43 Advances in Geospatial Applications for Environmental and Engineering Geology

Recent advancements in geospatial technologies have enhanced our ability to analyze, model, and predict geological and environmental processes with high precision. This session will explore the latest innovations in remote sensing, GIS, and data analytics applied to environmental engineering geosciences.

Sunday, 19 October 2025
1:30 PM - 5:30 PM
HBGCC, 214B

Designing Texas Solar Facilities: Expansive Clay Detection Using InSAR

Paper number: 43-3
Program: Technical Sessions
Time: 2:05 PM – 2:20 PM

Authors

Abstract

Potential Vertical Rise (PVR), as defined by TxDOT (Tex-124-E), represents the maximum heave (“uplift”) potential of soils based on laboratory swell tests under controlled conditions. PVR estimates are commonly used in geotechnical investigations for sites underlain by clays displaying expansive behavior to provide conservative, design-level values derived from subgrade conditions. However, while field and laboratory investigations are helpful for estimating PVR, the temporal and spatial coverage of these investigations are often incomprehensive. Interferometric Synthetic Aperture Radar (InSAR), a remote sensing technique that measures ground displacement by observing phase differences between successive satellite acquisitions, offers spatially continuous time-series evaluations of surface movement with millimeter-scale precision. This study aims to assess PVR estimates derived from traditional geotechnical methods versus those derived from InSAR in high-risk areas where the magnitude of PVR may be of concern during the development and operation of a solar facility.

Soil samples collected from central Texas indicate highly expansive clay (liquid limits up to 81%) with potential for measurable heave under full saturation (up to 4.5% swell). The PVR value derived from on-site soil was estimated at 2-inches (50.8-mm). InSAR data between 2020 and 2025 from the Sentinel-1 satellite mission was processed over the same region to refine and characterize soil behavior. The initial InSAR time-series analysis showed small net subsidence (~2.95-mm/year) attributed to groundwater withdrawal, which was detrended to isolate PVR. The detrended time-series shows annual cycles of subsidence during dry seasons and uplift during wet seasons, which are consistent with expansive behavior. Over the course of the study, soils generally display near-sinusoidal behavior with moderate heave, oscillating between approximately +5mm and -5mm of average annual displacement, or 0.4-inches (10-mm) of average vertical rise. However, the maximum vertical rise (taken as InSAR-derived PVR) was recorded in mid-2020 during drought conditions which led to excessive shrink-swell, revealing sharp subsidence and strong recovery in the order of 1.4-inches (36-mm). In comparison with the 2-inch PVR derived from on-site soils, InSAR data captured real-world responses to seasonal moisture fluctuations, land use changes, and long-term hydrogeologic trends that reflect current climate conditions, leading to more refined designs. These findings demonstrate InSAR as a valuable tool for risk-screening and long-term monitoring of solar facilities built on expansive soils, highlighting how InSAR models anticipated ground behavior.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412464

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