Groundwater along ECR is turning saline: study

Updated - September 13, 2015 07:41 am IST

Published - September 13, 2015 12:00 am IST - CHENNAI:

Groundwater in areas falling in the northern coastal region of East Coast Road has been growing saline over the past few years. However, the stretch between Palavakkam and Muttukadu still has good quality water.

This was one of the findings of a study on the groundwater aquifer along ECR taken up by Anna University’s Department of Geology. Rapid urbanisation and over-extraction of groundwater along the coastline from close to the Adyar river to Palavakkam on the ECR has led to seawater intrusion.

The total dissolved solids level, which determines the drinking water standards of groundwater, has deteriorated over the past five years in these areas that fall on the northern coastal region of ECR. The TDS level in the localities between Besant Nagar and Palavakkam is now at 6,000 mg/l. However, the groundwater aquifer in the nearly 17-km stretch between Palavakkam and Muttukadu backwaters still retains good quality with TDS level less than 1,000 mg/l, says the study.

Residents of Neelankarai recall that the water quality was good even a decade ago. “We used groundwater for cooking and drinking then. Now, we have installed an RO plant to treat groundwater and depend on municipal water supply for drinking needs. Each family spends a minimum of Rs. 600 a month on water,” said Srilakshmi Rao of Neelankarai.

According to the study, the groundwater aquifer in ECR is surrounded by seawater and the impact of domestic sewage carried by Buckingham canal. “But, the water table here has an advantage of quick rainwater percolation due to sandy layer. At least 80 per cent of the rainfall can be recharged into the ground,” said L. Elango, professor, Department of Geology, Anna University.

After northern coastal region, the southern parts of the ECR are also slowly getting urbanised leading to more groundwater extraction. “There is no question of depletion of groundwater table in this region as seawater will replace freshwater. But quality will deteriorate. The government must ensure that recharge mechanism is mandatory to protect the fragile water table in this region,” he added.

The study analysed water samples in over 50 wells in different regions — close to the coastline, close to the road and near Buckingham canal. Unlike Minjur, where clayey soil to some extent controls seawater intrusion, the sandy layer along ECR would allow mixing of seawater when groundwater is extracted indiscriminately.

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