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Short-term desalination of Pulicat lagoon (Southeast India) due to the 2015 extreme flood event: insights from Land-Ocean Interactions in Coastal Zone (LOICZ) models

Santhanam, H and Natarajan, T (2018) Short-term desalination of Pulicat lagoon (Southeast India) due to the 2015 extreme flood event: insights from Land-Ocean Interactions in Coastal Zone (LOICZ) models. In: Ecological Processes, 7 (1).

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Official URL: https://doi.org/10.1186/s13717-018-0119-7


Introduction: We investigated the magnitude and duration of desalination of Pulicat—a coastal lagoon ecosystem connected to the Bay of Bengal on the South-eastern coast of India—during the 2015 South India flood event which was a period of high-magnitude precipitation and riverine flooding. Methods: We estimated freshwater runoff into the lagoon using flow accumulation models for a period of 55 days (November 1 to December 25, 2015) using daily gridded precipitation data from the Global Precipitation Measurement and a digital elevation model. Using the estimates of freshwater runoff, direct precipitation and observed salinities, we simulated water and salinity fluxes of the lagoon using the Land-Ocean Interactions in the Coastal Zone model. Further, we also used Monte Carlo simulation to estimate the uncertainty in system salinity, the residual salinity at the boundary and the freshwater residence times in the lagoon. Results: We estimated that a high volume (~ 760 × 106 m3) of relatively low salinity waters (residual salinity = 23.47 psu) had been exported from the lagoon to the Bay of Bengal during the period which is likely to have caused a strong dip in the daily salinity profile of the coastal sea. We contend that the lagoon experienced ~ 40% desalination due to the 2015 event with a freshwater residence time of 18.5 days. Conclusions: The study highlighted the short-term, high-magnitude desalination undergone by Pulicat lagoon during the 2015 South India floods. Considering the high residual and exchange volumes obtained from the study, we conclude that Pulicat could be a major exporter of relatively low salinity waters to the Bay of Bengal during monsoons.

Item Type: Journal Article
Publication: Ecological Processes
Publisher: Springer Verlag
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Coastal zones; Desalination; Floods; Intelligent systems; Monte Carlo methods; Precipitation (meteorology); Runoff; Uncertainty analysis; Water, Bay of Bengal; Digital elevation model; Direct precipitation; Extreme flood events; Flow accumulation; Global precipitation measurements; Pulicat lagoon; South India, Lakes, accumulation; coastal lagoon; desalination; digital elevation model; extreme event; flood; flooding; monsoon; Monte Carlo analysis; precipitation (climatology); runoff, Bay of Bengal; India; Indian Ocean; Indian Ocean (South); Pulicat Lake
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Division of Mechanical Sciences > Civil Engineering
Date Deposited: 23 Aug 2022 10:39
Last Modified: 23 Aug 2022 10:39
URI: https://eprints.iisc.ac.in/id/eprint/76208

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