MC Explains: How govt plans to safeguard hydroelectric projects in the aftermath of Sikkim floods

It is in the Northeast that the government is looking to tap hydropower in a big way. Projects with an installed capacity of 5,000 MW are being built in the region.

It's been a week since Sikkim was hit by floods, which took a death toll of 82 and left more than 100 missing. The calamity struck when the South Lhonak glacial lake burst resulting in a Glacier Lake Outburst Flood (GLOF), which wiped off the 1,200 MW Teesta III hydroelectric plant (HEP) and damaged another HEP downstream called the Teesta-V plant. The Sikkim government had a majority stake in the Rs 14,000 crore Teesta project.

The calamity has once again brought the focus back on hydroelectric projects in India, which are increasingly becoming challenging to execute due to numerous factors. Here’s an explainer taking stock of hydroelectric projects in the country and the measures taken by the government to protect them during natural calamities.

Which are the major instances of damage to HEPs in India in the past decade?

Even before the GLOF in Sikkim, HEPs in India have time and again been battered by disasters, with a section of environmentalists questioning the need for such constructions which take decades to build, are expensive and also supposedly disturb the ecological balance in hilly areas.

In July, hydropower projects in Himachal Pradesh, Jammu & Kashmir and Uttarakhand were hit due to heavy rains in North India which caused floods in the valleys. Four plants of NHPC alone —Dul Hasti Hydro Electric Project (390 MW), Salal (690 MW) on the Chenab River in Jammu & Kashmir, Chamera II (300 MW) and Chamera III (231 MW) on the Ravi in Himachal Pradesh —were shut. The plants were flooded with silt and could not be used to generate power.

The commissioning of the 800 MW Parbati-II hydropower project, which was delayed by about 13 years due to tunnelling issues, also slipped further into FY25, due to the floods.

In January this year, Joshimath in Uttarakhand faced the worst land subsidence in its history and experts said the reasons were multiple, ranging from rampant infrastructure development to a fragile ecosystem and seismic zone. Many blamed the Tapovan Vishnugad hydroelectric power project, which is being built by state-owned NTPC Ltd. The construction of the project has been stalled since then.

On February 7, 2021, the Chamoli district of Uttarakhand was hit by unprecedented floods after a part of the Nanda Devi glacier broke, damaging two hydropower projects and leaving more than 200 people dead or missing. The floods washed away the 13.2 MW Rishiganga hydroelectric power project and the Tapovan project on the Dhauliganga river, a tributary of the Alakananda.

Uttarakhand was wrecked by another major flood in 2013 in Kedarnath that killed at least 5,000 people and damaged at least 10 hydropower projects.

So, has the Indian government taken a step back from HEPs?

The government continues to push for hydroelectric projects as they are a clean source of electricity compared to coal-fired power plants. In fact, the government intends to increase the overall share of hydroelectric projects to meet its target of having an installed renewable energy capacity of 500 GW by 2030.

As of March 31, 2023, India had an installed hydroelectric power capacity of 42,104.55 MW, which is 29 percent of the total reassessed potential capacity of 1,45,320 MW. The projects under construction account for a capacity of 15,023.5 MW. As such, at least 57 percent identified capacity is yet to be harnessed, according to the Central Electricity Authority (CEA), which is India’s apex power planning body.

Hydropower constitutes only 11 percent of India's total installed power generation capacity as of date. In 1962-63, hydropower constituted 52.78 percent of India's entire installed capacity, according to CEA data.

It is in the Northeast that the government is looking to tap hydropower in a big way. Projects with an installed capacity of 5,000 MW are being built in the region. The government has also proposed an 11,000 MW Siang hydropower project in Arunachal Pradesh, which, if approved, will be India’s largest hydropower project. As of now, the project is still at a “discussion stage”, said NHPC officials.

What steps are being taken in the Sikkim GLOF incident?

The CEA has now released guidelines for slope stability in hydropower projects. In the framework, made public on October 9, the CEA said the design, construction and maintenance of the slopes is one of the major challenges during the planning, construction and operation of hydropower projects. Generally, slope instabilities in hydropower projects are encountered during execution as well as operation.

“Hydropower projects usually involve heavy surface excavation for placing the dam, power intakes, surface power house and other structures that lead to the formation of excavated rock/soil slope. It is essential to maintain the stability of these slopes for unhindered and successful delivery of the project,” the CEA stated.

Defining ‘vulnerable projects’ as those with a capacity of 400 MW and above, the guidelines stated that the project authority or developer would be responsible for examining the upper reaches, including the reservoir, identifying fault sites and taking remedial measures for stabilisation.

The CEA has suggested slope stabilisation methods, practices to be followed both before construction and after commissioning of the project, and collection of records of all major slope failures including satellite imageries in and around the project area dating back to two decades.

“The examination of upper reaches may include study of hazards due to avalanche, GLOF (glacier lake outburst flood), landslide hazard analysis of slopes above the reservoir rim area, among others," it said.

What are the other measures taken by the government?

Prior to the Sikkim tragedy, the CEA in September had set up an expert panel to look into the technical problems and resultant cost overruns in hydroelectric projects, most of which are mired in multiple delays due to geological hurdles, weather effects or local protests.

The new panel will analyse the events of geological surprise(s) faced by hydroelectric projects and give its recommendations. It will also have to vet the additional time which may be needed due to the geological surprise faced, besides, examining the proposal for enhanced cost owing to geological surprise.

In December 2022, the government signed a contract with the Defence Research and Development Organization (DRDO) of the defence ministry for the implementation of an early warning system (EWS) for vulnerable hydro projects or power stations.

EWS is an integrated system of hazard monitoring, forecasting and prediction, disaster risk assessment, communication and preparedness for timely action to reduce disaster risks before hazardous events happen. It can save many lives by ensuring the evacuation of those living in the valley or such affected areas. However, the implementation of the same has not yet been completed.