Heavy Rains in Kerala

Why in news?

• Southwest monsoon has caused a series of floods and landslides in several districts of Kerala.
• One of the five shutters of the Cheruthoni dam on Idukki reservoir was opened as waters rose close to the maximum storage level.

Why is Idukki significant?

• Idukki is one of the largest arch dams in Asia that was commissioned in 1975.
• The Idukki lake sprawls across Kerala’s lifeline Periyar river.
• It was created by the arch dam of Idukki, and the smaller Cheruthoni and Kulamavu dams.
• The Idukki arch dam has no shutters.
• The Cheruthoni dam has been opened only twice (1981 and 1992), both during the northeast monsoon.
• The recent one is the third time and after a gap of 26 years.
• Notably, this is the first time that the dam was opened due to rains from southwest monsoon.

How is the southwest monsoon in Kerala?

• Kerala as a whole has received 15% excess rain and Idukki district got 41% excess until the first week of August.
• Persistent rain since the onset of the monsoon has left Idukki and other reservoirs downstream overflowing.

• The dam was opened to ease the pressure of water on the Idukki hydel reservoir.
• Also, for the first time, shutters of 22 dams including Idamalayar were opened due to heavy rains. 

Source: Indian Express