Seawater intrusion turns groundwater saline in Thoothukudi

The key parameters of groundwater such as pH value, electrical conductivity (EC), etc., had been found to be steadily increasing towards Pudhukkottai from the coastal area over the years.
Image used for representational purpose only (Photo | Albin Mathew, EPS)
Image used for representational purpose only (Photo | Albin Mathew, EPS)

THOOTHUKUDI: A comprehensive analysis of the groundwater quality of Thoothukudi with reference to various research papers since 1985 emphasises the possible intrusion of seawater as far as 12 km from the shoreline of the Thoothukudi city. The academicians zeroed in on the fact that seawater intrusion has disrupted the water quality due to the observance of vast hydrogeochemical variation in the groundwater.

According to professor Selvam of VOC College, who led the comprehensive study on geochemical studies, the key parameters of groundwater such as pH value, electrical conductivity (EC), total dissolved salts (TDS), calcium, magnesium, sodium, potassium, and chloride had found to be steadily increasing towards Pudhukkottai from the coastal area over the years, which suggest the possible intrusion of seawater underground.

"The research studies back in 1985, found the groundwater was suitable for all utilities except for the one km from the shore, however, the salinity had increased inland in the past 20 to 30 years", Selvam added.

Jesuraj, a research scholar from the geology department of VOC college, said that as per BIS(2012) standards, the desirable limit of pH value in drinking water is less than 6.5 and is non-potable above 8.5. Similarly, the desirable and not acceptable limit for Total Dissolved Solids (TDS) is 2000, for calcium is respectively 200, for chloride respectively is 1000, he added.

A research scholar, B Viveka, attached to Killikulam Agricultural College and Research Institute in Thoothukudi, who assessed over 200 groundwater samples collected from borewells, open wells, and tubewells located up to 10 km from the coastline, has concluded that the domination of Na+ and Cl- ions in the groundwater samples strongly indicate intrusion of seawater in Thoothukudi.

Assistant professor G Singaraja of Presidency College, who worked in groundwater research in Thoothukudi, said that the excess withdrawal of groundwater for industrial purposes and salt pan activities has led to seawater intrusion. It can be prevented only when the excessive pumping of groundwater is regulated, he added.

Public say that many fresh water bodies in and around the Thoothukudi corporation areas such as Kokur, Pulipanchankulam, and many small ponds have been converted into residential colonies and housing plots. Many water canals have been eaten up during road expansion, and are obstructed by elevated roads.

When asked, a senior official from the Central Ground Water Board (CGWB) on conditions of anonymity, concurred with seawater intrusion by excess pumping and also due to in-situ salinity. Over 14 districts including Thoothukudi witness groundwater salinity. Further, studies are on to find the salinity levels, he added.

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