EXTRACTING THE SPACE-BORNE RADAR BACKSCATTERING RESPONSES OF DIFFERENT ROCK UNITS FOR GEOLOGICALLY MAPPING TAFILALET REGION IN MOROCCO

Naoual El HAMMOUCH , Fatima El HAMMICHI , Hassan TABYAOUI , Ahmed GABER , Magaly KOCH , Mohammed MOURJANE

DOI: 10.21163/GT_2026.211.17

ABSTRACT: Rock surfaces affected by weathering usually exhibit distinctive spectral characteristics compared to their unaffected counterparts. Furthermore, certain rock units, particularly those with white color, such as carbonate rocks, evaporites, and white sandstone, have very similar spectral responses. This makes it extremely difficult to classify data using only optical remote sensing. On the other hand, by capturing these rock units' radar backscattering responses, completely polarimetric Synthetic Aperture Radar (PolSAR) data offer important insights about their external geometry and surface roughness. Their external geometries differ according to the different lithologies and geological formations since every rock unit has specific physical and chemical weathering characteristics. Consequently, such information facilitates improved classification and mapping. To achieve more accurate classification and geological mapping, this research uses fully polarimetric ALOS/PALSAR-2 data to extract the unique radar scattering responses of rock units along the Tafilalet region. The utilized imagery is decomposed into entropy, alpha, and anisotropy (H-α-A) distribution, Pauli decomposition, Wishart supervised classification with eight classes, and their polarization signatures (PS). Additionally, field validation is conducted to verify the classification outcomes. The Wishart supervised classification based on Synthetic Aperture Radar (SAR data), exhibits alignment with the geological map, surpassing the accuracy achieved using ASTER optical data. These findings indicate that the rocks within the Tafilalet study area have undergone varying degrees of weathering, resulting in distinct the surface roughness and corresponding scattering mechanisms of Synthetic Aperture Radar (SAR) data, which facilitate improved classification and mapping efforts.

Keywords: Radar images, Space-based; Supervised classification; Geologic mapping; Morocco.

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