Land subsidence on Java Island and its contributions to relative sea level change

Area of Science:

• Geosciences
• Environmental Science
• Remote Sensing

Background:

• Rising sea levels and land subsidence exacerbate coastal hazards.
• Many populated coastal areas lack data on land subsidence's contribution to relative sea level rise (RSL).
• Effective coastal adaptation planning requires understanding subsidence impacts.

Purpose of the Study:

• To assess land subsidence across Java Island using satellite radar data.
• To quantify the contribution of land subsidence to 21st-century RSL change.
• To identify the primary drivers of subsidence in coastal cities.

Main Methods:

• High-resolution land subsidence mapping using satellite radar interferometry (InSAR).
• Machine learning for spatiotemporal clustering of subsidence patterns.
• Attribution of subsidence mechanisms using ancillary geological and resource data.
• Construction of virtual tide gauges for RSL projections.

Main Results:

• Widespread, evolving land subsidence detected across Java's coastal cities, with rates from 1 to 15 cm/year.
• Resource extraction identified as the dominant subsidence driver across diverse settings.
• Subsidence is projected to dominate RSL budgets along over 75% of Java's northern coast within 25 years.

Conclusions:

• Urgent need to incorporate land subsidence data into RSL risk assessments.
• Findings highlight significant vulnerability of Indonesian coastal cities to accelerated RSL rise.
• Policy interventions addressing resource extraction are crucial for mitigating subsidence and coastal hazards.