A study by the Centre for Urban Water Resources at DHAN Foundation has indicated alarming levels of Total Dissolved Solids (TDS) in groundwater in certain parts of Madurai, particularly in the southern parts of the city.
The findings of the study shared ahead of the World Water Day which falls on Friday, showed the TDS levels in Vellakkal, Avaniapuram, Chintamani and nearby areas to be in the range of 2,000 mg per litre to 5,000 mg per litre. The acceptable range of TDS for drinking water is 500 mg per litre. The chloride level in these areas were also found to be correspondingly high.
Samples were collected from borewells in 51 places equally distributed across the 148 square kilometre of Madurai Corporation. Though water from borewells in households is predominantly not used for drinking water purposes, researchers involved in the the study said that the findings indicated depleting quality of groundwater in the city.
Reasons
While the terrain of Madurai city can be a natural reason for the TDS levels to be high in the southern parts, pollution and over-exploitation of groundwater could also be significant contributing factors, the researchers said.
S. Elamuhil, Project Executive at the Centre, said that the areas where TDS were within acceptable limits were the regions closer to Vaigai river’s flood plains and in regions made fertile by the Periyar irrigation system.
“There are certain pockets in this region as well where TDS levels are high, probably due to rocky nature of the soil,” he said. “On the other hand, the southern part is quite dry,” he added.
Lokesh Sinram, Environmental Engineer with the Centre, said that other likely reasons could be the pollution in the water tanks in the southern parts of the city. “We know that there is discharge of sewage and other effluents into some of the tanks in areas like Chintamani tank and Saamanatham tank,” he said, adding that the presence of garbage dumping yard at Vellakal should also be investigated.
“Our study has only indicated the possible problems. Further comprehensive studies are needed to establish the reasons,” he said.
Recharge
Mr. Elamuhil said that the study also highlighted the need for different groundwater recharging strategies to be adopted depending on specific needs of the localities. “If the terrain is rocky, as in places such as Uthangudi, Gomathipuram and areas near Vandiyur tank, rainwater harvesting at houses may not prove useful,” he said.
“Rainwater harvesting structures take water only up to few metres, beyond which water cannot percolate due to rocks. Instead, the government should create groundwater recharge shafts that can go 20 to 30 metre deep,” he added.
