Journal of Geological Remote Sensing

Surface Scattering Classification Using Dual‑Polarization ALOS PALSAR Data in the Zagros Fold–Thrust Belt, SW Iran

Document Type : Original Article

Authors

Sima Ameri 1
SeyedAbbas Najafi 2

1 Department of Remote Sensing and GIS, Faculty of Earth Sciences, Shahid Chamran University of Ahwaz, Ahwaz, Iran

2 Department of Petroleum Engineering, Abadan Faculty of Petroleum, Petroleum University of Technology, Abadan, Iran

10.48306/jgrs.2026.530660.1014
Abstract
This study presents a framework for identifying terrain-related surface scattering regimes using dual-polarization ALOS PALSAR (L-band) data over a 4,852 km² area in the central Zagros Fold–Thrust Belt, SW Iran. The methodology integrates three complementary radar-derived features: (1) a surface roughness proxy computed from spatial gradients of HH backscatter intensity, (2) the Polarization Ratio (PR), and (3) a modified Radar Vegetation Index (RVI). Following radiometric preprocessing and speckle reduction, features were log-transformed, standardized, and reduced using Principal Component Analysis (PCA). K-means clustering as a unsupervised classification was applied to the standardized SAR-derived features in order to identify five dominant scattering classes across the study area. Class-wise roughness distributions exhibit marked contrasts, ranging from highly homogeneous and low-roughness conditions to strongly heterogeneous and high-roughness domains. One-way ANOVA results indicate very strong statistical separation among classes (p < 0.001, η² = 0.801), signifying that over 80% of the total roughness variance is explained by class membership. High-roughness classes account for approximately 26.6% of the mapped area, and global roughness percentiles reveal a pronounced right-tailed distribution consistent with heterogeneous structural conditions. These results demonstrate that intensity-based roughness metrics combined with dual-polarization SAR indicators effectively capture spatial variability in radar scattering behavior. The framework is computationally efficient and objective, suitable for large regions. Although the resulting classes represent statistical scattering regimes rather than explicit geomorphological categories, the strong internal separability and spatial coherence of the clusters highlight the capability of L-band SAR to capture regional-scale surface heterogeneity. This approach offers a practical framework for unsupervised terrain analysis in structurally complex environments

Keywords

SAR Surface Roughness, Dual-Polarization SAR, Unsupervised Clustering, ALOS PALSAR, Zagros Fold&ndash
Thrust Belt
1.     Abdollahie Fard, I., Braathen, A., Mokhtari, M., & Alavi, S. A. (2006). Interaction of the Zagros Fold-Thrust Belt and the Arabian-type, deep-seated folds in the Abadan Plain and the Dezful Embayment, SW Iran. Petroleum Geoscience, 12(4), 347-362. (DOI: 10.1144/1354-079305-706)
2.     Alavi, M. (1994). Tectonics of the Zagros orogenic belt of Iran: new data and interpretations. Tectonophysics, 229(3-4), 211-238. (DOI: 10.1016/0040-1951(94)90030-2)
3.     Alavi, M. (2004). Regional stratigraphy of the Zagros fold-thrust belt of Iran and its proforeland evolution. American Journal of Science, 304(1), 1-20. (DOI: 10.2475/ajs.304.1.1)
4.     Bamler, R., & Hartl, P. (1998). Synthetic aperture radar interferometry. Inverse Problems, 14(4). (DOI: 10.1088/0266-5611/14/4/001)
5.     Berberian, M. (1995). Master “blind” thrust faults hidden under the Zagros folds: active basement tectonics and surface morphotectonics. Tectonophysics, 241(3-4), 193-224. (DOI: 10.1016/0040-1951(94)00185-C)
6.     Berberian, M., & King, G. (1981). Toward a Paleogeography and Tectonic Evolution of Iran. Canadian Journal of Earth Sciences, 18, 210-265. (DOI: 10.1139/e81-019)
7.     Cloude, S. R. (2010). Polarisation: Applications in Remote Sensing. Oxford University Press. (DOI: 10.1063/1.3502550)
8.     Falcon, N.L. (1961). Major earth-flexuring in the Zagros Mountains of south-west Iran. Quarterly Journal of the Geological Society of London, 117(1–4), 367-376. (DOI: 10.1144/gsjgs.117.1.0367)
9.     Hessami, K., Koyi, H., & Talbot, C. (2001). The significance of strike-slip faulting in basement Zagros fold and thrust belt. Journal of Petroleum Geology, 24(1), 5-28. (DOI: 10.1111/j.1747-5457.2001.tb00659.x)
10.  Lee, J.S., & Pottier, E. (2017). Polarimetric Radar Imaging: From Basics to Applications. CRC Press. (DOI: 10.1201/9781420054989)
11.  Moreira, A., Prats-Iraola, P., Younis, M., Krieger, G., Hajnsek, I., & Papathanassiou, K. (2013). A Tutorial on Synthetic Aperture Radar. IEEE Geoscience and Remote Sensing Magazine, 1(1), 6-43. (DOI: 10.1109/MGRS.2013.2248301)
12.  Motiei, H. (1993). Stratigraphy of Zagros [in Persian], in: Treatise on the Geology of Iran. Geological Survey of Iran Publications.
13.  Sella, G., Dixon, T., & Mao, A. (2002). REVEL: A model for recent plate velocities from space geodesy. Journal of Geophysical Research, 107(B42081), (DOI: 10.1029/2000JB000033)
14.  Sherkati, S., & Letouzey, J. (2004). Variation of structural style and basin evolution in the central Zagros (Izeh zone and Dezful Embayment), Iran. Marine and Petroleum Geology, 21(5), 535-554. (DOI: 10.1016/j.marpetgeo.2004.01.007)
15.  Sherkati, S., Molinaro, M., Frizon de Lamotte, D., & Letouzey, J. (2005). Detachment folding in the Central and Eastern Zagros fold-belt (Iran): salt mobility, multiple detachments and late basement control. Journal of Structural Geology, 27(9), 1680-1696. (DOI: 10.1016/j.jsg.2005.05.010)
16.  Shimada, M., Isoguchi, O., Tadono, T., & Isono, K. (2010). PALSAR radiometric and geometric calibration. IEEE Transactions on Geoscience and Remote Sensing, 47(12), 3915-3932. (DOI: 10.1109/TGRS.2009.2023909)
17.  Touzi, R., Bhattacharya, A. (2011). Polarimetric SAR urban classification using the Touzi target scattering decomposition. Canadian Journal of Remote Sensing, 37(4), 323-332. (DOI: 10.5589/m11-042)
Journal of Geological Remote Sensing
Volume 3, Issue 1 - Serial Number 3
December 2025
Pages 56-70

Home

Guide for Authors

Submit Manuscript

Reviewers

Contact Us