Incessant rain pumps up groundwater level in Chennai

The strong, incessant rain in November has improved the groundwater level in the city, with all 15 zones recording a rise in water table. Things have improved so much that the groundwater table at 14 zones rose by more than 1 metre, while some have gone beyond 2 metres. Overall, the city’s groundwater level has increased by an average of 1.64 metres.

According to data from the Chennai Metropolitan Water Supply and Sewerage Board (Metro Water), zones such as Thiru Vi Ka Nagar, Ambattur, Valasaravakkam and Alandur witnessed a rise of more than 2 metres.

Among the zones, Thiru Vi Ka Nagar registered the highest improvement, as the groundwater level in the zone in central Chennai region has risen by 2.66 metres. In October, the zone had groundwater at 5.22 metres. Just a month later, the same has increased to 2.56 metres in November.

At 1.70 metres, Anna Nagar zone has the shallowest groundwater level. In October, Anna Nagar had the groundwater at a depth of 3.57 metres.

Among the other core city zones, Tondiarpet and Royapuram have groundwater at a depth of 4.81 metres and 4.89 metres respectively. Teynampet and Kodambakkam have groundwater at 2.74 metres and 3.69 metres.

The only exception to the substantial rise recorded by the city was Sholinganallur zone that registered a rise of only 0.54 metre.

To put this rise in perspective, the groundwater level had increased by only 0.44 meter at the beginning of the northeast monsoon in October when compared to the level recorded in September.

When asked, an official from the utility said the groundwater level increased not only due to monsoon rain but also because of the proper maintenance of rainwater harvesting structures and community wells.

The Metro Water has several observation wells (open wells) across the city to measure the groundwater levels (shallow aquifer) every month.

The Chennai Metropolitan Water Supply and Sewerage Board (Metro Water) official website shows wrong figures of water levels in the city lakes. According to the website, the full tank level (or depth) of Poondi lake is 140 feet. However, the actual depth of the lake is just 34 feet. Similarly, the website shows the full tank level of Chembarambakkam lake as 85.40 feet. But the actual depth is around 24 feet.As per Metro Water website, the depth of Red Hills lake (Puzhal lake) is 50.20 feet, but the actual depth is 21.20 feet. When asked, an official said that the details of the lakes might have been updated mistakenly and assured that the corrections would be made accordingly.