Scared by scarcity, city pins hope on bountiful monsoon

With the recent spells of unexpected rains saving the Chennai Metropolitan Water Supply and Sewerage Board (Metrowater) from the drought this year, the officials are pinning their hopes on Northeast monsoon to refill the bone-dry lakes to manage supply next year.

 “The recent rains could not fill the lakes, but it has increased the groundwater levels. It is good to have saturated ground before the monsoon so that all the rainwater runs to the lakes,” a Metrowater engineer said.

The engineer also admitted that 2019 summer was the most difficult period for the water manager as Redhills, Chembarambakkam, Cholavaram and Poondi lakes, which are the major lakes supplying water to the city, went completely dry as the city witnessed a 193-day-long dry day before heavens opened in mid-June. 

While the Metrowater claims to be working towards the worst-case-scenario, K Srikanth, weather blogger, said that the initial inferences suggest that the Northeast monsoon would be near to normal. “November is the most significant month in terms of monsoon and the early predictions suggest a below normal rainfall. However, an exact forecast will be known after September 15,” he added.

As against the city’s requirement of 830 million litres per day (MLD), the Metrowater is only managing to supply 525 MLD by drawing water from new lakes and abandoned quarries. Meanwhile, abandoned quarries in Sikkarayapuram, one of the new augmentations, went dry as the Metrowater was taking 10 MLD.

“We have to see how the monsoon performs this year. Even though we hope for a good spell of rains, we have established arrangements to supply 525 MLD through the next year if the season fails. We are also expecting water from the Telugu Ganga project. Due to the rains, Sikkarayapuram quarries are also filling up,” another engineer said. Meanwhile, the Metrowater has also has taken measures to bring an additional 50 MLD from Neyveli. Presently, 35 million litres reach the city every day from Neyveli. “The water is being used for agricultural purpose and we are taking steps to divert the water from drinking purpose, too. This would help during next summer.” The Metrowater is also in a process to identify suitable technology to set up mini desalination plants in the core city areas with a capacity of 10 MLD.

On the other hand, S Janakarajan, former professor of Madras Institute of Development Studies (MIDS), pointed out that the catchment areas of the city lakes are encroached upon, which would impede the flow of water to these lakes.

“Only if the rain in catchment areas and inlet canals are cleared of encroachments, the lakes would brim. Apart from this, the authorities’ claims of increasing groundwater are not true. They are taking data of water levels in shallow aquifers, but peoples tap water from borewells going doing to several meters,” he added.

He added that the 80 per cent of the rainwater runoff to drains and only 20 per cent get recharged as groundwater. “If the monsoon fails, the situation will get worse next year, and the government should take steps to send water to the ground by digging recharging borewells.”

The city and its neighbouring districts receive an average annual rainfall of 1,300 mm and about 400 mm rainfall has been received till now.

However, the Metrowater engineer said that the public works department (PWD) has taken up desilting of canals and is removing encroachments from the canals feeding Ayanmabakkam lake. “We are going to augment more sources in coming years and the city will get all-weather water supply of 1,150 MLD in five years,” he said.

The engineer also explained that abandoned quarries near Pulipakkam, Nallampakkam and Keerapakkam would be augmented to the city’s water sources next year and the second desalination plant in Nemmeli (150 MLD) would provide at least 75 MLD from next September. Metrowater also plans to tap water from upcoming check dams on Palar River.

Presently, of the daily supply of 525 MLD, the Metrowater is tapping 180 MLD from Veeranam lake, 180 MLD from desalination plants and 10 MLD from Retteri lake.

Eyeing to recharge most of the rainwater during the monsoon, the Chennai Corporation and Metrowater has been inspecting buildings in the city to implore owners to create rainwater harvesting structures. “If the groundwater effectively recharged during the monsoon, most of our problem will be solved. Residents would turn up to us if their borewells go dry,” an official said.