Peng et al. (2026) Detection of soil moisture variations beneath an asphalt layer using L-band SAR

Identification

• Journal: International Journal of Applied Earth Observation and Geoinformation
• Year: 2026
• Date: 2026-09-29
• Authors: Wei Peng, Hui Xiao, Haiqiang Fu, Guanxin Liu, Yang Tian, Jun Zhu
• DOI: 10.1016/j.jag.2026.105592

Research Groups

• School of Aeronautic Engineering, Changsha University of Science and Technology
• The School of Geosciences and Info-Physics, Central South University
• Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University
• The Shenzhen Research Institute, The Hong Kong Polytechnic University

Short Summary

This study investigates the detection of soil moisture variations beneath an asphalt layer using L-band SAR. Results show that subsurface echoes remain detectable through at least 9 cm of asphalt and that InSAR observables exhibit distinct responses to infiltration-induced subsurface moisture variations.

Objective

• Investigate the capability of L-band SAR/InSAR for detecting moisture anomalies beneath asphalt-covered roads

Study Configuration

• Spatial Scale: Laboratory-scale experiment in a microwave anechoic chamber
• Temporal Scale: Real-time monitoring during controlled infiltration experiments

Methodology and Data

• Models used: Complex coherence formulation, radar equation coupled with local plane-wave propagation model for lossy medium
• Data sources: L-band SAR sensor, time-domain reflectometry (TDR) measurements of soil volumetric water content

Main Results

• Subsurface echoes remain detectable through at least 9 cm of asphalt using an L-band Mini-SAR
• InSAR observables exhibit distinct responses to infiltration-induced subsurface moisture variations:
  • Interferometric phase decreases linearly with increasing soil VWC (r = −0.992)
  • Coherence loss occurs mainly along the edges of the infiltration apparatus and in areas with large moisture gradients
  • Nonzero closure phase increases as infiltration progresses, concentrated near low-coherence boundaries and high-phase-gradient zones

Contributions

• Provides theoretical and methodological support for improving the subsurface detectability of airborne and vehicle-based L-band SAR sensors
• Demonstrates the potential of InSAR-based detection of soil moisture variations beneath asphalt layers

Funding

• This study was funded by [project/program name], reference code [code]

Citation

@article{Peng2026Detection,
  author = {Peng, Wei and Xiao, Hui and Fu, Haiqiang and Liu, Guanxin and Tian, Yang and Zhu, Jun},
  title = {Detection of soil moisture variations beneath an asphalt layer using L-band SAR},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2026},
  doi = {10.1016/j.jag.2026.105592},
  url = {https://doi.org/10.1016/j.jag.2026.105592}
}