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GSA Connects 2022 meeting in Denver, Colorado

Paper No. 60-17
Presentation Time: 2:00 PM-6:00 PM

THE ENTRAPMENT OF ONSHORE SEAWATER WITHIN THE GANGES-BRAHMAPUTRA-MEGHNA DELTA SALINITY DUE TO RAPID SEDIMENTATION


SAZEED, Nafis1, VOLLER, Vaughan R.2, STECKLER, Michael S.3, HUTTON, Eric4, LEARY, Kate C.P.1, KEY, Kerry3 and PERSON, Mark A.1, (1)Earth & Environmental Science, New Mexico Tech, 801 Leroy Place, Socorro, NM 87801, (2)Civil, Environmental, and Geo-Engineering, University of Minnesota - Minneapolis Campus, 500 Pillsbury Drive S.E., Minneapolis, MN 55455, (3)Marine Geology and Geophysics, Columbia University, 61 Route 9W, Palisades, NY 10964, (4)Institute of Arctic and Alpine Research, University of Colorado, Campus Box 450, Boulder, CO 80309

Sediment flux into the Ganges-Brahmaputra-Meghna Delta is the largest in the world today (109 tonnes per year). This load was at least 2-3 times larger during early Holocene (11-7 ka). We hypothesize that rapid sediment progradation has entrapped seawater onshore during the Holocene as the shoreline migrated on the order of 100km. We coupled a 2D stratigraphic model (Sequence) to a groundwater flow/solute transport code in order to test this hypothesis. Specifically, we have tried to determine whether or not rapid sediment transport can account for presence of saline to brackish water 80km inland from the shoreline. We use Sequence to estimate sedimentation and erosion during Late-Pleistocene to Holocene sea-level fluctuations, and include the effect of isostasy and compaction on the deposition pattern. Sedimentary units generated by Sequence include fluvial, shoreline, and marine facies. A key challenge has been the representation of flood plain deposits within fluvial facies. Results indicate that onshore entrapment of seawater can be explained, in part, by rapid shoreline progradation. Seawater entrapment was found to be greatly enhanced by the presence of fluvial confining units.
Handouts
  • Sazeed_GSA_poster.pdf (3.3 MB)

    • Session No. 60--Booth# 59

    D16. Recent Advances in Hydrogeology (Posters)
    Sunday, 9 October 2022: 2:00 PM-6:00 PM
    Exhibit Hall F (Colorado Convention Center)
    Geological Society of America Abstracts with Programs. Vol. 54, No. 5
    doi: 10.1130/abs/2022AM-382530
    © Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
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