Groundwater flow system in Bengal Delta, Bangladesh revealed by environmental isotopes

Ratan K. Majumder, M. A. Halim, Bidyut Baran Saha, Reo Ikawa, Toshio Nakamura, Makoto Kagabu, Jun Shimada

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Abstract

A total number of 328 groundwater samples are analysed to evaluate the groundwater flow systems in Bengal Delta aquifers, Bangladesh using environmental isotope (2H, 18O, 13C, 3H, and 14C) techniques. A well-defined Local Meteoric Water Line (LMWL) δ2H = 7.7 δ18O + 10.7 ‰ is constructed applying linear correlation analyses to the monthly weighted rainfall isotopic compositions (δ18O and δ2H). The δ18O and δ2H concentrations of all groundwater samples in the study area are plotted more or less over the LMWL, which provides compelling evidence that all groundwaters are derived from rainfall and floodwater with a minor localized evaporation effects for the shallow groundwaters. Tritium concentration is observed in 40 samples out of 41 with values varying between 0.3 and 5.0 TU, which represents an evidence of young water recharge to the shallow and intermediate aquifers. A decreasing trend of 14C activity is associated with the heavier δ13C values, which indicates the presence of geochemical reactions affecting the 14C concentration along the groundwater flow system. Both vertical and lateral decrease of 14C activity toward down gradient show the presence of regional groundwater flow commencing from the unconfined aquifers, which discharges along the coastal regions. Finally, shallow, intermediate, and deep groundwater flow dynamics has revealed in the Bengal Delta aquifers, Bangladesh.

Original languageEnglish
Pages (from-to)1343-1352
Number of pages10
JournalEnvironmental Earth Sciences
Volume64
Issue number5
DOIs
Publication statusPublished - Nov 1 2011

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Water Science and Technology
  • Soil Science
  • Pollution
  • Geology
  • Earth-Surface Processes

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    Majumder, R. K., Halim, M. A., Saha, B. B., Ikawa, R., Nakamura, T., Kagabu, M., & Shimada, J. (2011). Groundwater flow system in Bengal Delta, Bangladesh revealed by environmental isotopes. Environmental Earth Sciences, 64(5), 1343-1352. https://doi.org/10.1007/s12665-011-0959-2