Simulating Extraction-induced Subsidence in the Mekong Delta: Investigating the Effects of Discretization and Conductivity Uncertainty

Simulating Extraction-induced Subsidence in the Mekong Delta: Investigating the Effects of Discretization and Conductivity Uncertainty | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Simulating Extraction-induced Subsidence in the Mekong Delta: Investigating the Effects of Discretization and Conductivity Uncertainty Bente R. Lexmon, Artur Guzy, Paul J.J.F. Torfs, Hung Van Pham, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7609506/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 15 You are reading this latest preprint version Abstract The densely populated Mekong Delta hosts valuable ecosystems and serves as a vital agroeconomic hub in the region. It is increasingly impacted by environmental challenges such as flooding and salinization, exacerbated by rising sea levels. Relative sea - level rise in the Mekong Delta is increasingly amplified by anthropogenic land subsidence, much of which is driven by groundwater extraction-induced aquifer-system compaction. Previous studies have quantified the spatiotemporal behavior and potential evolution of extraction-induced land subsidence in the Mekong Delta via the world’s first delta-wide 3D hydrogeological-geomechanical subsidence model. While these first quantifications provided valuable insights, uncertainties in the resulting simulations regarding several deterministic, model-specific aspects remain unstudied. In this study, we test the robustness of the model by quantifying uncertainty from spatial variability in aquifer hydraulic conductivity via a Monte Carlo ensemble and from vertical aquitard discretization by refining aquitards. Four adapted versions were run for 1991–2020 and compared with InSAR-derived subsidence data for 2006-2010 and 2015-2018 and sparse subsidence benchmark records. Our results show that, at the delta scale, the model performance is robust: the ensemble spread due to hydraulic conductivity is ∼1% of the mean cumulative subsidence, and refining aquitards from one to five model layers changes the mean annual compaction by <1%. Locally, differences reach ∼11% of cumulative subsidence in zones of steep drawdown in mid-depth aquitards, as the five-layer model better captures delayed pore-pressure diffusion and internal head gradients. InSAR agrees with the reference and five-layer models in terms of pattern and magnitude, whereas hydraulic conductivity ensembles tend to overpredict subsidence. Recent InSAR rates exceed modeled values, perhaps suggesting a slight model underestimation but likely also indicating that other land subsidence processes (e.g., shallow compaction) also contribute to the total subsidence experienced in the delta. The monitoring results from the benchmarks broadly support modeled trends, with good agreement at two sites and underestimation at one. Our study provides valuable insights and concrete recommendations for model setup to aid other large-scale hydrogeological numerical modeling applications aimed at quantifying extraction-induced subsidence. Our specific model for the Mekong Delta reveals that the numerical delta-scale projections of hydrogeological and geomechanical behavior are robust, whereas hotspots of greater uncertainty indicate locations where refined layering and targeted hydraulic conductivity characterization would improve future assessments the most. Full Text Additional Declarations No competing interests reported. Supplementary Files SimulatingExtractioninducedSubsidenceintheMekongDeltaInvestigatingtheEffectsofDiscretizationandConductivityUncertaintySupplementary.pdf Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 21 Apr, 2026 Reviews received at journal 30 Mar, 2026 Reviews received at journal 26 Mar, 2026 Reviews received at journal 26 Mar, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviewers agreed at journal 26 Feb, 2026 Editor invited by journal 19 Feb, 2026 Reviews received at journal 10 Dec, 2025 Reviewers agreed at journal 20 Oct, 2025 Reviewers agreed at journal 20 Oct, 2025 Reviewers invited by journal 19 Oct, 2025 Editor assigned by journal 25 Sep, 2025 Submission checks completed at journal 19 Sep, 2025 First submitted to journal 19 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7609506","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":538549157,"identity":"e7621dbc-0c52-46e5-8714-ac9d1d980668","order_by":0,"name":"Bente R. 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It is increasingly impacted by environmental challenges such as flooding and salinization, exacerbated by rising sea levels. Relative sea - level rise in the Mekong Delta is increasingly amplified by anthropogenic land subsidence, much of which is driven by groundwater extraction-induced aquifer-system compaction. Previous studies have quantified the spatiotemporal behavior and potential evolution of extraction-induced land subsidence in the Mekong Delta via the world’s first delta-wide 3D hydrogeological-geomechanical subsidence model. While these first quantifications provided valuable insights, uncertainties in the resulting simulations regarding several deterministic, model-specific aspects remain unstudied. In this study, we test the robustness of the model by quantifying uncertainty from spatial variability in aquifer hydraulic conductivity via a Monte Carlo ensemble and from vertical aquitard discretization by refining aquitards. Four adapted versions were run for 1991–2020 and compared with InSAR-derived subsidence data for 2006-2010 and 2015-2018 and sparse subsidence benchmark records. Our results show that, at the delta scale, the model performance is robust: the ensemble spread due to hydraulic conductivity is ∼1% of the mean cumulative subsidence, and refining aquitards from one to five model layers changes the mean annual compaction by \u003c1%. Locally, differences reach ∼11% of cumulative subsidence in zones of steep drawdown in mid-depth aquitards, as the five-layer model better captures delayed pore-pressure diffusion and internal head gradients. InSAR agrees with the reference and five-layer models in terms of pattern and magnitude, whereas hydraulic conductivity ensembles tend to overpredict subsidence. 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