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Title: Identification of seawater intrusion signatures through geochemical evolution of groundwater: a case study based on coastal region of the Mahanadi delta, Bay of Bengal, India
Authors: Behera A.K.
Chakrapani G.J.
Kumar S.
Rai N.
Published in: Natural Hazards
Abstract: The study dealt with seawater intrusion process in a coastal aquifer system in the Mahanadi river delta region in the east coast of India along the Bay of Bengal. The aquifers of Mahanadi delta are characterized as shallow aquifers (< 50 m) and deeper aquifers (> 50 m). Electrical conductivity (EC) of groundwater varied from a fresh of 146 ?S/cm (NW of the Mahanadi delta) to a saline of 33,900 ?S/cm (close to sea coast) with cation dominance in the order Na+ > Ca2+ > Mg2+ > K+ and anion dominance of Cl? > HCO3- > SO42-. The hydrochemical facies changed from Ca–Mg–Na–HCO3 type to Na–Cl type along the groundwater flow direction due to ion exchange processes. A strong positive correlation (r > 0.9) between Cl? with EC, Na+, Mg2+, Ca2+, SO42- and K+ was observed, which indicated the influence of seawater on coastal aquifer. The ionic ratios (Na+/Cl?, HCO3-/Cl?, Mg2+/Ca2+, SO42-/Cl?, Ca2+/(HCO3-/SO42-)) also suggested that the groundwater is affected by seawater intrusion. Stable isotope compositions (?18O and ?2H) varied from ? 1.86 to ? 6.87 ‰ for ?18O and from ? 10.79 to ? 45.42 ‰ for ?2H, implying the mixing of saline water and fresh groundwater in the coastal region of the Mahanadi delta. The proportion of seawater in groundwater was estimated to vary from 0% in the upper-delta formation to 72% in the lower-delta formation of the Mahanadi delta (close to seacoast), which was due to inland intrusion of seawater. In a first ever study on this coastal aquifer along the Bay of Bengal, where a large population is dependent on agriculture, seawater intrusion into the fresh groundwater has been quantified. The issue of seawater intrusion into the coastal aquifer in this region may become a serious disaster, if appropriate management strategies are not implemented in time. © 2019, Springer Nature B.V.
Citation: Natural Hazards (2019), 97(3): 1209-1230
Issue Date: 2019
Publisher: Springer Netherlands
Keywords: Bay of Bengal
Cation exchange
Coastal aquifer
Mahanadi delta
Seawater intrusion
Stable isotopes
ISSN: 0921030X
Author Scopus IDs: 57210313858
Author Affiliations: Behera, A.K., Department of Earth Sciences, Indian Institute of Technology Roorkee, Uttarakhand, 247667, India
Chakrapani, G.J., Department of Earth Sciences, Indian Institute of Technology Roorkee, Uttarakhand, 247667, India
Kumar, S., Hydrological Investigations Division, National Institute of Hydrology, Roorkee, Uttarakhand 247667, India
Rai, N., Department of Earth Sciences, Indian Institute of Technology Roorkee, Uttarakhand, 247667, India
Funding Details: AKB acknowledges University Grant Commission (Grant Number: 6405-14-044), New Delhi, for providing Junior Research Fellowship to carry out the research work. The two anonymous reviewers and the editor are thanked and gratefully acknowledged for their critical reviews of the manuscript. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Corresponding Author: Behera, A.K.; Department of Earth Sciences, Indian Institute of Technology RoorkeeIndia; email:
Appears in Collections:Journal Publications [ES]

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