Staff Highlights: Prof. Quoqiang Shi

Urbanization brings rapid development but also exacerbates geological and environmental risk, such as land subsidence, infrastructure instability, and landslides. These challenges threaten the safety of millions and demand advanced monitoring solutions.

Prof. Guoqiang Shi and his team work on urban remote sensing, leveraging Interferometric Synthetic Aperture Radar (InSAR) to monitor and analyse urban geological vulnerabilities from underground, ground surface, to the built upper ground. By integrating InSAR remote sensing, big data analytics and artificial intelligence (AI), the team aims to provide critical insights for urban resilience, infrastructure maintenance, and sustainable development.

Topic 1: Uneven Settlement in Coastal Reclamations

Reclaimed areas, common in land-scarce cities like Hong Kong, are prone to uneven settlement due to soft subsurface layers. Constrained by its steep terrain, Hong Kong has over 25% of its developable land reclaimed from the sea.

Using spaceborne InSAR, we detected rapid subsidence at Hong Kong International Airport’s Third Runway, a major reclaimed project. Our high-resolution data revealed soil compression patterns and fill-layer dynamics, offering engineers and policymakers actionable insights for soil reinforcement, infrastructure planning, and future reclamation projects (e.g., the ‘Lantau Tomorrow Vision’). This work underscores the need for continuous monitoring in reclaimed zones to prevent long-term risks.

Topic 2: Groundwater and Urban Land Subsidence

Unlike the artificial foundations in Hong Kong, the Yangtze River Delta (YRD) has vast and flat areas of natural sediments. Excessive groundwater extraction has caused severe subsidence in cities like Suzhou, where some areas sank over 2 meters before extraction was banned in 1997. Using InSAR, we quantified the slowdown in subsidence post-ban, demonstrating the policy’s effectiveness. However, traditional geological and surveying methods failed to evaluate the groundwater policy on a city-wide scale. Figure 2 illustrates the post-ban recovery (slowing) of Suzhou’s land subsidence, as captured by satellite InSAR. These findings are vital for groundwater management in vulnerable regions (e.g., the North China Plain), supporting sustainable urban planning and resource policies.

Topic 3: Infrastructure Health and Slope Safety

Beyond subsurface risks, InSAR enables large-scale structural and slope safety monitoring. In Hong Kong, we applied it to assess highway stability and generate 3D building point clouds, identifying high-risk structures. Risky slopes/landslides adjacent to buildings/transportations can be surveillance timely and located for accurate mitigation and evacuation planning. As satellite data improves, InSAR is becoming indispensable for smart city platforms, offering precise, real-time diagnostics for next-generation urban resilience solutions.

Welcome to join Prof. Shi’s team!

Prof. Shi and his team are advancing InSAR algorithms for complex urban terrains and developing AI-driven models to mine geohazard data. They welcome students from diverse academic backgrounds to join LSGI and join our group. For contact details, please refer to the information below.

They are looking forward to collaborating with you!

Personal web: https://guoqiangshi.github.io/

LSGI web: https://www.polyu.edu.hk/lsgi/people/academic-staff/

Email: guoqiang.shi@polyu.edu.hk

References:

1. Jiang Z, Shi G, Wu S, et al. Unveiling multimodal consolidation process of the newly reclaimed HKIA 3rd runway from satellite SAR interferometry, ICA analytics and Terzaghi consolidation theory. Remote Sensing of Environment, 2025, 318: 114561. https://doi.org/10.1016/j.rse.2024.114561
2. Shi G, Huang B, Leung A K, et al. Millimeter slope ratcheting from multitemporal SAR interferometry with a correction of coastal tropospheric delay: a case study in Hong Kong. Remote Sensing of Environment, 2022, 280: 113148. https://doi.org/10.1016/j.rse.2022.113148
3. Shi G, Ma P, Hu X, et al. Surface response and subsurface features during the restriction of groundwater exploitation in Suzhou (China) inferred from decadal SAR interferometry. Remote Sensing of Environment, 2021, 256: 112327. https://doi.org/10.1016/j.rse.2021.112327
4. Shi G, Lin H, Bürgmann R, et al. Early soil consolidation from magnetic extensometers and full resolution SAR interferometry over highly decorrelated reclaimed lands. Remote Sensing of Environment, 2019, 231: 111231. https://doi.org/10.1016/j.rse.2019.111231
5. Shi G, Lin H, Ma P. A hybrid method for stability monitoring in low-coherence urban regions using persistent and distributed scatterers. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2018, 11(10): 3811-3821. https://doi.org/10.1109/JSTARS.2018.2867832