The Hindu 03.02.2010
“Improvement in quality of groundwater along coast”
Priti Narayan
| Total dissolved salts, chloride-alkalinity ratio gone down: study |
PUDUCHERRY: A recent study suggests that quality of groundwater in areas along the coast in Puducherry may have improved to a certain extent over the last 15 years.
The study, conducted by an official of the Puducherry Pollution Control Committee (PPCC) and a student of Mysore University, said that total dissolved salts in groundwater (in milligrams per litre) and chloride-alkalinity ratio were less in many areas located near the sea in 2008 when compared to the levels in 1993.
The official involved in the study said that the chloride-alkalinity ratio, which is an indicator of saltwater intrusion, has gone down considerably. A ratio of over one indicates considerable saltwater intrusion, but the ratio has fallen below one in many areas, the official said.
According to the study, the change has been most pronounced at Kirumampakkam, where the ratio has come down from 7.83 to 0.37, and at Pillayarkuppam, from 5.99 to 1.69 from 1993 to 2008. Levels have also fallen at Pannithittu, Eachankadu, Manapet and Pudukuppam.
The level of total dissolved salts in most areas has also gone down. Apart from Kirumampakkam and Pillayarkuppam, Manapet has witnessed a significant drop from 2558.5 mg per litre to 920.4 mg per litre, according to the study. But, in some areas such as Veerampattinam, Pannithittu and Kirumampakkam, the total dissolved salts level stand below the permitted level of 500 mg per litre. The level has, in fact, increased at Andiarpalayam, from 617.17 to 1,069.2 mg per litre from 1993 to 2008.
The official said that samples collected and analysed in 2008 were from the same borewells selected in 1993. Samples were taken from 21 locations along the coast, in three seasons of the year, he said.
The overall decrease in salinity of groundwater has resulted in a change in biodiversity in the areas, the official said. Species such as aloe have been restored, and coconut and palmyra are flourishing, he added.
The positive change in quality of groundwater may be due to the government prohibiting establishment of water- based industries (those consuming 10,000 litres of water or more for everyday production and processing) over the years. Since 2004, the monsoons have also been favourable, said an official of the State groundwater unit. The setting up of check-dams may have also helped, he added.
