Regional land cover mapping in the humid tropics using combined optical and SAR satellite dataa case study from Central Sulawesi, Indonesia

The frequent mapping of the spatial extent of land cover and its change from satellite data at the regional level provides essential input to spatially explicit land use analysis and scenario modelling. The accuracy of a land cover map is the key factor describing the quality of a map, and hence affecting the results of land use modelling. In tropical regions, land cover mapping from optical satellites is hampered by cloud coverage and thus alternative data sources have to be evaluated. In the present study, data from Landsat-ETM+ and Envisat-ASAR satellite sensors were tested for their ability to assess small scaled landscape patterns in a tropical environment. A focus was on the detection of intensively managed perennial and intra-annual cropping systems (cocoa, rice). The results confirm previous knowledge about the general potential and advantages of multi-temporal SAR data compared to mono-temporal SAR-based mapping but also show the limitations of different polarization modes in SAR analysis for land cover mapping. In the present case study, cross-polarized data from Envisat-ASAR did not yield notable profit for tropical land cover mapping compared to common, co-polarized time series of ASAR data. However, the general outcome of the study underlines the synergy of optical and radar satellite data for land cover mapping in tropical regions.