Estimating spectral separability of satellite derived parameters for burned areas mapping in the Calabria region by using SPOT-Vegetation data

Abstract

In the Mediterranean regions, fires are considered a major cause of land degradation. Every year, around 45,000 forest fires break out in the Mediterranean basin causing the destruction of about 2.6 million hectares ( FAO, 2001). In Italy, as in other countries of the Mediterranean Basin, a small number of fires generally destroy a large percentage of the total burned areas every year. In these cases, the use of coarse resolution satellite sensors appears to be very useful for the discrimination of burned areas. In this study, SPOT-Vegetation (SPOT-VGT) data at full spatial resolution were analysed in order to investigate the spectral features of burned areas observed in the Mediterranean ecosystems in the Calabria Region during the 1998 fire season. Among the total fire events occurred in the considered period wildland fires larger than 1000 ha were selected for this study. SPOT-VGT imagery acquired before and after fire events were considered. Single channels or spectral indices suitable/or specifically designed for burned areas mapping were analysed. In particular near-infrared (NIR), short-wave infrared reflectance (SWIR), albedo, normalized difference of vegetation index (NDVI), normalized difference of infrared index (NDII), burned area index (BAI), global environmental monitoring index (GEMI) and soil adjusted vegetation index (SAVI), were considered in this study. The changes observed before and after fire occurrence in the considered parameters were presented and discussed. Results showed that among the spectral indices considered in this work, the highest discrimination capability was generally observed for NDII, SAVI, GEMI, BAI and NIR, nevertheless, strongly differences were observed from one fire event to another, and this fact suggests that the discrimination capability must be analysed coupled with the specific land covers affected by fire.