Why are India's hydroelectric dams, hydropower plants triggering catastrophic flash floods

By Sila Wati*  

From a layman's point of view, without going into technical details, we have witnessed the disastrous nature of dam failures many times. Such incidents are hazardous not only to the lives and property of people in Sikkim but also to the entire ecosystem and biodiversity of North East India, which may take many years to recover.

If we look at the devastation caused by the recent dam failure in Himachal Pradesh, we can estimate how much grief and suffering this has caused to the local population.

On August 1, the Malana dam failed, causing major loss of life and property in several villages downstream. The death toll  reached 22, with more than 30 people missing. More than 100 roads were closed, causing further inconvenience to the lives of people in the area.

Malana-I Hydroelectric Power Station is an 86MW run-of-river hydroelectric power plant located in Kullu, Himachal Pradesh. The power station has been generating electricity since 2001.

According to reports, the water level had been overflowing for 10 to 15 days before the disaster struck, and eventually a “torrential downpour” caused the dam to collapse, wreaking havoc in the valley.

Another disaster that cannot be ignored due to the collapse of the dam is undoubtedly the October 4, 2023 South Lonac Lake Outburst. This disaster led to the Great Fin Modal Flood which resulted in the destruction of the Chungthang Dam, the largest dam in Sikkim. 

The Tista Work H hydroelectric project, which cost Rs 139.65 billion and had a capacity of 1,200 MW, has been abandoned. The project was an important source of revenue and the Sikkim government held a 60% stake in the project. The total loss due to this disaster is estimated to be over Rs 2,500 crore, close to 60% of the state's GDP in 2022-23. 

The impact on the power sector is two-fold, with assets worth nearly Rs 1,400 crore having become non-performing and the loss of revenues from the Tista Work H hydropower project. Sikkim is also entitled to power from the project, which means an annual revenue loss of Rs. 300-400 crores. 

The Government of India allocated of Rs. 2.45 billion from the National Disaster Relief Fund (NDRF) for immediate relief and rehabilitation. Experts in various fields conducted a post-disaster needs assessment and identified the requirements for full rehabilitation and reconstruction to be of a total amount of Rs 36.73 billion.

Are these natural disasters? Or are they man-made disasters?

With two such catastrophic incidents in less than a year, should we feel at risk for building so many dams in North East India?

There are at least two mega dams coming up in the Dibang Valley region alone, and work has already begun on one of them. These dams are being built to generate more hydroelectric power than the dams mentioned above. So, should we be prepared for a bigger disaster?

The 2,880 MW Dibang Multipurpose Hydroelectric Project is currently under construction and at 278 meters high, it will be the tallest dam in India. It will generate 11,223 million units of hydropower annually. It is understood that after the completion of the project, the Arunachal Pradesh government will receive 12% free power from the Dibang Hydroelectric Power Plant, while another 1% free power will be donated to the region through the MP Local Development Fund.

The remaining energy will be sold to other northeastern and eastern states of India.

Then there is the 3,097 MW Ettaling Hydroelectric Project, which is also a run-of-river project whose construction is most likely to begin in 2027. This project is expected to generate 1,275.2 billion watt-hours of electricity.

God alone knows the extent of the devastation that will be inflicted on the downstream areas once these dams collapse.

We do know that hydropower/ hydroelectric dams have advantages. First, hydropower is a renewable energy source. Unlike conventional fossil fuel energy sources, the use of hydropower does not release any pollutants into the air or sewage. It can be produced within India, thus reducing our dependence on other fuel sources. Moreover, it provides low cost electricity and long term durability as compared to other sources of energy.

Hydroelectric dams/ hydropower plants should also help in flood control. But paradoxically, we have witnessed catastrophic flash floods triggered by them so far.

The monsoon has been very unfavorable for the Dibang Valley region as it has been for the rest of the state. This fact makes us think whether these dams are good or bad for us.

Arunachal Pradesh needs to ensure the safety of dams from construction to operation. They need to comply with the provisions of the Dam Safety Act, 2021.

The Act was introduced in December 2021 to address the persistent problem of inadequate monitoring and maintenance leading to dam failure-related disasters. The Act establishes responsibilities at the national and state levels to ensure the safety of dams in order to address these issues.

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*Content creator, graduate from the Sociology Department of New Delhi University, living in Itanagar