Land subsidence in Jakarta in Three Dimensions (2014-2025) using InSAR-GNSS Datum Connection and the Strapdown Decomposition

Abstract

Coastal megacities face compounding hazards from rising sea levels and land subsidence. Jakarta, one of the fastest-sinking megacities, already experiences recurrent flooding amplified by rapid land subsidence. Assessing and mitigating this hazard requires reliable estimates of three-dimensional ground motion over wide spatial and temporal scales in a well-defined geodetic reference frame and

Summary

This paper presents a novel method for mapping 3D land subsidence in Jakarta by combining InSAR and GNSS data. The key innovation is a datum connection procedure that aligns multi-track InSAR data to a common reference frame, providing a comprehensive understanding of Jakarta's land deformation within a globally consistent reference.

Key Insights

• •The study introduces an "optimization-constrained strapdown decomposition" to align InSAR data from different tracks, converting line-of-sight velocities into a global coordinate system.
• •The method minimizes the occurrence of negative transversal velocities to estimate the relative datum offset between ascending and descending InSAR tracks, improving the accuracy of subsidence mapping.
• •The research identifies six spatially localized subsidence bowls in Jakarta, with vertical velocities reaching up to -78.5 mm/yr, highlighting areas of critical concern.
• •Horizontal velocities exceeding 10 mm/yr along the rims of subsidence bowls, including distinct north components, indicate substantial lateral ground movement, a factor often overlooked in subsidence studies.

Practical Implications

• •The 3D characterization of land subsidence provides valuable insights for risk assessment, flood mitigation, and urban planning, informing infrastructure management and building stability analysis.
• •The study emphasizes the need for additional monitoring infrastructure, such as Integrated Geodetic Reference Stations (IGRS), to improve the accuracy of datum alignment between InSAR and GNSS data.
• •Future research should focus on expanding the monitoring network, using higher-resolution SAR data, and investigating the correlation between groundwater extraction and subsidence patterns to mitigate the hazard.

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