On October 4, 2023, a devastating glacial lake outburst struck North Sikkim, sending shockwaves across the northeastern state. The lake outburst occurred in Lhonak Lake, resulting in a sudden and alarming rise in the water level of the Teesta River. The water level surged to 30 feet in an instant, causing widespread flooding and damage in the Himalayan state.
The Chungthang dam washed away due to substandard construction, causing widespread devastation.
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This tragedy is a stark reminder of the dangers of unscientific and large dams. The Chungthang dam was one of eight small dams on the Teesta River, and local ethnic groups had long protested against its construction due to the risk of landslides and earthquakes in the region. However, the government ignored their concerns.
Despite the clear risks, the BJP government is currently moving forward with the construction of the Lower Subansiri Hydropower Project at Gerukamukh along the Assam-Arunachal Pradesh border, ignoring the objections and resistance from organizations. Geologists warn that the area is prone to earthquakes, and there is a high probability of a major earthquake occurring during the dam’s construction or operation. There have been repeated reports of damages to the dam came to light.
Then in 1950, an earthquake measuring 8 on the Richter scale caused mountains to fall and block the river Subansiri, the heart of northern Assam, for three days. The river has been flooded for three days and the waters of the Subansiri have taken the form of a devastating explosion. There were about 1,000 people killed in that incident.
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Two of the five plates that make up the Earth are the Indian Plate and the Eurasian Plate. The Himalayas were formed by the collision of these two plates. These two plates are still in motion and therefore there is a high probability of earthquakes in this region.
The recent devastating earthquake measuring 7.6 on the Richter scale in Nepal and landslides in the mountains of Arunachal Pradesh caused by heavy rains indicate future danger to the Lower Subansiri Project.
WAPCOS, an agency of the Government of India said in a report that the Lower Subansiri Hydropower Project is located in the ‘V’ zone of the Earth and is prone to landslides due to its soft rock formations.
The agency added that the dam would cause 2,56,402 cubic meters of water per second to flow into the plains and cause flooding of 30 feet in the southern region within 35 minutes, which is likely to lead to the destruction of the river island of Majuli along with the entire north of Assam.
A report titled “Report On Downstream Impact Study Of The Ongoing Subansiri Lower Hydroelectric Power Project At Gerukamukh Of National Hydroelectric Power Corporation Limited”, by an expert committee comprising experts from Dibrugarh University, University of Guwahati and Indian Institute of Technology Guwahati have mentioned the same.
On May 27, 2020, after heavy rains, the water level of the Subansiri River rose two feet above the main dam of the project. The main road leading to the project was destroyed and a large part of the guard wall of the project collapsed.
According to the Central Water Commission, the Subansiri River carries about 9,000 tonnes of sediment. This amount of sediment will come and accumulate in the dam. It is learnt that no technical measures have been taken to remove the sediment.
After the construction of the Ronganodi dam, which was way smaller than the Subansiri dam, the water of the Ronganodi dried up for two years and the area became a desert.
On the night of July 14, 2008, 22 people were killed when water from the Ronganodi Project flooded hundreds of villages in Lakhimpur, Bihpuria and Naobaicha.
The people of North Assam have been suffering for years due to the release of water by NEPCO and Dikrang.
In addition, the floods in Goalpara and Dhubri districts in 2004 caused by the release of water from power generation projects in Meghalaya and the damage caused by the water of the Kurisho dam in Bhutan in 2007 in southern Assam are well known.
The Sikkim dam disaster is a stark warning of the dangers of unscientific and large dams.