When all the five shutters of the Cheruthoni dam in Kerala’s Idukki were opened after heavy rainfall in 2018, it was then that people realised the gravity of the danger, which was about to hit the state. The excess water from the dam as well as other dams, many of which were released overnight, washed away thousands of houses, roads, lives and livelihoods.
Many, including political parties, attributed the disaster to ineffective dam management than a natural disaster caused by heavy rainfall. A High Court-appointed amicus curiae also recently pointed out that lapses in dam management exacerbated the impact of the floods in Kerala.
One of the important aspects that the amicus curiae, Jacob P Alex, highlighted in the report is that despite the mandate by the National Disaster Management Authority (NDMA), none of the dams in the state had an Emergency Action Plan (EAP), a document detailing the plan to prevent or lessen the effects of a failure of the dam or appurtenant (secondary) structure. The alerts, also, were not issued based on the EAP guidelines, it pointed out.
When TNM contacted Kerala Dam Safety Authority (KDSA), an official, who did not wish to be named, said that the new, updated EAP Guidelines for each dam is still in the process of being finalised. This even as the Indian Meteorological Department (IMD) predicts the onset of the southwest monsoon by June 6.
“Every dam engineer prepares the EAP for the respective dams. There are 16 dams under the Irrigation Department. This year, as part of monsoon preparedness, we have formulated EAP guidelines for 13 out 16 dams so far, although it is yet to be approved by the Central Water Commission (CWC). It has to be presented before the relevant stakeholders and then issued as a Government Order; that is the standard procedure,” the official said.
The team is in the process of revising the guidelines to be modelled around the dams at Cherrapunji in Meghalaya, as directed by the CWC. “We hope this will be completed in one or two months. Until then, we have requested the government to use our model of EAP during the course of the monsoon,” added the official.
In addition to the EAP, every reservoir must have a dam specific rule curve - which specifies the water level or empty space to be maintained in a dam at different points of the year. However, according to the amicus curiae report, the affidavit filed by the government and other departments did not mention if the dams were operated as per rule curve during floods. It only recommended reviewing the rule curves for conservation and operations during floods.
The official at the DSA department admitted that “the dams under the Irrigation Department did not operate based on the rule curve last year but based on certain warning levels”.
“The first level of water rise is the first warning. When the first warning is received, the dam engineer will inform the officials concerned, including the District Collector, who is also the Chairman of the District Disaster Management Authority. They make arrangements to announce the warning and evacuate people. The dam will be opened after the second and third warnings are issued. This was the procedure until last year. After the 2018 floods, the KSDMA decided to prepare rule curves for the dams this year to improve the operation of the reservoirs,” said the official.
The official also said that the dams in Kerala are conservation dams and don't have the provision for flood cushion (the storage space in dams marked to absorb unexpected high flows), another flaw underscored in the amicus curiae report.
“The dams are always kept full to conserve water. Last year, they were filled during the onset of the monsoon and opened when there was a warning alert,” added the official.
On August 14, 2018, water levels in the dams were already at Full Reservoir Level (FRL) or very close to FRL when the state received more than normal rainfall in June to July.
With the rule curve model in place this year, during the initial period of monsoon, the water level should be maintained below the Full Reservoir Level – this the highest storage level when the dam is no longer in a position to hold inflow of water. “When the northeast monsoon subsides, we do away with the cushion (empty space) and let the level rise - that is the fundamental principle to the rule curve,” added the official.
On the other hand, an official from Kerala State Electricity Board (KSEB), which manages more than 50 dams to meet the electricity demand in the state, said that there are no specific directives for the rule curve. "Generally, 10 to 15 days of water is maintained for power generation. If the summer rains are heavy, accordingly the demand for electricity is also high. Only then the rule curve is followed," explains the KSEB official. In 2018, however, the southwest monsoon rains were heavy but the demand was less. "While we expected 80 million units (MU) of power, only 60 MU was consumed. So, there was summer rain water for 21 days. If the demand had gone above 80 million units, the water level for electricity production would have reduced by 10 to 15 days. Since there was no demand, we were unable to produce electricity or release the water prior to monsoon," the official told TNM. This year, the demand for electricity is high although the summer rains were poor. "Hardly 10 days of water in the damis available for power generation," the official added.
All dam engineers have also been directed to conduct pre-monsoon dam inspection and rectify any defects and operational problems before May 31. The team is also in the process of chalking out long-term measures for the early flood warning system.