get the TVDI model accordingly. By improving the TVDI model, Combined with the measured soil moisture data, Verification and Compared previous and after the improved TVDI model; To monitor and analyze the temporal and spatial variation characteristics of drought by using the improved TVDI model; Based on the meteorological data, terrain data, land cover types data analyze TVDI model TVDI model t response ability of drought. Get the following conclusion:1. through the characteristics of land surface temperature, vegetation index space to dry edge correction, geothermal topographic correction, the improvement of EVI instead of NDVI, and the results show that the improved 1, June TVDI and the correlation coefficient of soil relative water content, respectively by the improved before 0.346, 0.359, 0.617, 0.631, to the improved TVDI index and the correlation of the measured soil moisture increased significantly.2. using the improved and verified TVDI model drought monitoring in the study area,results show that: From the time perspective in 1-6 months, he most serious drought in April, the drought area proportion is as high as 80.90%; From the perspective of space dry-hot valley area in Dongchuan is more serious, but mountain area In the southeast of Qujing City light of drought. This result and the statistical data of drought in 2012 0n January and June basically the same, show that the improved model is suitable for monitoring drought in central yunnan.3. through analysis the relationships between TVDI index and temperature, rainfall, altitude, land cover types, the results showed that: he land surface temperature is positively correlated with TVDI,but the rainfall is negatively associated with TVDI; From the perspective of altitude, the drought mainly concentrated at middle- low altitude of 1000-2500 meters areas, at an altitude of 1000 meters of the following and 3000 meters above the region, the proportion of the drought area decline; The TVDI index is different in the changing characteristics of different land cover types, The bare land, cultivated land, construction land is sensitive response to drought, Woodland shows certain hysteretic nature. The results and the actual soil moisture content with temperature, rainfall, altitude and land cover changes in characteristics of different types are basically the same, so remote sensing inversion model of TVDI may response to the drought changing in characteristics in the central Yunnan Province. |
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