Soil Moisture Inversion Based On Remote Sensing Image

Soil moisture is an important index for monitoring land degradation, and is also a main parameter in climate, hydrology, ecology, agriculture and other fields. It plays an important role in the exchange of water and energy in surface and atmosphere. At the same time, the condition of soil moisture can reflect the health status of ecological environment, which is also one sensitive indicative factor of natural disasters, such as drought and flood. Remote sensing is a method of retrieving soil moisture, which can not only overcome the shortcomings that are time-consuming, laborious, and point to an area in traditional monitoring, but also can achieve monitoring and evaluation fast, timely and dynamical. It is highly significant to monitor soil moisture by means of remote sensing, which can provide information on large area quickly and easily.In this paper, we have collected related research materials which are using remote sensing retrieving soil moisture quantitatively at home and abroad, remote sensing image data, DEM data and temperature data in the city of Baiyin in Gansu province. On the basis of above materials, taking the Baiyin city as research area, according to the geometric relationship between the sun's rays and terrain, using the DEM data and considering mountain influence of slope, aspect and shadings, we build an astronomical radiation distribution computing model under undulating terrain through the geographic information system technology. Also, air temperature parameter is corrected by terrain factors, such as elevation, slope, aspect and terrain shadings, which reveals temperature diversity with terrain in detail. This model can accurately calculate mountain astronomical radiation spatial distribution. Combining with Landsat5 / TM6 remote sensing data and making use of mono-window algorithm, land surface temperature can be obtained by retrieving. In line with land surface temperature, Temperature-Vegetation Dryness Index (TVDI) can be get further. By use of ENVI spatial modeling tool, we can retrieve a distribution map of TVDI, which can better reflect soil moisture in research area. Experiments demonstrate that TVDI can reveal the drought condition in baiyin city, which is a better method of monitoring soil moisture fully considering terrain factors.