| Soil moisture is one of the important indicators affecting the ecological environment.The dynamic monitoring of soil moisture can provide an important theoretical basis for hydrology,agriculture,ecology and drought monitoring.Using the combination of remote sensing data and land surface model to monitor soil moisture in real time and effectively is of great significance to predict regional dry and wet conditions and adapt to regional and global climate change.Located in the arid part of Northwest China,Yanqi Basin in Xinjiang is an important part of Tarim River.The geographical environment of Yanqi basin is complex and the ecological environment is fragile.The study of soil water status in Yanqi basin is of great significance to the stability and health of the regional ecosystem.Taking Yanqi Basin as the study area,using high-resolution data Landsat8,combined with the improved modified soil adjusted vegetation index（MSAVI）and surface temperature（Ts）,this paper constructs Ts-MSAVI feature space,inverses the soil moisture in the study area respectively,and verifies it by using satellite synchronous field measurement,Then,the effects of different factors on Temperature Vegetation Drought Index（TVDI）were analyzed.Fast,efficient and accurate acquisition of soil moisture in Yanqi basin provides theoretical basis and practical reference for the control of soil and water loss and water resources.The results show that:（1）Using Landsat8 data from 2016 to 2020,using MSAVI vegetation index and surface temperature ts,the Ts-MSAVI feature space is constructed based on TVDI model.The Ts-MSAVI feature space presents an obvious triangular scatter diagram,and the R~2of the dry and wet sides of the Ts-MSAVI feature space is more than 0.8.This area is dominated by drought（0.6wetland>forest land,cultivated land,grassland>bare rock,saline alkali land>construction land>sandy land;in a certain range,the area with high elevation The region with small TVDI value,high soil moisture and low elevation has large TVDI value and low soil moisture.The soil moisture increases with the increase of altitude;TVDI value increases with the increase of air temperature,on the contrary,TVDI also decreases with the decrease of air temperature;NDVI is positively correlated with TVDI,and NDVI index has a certain indicating effect on soil moisture;The changes of TVDI and ts show different correlation laws in Yanqi Basin.The areas with the strongest positive correlation are mainly distributed in the middle and northeast of the study area,and the areas with the strongest negative correlation are mainly distributed in the southeast of the study area.Through the above research work,the temporal and spatial distribution characteristics of soil moisture in Yanqi Basin and the effects of different factors on soil moisture are obtained.The results show that TVDI method can be used in this study area to monitor the soil moisture status in Yanqi Basin,which is closer to the actual distribution of soil moisture,and also has a certain practical role. |
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