India’s Koyna dam in the western state of Maharashtra has been subject to some concern over recent weeks. Local media reported cracks appeared above the nearby switchyard in the wake of heavy rains in the western ghats.
Exceptionally heavy monsoon rains and the subsequent flooding took a toll of more than 1000 lives across the state and affected around 10M people.
The water level in the Koyna dam reservoir had reached alarming levels when as much as 322mm of rainfall was recorded in the catchment area over 24 hours. The Koyna river takes its source at Mahabaleshwar along with four other rivers (Krishna,Venna,Solshi and Savitri). Mahabaleshwar receives the second highest rainfall in the world. With the 103m high dam in danger of overflowing, authorities took the decision to increase discharge from the 2797Mm3 reservoir to close to 100,000m3/sec. Water resources minister Ajit Pawar quashed rumours of cracks in the Koyna dam itself, which was constructed in 1964, and said it was safe. The issue was also raised in the Indian Parliament. There were, however, minor cracks/landslides reported above the dam’s switchyard, some 25km away.
Concerns were also raised by Mr. R.R. Patil, Home Minister, Maharashtra State that neighbouring Karnataka state was in some way responsible for increasing the impact of the floodwaters by failing to release sufficient water from the downstream Almatti dam.
Numerous villages along the Koyna-Krishna river basin already faced submergence and after the Koyna reservoir was forced to release huge quantities of water for fear of being overtopped, it was expected that Alamatti would release similar quantities to prevent water from backing up. However, Maharashtra accused Karnataka of not releasing the promised quantity of water from Alamatti, leading to a worsening of the flood situation for large areas in the Satara, Sangli and Kolhapur Districts. The state authorities had to call in the Army to rescue marooned citizens.
The state government intends to take issue with Karnataka for violating the norms of storage and release of Almatti waters with the inter-state water sharing tribunal.
Perhaps most remarkably, in late June the Associated Chambers of Commerce and Industry of India issued a press release warning that water levels of major hydro reservoirs in southern India had witnessed sharp falls specifically naming Koyna.