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Cape Coral Ground Subsidence Investigation Series
By Jose Alberto Suarez • September 2026

Satellite Evidence • Infrastructure Risk • Public Records

Before we can ask what ground movement means for Cape Coral’s infrastructure, we need to understand what researchers measured—and what those measurements can establish.

This first installment begins with the satellite evidence. The aim is to give residents, construction professionals and public officials a clear foundation for evaluating the questions that follow.

The research behind the investigation

In 2023, Gökhan Aslan, Ivanna Penna, Ziyadin Cakir and John Dehls published Brackish-water desalination plant modulates ground deformation in the city of Cape Coral, Florida in Science of Remote Sensing.

The researchers analyzed 305 Sentinel-1A/B radar images from two ascending orbital tracks, covering mid-2015 through April 2022. Their analysis identified an elongated deformation zone extending northeast to southwest across approximately 100 square kilometers of northern Cape Coral.

The paper’s results and conclusions report a maximum rate of approximately 32 millimeters per year in the satellite’s line-of-sight direction. Its abstract instead reports rates up to 25 millimeters per year. That numerical difference warrants clarification from the authors; this series will preserve the distinction.

The authors compared deformation with groundwater records and well locations. They concluded that groundwater pumping associated with the northern brackish-water reverse-osmosis system was the primary factor responsible for the observed subsidence. That is the researchers’ interpretation of their combined evidence. Read the original study.

How a satellite measures movement

Interferometric Synthetic Aperture Radar—InSAR—compares the phase of radar signals recorded during repeated satellite observations. Changes in those signals can reveal changes in the distance between the satellite and reflecting features on the ground.

Buildings and other persistent reflecting surfaces can help provide usable measurements over time. Processing many observations allows researchers to examine how deformation varies across an area.

The measurement is taken along the radar’s viewing direction. Converting it into purely vertical movement requires additional assumptions or information about movement in other directions. USGS explanation of InSAR.

How to read a deformation map responsibly

A deformation map needs its legend, units, observation dates and measurement direction to be meaningful.

Before drawing a conclusion from a colored area, ask:

• Does the map show a rate of movement or accumulated displacement?

• What period does it cover?

• What reference point or area was used?

• Where are usable measurements available?

• What uncertainty accompanies the result?

Atmospheric conditions, vegetation and changes to the observed surface can interfere with radar measurements. A blank area should not automatically be interpreted as stable ground. USGS discussion of InSAR limitations.

For this investigation, every map we present should carry enough context for readers to understand what its colors represent.

What this means for an individual property

A regional deformation study is a starting point for further investigation. It cannot, by itself, determine whether a particular foundation is damaged, explain a specific roadway depression or establish that a building is unsafe.

Those are separate questions requiring evidence at the relevant location.

As a construction professional, I would want to see the regional observations considered alongside site conditions, surveys, construction history, inspections and appropriate geotechnical information. A connection should be demonstrated through that work before it is presented as an explanation for a particular failure.

The same standard applies in the other direction: uncertainty about an individual property is not a reason to dismiss a regional measurement.

The time boundary matters

The observation period described above does not establish present-day movement.

A useful next step would be a comparable analysis of subsequent observations, with its methods and uncertainty documented. The questions should be specific:

Has the pattern persisted? Has its rate changed? Has its geographic extent shifted?

An updated assessment should also explain how its measurements can be compared with the earlier results. Differences in processing or reference choices need to be considered before interpreting an apparent change.

These are proposed next steps for this series—not a claim that no subsequent monitoring exists.

Where the investigation goes next

My role in this series is to examine published evidence, explain its practical relevance and identify questions that require further technical work. I approach that responsibility as a Florida licensed contractor and construction professional.

In Part 2 — Groundwater Extraction and the Subsidence Hypothesis, we will examine how the researchers connected groundwater conditions with surface movement, the assumptions behind their model and the evidence needed to evaluate that explanation further.

Our standard remains straightforward: make the sources accessible, distinguish measurements from interpretations, and state uncertainty clearly.

Sources & Documentation

1. Aslan, G., Penna, I., Cakir, Z., and Dehls, J. (2023). Brackish-water desalination plant modulates ground deformation in the city of Cape Coral, Florida. Science of Remote Sensing, 7, 100077. Original paper.

2. U.S. Geological Survey. Measuring Land Subsidence from Space. Technical explanation.

3. U.S. Geological Survey. Detection and Measurement of Land Subsidence … Coachella Valley, California, 1996–2005. Methodology cited for general InSAR limitations, not as evidence about Cape Coral. Methods discussion.

Explore the series · Read the opening follow-up

Editorial and technical notice

The Cape Coral Ground Subsidence Investigation Series is independent analysis and public-interest commentary produced from publicly available research, government records and other documented sources. It does not constitute a site-specific geotechnical, structural, engineering or legal determination. Conditions affecting an individual property require evaluation by appropriately qualified professionals.