Use of Radarsat-2 polarimetric SAR images for fuel moisture mapping in the Kruger National Park, South Africa

Abstract

Fully polarimetric Radarsat-2 imagery from wet and dry conditions over the South African Lowveld is compared to assess its value for fuel moisture mapping. Imagery was acquired at two different dates, in May (end of summer, wet) and in August (mid of winter, dry). Sample plots were classified into two broad Lowveld site types (herbaceous-dominated and shrub and tree-dominated). Linear and circular polarized backscatters, polarimetric discriminators and polarimetric decomposition parameters were computed to find suitable parameters for fuel moisture estimation. The results show a significant distinction between wet and dry conditions for C-HH, C-HV, C-RR, and C-LL, all Freeman-Durden and van Zyl decomposition parameters and some polarimetric discriminators (dmin, Prmax, Prmin, Smax, Smin). In almost all cases the normalized difference between wet and dry condition is lower for the shrub and tree-dominated sites. The Freeman-Durden double bounce scattering decomposition parameter performs best in both site types.