Quantitative Study On Estimation Of Vegetation Water Based On MODIS Data And Canopy Spectra Of Vegetation

Water plays an extremely significant role in life activities of crops and is also one of the major factors that influence the process of photosynthesis and ultimate yields. The quantitative remote sensing research on vegetation water content must benefit greatly for forest fire monitoring, crop drought monitoring and ecological security assessment.With the obvious improvement of satellite and sensor technology, as well as the gradually thorough research on mechanism of remote sensing, great advancement of theory and method of resolving vegetation water has occurred, either. In this dissertation, combining the MODIS data and the larch moisture content data in the Greater Hinggan Mountains forested areas, I mainly construct statistical model between vegetation index and fuel moisture content and evaluate equivalent water thickness by using MODIS LAI product and PROSAIL model, which is a radiative transfer model coupling leaf and canopy, and build inversion models of equivalent water thickness based on MODIS data.The chief outcomes of this study are as follows:1) The results from analyzing the correlation between Sampling Data of fuel moisture content and vegetation index indicate that the fuel moisture content has obvious correlation with VIgreen,VARI,NDWI and NDII6, but no correlation with EVI and NDVI, and VIgreen,VARIand NDWI correlate each other closely..2) The regression model between relative fuel moisture content and vegetation index is established. It has been found that the preferable single-element regression model(R~2:0.726) is quadratic polynomial regression between the first principal component of VIgreen, VARI, NDII6 and fuel moisture content, while the preferable dualistic regression model(R~2:0.763) is binary linear regression relation of VARI, NDWI and fuel moisture content.3) The PROPSECT Model is used to simulate the variation of canopy reflectance under different biochemical parameters compounding, and estimate equivalent water thickness based on MODIS LAI products. The results shows that equivalent water thickness has a notable impact on three bands of the MODIS, band4 (1240nm), band5(1640nm) and band6(2130nm). Furthermore, the inversion model of equivalent water thickness and vegetation index was built, and the exponential relation was presented between the NDWI and equivalent water thickness by comparison.4) The qualification analysis was conducted on the fuel moisture content and equivalent water thickness. The result shows that the fuel moisture content has strong correlation with equivalent water thickness, but no apparent functional relation.