Estimation of biophysical parameters of rice using sentinel-1a sar data in udham singh nagar (Uttarakhand)

Abstract

Udham Singh Nagar is the major rice producing area of Uttarakhand state, and falls in Tarai region. Sentinel-1A satellite launched in 2014 as part of the European Union's Copernicus program provides Synthetic Aperture Radar (SAR) data. SAR images are independent of weather conditions and solar illumination and allow observations of different features of earth. The dual polarized (VH and VV) sentinel 1A data has been used to estimate the rice biophysical parameters which are Leaf Area Index (LAI), Fraction of Photosynthetically Active Radiation (fPAR), Crop Height, Biomass and Water Content. The revisit time of Sentinel 1A is 12 days and a higher resolution of 20m. SAR data were pre-processed by applying European Space Agency’s Sentinel Application Platform (SNAP). The SAR maps for various biophysical parameters (Leaf Area Index (LAI), Fraction of Photosynthetically Active Radiation (fPAR), Crop Height, Biomass and Water Content) of rice crop were developed in ENVI-4.8. The relationship between Sentinel-1A backscattering coefficients σ0VV, σ0VH and (σ0VV/σ0VH) were analyzed, for this multitemporal data of Sentinel-1A were taken from June 2017 to September 2017 over Udham Singh Nagar, Uttarakhand. The regression models were developed between biophysical parameters and ratio of backscattering coefficients (σ0VV/σ0VH). The value of coefficient of determination for Leaf Area Index (LAI), Fraction of Photosynthetically Active Radiation (fPAR), Crop Height, Biomass and Water Content were found as 0.53, 0.47, 0.50, 0.63, 0.34 respectively which exhibit that these biophysical parameters are significantly, consistently and positively correlated with the ratio of backscattering coefficients (σ0VV/σ0VH) throughout all growth stages from transplanting, tillering and heading. On the basis of results obtained it can be concluded that Sentinel-1A SAR data has great potential for estimation of biophysical parameters of rice crop.