Bountiful flow is being witnessed on the Cauvery river in a sustained manner during the northeast monsoon (October-December). As on date, the realisation of the Cauvery water, as measured at Biligundlu, was 118.62 thousand million cubic feet (tmcft) since October 1.
It was during the 2010 monsoon that the realisation crossed the three-digit figure, which was 107 tmcft.
According to Karnataka State Natural Disaster Monitoring Centre (KSNDMC), between October 1 and November 25, south interior Karnataka region received 454 mm of rainfall against a normal of 185.7 mm, highest for the region in the last 50 years. This coupled with rains in Tamil Nadu augmented the quantum of water flow to the Mettur dam.
A perusal of the data of flows measured at Biligundlu, located on the border of Karnataka-Tamil Nadu, since 1974-75 reveals that the cumulative realisation during the monsoon exceeded the three-digit figure on 10 occasions, including the current year.
[The year 1974-75 has been taken into account as it was in 1974 that the 1924 inter-State agreement on the sharing of the Cauvery river water came for review].
Till now, the highest quantity during the three-month-period was 167 tmcft in 2005 followed by 152 tmcft in 2000 and 137 tmcft in 1977.
The current month’s realisation of the Cauvery water by Tamil Nadu - 70.34 tmcft - has become the highest quantum for November in the last 47 years.
The previous best was 61.18 tmcft in 2010. Last month, the State received 48.28 tmcft. As on Monday, the total realisation for the current year (since June 1) was 210.08 tmcft, an excess of 53.4 tmcft for the elapsed period of the year.
Mettur reservoir
The Mettur reservoir, about 70 km downstream of Biligundlu, remained at the full level of 120 ft with the storage being 93.47 tmcft. About 22,830 cubic feet per second (cusecs) was being discharged through the river while the inflow was 21,725 cusecs.
Karnataka is mandated to release 177.25 tmcft of water to Tamil Nadu every year between June 1 and May 30. Notwithstanding the fluctuations in the monthly discharge, the cumulative outflow from the KRS and the Kabini since the last three years is over and above what is prescribed by the apex court.
In 2020-21, the cumulative discharge from the KRS and the Kabini was 222 tmcft, it was 284 tmcft in 2019-20, and 432 tmcft in 2018-19, as per data from KSNDMC.
