An Empirical Approach to Map the Paddy Crops at the Ripening Stage Using SLC and GRD Sentinel-1 Data

Mapping the pre-harvest phenology of paddy crops in the coastal delta region is essential to investigate cyclonic storms’ impact on the anticipated crop yield for making informed agro-economic decisions. The present study was conducted for Agastheeswaram block, Kanniyakumari District, Tamil Nadu, which is being affected by frequent cyclonic storms that bring catastrophic damage to the paddy crops. The GRD (Ground Range Detected) and SLC (Side looking Complex) products of a Sentinel-1 C-band data in dual-polarization (VV+VH) were instrumental in this study. The SAR-based new empirical simulation PS3 (Paddy Stage 3) was proposed as a function of DPSVI (Dual Polarization SAR Vegetation Index) and Entropy measures retrieved from SLC and GRD products. The accuracy assessment with ground observations has demonstrated that the PS3 has higher potential (Overall Accuracy = 86.36%, Kappa Coefficient = 0.73, Precision = 0.88, Recall = 0.84) to delineate the paddy crops at their ripening phase.