Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing.

Area of Science:

• Geosciences
• Remote Sensing
• Environmental Science

Background:

• Surface subsidence is a critical geohazard.
• Understanding its drivers, like groundwater changes, is essential for urban planning.
• Beijing has experienced significant land subsidence.

Purpose of the Study:

• To investigate the relationship between surface subsidence and groundwater changes in Beijing.
• To quantify surface subsidence using advanced remote sensing techniques.
• To analyze the correlation between groundwater level fluctuations and land subsidence patterns.

Main Methods:

• Utilized Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) with ENVISAT ASAR images to map subsidence.
• Verified InSAR results with ground leveling data, achieving accuracy better than 5 mm/year.
• Employed Gravity Recovery and Climate Experiment (GRACE) data to derive groundwater change trends.

Main Results:

• Identified prominent and uneven surface subsidence in Beijing, with Tongzhou experiencing over 140 mm/year.
• Observed a consistent long-term decreasing trend between groundwater changes and surface subsidence.
• Found that the spatial extent of subsidence funnels was generally wider than groundwater depression areas.

Conclusions:

• Groundwater changes have a significant impact on surface subsidence in Beijing.
• A strong correlation exists between groundwater depletion and land subsidence.
• The findings provide crucial insights for sustainable groundwater management and urban development.