Accurate Drought Monitoring Based On Temperature Vegetation Drought Index

Global warming makes all kinds of extreme climate events more frequent.In recent years,many places in China have suffered from drought,and the frequent high temperature drought in summer and drought in autumn in the Yangtze River Basin have caused serious negative impact on the lives of local residents and socioeconomic development.At present,there are large-scale and medium-scale drought monitoring institutions and data products at home and abroad,such as drought monitoring products of China Weather Network and Cloud Platform for China's Geographic Situation Monitoring.However,the low spatial resolution of these products,or the time lag of product release,is not conducive to reduction and agricultural planning of the local emergency disaster.Remote sensing technology can quickly obtain a wide range of regional information,and has become the main method of global and regional drought monitoring.Therefore,it is of great scientific significance and practical value to study the drought monitoring methods which are suitable for Jiangxi Province.Based on the short-term extreme high temperature and drought events in summer and autumn in Jiangxi Province,the Landsat model with high spatial resolution is used Based on the relationship between TVDI and soil moisture,the drought is monitored.The results are verified by the rainfall anomaly index(P_a),standardized precipitation index(SPI),meteorological data and the ground measured soil moisture data.The analysis is based on the validity and accuracy of drought remote sensing monitoring results of T8.On this basis,the spatial and temporal distribution characteristics of drought and the relationship between drought and land use types are analyzed.The relationship between the landform characteristics,crop types and water resources of drought prone areas in Jiangxi Province is obtained,and the disaster causing mechanism of drought in Jiangxi Province is revealed.The main conclusions are as follows:(1)Temperature Vegetation Drought Index(TVDI)is a remote sensing monitoring index of agricultural drought,which has been widely used.This index is based on the relationship between land surface temperature(LST),normalized vegetation index(NDVI)and soil water content.In this paper,the Temperature Vegetation Drought Index TVDI is constructed based on landsdat 8 remote sensing data,and the drought extraction of Jiangxi Province is studied.According to the results of TVDI monitoring in the summer of 2013,the drought in the south of Jiangxi Province is not obvious in August.The drought in the middle and north of Jiangxi Province is mainly moderate drought and severe drought.The drought in Nancheng area is more serious.The moderate drought in Boyang,Jingdezhen,Nanchang and other places appears in various degrees.The drought is mild in Zhangshu area,and the large-scale drought in Northwest Jiangxi Province.According to the drought monitoring results in 2019,this drought event in Jiangxi Province is mainly light drought and moderate drought,among which Suichuan,Ganxian,Boyang,Jingdezhen,Nanchang and other places in Jiangxi Province have a large area of moderate drought.In some areas,there is a special drought,and the affected area is large.(2)This paper selects Yichun City in Jiangxi Province for analysis and verification.Based on the data of Landsat 8 and MODIS in 2013,the image data of these two kinds of satellites are compared and analyzed.It is found that the drought area can be clearly observed on the map based on the Landsat 8-tvdi value.The whole region is in a state of drought.The spatial distribution of tvdi-tvdi data in Yichun city is highly consistent with that in the south of Yichun city.The areas with low TVDI value are scattered in the northwest of Yichun City,mainly normal and humid.However,the spatial resolution of Landsat 8-tvdi is distinctly higher than that of modis-tvdi.Landsat 8-tvdi model has good adaptability in large-scale drought monitoring.(3)In this paper,we collect the meteorological station data of Jiangxi Province from1960 to 2010,and use P_a index and SPI index as evaluation indexes to test the drought remote sensing extraction results of Jiangxi Province in August 2013 and October 2019.The results show that the drought monitoring results of Jiangxi Province based on Landsat 8-tvdi in August 2013 are basically consistent with the results of P_a and SPI index.The results based on Landsat 8-tvdi in October 2019 are basically consistent with the drought monitoring results of 8-tvdi in Jiangxi Province.In addition,they also are basically consistent with the results of P_a and SPI index,which shows that the drought remote sensing monitoring using TVDI has the same effect as P_a and SPI,and the drought distribution map based on TVDI can reflect more detailed information of drought distribution.In the aspect of drought monitoring in Jiangxi Province,Landsat 8-tvdi index model has important practical significance.(4)Through the establishment of Jiangxi Province drought disaster risk zoning map,the drought monitoring results of Jiangxi Province based on Landsat 8-tvdi are analyzed.Through the research and analysis of the relationship between land use types and remote sensing drought distribution,it is found that there are more wetlands and forest areas in the areas with low TVDI value.The degree of dryness in the construction area is more serious than other land types with highest TVDI value,followed by cultivated land and grassland.The land use types corresponding to higher TVDI values are mainly construction land,bare rock and sandy land.The TVDI value of water body is the lowest,followed by forest land.It shows that the pine and Chinese fir forests in Jiangxi Province have better drought resistance ability.According to the drought resistance ability of the existing crops,the drought risk zoning map of this region can be made to provide important supporting data for reduction of emergency disaster in our province.