Coastal monitoring

Climate Adaptation and Coastal Monitoring: InSAR at the Core of a Changing Shoreline

GeoKinesia

21 NOVEMBER, 2025

Newsletter

Climate Adaptation and Coastal Monitoring: InSAR at the Core of a Changing Shoreline

Coastal monitoring
In this Newsletter, we explore one of today’s most relevant environmental challenges — how InSAR technology supports climate adaptation and coastal monitoring worldwide.

Coastal zones are among the most dynamic and vulnerable environments on the planet. They host half of the global population, generate major economic output, and yet are now facing converging pressures from sea-level rise, land subsidence, and climate-driven extreme events. Across the world’s deltas and estuaries, the line between land and sea is shifting—not only because the oceans are rising, but because the ground itself is sinking. In some deltaic areas, relative sea-level rise exceeds 10 millimeters per year, far outpacing global averages. Recent analyses using satellite interferometry (InSAR) have revealed that in many cities, subsidence is the dominant component of flood risk (Wu et al., 2022). A reality also reflected in our latest rapid-response work addressing severe inundation in Mexico.

InSAR—Interferometric Synthetic Aperture Radar—provides millimeter-precision measurements of ground deformation over wide areas, offering an unprecedented view of how coastlines are physically changing. By tracking ground motion through time, InSAR makes it possible to map vertical land motion (VLM), detect early signs of infrastructure settlement, and quantify the contribution of human activities such as groundwater extraction and land reclamation.

Global subsidence hotspots detected by Sentinel‑1 InSAR, adapted from Wu et al. (2022)
Fig 1– Global subsidence hotspots detected by Sentinel‑1 InSAR, adapted from Wu et al. (2022)

A recent emergency geospatial assessment was carried out in Mexico to support civil protection authorities following severe rainfall and flooding. Using satellite radar imagery and automated inundation detection, flood-affected areas were rapidly mapped across the Veracruz–Hidalgo border region, including the mountainous zone northwest of Poza Rica. The analysis provided actionable insights on inundation extent and terrain response, assisting in prioritizing emergency operations and post-event evaluation. The project demonstrated the effectiveness of high-precision, time-critical remote-sensing analyses under demanding operational conditions.

Fig. 2 – Emergency flood-mapping project for civil protection authorities in Mexico
Fig. 2 – Emergency flood-mapping project for civil protection authorities in Mexico
Across 99 global coastal cities, studies show that one third are subsiding faster than 10 millimeters per year, particularly in Southeast Asia, but also in parts of Europe and North America (Wu et al., 2022; Minderhoud et al., 2025). New continental-scale datasets, such as the European Ground Motion Service (Thiéblemont et al., 2024), now reveal that nearly half of Europe’s low-lying floodplains experience downward motion above one millimeter per year, most prominently around harbors and reclaimed coastal zones.
Fig. 3 – European coastal deformation trends from EGMS, adapted from Thiéblemont et al. (2024)
Fig. 3 – European coastal deformation trends from EGMS, adapted from Thiéblemont et al. (2024)
Yet vertical motion alone is not the whole story. Coastal flooding is increasingly the result of compound processes, where subsidence, sea-level rise, and storm surges combine to amplify inundation. Hydrodynamic models incorporating InSAR-derived land subsidence confirm that these interactions are highly non-linear. In Haikou, China, coupling satellite-based deformation data with Delft3D simulations showed that flood extents could increase by up to 40 percent by 2100 when subsidence and sea-level rise are considered together (Wu et al., 2024). Such compound effects are not unique to Asia; similar dynamics have been observed in the Mississippi and Po deltas, where groundwater regulation and sediment recharge programs are reducing local relative sea-level rise
Fig. 4 – Flood model of Haikou showing subsidence and inundation patterns, adapted from Wu et al. (2024)
Fig. 4 – Flood model of Haikou showing subsidence and inundation patterns, adapted from Wu et al. (2024)

InSAR analyses across South and East Asia reveal clear patterns of subsidence in several major coastal cities. Persistent Scatterer deformation data show significant ground lowering in Chittagong (Bangladesh), Tianjin (China), Manila (Philippines), and Karachi (Pakistan). The affected areas coincide with dense residential and industrial zones where excessive groundwater extraction and rapid land reclamation have accelerated vertical land motion (Wu et al., 2022). These findings illustrate how InSAR data can directly link human activity to coastal vulnerability, providing a powerful basis for adaptive planning and infrastructure management.

Fig. 5 – Selected coastal cities with significant subsidence (>10 mm yr⁻¹) from Sentinel‑1 (Wu et al., 2022)
Fig. 5 – Selected coastal cities with significant subsidence (>10 mm yr⁻¹) from Sentinel‑1 (Wu et al., 2022)
Understanding and adapting to these dynamics requires integrating geospatial data with social dimensions. Studies in flood-affected communities show that people’s attachment to place often outweighs risk perception, influencing relocation decisions even in chronically flooded zones (Hulio et al., 2023). In this context, the most powerful adaptation strategies are those that align physical monitoring with community planning—combining InSAR-based deformation trends with local decision-making frameworks.
Across Europe, Asia, and the Americas, InSAR is now central to the way we observe and interpret climate adaptation needs. Regular deformation baselines from Sentinel-1 satellites, available every 6 to 12 days, can identify hazardous subsidence corridors in ports, levees, and urban infrastructure. Integrating these with GNSS reference data and hydrodynamic models offers a full picture of relative sea-level change, allowing engineers and planners to anticipate risk rather than react to disaster (Minderhoud et al., 2025). At the same time, advanced analytical techniques—such as augmented InSAR, which merges physical models with phase data to enhance precision in dense urban environments—are pushing accuracy to new levels (Reinders et al., 2021).
These advances underline an important shift: coastal adaptation is no longer just a matter of building higher dikes or relocating people. It is a continuous process of observation, interpretation, and adjustment. By combining InSAR, hydrological modelling, and socio-economic analysis, we can now approach climate resilience as a living system—one that can be monitored and managed with precision. For GeoKinesia this represents an opportunity to translate scientific observation into practical adaptation solutions for coastal regions worldwide.
The next frontier lies in building operational coastal observatories—integrated systems where satellite monitoring, ground sensors, and human data flow into shared digital platforms. In these observatories, InSAR will not only measure motion but will guide sustainable adaptation, balancing urban development, natural defenses, and community safety. Coastal adaptation, seen through this lens, becomes not just a reaction to change but a managed evolution of the landscape itself.
References
  • Belhadj‑Aïssa, S. et al. (2024). Separation of water‑level change from atmospheric artifacts using L‑band InSAR. Earth & Space Science.
  • Li, Z. et al. (2025). Time‑series InSAR + ML for coastal wetland fine mapping. International Journal of Digital Earth.
  • Minderhoud, P.S.J. et al. (2025). From InSAR‑derived subsidence to relative sea‑level rise: a call for rigor. Earth’s Future.
  • Reinders, K.J. et al. (2021). Augmented satellite InSAR for tunnelling deformation. Tunnelling and Underground Space Technology.
  • Thiéblemont, R. et al. (2024). Assessing current coastal subsidence at continental scale (EGMS). Earth’s Future.
  • Wu, G. et al. (2024). Modelling SLR, land subsidence and TCs in compound flooding. Ocean & Coastal Management.
  • Wu, P.C. et al. (2022). Subsidence in coastal cities observed by InSAR. Geophysical Research Letters.
  • Hulio, A.F. et al. (2023). Preferences of flood victims for post‑flood housing. Climate Risk Management
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