Climate-smarter Himalayan infrastructure
In June 2021, a massive debris flow on the Melamchi River killed at least 30 people, submerged settlements, and nearly destroyed Nepal’s biggest infrastructure project to supply water to Kathmandu.
Scientists blamed the climate crisis. A wall of mud raced down the river after unprecedented rainfall at the beginning of the monsoon on glacial deposits left by melted ice.
Boulders and mud paste buried the headworks of Melamchi Water Supply Project under 20m of debris, resulting in damage worth more than Rs2 billion. Timely closure of the gate saved the project’s 26km tunnel to Kathmandu from irreversible damage.
“Melamchi project cost $800 million and nearly 25 years to complete, but it took just one weather event to render it nearly useless,” says water expert Madhukar Upadhyay. “It only goes on to prove that our landscape is not suitable for large infrastructure projects. And now we have climate change in the mix.”
Nepal’s only reservoir project on the Kulekhani was commissioned in 1982 and was supposed to have a lifespan of 100 years. But a cloudburst in the catchment area in 1993 deposited so much debris into its lake that the cascade project that generates 106MW of electricity will now function for only another 30 years.
The Himalayan mountains are warming between 0.3 to 0.7°C faster than the global average, and a report by the International Centre for Integrated Mountain Development (ICIMOD) predicted that even in the best-case scenario, more than one-third of the remaining ice will melt during this century. If current global heating trends continue, two-thirds of the ice will be gone.
Meltwater from Himalayan glaciers collect behind fragile moraine dams, increasing the threat of Glacial Lake Outburst Floods (GLOFs) that can wash away infrastructure: hydropower plants, highways, bridges and canals.
As it is, many of these projects have either ignored or falsified their Environmental Impact Assessment (EIA). They are built along rivers that have not been properly assessed for extreme weather.
A paper last month in the journal Nature Geoscience titled ‘High Mountain Asia hydropower systems threatened by climate-driven landscape instability’ has a checklist to minimise climate-driven hazards on Himalayan infrastructure.
‘Maps of the distribution of paraglacial zones, sediment yield and hazard susceptibility that better delineate current and future unstable landscapes and erosion-prone regions should be produced,’ states the paper. ‘Policy development regarding maintaining existing and planning of new hydropower projects should be guided by such hazard and risk maps.’
Researchers point out that storage capacity design should consider potential storage losses associated with increasing sediment loads due to climate change, and provide additional storage, sediment bypassing, sluicing, dredging and drawdown flushing to minimise sedimentation and increase reservoir lifespans.
Catchment management can reduce slope instability and erosion rates with reforestation and check dams. ‘For existing reservoirs, a reassessment of sediment management solutions aimed at enhancing sustainable sediment management is recommended,’ the Nature Geoscience paper states.
Upadhyay agrees: “The first thing is to study and assess the area before the start of the project. In case they are already functioning, we have to monitor how they are affected, which will give us insights into future weather patterns. But most importantly, we need localised forecasts.”
Indeed, the paper also recommends monitoring, forecasting and early-warning systems to be developed and implemented. ‘Strategically oriented monitoring networks that measure high-altitude climate, glacier and permafrost dynamics, glacial lakes, unstable slopes and water and sediment fluxes should be expanded for high-risk areas,’ it adds. Nepal has either too much or too little water. Seasonal floods and the weather extremes here predate climate change. Other disasters not related to climate, such as earthquakes, multiply the risk for infrastructure.
And yet, there is no proper mechanism even to assess loss and damage post-disaster which is ironic given Nepal’s strong stance on climate justice at international climate conferences.
“Loss and damage as an issue has been highly politicised, but it is also rooted in climate justice, and what we are experiencing today is a cumulative impact of the last 150 years,” explains climate scientist Ajaya Dixit. “Nepal must continue to be a part of this discourse, but we must also do our bit. We must not just lobby for funds but also for support and partnerships to actively address changes due to the climate.”
Nepal’s current response to climate disasters is limited to search, rescue and relief. Mitigating and adapting to risk, for example by reducing the level of glacial lakes such as Imja and Two Rolpa, are dependent on funding.
Nepal now has better standardised data through the BIPAD portal under the National Disaster Risk Reduction And Management Authority (NDRRMA). The next step is to map hazards, prioritise infrastructure and people most at risk through local first responders.
Adds Dixit: “We need a large-scale systemic change to adapt to the climate crisis but for now we can start with developing and implementing a robust assessing mechanism. And it is unacceptable that our infrastructure still follows designs, methods and metrics from the time when climate change was not even in our vocabulary.”
Such is Nepal’s hydropower potential that it has provided it geopolitical leverage. India is increasingly expanding its investment on Nepal’s rivers, and building large reservoir projects. Chinese companies are building hydropower projects directly downstream from high-risk glacial lakes in Tibet.
Climate disasters raise the issue of a cross-border risk, since many of Nepal’s start in China, where there are many glacial lakes that are at bursting point. GLOFs originating in China have in the past destroyed highways and hydropower projects on the Bhote Kosi.
Research by Chinese scientists on the Nyainqêntanglha mountains on the Tibetan Plateau even five years ago showed that the frequency of destructive GLOFs were increasing, and they proposed urgent mitigation measures.
‘Potential damage from GLOF disasters is significant,’ wrote Shijin Wang and Lanyue Zhou in the International Journal of Disaster Risk Science, ‘There is an urgent need for (Chinese) government departments to implement engineering measures on all potentially dangerous glacial lakes.’
Nepal is increasingly reliant on selling its surplus electricity to India. Power generation in the monsoon exceeds 2,100MW even as average domestic demand stands at just 1,550 MW. Another 2,500MW of electricity will be added to the grid in the next two years, while 3,000MW of new projects are in the pipeline.
But these projections are at the mercy of future climate-induced risk. Says Upadhyay: “If hydropower is indeed our future, we must treat it with that kind of seriousness and commitment. We must bring in experts who think not only in monetary terms, but holistically at how the climate crisis is changing the Himalayan landscape.”
Read more: Climate risk to hydropower investment, Ajaya Dixit