Study On Soil Moisture Retrieval And It's Spatio-Temporal Variation With Remote Sensing

Soil moisture is an important indicator for climate,water resources,economy and agriculture. It plays an important role on the water and energy exchange at the land surface/atmosphere interface. The change of the soil moisture will lead to change of the thermotics characteristic of soil and optical properties of surface, even to the change of climate.The information of the land soil moisture change in regional and large-scale is important to the research as the balance of land-atmosphere interaction, land hydrology, improving the forecast accuracy of regional and GCM, monitoring of flooding and drought, assessment of the growth condition of corps, the natural and ecology problems.It is significant to do research on spatial and time variability of soil moisture and on how to monitor soil moisture by remote sensing, which can provide information on large area quickly and easily.After analyze all kinds of information about soil moisture reversion and compare different quantitative remote sensing models, we think it is reasonable to use Ts/NDVI model to retrieve depth soil moisture and do research on respect factors of the soil moisture with principal components analysis.To summarize, main findings of this study are:1. After analyze the ground truth data, and interpolated 0-20cm and 20-40cm depth soil moisture in May 2004, September 2004, November 2004, March 2005 and May 2005 with Kring method, the result show that it was the middle of the space-related that the mean Nugget/Sill was 58.53% in 0-20cm depth and was 55.58% in 20-40cm depth soil. In the region caused by non-regional variations in more than 50 percent, the non-regional factors performance of the role of the more obvious,which match the actual situation in Yizheng ,Yizheng close to the Yangtze River,so the soil moisture by man-made factors are considerable.2. We use Ts/NDVI model to monitor soil moisture in Yizheng in May,September,November of 2004 and March,May of 2005, based on the MODIS products MOD11A2 and MOD13A2. Validation of the retrieved information by the field data has show that the model is very well to obtain the depth soil moisture. We find that the space continuity and detail performance of soil moisture by remote sensing is better.3. We obtain the distribution of moisture in the overall trend with remote sensing, the result show that there are two high-value soil moisture area in Yizheng, one is in the south of the Yangtze flood plains, and another is in the north-west plains. The low-value soil moisture area is mainly distributed in the central hilly region. 4. we analyze the factors which impact the spatial distribution of soil moisture in Yizheng with remote sensing, the respect factors contain Terrain,Bulk Density,Soil Porosity,Soil Non-capillary Porosity,Cultivated Thickness and Groundwater Depth.The result show that the main factors are Groundwater Depth, Terrain and Cultivated Thickness in 0-20cm depth soil and Terrain, Groundwater Depth and Cultivated Thickness in 2040cm depth soil under medium moisture. The main factors are Terrain and Cultivated Thickness in 0-20 cm , but the factors in this research are not the main factors in the 2040cm depth soil moisture under high moisture and low moisture.