Abstract
The aim of this work was to map Red Mediterranean soils, for which no previous mapping approach exists, using optical multispectral satellite remote sensing data. This case study explores the use of SPOT XS images over the viticultural Southern Rhone Valley, France, to map exposed vineyard soils. Field spectral measurements were used to distinguish Red Mediterranean soil surfaces during Spring 1999. A supervised maximum likelihood classification was applied to sparsely vegetated and unvegetated surfaces of two spring images from 1995 and 1997, drawing on the field training set and available soil data. Similar global spatial segmentation was obtained despite different soil surface states on these dates. Classification performances were higher than 84% in both images. Mean classification accuracies of Red Mediterranean soils at seven reference surfaces were 60% in 1995 and 70% in 1997. This suggests that the direct use of optical remote sensing data at medium resolution can be useful for mapping bare Red Mediterranean soils.
Acknowledgements
The author thanks the Centre National d'Etudes Spatiales for support with the SPOT imagery through the ISIS Programme. The author is indebted to the Syndicat Général des Vignerons des Côtes-du-Rhône, partner of this study. Thanks to Professor Michel-Claude Girard for providing guidance in this investigation, H. Icole for support in the field and Professor Tim Warner for his instructive comments.