The Sardar Sarovar Narmada Nigam Limited (SSNNL) in Gujarat began releasing water into the Irrigation By-Pass Tunnel (IBPT) on Tuesday after the dam level fell below the drawdown level of 110.64 metres (363 feet). Currently, at 110.37 metres, about 3,000-9,000 cusec water is being released into the IBPT that will provide drinking water to several cities, towns and villages in the state until June 30, officials said.
For the first time, the SSNNL has also shut both its power houses – the River Bed Power House (RBPH) as well as the Canal Head Power house (CHPH).
The decision to release water into the IBPT comes ahead of the March 15 deadline announced by the state government for farmers drawing water from the main canal for irrigation. Officials explain that usually, even when the RBPH is shut for operations due to low water level, the CHPH uses the water for generation of power before the water is released into the main canal.
However, with the dam reservoir hitting the dead storage below 110.64 metres, the water being released into the main canal has been restricted to the minimum requirement of 8,000 cusec. An additional 600 cusec of water is also flowing out through the Godbole Gate into the downstream of Narmada that passes through Bharuch district.
A report on the progress (including social and economic development schemes) of Sardar Sarovar project for the month ending January 2018 states that the Narmada Control Authority (NCA) had permitted the closure of the main gates of the dam on June 16 for impounding of water in the reservoir for Full Reservoir Level (FRL).
As on January 31, when the water level was 112.65 metres, the CHPH generated 544.163 MW of power since March 2017. In the previous year, up to March 2017, the CHPH had generated 6,101.741 MW power. The RBPH, on the other hand, which generated 3,4759 MW power up to March 2017, has been shut since June, having generated only 376.608 MW in comparison this year. According to officials, the current level of the dam is the lowest in a decade. Therefore, this is also the first time that both the power houses have been closed.
P C Vyas, Chief Engineer, SSNNL, said that although Madhya Pradesh has been releasing water intermittently from its Omkareshwar reservoir, the decision to release water into the IBPT is to ensure drinking water supply. “Once the level of the Narmada dam reservoir falls below 110.64 metres, we cannot operate the power houses.
The water is being released into the main canal and simultaneously into the IBPT. The main canal will receive water until March 15, which marks the end of the Rabi season. After this, the farmers have been requested not to demand water for irrigation in summer. They can grow crops on their own. The Narmada Command has no provision to provide water for irrigation during summers. Currently, only about 45 per cent water is available in Narmada basin,” he said.
Vyas added that while MP is releasing about 5,100 cusec water as and when its Omkareshwar reservoir can manage, the water in the dead storage should suffice for the state until June 30. “We will release water into the IBPT in phases. The water should suffice until June 30 for drinking supply,” said Vyas.
The gross storage capacity of the reservoir is about 7.7 Million Acre Feet (MAF) while live storage capacity is 4.75 MAF. The dead storage capacity below minimum drawdown level is 2.97 MAF. The RBPH is an underground powerhouse stationed on the right bank of the river located about 165 metres downstream of the dam, while the CHPH is a surface power station having a total installed capacity of 250 MW (5 x 50 MW).