The Research Of Monitoring On Drought Of Maize Based On Landsat 8 Growing Time Series Remote Sensing Data

Objective:Scientific and rational use of water resources in arid regions is one of important factors that affect crop growth and development and social stability.Precision monitoring of drought stress in crops is the basis of precision irrigation and is the way to improve resources use efficiency in crop production.In this study,data analysis of satellite Landsat 8 was used to evaluate the changing rule of vegetation indices of maize growth duration and the relationship between vegetation indices and the agricultural drought indices;to probe the theory and method for the data of Landsat 8 applied to monitor the drought during maize growth period and reveal maize drought process and the characteristics of spatial distribution of drought.With the above,this study will provide theoretical basis for precision irrigation and the technique and method for high efficiency agriculture.Methods:The agriculture drought parameters of maize growth period and the quantitative relationship between these parameters and 8 kinds of drought remote sensing monitoring indices were studied through “3S” technique and established new drought monitor indices of vegetation index for maize.On this foundation,the new drought monitor vegetation index will be applied to the drought stress monitor during maize growth period from 2014 to 2016 in experimental sites and the method for drought stress monitor during maize growth period by satellite data analyzing will be put forward.Results:(1)The precision monitor based on the data of Landsat 8 of the planting area of maize was realized.According to the growth characteristics of the crops in the experimental sites and the difference of growth stages,we extracted the maize planting areas using the decision tree technology from 2014 to 2016.In 2016,the extraction precision was the highest by contrast;it was the lowest in 2014.The drought degree affected the precision of extraction in a certain degree.The year with adequate rainfall and the high growth uniformity of maize were conducive to improve the precision of extraction.(2)We analyzed eight indices: CTWDI,NDVI,NDWI,MSI2,VSWI,MBDI,TVDI,LST and induce a new kind of maize drought monitor index: CTWDI.The correlation analysis between vegetation indices and relative soil water content,maize canopy water content and chlorophyll content were applied and the results showed that among them,the relativity between CTWDI chlorophyll content was the highest.(3)The high yield of maize in experimental site was realized under the condition of sufficient water and fertilizer supply and the vegetation index of which varied consistently among the planting years,especially,in the late growth stage of maize.Taking the high yieldfield as the sample of water sufficient and using supervised classification,the drought degree that was relative to high yield fields would be examined through analyzing the difference of drought vegetation index.Analyzed time-spatial variation characteristics of NDVI,MSI2,CTWDI of maize groeth period during 2014-2016,found that drought risk assessment of three years in maize growth period.(4)By using the CTWDI,the drought degree of maize in experimental site was graded from2014 to 2016.At the same time,according to the survey of yield data the classification result of maize drought remote sensing was tested for accuracy.The results showed that,the whole precision and the kappa coefficient was 87.3%,0.84,83%,0.71 and 81.2%,0.57 for 2014,2015 and 2016,respectively.It is showed that,the more drought of the year the more reliable of the data of drought monitor is.Conclusion:Based on Landsat 8 growing time series remote sensing data,the monitoring results of maize drought in the study area were better,and drought monitoring of maize in the study area was realized by remote sensing technology.