ESTIMATION OF THE RICE YIELD IN THE MEKONG DELTA USING SAR DUAL POLARISATION DATA

摘要

Food security has currently become a key global issue due to rapid population growth in many parts of Asia, as well as the effects of climate change. For this reason, there is a need to develop a spatio-temporal monitoring system that can accurately assess rice area planted and rice production. Changes in rice cultivation systems have been observed in various countries of the world, especially in the Mekong Delta, Vietnam. The changes in cultural practices have impacts on remote sensing methods developed for rice monitoring, in particular, methods using new generation radar data. The objective of the study was to estimate the rice yield using time-series Synthetic Aperture Radar (SAR) imagery. Field data collection and in situ measurement of rice crop parameters were conducted in An Giang province, Mekong Delta in 2010. The average values of the radar backscattering coefficients that corresponded to the sampling fields were extracted from the TerraSAR-X StripMap (TSX SM) images taken during a crop season. The temporal rice backscatter behaviour was analysed for HH (Horizontal transmit and Horizontal receive), VV (Vertical transmit and Vertical receive), and polarisation ratio data. For rice yield estimation, the predictive model based on multiple linear regression analysis (Lam-Dao, N. et al., 2009a) between in situ measured yields and polarisation ratios attained good correlation and thus proved to be a potential tool for estimating rice production in the study area.