Crop Drought Evaluation In Western Jilin Province Based On Multi-source Remote Sensing Data

Drought is a kind of meteorological disaster which has great influence on human society,and it brings incalculable losses to the world every year.Although the technology is advancing,in the field of agriculture,countries are still unable to shake off the drought and its consequences.In order to keep abreast of the drought,especially the agricultural drought,long-term monitoring and timely feedback are needed in various regions.The traditional method of monitoring drought is costly,small coverage and low precision,but using remote sensing for drought monitoring can achieve low cost,high coverage and high precision.Currently,there are many types of satellites,remote sensing images collected by various satellites are meeting the growing needs of society.This paper uses the remote sensing satellite data such as MODIS and Landsat8 to study and evaluate the drought situation in western Jilin at the end of July 2018.The disaster-reported townships in western Jilin Province were taken as the key research objects.Using multi-temporal Landsat8 data,multi-temporal Sentinel 2 data and single-time Single phase Gaofen-2 remote sensing satellite data to analyze the vegetation indices,including RVI,NDVI,GNDVI and EVI.The results show that Landsat8 and Sentinel 2 can adapt to the vegetation information extraction at the township level better.And Gaofen-2 data can adapt to the vegetation information extraction at the village level better.For the vegetation index,the NDVI is the optimal calculation method.The EVI is comparable to the NDVI,which can also be used to analyze the growth of surface crops.In order to calculate drought conditions by TVDI,the NDVI and EVI need to be as the basis.Compare the TVDI results calculated by the two indexs,the results show that the TVDI-based-NDVI is better the TVDI-based-EVI in the fit of dry and wet edge equation and the stability of calculation results.Then grading the results of TVDI-based-NDVI by no basis,and get four grades,without drought,light drought,moderate drought and heavy drought.Sampling point information from disaster-reported townships at the end of July 2018 are used to verify the classification results.And the verification results are good.It shows that the calculation and classification methods can reflect the drought conditions of surface crops better.Therefore,the TVDI-based-NDVI method was used to evaluate the drought in western Jilin Province and disaster-reported townships.The MODIS data was used to evaluate the overall drought situation in western Jilin.From the end of July to the beginning of August 2018,the drought grade in the west of Jilin Province was like a dustpan,and the pass of the open dustpan is to the north.The drought situation was getting heavier from north to south,and getting heavier from inside to edge.The drought was severe in Tongyu County,Qianguo County and Changling County,the drought was light in Taobei District,Zhenlai County and Ningjiang District.The drought in western Jilin Province is mainly controlled by rainfall factors.Soil,elevation and slope,and land use conditions have an important impact in the dry areas.Different types of soil have different water retention capacity,in the dry areas,the drought areas with good soils are weaker than others.As the slope increases,the drought situation is relatively enhanced.In areas with relatively high elevations,as the elevation increases,the drought worsens.The drought is relatively light,with farmland near the surface water and far from the town and the road.The drought will be lighter becomes more concentrated.The drought will be lighter when the feilf become more concentrated.