- Hydropower projects in Nepal are at risk due to climate change.

- The incidents in Bhairabkund and Rasuwa have exposed the lack of hydrological studies and structural weaknesses.

- It is necessary to improve risk assessment and the selection of safe locations in hydropower projects.

According to preliminary observations, there are notable similarities between the two separate disasters that occurred in Bhairabkund and Rasuwa. In both events, the hydrological studies were incomplete, and the extreme weather conditions and the possibility of glacial lake outburst floods were overlooked.

Globally, due to rising temperatures, weather patterns are becoming increasingly abnormal worldwide. In Nepal, glaciers are melting rapidly, increasing the risk of glacial lake outburst floods. Unusual rainfall, hailstorms, and high temperatures have caused significant imbalances in the water cycle. This is having long-term effects on agriculture, tourism, infrastructure, and water resources. Nepal is also being affected by these changes. Such risks arising from climate change have emerged as major challenges to the sustainable development of hydropower projects.

For example, we failed to learn the lesson from Bhairavkund. After the 2015 earthquake, the monsoon floods completely damaged the Bhairavkund (3 megawatt) project in Sindhupalchok. This project was based on the Bhairavkund River in a high Himalayan region, where there are extreme seasonal variations in river flow and geological instability. The design of the project did not adequately address rapid flows, the risk of glacial lake outburst floods, and the sensitivity of the seismic zone. There were structural weaknesses in the penstock materials and installation, and the tunnel walls were not sufficiently waterproofed. Geological testing was also only superficial.

The earthquake caused cracks in the tunnel and penstock, while the flood completely washed away the diversion weir (a structure built across a river or stream to raise the water level and divert water). The settling basin was blocked by sediment, and the transmission line and switchyard were also swept away. Since the powerhouse and office buildings were constructed right on the riverbank, they were also affected by the flood. The lack of an early warning system and inadequate emergency response structures led to the suspension of the project’s operations. Incomplete hydrological and geological studies during the design phase, selection of a risky site, and lack of structural flexibility were the main causes.

The recurrence of Bhairavkund is the Rasuwa flood. Analyzing the Bhairavkund event shows that modern hydrological studies and practical environmental impact assessments were hardly considered there. In Bhairabkund, structural decisions were likely made based on traditional practices and cost priorities rather than scientific data and forecasts.

The devastating flood that struck Rasuwa on July 8, 2025 destroyed a hydropower project. According to preliminary investigations, the main cause of this flood was the outburst of a supraglacial lake near the China border. It affected power production of over 200 megawatts, resulted in 9 deaths, and halted cross-border trade between Nepal and China.

The headworks and dam of the Rasuwagadhi (111 MW) project were completely destroyed. The switch gates of Trishuli Three-A (60 MW) were washed away, and water rose up to the tailrace (the channel where water is discharged after electricity generation) at the Devighat and Trishuli projects, disrupting power production. The Miterei Bridge connecting China and Nepal was swept away, halting import-export and supply chains. Approximately 8 percent of the electricity grid was damaged, and structures such as charging stations, trucks, containers, vehicles, and customs yards were completely destroyed. The flood has also had long-term effects on the housing and livelihoods of local residents.

Analysis of the Bhairabkund event indicates that modern hydrological studies and practical environmental impact assessments were rarely considered there. Although detailed technical information is not available, the likelihood that factors such as the risk of glacial lake outburst floods, changes in seasonal patterns, or extreme fluctuations in water flow were incorporated into the design is very low. Moreover, it can be inferred that hydrological modeling capturing the long-term behavior of water resources, geological stability assessments, and emergency flood simulations were also neglected. Environmental impact assessments appear to have been mostly limited to paperwork, with weak implementation and monitoring.

According to preliminary observations, there are notable similarities between the two separate disasters that occurred in Bhairabkund and Rasuwa. In both events, hydrological studies were incomplete, and the possibilities of extreme weather scenarios and glacial lake outburst floods were overlooked. The structures were built in risky locations, such as riverbanks or landslide-prone areas, without conducting geological stability assessments based on the existing rocks. The lack of early warning systems, environmental impact assessments limited to paperwork, and weak implementation were common problems. The technical and financial preparedness of small and medium investors was low, causing delays in emergency management and reconstruction. Insurance and protection systems were inadequate, weakening structures that could have enabled rapid relief after damages. These similarities indicate a strong possibility that we have not seriously learned lessons from past tragedies.

Damage to headworks and dam is expected in such a devastating flood, but the damage to the powerhouse, office, and residential buildings indicates a weakness in the technical design. These structures should have been built in protected high-altitude areas, but because they were constructed in risky locations, additional damage occurred. This clearly shows that there were serious errors in risk assessment and the selection of safe sites in the structural planning.

An early warning system must be established in areas prone to glacial lake outburst floods. Future seasonal scenarios should be included in hydrological studies. For construction, safe geographical locations must be selected, mandatory geological testing conducted, and monitoring mechanisms strengthened to ensure the implementation of environmental impact assessment reports. Technical assistance and improved insurance systems should be provided to small investors. Similarly, it is essential to strengthen cross-border data and information exchange.

Along with this, insurance companies are also affected due to unclear risk assessments and pressure from compensation claims. There are signs of increased insurance costs and stricter insurance procedures. Risks related to hydropower projects have now become a serious concern not only technically but also financially and strategically. These destructive events have deeply impacted not only the infrastructure but also the financial system. Banks that have invested in hydropower projects are facing significant risks. Especially, delayed repayment of loans related to small and medium projects may increase the level of non-performing assets, which affects liquidity and risk management.

Yesterday’s Bhairabkund and today’s Rasuwa are tragic examples of this. If we do not learn serious lessons from these events, such disasters will cause even greater loss of life, investment, and hinder development in the future. Therefore, hydropower projects must now become not only energy production ventures but also the foundation of national security and sustainability.

Source: Kantipur