Groundwater Contamination and Mitigation Strategies in Coastal Aquifers: A Modeling Approach for the Varahanadhi Sub-Basin

Groundwater Contamination and Mitigation Strategies in Coastal Aquifers: A Modeling Approach for the Varahanadhi Sub-Basin | 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 Research Article Groundwater Contamination and Mitigation Strategies in Coastal Aquifers: A Modeling Approach for the Varahanadhi Sub-Basin Raj Kishor Mohanty, Kantharaj Murali, Daya Shankar Singh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8288027/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Coastal aquifers serve as crucial freshwater reserves for domestic, agricultural, and industrial use; however, rapid urbanization and overexploitation have disrupted their natural equilibrium and accelerating seawater intrusion and deteriorating groundwater quality. The study area, Varahanadhi sub-basin is itself a witness; although it is very critical for their socio-economic and hydrogeological significances. This study utilized bromide distribution to understand the extent and dynamics of seawater intrusion by the numerical groundwater flow and solute transport modeling by using MODFLOW and MT3DMS software with the integration of hydrogeological, groundwater level, and water quality data from 2020 and 2023. Simulation results revealed higher bromide concentrations in the coastal zones, confirming active seawater intrusion and the variable-density flow modeling approach, effectively captured the influence of pumping, recharge, and aquifer properties on solute migration. Therefore, to mitigate this problem three artificial recharge strategies; recharge ponds, recharge borewells, and recharge shafts were tested through simulation scenarios. Among these, the recharge shaft emerged as the most effective intervention, reducing bromide levels from 10 mg/L to 0.1 mg/L in shallow aquifers and from 10 mg/L to 1 mg/L in deeper layers. This indicates its strong capacity to restore hydraulic balance and restrict the lateral migration of saline water. The comparative performance of recharge structures demonstrates that the efficiency of mitigation strongly depends on the recharge rate, infiltration depth, and hydraulic connectivity of the aquifer system. These findings establish a scientific framework for coastal aquifer restoration, demonstration that recharge shafts are the most efficient and scalable solution to mitigate seawater intrusion in the Varahanadhi sub-basin. Thus, the numerical modeling effectively elucidates aquifer behavior under saline stress and guides sustainable management strategies. Numerical Modeling Coastal Aquifers Groundwater Seawater Intrusion MODFLOW MT3DMS Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 28 Jan, 2026 Reviews received at journal 10 Jan, 2026 Reviews received at journal 08 Jan, 2026 Reviews received at journal 05 Jan, 2026 Reviewers agreed at journal 01 Jan, 2026 Reviewers agreed at journal 31 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviewers agreed at journal 18 Dec, 2025 Reviewers invited by journal 16 Dec, 2025 Editor assigned by journal 08 Dec, 2025 Submission checks completed at journal 08 Dec, 2025 First submitted to journal 05 Dec, 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-8288027","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":561151057,"identity":"9e39e57a-e6df-4b20-afc1-6a3750c3eca5","order_by":0,"name":"Raj Kishor Mohanty","email":"","orcid":"","institution":"Indian Institute of Technology Madras","correspondingAuthor":false,"prefix":"","firstName":"Raj","middleName":"Kishor","lastName":"Mohanty","suffix":""},{"id":561151060,"identity":"8c140b93-1595-40d6-bdff-cfec64d23281","order_by":1,"name":"Kantharaj Murali","email":"","orcid":"","institution":"Indian Institute of Technology 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Sub-Basin","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-geoscience","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Geoscience](https://www.springer.com/journal/44288)","snPcode":"44288","submissionUrl":"https://submission.nature.com/new-submission/44288","title":"Discover Geoscience","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Numerical Modeling, Coastal Aquifers, Groundwater, Seawater Intrusion, MODFLOW, MT3DMS","lastPublishedDoi":"10.21203/rs.3.rs-8288027/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8288027/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCoastal aquifers serve as crucial freshwater reserves for domestic, agricultural, and industrial use; however, rapid urbanization and overexploitation have disrupted their natural equilibrium and accelerating seawater intrusion and deteriorating groundwater quality. The study area, Varahanadhi sub-basin is itself a witness; although it is very critical for their socio-economic and hydrogeological significances. This study utilized bromide distribution to understand the extent and dynamics of seawater intrusion by the numerical groundwater flow and solute transport modeling by using MODFLOW and MT3DMS software with the integration of hydrogeological, groundwater level, and water quality data from 2020 and 2023. Simulation results revealed higher bromide concentrations in the coastal zones, confirming active seawater intrusion and the variable-density flow modeling approach, effectively captured the influence of pumping, recharge, and aquifer properties on solute migration. Therefore, to mitigate this problem three artificial recharge strategies; recharge ponds, recharge borewells, and recharge shafts were tested through simulation scenarios. Among these, the recharge shaft emerged as the most effective intervention, reducing bromide levels from 10 mg/L to 0.1 mg/L in shallow aquifers and from 10 mg/L to 1 mg/L in deeper layers. This indicates its strong capacity to restore hydraulic balance and restrict the lateral migration of saline water. The comparative performance of recharge structures demonstrates that the efficiency of mitigation strongly depends on the recharge rate, infiltration depth, and hydraulic connectivity of the aquifer system. These findings establish a scientific framework for coastal aquifer restoration, demonstration that recharge shafts are the most efficient and scalable solution to mitigate seawater intrusion in the Varahanadhi sub-basin. Thus, the numerical modeling effectively elucidates aquifer behavior under saline stress and guides sustainable management strategies.\u003c/p\u003e","manuscriptTitle":"Groundwater Contamination and Mitigation Strategies in Coastal Aquifers: A Modeling Approach for the Varahanadhi Sub-Basin","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-19 13:31:40","doi":"10.21203/rs.3.rs-8288027/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-28T08:46:29+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-10T13:42:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-08T09:58:11+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-05T10:23:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"155381289330089143838869124176942627329","date":"2026-01-01T05:04:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"108202006419800596775601871909834682923","date":"2025-12-31T08:53:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"15422553781638435973636114281977427888","date":"2025-12-21T13:43:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"127880195119010435089016124864319745078","date":"2025-12-18T09:37:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-16T10:21:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-09T04:00:51+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-09T03:59:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Geoscience","date":"2025-12-05T12:46:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-geoscience","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Geoscience](https://www.springer.com/journal/44288)","snPcode":"44288","submissionUrl":"https://submission.nature.com/new-submission/44288","title":"Discover Geoscience","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"11fb723d-1402-432f-a3d7-1ff24369aa4d","owner":[],"postedDate":"December 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-15T07:23:27+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-19 13:31:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8288027","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8288027","identity":"rs-8288027","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}