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A Geophysics-Informed Framework for Modeling Critical-Zone Subsurface Structure

Year: 2026
Type: preprint
Abstract: Critical-zone (CZ) subsurface structure shapes water storage, flow, weathering, and ecosystem function in mountain catchments. Because direct observations are sparse, geophysical imaging provides a valuable way of estimating its spatial variability, but inversion regularization and image interpretation may influence the inferred interfaces. We present a geophysics-informed framework that directly constrains process-based predictions of CZ structure by integrating geomorphic modeling, rock-physics conversion, seismic forward modeling, and stochastic calibration. We apply the framework at the Treeline site in the Dry Creek Experimental Watershed. Mobile-regolith thickness is modeled through production and hillslope transport, while fresh-bedrock geometry is related to relief above hydrologically connected channels. Candidate structures are converted to P-wave velocity and evaluated against measured seismic-refraction first arrivals. The calibrated models reproduce the measured travel times on the calibration and held-out profiles with similar performance. Among the calibrated parameters, the relief ratio is the most tightly constrained, indicating that fresh-bedrock relief near half the channel-relative surface relief best reproduces the observed travel times. Interfaces from an existing seismic inversion show consistent spatial patterns but are smoother than the process-based interfaces, potentially reflecting inversion smoothness regularization. By connecting geomorphic formation hypotheses with near-surface geophysical observations, the framework produces relevant structural fields and provides a basis for studying links among landscape evolution, subsurface architecture, and hydrologic processes.
DOI: 10.22541/essoar.15007118/v1
Author: Hang Chen
Institution: University of Iowa
Subfield: Geophysics
Open Access status: gold
OpenAlex ID: W7197022726
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