Morphological discrimination amongst geological rock surfaces of Zagros thrust belt via SAR backscattering modelling

Nowadays, processing and interpretation of remote sensing satellite images is the only method of surface geological rock surfaces mapping. This doubtlessly requires time-consuming field observations for complementary morphological information, i.e. field measurements in geomorphology is unavoidable since the hyper-spectral images that are used for geological mapping do not discriminate the lithologies texture and cannot be used to determine the geological morphology. However, due to the impassable and fault cliffs, comprehensive field operations within a geological map is almost impossible. Microwave or radar remote sensing via Synthetic Aperture Radar (SAR) images is capable of obtaining the surface morphology and alteration zones discrimination based on lithologies texture. To fulfill this aim, the Integral Equation Model (IEM), which has been proposed by Fung et al. (1992) and has been developed and improved several times, seems to be the most outstanding method being adopted to model the SAR backscattering coefficient against the surface roughness. Nonetheless, it needs to be asserted that the Euclidean calculation of this parameter is not capable enough to measure the morphology of a feature. In this paper, using the power-law geometry capability, one can improve the alteration zones discrimination. To implement and evaluate the proposed method of geomorphological mapping, IEM 𝜎° results for a region on the Zagros fold-thrust belt, in western Iran, were compared with the satellite SAR backscattering data in the L-band (i.e. ALOS-PALSAR) and the X-band (i.e. TerraSAR). Besides, the efficiency of the SAR data processing versus the geological field observations provide an average of more than 20% improvement in terms of the power-law geometry in comparison with the Euclidean geometry. Although this improvement for moderate rough formations is less than 3% at high frequency (X-band), it is about 30% for rough formations at low frequency (L-band).