Soil moisture retrieval in farmland using C-band SAR and optical data

Soil moisture retrieval in vegetation-covered area with space borne synthetic aperture radar is a challenging process due to the impact of vegetation on the multiple scattering of electromagnetic wave. In this paper, a semi-empirical method is proposed to estimate farmland soil moisture by active microwave remote sensing and optical remote sensing. By integrating the vegetation water content estimated from optical data and thermal infrared data into a coupling model based on a water–cloud model, the influence of vegetation on microwave backscattering coefficient was eliminated and thus soil moisture in vegetation-covered area was accurately retrieved. The experiment of soil moisture retrieval was carried out using Radarsat-2 and Landsat 8 datasets in western Great Khingan Mountains, Inner Mongolia, China. The research showed that the accuracy of the coupling model is high and the R2 is up to 0.69 using HH polarization. Moreover, the effects of crop types on soil moisture retrieval, particularly barley, could also be distinguished using the coupling model. © 2017, Korean Spatial Information Society.