Thiruvananthapuram: The Kerala State Electricity Board (KSEB) has denied allegations that devastating floods were caused by the sudden opening of the sluice gates of the hydel power reservoirs in the eastern parts of the state. The state-owned utility said that the allegations were malicious and unfounded.
The KSEB insisted that it collected water in the reservoirs and regulated the flow in accordance with meteorological data and the pattern of rainfall from previous years. The utility said that the Met department had not issued any warnings of an extremely heavy rainfall in August.
On forecast
The Met department had issued a long-term forecast for June-September as early as April. They followed up with another forecast in May. Both the reports forecast normal rainfall during the southwest monsoon. Even in the August 3 forecast for the second quarter, the agency said to be prepared for average rainfall for August and September.
The agency also issues forecast on a daily and weekly basis. In the July 26 weekly bulletin, the agency warned of above average rainfall in north India and the peninsula between August 2 and 8. Even this bulletin did not have any mention of heavy rain.
In the bulletin issued on August 9 for the period between August 9 and 15, the agency forecast very heavy rain (115.6 millimetre to 204.4 millimetre) only on August 9. Extremely heavy rain (above 204.4 millimetre) was not forecast at any point. These bulletins did not have anything alarming.
On preparations for releasing water
The water flow to the dams increased by July second week. Taking this into account, all small hydroelectric plants were run in full capacity. Small dams such as Kallarkutty, Lower Periyar, Kakkayam, Moozhiyar, Poringal, Sholayar and Banasura Sagar were opened in July itself.
As the rain intensified and the water level at various dams went up, the KSEB chairman and managing director called a high-level meeting and fixed maximum water levels for Idukki, Pampa, Kakki and Idamalayar dams for the water to be released. The dam safety chief engineer was entrusted with the responsibility to open the dams after informing the district administration and the disaster management agency.
Subsequently, different alert levels were issued for the dams. The Kakki dam was put on blue alert on July 24 and orange alert on August 3. A red alert was issued on August 8.
In Pampa, a blue alert was issued on July 17 and orange alert on July 26 but the orange alert was withdrawn on July 30 when the rain subsided. However, the orange alert was restored on August 9 when the rain intensified. A red alert had to be issued the same day.
In Idukki, a blue alert was issued on July 26 and orange alert on July 30 and a red alert on August 9. In Idamalayar, a blue alert was issued on July 25 and orange alert on August 1 and a red alert on August 8. The dams were opened on different days after giving ample warnings. No dam was opened at nighttime.
In the case of the Banasura Sagar dam, the KSEB could not wait to send out an alert because it is an earthen dam. The dam’s full reservoir level is also its maximum reservoir level. It was dangerous to keep water above that level. There is no other way but to drain water once the maximum level was reached.
As the KSEB noticed large inflows into the dam, the officers opened the shutters from July 14 to August 5. The district administration and the local media were informed.
The KSEB had opened all its small reservoirs in July itself to drain excess water. There was no reason to open the dams until August. When you open a reservoir, what flows out is not the stored water, but a part of the excess water flown in due to the heavy rain.
The flood in Periyar
The Idukki reservoir received 1,186 million cubic metres (mcm) of water between August 14 and 19, when the flood situation was aggravated downstream. Yet only 525 mcm water was released from it to the Periyar river. In other words, 661 mcm water was retained in the dam, controlling the flow to the river and lessening the impact of the flood.
The reservoir also received an additional 760 mcm per second water from the Mullaperiyar dam. Still the Idukki dam released only 1,600 mcm per second to Periyar River.
The KSEB had initially decided to go for a trial run at Idukki when the water level reached 2,397 feet. That level was reached on August 8 night. The same day, water level at the Idamalayar dam breached the full reservoir level of 169 metres and reached 169.95 metres. A red alert had to be issued and the dam opened.
The outflows from the Idamalayar and the Idukki dams end up in the same Periyar river. So the trial run at Idukki was postponed by a few hours to gauge the impact of the outflow from the Idamalayar dam.
A trial run followed at 12.30 pm on August 9 after issuing all necessary warnings. Though the trial run was planned only for four hours, the water level breached the red alert level of 2,399 feet and touched 2,401.10 feet, forcing the KSEB to open all shutters of the dam.
The draining of water continued from 8 am on August 10. The suspension of the trial run by a few hours did not create any problems. On the contrary it lessened the impact of the flood on the first day at least.
The flood in Pampa
The water that flowed into Pampa River from the Pampa and Kakki reservoirs and the hydropower plants was 1,473 cmc per second, or just below 29 per cent of the water that flowed through the river. This shows that the flood was caused by the natural rainwater that ended up in the river, and not the water that was released from the dams.
On KSEB's profit
It is wrong to assume that the KSEB earned a profit of crores of rupees when the dams filled up. The good rain has helped increase power generation and store maximum water in the reservoirs. Yet the reservoirs in Kerala store only enough water to generate 30 per cent of the electricity the state requires.
