Rice field mapping and monitoring with RADARSAT data
The aim of this paper is to assess the use of RADARSAT data for rice field mapping and monitoring. The specific characteristics of RADARSAT data, i.e. the radar polarization, the spatial resolution, the range of incidence angles and the repeat cycle, have been studied. Experimental data have been collected over one of the most important irrigated flood plains of Indonesia and analysed along with RADARSAT data. The radar backscatter coefficient sigma of rice fields appears to have a significant temporal variation. However, the dynamic range of RADARSAT data is found lower than that of the ERS data due to a higher backscatter at HH than at VV polarization at early stages. At a higher incidence angle (42 compared with 23), the sigma of the fine resolution F3 mode reaches a saturation level earlier compared with the standard resolution mode, which appears consequently to be most appropriate for rice field mapping. The mapping result, based on the temporal change of the radar backscatter, was found to have an accuracy of 87% compared with the available map. In order to follow the growing cycles and improve the management of irrigated perimeters, a methodology for Golongan (fields with the same irrigation scheme) mapping have also been developed. The results appear promising and rice mapping operations using RADARSAT data can be foreseen.