Palar accounts for 43.91 tmc ft and the Coleroon carries around 38 tmc ft
Around 125 thousand million cubic feet (tmc ft) of water, or 1.3 times the Mettur dam’s capacity, drained into the sea through several rivers of Tamil Nadu since October 1 and mostly in November.
The highest contribution to the overall quantum has come from the Palar, which accounts for 43.91 tmc ft, as recorded at the Vayalur check-dam in Chengalpattu district.
The surplus water discharge began in the middle of October, but the rate of flow had gone up since November 7, ranging from half a tmc ft a day to nearly 4 tmc ft a day.
After 118 years, the Palar anicut, near Ranipet, registered a six digit figure. In November 1903, it recorded 1.2 lakh cubic feet per second (cusecs), says a senior official of the Water Resources Department.
A report, published in The Hindu on November 16 that year said, “The Palar Anicut has been washed away.” The official adds that the restoration work was completed two years later.
In terms of the surplus water discharge in November this year, the Coleroon comes next to the Palar. According to the recordings done at the Lower Anicut, about 22 km from the Veeranam tank in Cuddalore district, around 38 tmc ft drained into the sea. The quantum varied from 2.21 tmc ft on November 12 to 4.28 tmc ft on November 19.
The Pennaiyar released about 26.5 tmc ft into the sea, as measured at the Sornavur Anicut. Though the discharge commenced on November 3, it gathered momentum on November 12. As much as 3.4 tmc ft flowed on November 19. At the noon of November 19, the anicut registered a flow of about 1.59 lakh cusecs.
The Kosasthaliayar, one of the sources of Chennai’s drinking water, accounted for about 13 tmc ft draining into the sea, according to the readings at the Vallur check-dam. The Chembaramapakkam and Red Hills tanks discharged nearly 1.7 tmc ft each through the Adyar and the surplus course.
A water expert says one should not get unduly worried about certain amounts of water draining into the sea as this will help to maintain ecological balance. Ordinarily, 10% of the annual yield of every river should drain into the sea.
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