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201-3 The Subsurface Time Machine: Modeling Compaction Dynamics
Session: Land Surface Subsidence—Processes, Impacts, and Ongoing Challenges
Presenting Author:
Joseph Davis Hughes
Authors:
Davis Hughes, Joseph D1, Ellis, John H.2, White, Jeremy3, Saberi, Laila4r>
(1) INTERA Incorporated, Chicago, IL, , (2) Intera Inc, Houston, TX, USA, (3) INTERA Incorporated, Fort Collins, Coloradp, USA, (4) INTERA Incorporated, Chicago, Illinois, USA,
Abstract:
Time, not just depth, is a governing dimension of subsidence. This presentation uses one-dimensional MODFLOW CSUB models to explore how interbed representation controls lag behavior, critical head evolution, and long-term compaction trajectories. The first part of the presentation contrasts delay versus no-delay interbeds, showing how models that omit delay artificially shorten system memory, accelerate preconsolidation head ratcheting, and distort future subsidence predictions under recovery or stabilization scenarios. The second part examines how many delay interbeds are needed to realistically capture subsurface behavior, progressing from single equivalent interbeds to multi-interbed configurations, and demonstrating the diminishing returns of excessive discretization. Sensitivity tests highlight the dominant role of interbed thickness and vertical hydraulic conductivity in setting characteristic response times. The presentation illustrates how simplified vertical models can clarify subsidence mechanics while avoiding unnecessary complexity.