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

Abstract

Nowadays, processing and interpretation of remote sensing satellite images is the only method of surfacegeological rock surfaces mapping. This doubtlessly requires time-consuming field observations forcomplementary morphological information, i.e. field measurements in geomorphology is unavoidable sincethe hyper-spectral images that are used for geological mapping do not discriminate the lithologies textureand 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 remotesensing via Synthetic Aperture Radar (SAR) images is capable of obtaining the surface morphology andalteration 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 againstthe surface roughness. Nonetheless, it needs to be asserted that the Euclidean calculation of this parameteris not capable enough to measure the morphology of a feature. In this paper, using the power-law geometrycapability, one can improve the alteration zones discrimination. To implement and evaluate the proposedmethod of geomorphological mapping, IEM 𝜎° results for a region on the Zagros fold-thrust belt, in westernIran, were compared with the satellite SAR backscattering data in the L-band (i.e. ALOS-PALSAR) and theX-band (i.e. TerraSAR). Besides, the efficiency of the SAR data processing versus the geological fieldobservations provide an average of more than 20% improvement in terms of the power-law geometry incomparison with the Euclidean geometry. Although this improvement for moderate rough formations is lessthan 3% at high frequency (X-band), it is about 30% for rough formations at low frequency (L-band).