Environment & Climate
Himalayan study models worst-case glacial flood scenarios along China-Nepal border
Researchers assessed simulated rock and ice avalanches in Tibet's Poiqu river basin, finding potential flood discharges far exceeding previous estimates.
The short version
- A study in Natural Hazards and Earth System Sciences evaluated worst-case glacial lake outburst flood (GLOF) risks from current lakes Galongco and Jialongco, as well as a potential future lake upstream of Nyalam, Tibet.
- Simulations showed avalanche-triggered outbursts could cause water discharges at the Nepal border more than 15 times larger than previously anticipated.
- Estimated warning times are extremely limited, lasting 5 to 11 minutes in Nyalam and 30 minutes at the border with Nepal.
- Authors concluded that recent water-lowering measures at Jialongco would have little effect against massive floods, urging improved early warning systems and land-use zoning.
Key facts
- Simulated worst-case GLOFs in the Poiqu river basin could produce discharges at the Nepal border more than 15 times greater than historical observations or gradual breach projections.[Hacker News]
- Projected advance warning times for communities downstream of the assessed lakes are 5 to 11 minutes in Nyalam and 30 minutes at the Nepal border.[Hacker News]
- Galongco's surface area expanded by 450 percent from 1.00 to 5.46 square kilometers over recent decades, making it the basin's largest lake.[Hacker News]
- At least 17 GLOF disasters have been recorded in Tibet since 1935, with a frequency of about 1.3 events per year documented across the Himalaya since the 1980s.[Hacker News]
- The study noted that recent water-level reduction efforts at Jialongco would offer limited protection against high-magnitude floods due to infrastructure built directly within Nyalam's flood zone.[Hacker News]
What remains uncertain
- The precise timing and eventual formation of the modeled future glacial lake upstream of Nyalam remain uncertain.[Hacker News]