Following a series of heavy pre-monsoon rains that triggered localized landslides in the upper catchment areas of Sindhupalchowk, the Ministry of Water Supply has announced an emergency mitigation strategy to ensure the uninterrupted flow of water to the Kathmandu Valley throughout the upcoming rainy season.
In a bid to break the multi-year cycle of shutting down the system every monsoon due to heavy debris, engineering teams have begun deploying temporary geogrid walls and reinforced barrier systems. These structures are being strategically erected to shield the vulnerable intake and headworks from cascading hillside failures.
Engineering Against the Elements
The Melamchi Water Supply Project—long considered the primary lifeline for easing Kathmandu’s chronic water scarcity—has remained intensely vulnerable to extreme weather since the catastrophic 2021 floods buried its primary infrastructure under 24 meters of debris. Until now, the project’s executive management had to completely suspend water diversion during the high-precipitation months to protect the intake tunnel from being choked by mudslides and boulders.
This year, however, authorities are opting for an active defense mechanism rather than a passive shutdown.
According to technical details released by the Ministry, the new resilience plan involves:
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Geogrid Earth Retention: High-strength polymer geogrid grids are being used to stabilize vulnerable slopes directly overlooking the primary intake channel at Ambathan.
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Flexible Debris Deflectors: Heavy-duty steel and geosynthetic barriers are being anchored above the headworks to catch or divert smaller-scale rockfalls before they can clog the Duwali diversion gates.
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Upstream Monitoring: The installation works are being paired with localized community-based early warning networks to monitor sudden changes in the upper river basin’s sediment load.
A Stopgap Until Permanent Relocation
While the installation of geogrid walls offers a vital defensive line for the 2026 monsoon, ministry officials freely admit it is an interim fix.
The long-term master plan involves permanently relocating the entire buried water source to Sarkathali—roughly one kilometer further upstream from the current Ambathan site. A definitive design for the new, highly resilient intake system is currently being finalized with backing from the Asian Development Bank (ADB), though construction is expected to take at least two years.
For the estimated two million residents of the Kathmandu Valley relying on the bulk water supply network, the success of these temporary geogrid walls over the next three months will dictate whether their taps remain running, or if they will be forced to look to expensive private tankers and depleting groundwater resources until autumn.