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Desmond Kangah’s work uses Sentinel-1 radar satellite data to measure how the ground in East Baton Rouge Parish, Louisiana, is moving, then applies machine learning and a forecasting model to show where that movement is concentrated and where it may continue. Two 2026 studies describe the approach: his Spring 2026 civil engineering thesis at Louisiana State University, and a co-authored paper in the IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (JSTARS) focused on transportation infrastructure. Both identify patterns that point to where people should look more closely. Neither establishes that a particular road or bridge is safe or unsafe.

The four-step workflow

Kangah’s approach moves through four stages. Each stage answers a different question, and the outputs of one stage are not the same kind of evidence as the next.

  1. Measurement. Sentinel-1 radar images of the same ground are collected repeatedly over time. Interferometric processing compares those images to estimate how the land surface has moved between acquisitions, producing a time series for each measurement point. The thesis reports 246 ascending-track acquisitions. The EGU conference abstract for the same work describes Sentinel-1 Small Baseline Subset (SBAS) time series covering 2017 to 2025.
  2. Interpretation. Ensemble machine learning models are trained to map where subsidence is concentrated and how susceptible an area is. Explainable AI methods then show which conditions drive those results, such as fault proximity or groundwater withdrawal.
  3. Forecast. A physics-constrained long short-term memory (LSTM) network projects future deformation rates. In the thesis, these are model projections through 2030, not observations of what has already happened.
  4. Targeted follow-up. Flagged areas are the places where engineers would direct independent checks and site inspection. The studies treat this step as the job of people, not of the map.

InSAR, short for interferometric synthetic aperture radar, measures surface movement over repeated observations. It does not see cracks, measure load on a structure, or tell an engineer what is happening inside a pier or embankment. That distinction matters for everything that follows.

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Two studies, two methods

The thesis and the transportation paper share a study area, a satellite sensor, and a general goal. They differ in the InSAR method, the models, and the question each one answers. They should not be read as the same analysis reported twice.

Element LSU thesis (Spring 2026) IEEE JSTARS paper (2026)
Study area East Baton Rouge Parish, Louisiana East Baton Rouge Parish, Louisiana
Satellite data Sentinel-1 Sentinel-1
InSAR method Small Baseline Subset (SBAS) Persistent-scatterer InSAR (PSI)
Models and explanation Ensemble machine learning, physics-constrained LSTM, explainable AI Random Forest (RF) and SHapley Additive exPlanations (SHAP)
Primary question Where subsidence is concentrated and how it may evolve through 2030 Localized deformation and stability near major interchanges and bridges
Acquisition count 246 ascending-track acquisitions Not stated in the paper’s available abstract text
Main reported drivers Spatial concentration near fault structures and areas of intensive groundwater withdrawal Fault proximity and lithologic variability as dominant controls; precipitation as a secondary contributor

The distinction between methods matters for interpretation. SBAS, used in the thesis, is built for mapping deformation patterns over broad areas and feeding them into a temporal model. PSI, used in the paper, tracks stable reflective points on the ground, which suits assessing movement at specific built features such as bridges and interchanges. The two outputs answer different questions and should not be presented as interchangeable.

What the thesis reports

Where the ground is moving

The thesis reports subsidence that is spatially concentrated near fault structures and in areas of intensive groundwater withdrawal within East Baton Rouge Parish. The concentration is the finding; the thesis does not present it as a universal cause-and-effect relationship across all locations.

How well the models fit the data

The thesis compares several models. The figures below are the thesis’s own reported values. They describe model performance in the thesis’s evaluation, not accuracy at any particular bridge or intersection.

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Model Reported R² Reported AUC Other reported value
Extra Trees 0.92 0.97 Not stated
Random Forest 0.88 0.94 Not stated
Physics-constrained LSTM 0.83 Not applicable Pearson r = 0.92

The ensemble models are described as susceptibility classifiers, which is why AUC is reported for them. The LSTM is a forecasting model and is evaluated with regression measures.

The 2030 projection

The thesis’s forecast projects a mean velocity of −0.53 mm/year, accumulating to −6.42 mm over the five-year forecast period through 2030. These are the model’s projections. They are not measurements of deformation that has occurred after the study. The cumulative figure is not a simple five-year multiple of the mean rate; five years at −0.53 mm/year would be about −2.65 mm. The sources available for this article do not describe how the cumulative value was constructed, so it should be read as the model’s own output rather than a derived product of the mean velocity.

What the transportation paper reports

Localized signals near interchanges and bridges

The paper reports localized deformation near major interchanges and bridges in the parish. Signals are stronger in fault-bounded corridors and in areas where the subsurface is stratigraphically variable, meaning the soil and rock layers change over short distances. The paper’s own framing is that these are areas that warrant attention, not confirmed hazards.

Which factors the model ranks highest

Using Random Forest with SHAP explanations, the paper identifies fault proximity and lithologic variability as the dominant controls on deformation susceptibility. Precipitation is identified as a secondary contributor. SHAP shows how much each input pushes a prediction up or down, which is useful for checking whether the model is responding to physically plausible conditions. It does not prove that any one factor causes movement.

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The GNSS check

The paper compares its InSAR time series with independent GNSS observations from reference stations. This is a consistency check: it shows whether the satellite-derived movement agrees with a separate measurement method at the locations tested. It does not validate every pixel or every infrastructure asset in the study area.

The paper’s own summary of its contribution reads: “By combining PSI, RF, and SHAP, the framework enhances interpretability, improves deformation-susceptibility mapping, and supports infrastructure risk assessment.” (Ahmed Abdalla, Desmond Kangah, and Abdelrahim Salih, IEEE JSTARS, 2026.)

Reading the numbers without overreading them

  • Projections are not observations. The 2030 values are what the model expects under its assumptions. Measured deformation from the satellite time series is a different kind of number.
  • Susceptibility is not cause. A map that shows an area resembles places where deformation has been detected tells you where to look, not why the ground is moving there.
  • Fit scores have a scope. An R² of 0.92 describes how well a model reproduced the thesis’s data. It does not guarantee the same accuracy in a different parish, with different data, or at a single structure.
  • Agreement with GNSS is partial. Consistency at the points compared supports the method. It is not a blanket statement about every location.
  • Method outputs differ. A PSI point’s movement, an SBAS area’s trend, and a model’s susceptibility score are three different products, even when they cover the same street.
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What these studies do not establish

The thesis and the paper describe analysis methods and their results for East Baton Rouge Parish. They do not describe an operational warning service, a deployed monitoring system used by a transportation agency, or any measured outcome in which the approach prevented damage. Whether the workflow would perform the same way in other parishes or on other datasets is not tested in these sources.

How the outputs fit an inspection workflow

The studies do not prescribe an inspection procedure. The sequence below is one way a transportation engineer could use these kinds of outputs, drawn from the logic of the studies themselves.

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  1. Review the InSAR time series for the corridor or structure of interest, noting where movement is persistent rather than a single anomaly.
  2. Check the flagged locations against an independent measurement, such as GNSS or conventional survey data, before drawing conclusions.
  3. Compare the pattern with mapped fault locations, subsurface variability, and recent precipitation records to see whether the pattern is consistent with the drivers the paper identifies.
  4. Prioritize the locations for site inspection, where condition is observed directly.
  5. Let the engineering judgment of qualified staff determine any action. The model output is one input to that judgment.

Where to read the sources

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