Sar Imaging In The Estimation Of The Aboveground Biomass Of Wetland Vegetation

Wetland is one of the major land ecosystems with significance to discover the characteristics and ecological laws. The estimation of wetland biomass by Synthesize Aperture Radar (SAR) is a novel subject. As a new type sensor, SAR has advantages for wetland applications such as all time, all weather, sensitive on water and definite capability through the ground. Therefore, it can be apply for generating some important information about wetland ecology and hydrology, especially with the complex ecological habitat of the transitional place between land and water, radar images can be a supplement of optical images for wetland biomass estimation.In this paper, as a case study of SAR application on Honghe National Natural Reserve (HNNR), the wet weight and dry weight field data of 17 quadrats of diverse vegetation in a growing season from the study area in 2009 were gathered and ASAR/PALSAR/TM images were acquired at the same time with field work. The backscattering coefficient of polarimetric radar, NDVI index of TM image and wet and dry weight data was taken as correlation variable, the fitting equations of regression models and water cloud model were built to estimate biomass, a validation was made from 8 measured quadrats as the test samples to evaluate the accuracy assessment and the difference between SAR and TM in wetland biomass estimation. The conclusions of the research are got as following.As the value of fitted models, the relations in linear equations of ASAR image in VV polarization are higher than other conditions, and the value of R2 is 0.622, from the accuracy assessment and the biomass estimation diagrams, the results in HH polarization of ASAR image condition approach to better.As the results of fitted equations and accuracy assessment of Water Cloud Model using SAR images, the difference between correlations and average residual coefficients is closely, but the biomass estimation diagrams varies obviously compare to original circumstances.The results of linear regression biomass estimation in HH polarization of ASAR image situation are better than TM image. It announces the efficient complementary between the SAR image and optical remote sensing image in wetland biomass estimation.