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Another Bengaluru in the making? Chennai’s main drinking water source Veeranam lake dries up

Water inflow stops from Mettur dam, other reservoirs experiencing a decline too

Published: Tuesday 16 April 2024, Down To Earth

After Bengaluru, Chennai residents are facing the worrying prospect of a water crisis as summer heat intensifies — Veeranam Lake, one of the city’s primary water sources, has already run dry. 

The water storage in Veeranam Lake was recorded at zero million cubic feet (mcft) on April 15, 2024, according to data by the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB). Last year, on the same date, the lake held 687.40 mcft of water, while its total capacity is 1,465 mcft.

Veeranam Lake serves as a crucial drinking water source for Chennai. However, its supply was halted on February 28, 2024, due to the lack of inflow from the Mettur dam, pushing the reservoir into dead storage. 

The other reservoirs are also experiencing a decline. On April 15, the storage in Poondi lake was 1,323 mcft out of a total capacity of 3,231 mcft. Cholavaram Lake had 216 mcft, with a total capacity of 1,081 mcft. 

Puzhal lake recorded 2,808 mcft out of a total capacity of 3,300 mcft. Kannankottai Thervoy Kandigai had 408 mcft, against a total capacity of 500 mcft. Chembarambakkam lake held 2,578 mcft, with a total capacity of 3,645 mcft.

On April 5, 2024, Down To Earth reported that water levels in Cauvery basin were classified as deficient by Central Water Commission (CWC). Water levels in the basin dropped to 21 per cent from 23 per cent the week before.

As April progresses, Chennai residents are bracing themselves for the frightening prospect of worsening water scarcity. Borewells in Medavakkam, a neighbourhood already suffering from the shortage, are running dry, leaving residents with few options other than relying on dwindling groundwater or expensive private water tankers. This demonstrates the severe lack of piped water supply in the area.

Chennai uses a variety of water sources, including surface water, groundwater and desalinated seawater. According to CMWSSB data, the average groundwater level in January this year was 3.46 metres, rising to 4.22 metres in February and then to 4.91 metres in March. The city also relies on three desalination plants: one in Minjur with a capacity of 100 million litres per day (MLD) and two in Nemmeli with capacities of 110 MLD and 150 MLD, respectively. 

This year, the water supply authority appears to be more confident in its ability to meet Chennai’s water needs until September-October. A senior official from CMWSSB stated, “We have enough surface water to supply Chennai until September-October. The total storage level of surface water is 13.222 tmc, with the current storage level in these sources being 7.746 tmc. Last year’s storage level around the same time was 9.262 tmc.”

Despite a monthly demand of 2,232 MLD, CMWSSB supplies 1,070 MLD, albeit with a persistent demand-supply gap. Chennai, with a population of 9 million, suffers from a chronic imbalance in water demand and supply. Historically, CMWSSB has provided 830 MLD per day, up from 525 MLD in 2019, which was supplied on alternate days.

According to a joint study conducted in October last year by Anna University, Chennai and the Indian Institute of Technology, Madras, Chennai’s widening water demand-supply gap is expected to reach nearly 466 MLD by 2030, exacerbated by factors such as rapid urbanisation and climate change. 

Professor L Elango, the study’s lead author, emphasised the city’s acute water scarcity, particularly during the summer months, citing depleted groundwater sources, seawater intrusion and insufficient rainfall. By 2030, Chennai’s water demand is expected to reach 2,365 MLD, with an estimated supply of 1,988 MLD by 2040 and 2,049 MLD by 2050.

The study forecasted that the unmet demand would rise to about 717.5 MLD by 2040 and a substantial 962 MLD by 2050.

Elango advocated for a multifaceted approach to water resource management, emphasising the importance of groundwater recharge, desalination expansion and the use of reclaimed water to address the growing deficit. 

The study’s findings suggested that implementing various interventions concurrently could significantly reduce the gap between water supply and demand, with a projected drop to 110 MLD by 2030, 250 MLD by 2040 and 454 MLD by 2050.

But to address the city’s water deficit, concerted efforts are required to prioritise groundwater recharge and reclaimed water utilisation, as well as water consumption reduction. 

However, there are concerns that even initiatives like rainwater harvesting and the implementation of desalination plants, may not be enough, said BV Mudgal, a retired professor from the Centre for Water Resources at Anna University.

There’s a critical need for sustainable solutions to safeguard water access, he said. Highlighting the city’s heavy reliance on rainfall, Mudgal noted that while the average annual rainfall, which is 900-1,000 mm, remains relatively constant, the demand for water surpasses the available supply due to population growth, a trend expected to persist.

“There’s an urgency to augment the water supply, as Chennai’s own rainfall alone cannot meet the escalating demand,” Mudgal said, advocating for the utilisation of wastewater from industries and underscores the importance of regular conservation efforts. 

Additionally, he pointed out the challenges posed by cyclonic rainfall, which concentrates along the coast within a limited area of 10-15 kilometres. “Given Chennai’s flat terrain, storing such rainfall proves difficult, necessitating alternative methods like groundwater recharge and rainwater harvesting,” he said.

Former director of the Centre for Climate Change and Adaptation Research at Anna University, K Palanivelu, attributed the water crisis in Chennai to a combination of climate change and inadequate management of rainwater. 

“Without effective policy governance and widespread adoption of rainwater harvesting practices, Chennai may soon face Day Zero, a scenario where the city’s water sources are completely depleted,” Palanivelu warned.

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