Geological Society of America

60 D16. Recent Advances in Hydrogeology (Posters)

Sunday, 9 October 2022
2:00 PM - 6:00 PM
Exhibit Hall F

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

Paper number: 60-17
Program: Technical Sessions
Time: 2:00 PM – 6:00 PM

Authors

Nafis Sazeed Presenting Author
New Mexico Tech, Socorro, NM
Vaughan R. Voller
University of Minnesota - Minneapolis Campus, Minneapolis, MN
Michael S. Steckler
Columbia University, Palisades, NY
Eric Hutton
University of Colorado, Boulder, CO
Kate C.P. Leary
New Mexico Tech, Socorro, NM
Kerry Key
Columbia University, Palisades, NY
Mark A. Person
New Mexico Tech, Socorro, NM

Abstract

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.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-382530

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