India marks 12.6% of its landmass as landslide-prone. Uttarakhand accounts for 18.47% of its area in the high-to-very-high susceptibility band, driven by hydropower, highways, and urban sprawl carving into young, fragile slopes. Mizoram still leads state-wise susceptibility charts, followed by Kerala. If current trends hold, Sikkim will claim that grim title.
In 15 years, Sikkim has inverted. Once a high-altitude sanctuary for red pandas, Himalayan monals, blood pheasants, and 4,500+ species of flowering plants including 500+ orchids, the state is now a case study in development-induced subsidence.
Dams, Tunnels, and a Valley Cracking Open
Sikkim’s Teesta river basin holds over 8,000 MW of hydropower potential. As of 2019, 47 hydropower projects in Sikkim and West Bengal were at various stages, totaling 6,753.5 MW installed capacity. The state’s own push since 2003 has seen “over 168 large dams proposed in the Eastern Himalayan Region”.
Two major projects operate today: Dikchu and Legship. The 1,200 MW Teesta-III at Chungthang — Sikkim’s largest — was obliterated on 4 October 2023 when South Lhonak glacial lake burst. The GLOF killed at least 55 people and up to 94 by some counts, displaced 2,563, and affected 88,400 people with 33 bridges destroyed. Yet it is still being rebuilt.
The tunneling that feeds these projects has left slopes hollow. Drive from Singtam toward Chungthang: the highway is sinking, slumping, splitting. Above Dikchu dam, a 2023 landslide damaged the Dikchu-Rakdong Road in Sokpay village affecting 18 families. Villagers in Rakdong and Tintek now report widening fissures in homes and fields — classic subsidence markers seen in Joshimath-style sink zones.
“We heard the mountain groan at night. In the morning, the kitchen wall had a crack I could put my hand through,” says a resident of Lower Rakdong, requesting anonymity. “NHPC said it’s natural. But the blasting for the tunnel is not natural.”
Cross Tashiding bridge: Simolay, Dalep, Hingdam to Kezwing are all on the move. So is the Bermiok belt above the Sirwani dam site on the Teesta. The pattern is clear — where dams and tunnels go, the land sinks.
Dzongu and Toong: When the GLOF Hit Home
The 2023 GLOF did not just take the Chungthang dam. It scoured Dzongu, the Lepcha reserve in North Sikkim, cutting off 100 villages. Toong, a village downstream, was inundated; homes, fields, and the only connecting bridge vanished in hours. Relief teams documented 70+ deaths and 140 displaced persons in the initial phase.
“Toong was never on any landslide map,” says a Dzongu youth volunteer who helped with body recovery. “The river took it in 20 minutes. Now every rain, we think it’s coming back.”
Dzongu remains cut off for weeks each monsoon. The debris from Teesta-III raised the riverbed by 15–20 feet downstream in Kalimpong, displacing 70+ families. Ecologists call it a “sediment tsunami” — 270 million cubic meters of material — that has choked fish spawning grounds and buried riparian forests.
The Promise, the U-Turn, and Teesta Stage-V
The current SKM government came to power in 2019 after ending 25 years of SDF rule. During that campaign, hydro projects were a flashpoint. Activists and opposition leaders demanded scrapping of dams, citing corruption and ecological risk. Yet since 2019, stalled projects have been revived, not scrapped.
Many dams had frozen due to corruption probes and corporate collapse. Lanco Teesta Hydro Power in Sirwani, developer of the 500 MW Teesta-VI project, went into insolvency after failing to repay a Rs 3.13 billion loan to ICICI Bank. NHPC took over the project through NCLT for Rs 897.50 crore, with an estimated completion cost of Rs 5,748.04 crore.
Other stalled projects — Panan, Rangit IV — were also tied up in regulatory issues, land acquisition challenges, and high costs. Rangit IV, awarded to Jal Power Corporation in 2004, was later acquired by NHPC via NCLT.
Now, new clearances are moving. NHPC tenders show active work at Teesta-V Power Station, including maintenance and construction. Teesta Stage-IV, a 520 MW project in Mangan, is under conceptualization with a 2027 start date. The Central Water Commission sought bids in 2025 for a cross-sectional survey of the Teesta River in Sikkim, a precursor to more projects.
The irony: Sirwani, above which Bermiok and surrounding villages are already sinking, hosts Teesta-VI. Locals say the project was “on the verge of being scrapped” after Lanco’s bankruptcy. Instead, it’s being completed by NHPC within five years. New MoUs have replaced old ones, and construction has restarted across the Teesta basin.
The Biodiversity Bill
Sikkim’s forests are part of the Eastern Himalaya biodiversity hotspot. Teesta and Rangit basins shelter golden mahseer, snow trout, and rare amphibians. Muck-dumping from HEPs has silted streams; tunneling has lowered water tables. Road cuts for dam access have fragmented Khangchendzonga National Park’s buffer, home to red pandas and Himalayan tahr. The IUCN lists 23% of Sikkim’s endemic flora as threatened. Each new project pushes that number up.
Blasting frequencies have disrupted nesting of the Himalayan monal and Satyr tragopan. The state animal, red panda, is now forced into narrower, steeper corridors above 3,000 m because its mid-altitude bamboo belts are being cleared for approach roads.
Engineering vs Geology
New road-widening is sanctioned even where slopes visibly creep. Singtam-Legship highway works continue despite annual monsoon washouts. The Geological Survey of India has completed 1:50,000 landslide susceptibility mapping for 19 states/UTs, including Sikkim, yet DPRs still clear projects in “high” zones.
Sikkim Himalaya show 11.54% and 10.29% of watersheds fall in High Susceptibility Zones. Another assessment notes 0.34 million km² of India under high/very high risk. The data exists. The political will to heed it does not.
Sikkim’s rainfall is intensifying. Temperatures are rising — Jorethang hit 40°C in 2004, a record for a hill town. The WMO listed the 2023 Sikkim GLOF among Asia’s worst climate disasters. Glacial lakes in the region have doubled since 1984.
Development, For Whom?
The CAG has flagged Rs. 2,514.49 crore annual losses from Sikkim’s hydropower push, with Rs. 1,105.47 crore retained by the Power Dept and no penalties for delays. Rongnichu and Teesta-III remain stalled or damaged due to fund crunches and mismanagement.
Meanwhile, blocked highways each monsoon cut tourist inflow, rot cash crops, and isolate villages. The revenue loss compounds. The human loss is irreversible.
The Ledger
The government calls this development. The ground calls it subsidence. If Sikkim continues building dams on sinking slopes and highways on sliding soil, it will not just surpass Mizoram as India’s landslide capital. It will become a monument to how we mistook megawatts for progress, and buried a living Himalaya under concrete.
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