The cumulative outflow from the Krishnaraja Sagar (KRS) and the Kabini reservoirs between June 1 and September 10 has been higher compared to the outflow in the same period during the last three years.
Above normal rainfall during the current monsoon season has resulted in heavy inflow to the reservoirs as a result of which the corresponding outflow was also steady and high. Against Karnataka’s obligation to release 177.25 thousand million cubic feet (tmcft) to Tamil Nadu during a water year (June to May), the cumulative outflow from the two dams from June 1 to September 10 was 291 tmcft, according to Karnataka State Natural Disaster Monitoring Centre (KSNDMC).
The outflow from the KRS on September 10 was at the rate of 20,913 cusecs and it was 15,550 cusecs from the Kabini. At this rate, the cumulative discharge since June is expected to cross the 300-tmcft mark within the next few days.
In contrast, the cumulative outflow from both the Kabini and the KRS dams from June to September 10 was 94 tmcft while it was 93 tmcft during the same period in 2020 and 146.37 tmcft in 2019.
But 2018 was an exceptional year and the cumulative outflow from both the dams between June 1 and September 10 was 348.95 tmcft owing to extreme rains and catastrophe in Kodagu from which the district was still recovering.
The combined outflow so far is also higher than the quantum of discharge during the entire water year from June 2021 to May 2022. The total discharge was 237 tmcft in that period while it was 224 tmcft during June 2020 to May 2021 and 285.33 tmcft from June 2019 to May 2020, according to KSNDMC.
Also, the outflow so far from both the dams this year does not include the additional water accruing in the rivers due to heavy to very heavy rains in the downstream of KRS and Kabini which saw flooding in Arkavathi and its tributaries in Ramanagaram.
Besides, there were flash floods in the tail end regions of Mysuru, Chamarajanagar and Mandya districts as various rivulets and streams were also in spate all of which eventually join the Cauvery to flow into Stanley reservoir in Mettur.
South-interior Karnataka region comprising 11 districts and parts of which constitute the Cauvery catchment, has received more than two-fold the normal rains this year. Against a normal rainfall of 269 mm, the belt has received 645 mm of rainfall between June 1 and September 11, according to KSNDMC.
Kodagu, the district from where the Cauvery originates, has received 2,291 mm of rainfall against a normal of 2,060 mm while Chikkamagaluru - from where the river Hemavathi originates and is major tributary of the Cauvery – has received 1,335 mm of rainfall against a normal of 1,653 mm all of which has contributed to increase in the cumulative outflow from the reservoirs.
