AI Article Synopsis

  • The Lower Barun Lake in the Nepal Himalaya is critically vulnerable to Glacier Lake Outburst Floods (GLOFs) due to its large size and steep terrain, prompting a study of its future changes under various climate scenarios.
  • Researchers used a numerical model to estimate the lake's evolution and potential avalanche risks based on current conditions and projected climate impacts, correlating model predictions with observed data.
  • Findings indicate that under two climate scenarios, the lake could reach its maximum length between 2061 and 2075, with significant risks of mass movement hazards, particularly along the southern shore as the lake expands.

Article Abstract

The Lower Barun Lake, the largest glacier-fed lake in the Nepal Himalaya, has been designated as critically or highly vulnerable to Glacier Lake Outburst Floods (GLOFs) due to the lake's massive volume and steep side walls that are susceptible to mass movements. The current study estimates the future evolution of the lake's extent and its exposure to potential avalanche under different climate scenarios by simulating the evolution of the Lower Barun glacier, which feeds the lake. We then assess this exposure (i) at the lake's current extent, (ii) when the lake length grows to 75 % of its maximum length, and (iii) when the lake length reaches its maximum possible length. We use a mass conservation based numerical flowline model for our analyses. The model was forced by the glacier surface mass balance (SMB) and meteorological data collected from weather stations in Kathmandu, Nepal and Darjeeling, India. Modelled lake lengths matched measured lengths within an RMSE of ∼200 m. Analyses show that under SSP2-4.5 and SSP5-8.5 scenarios, the lake will reach its maximum length by 2075 ± 2 and 2061 ± 1, respectively. The largest uncertainty in future lake length fluctuations is approximately 200 m. Our study reveals that in current conditions, the zone where the angle of reach of potential avalanches is highest lies on the slopes along the right shore (south side) of the lake. The angle of reach shifts upstream and steepens-and the mass movement hazard increases-as the lake grows in the future.

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Source
http://dx.doi.org/10.1016/j.scitotenv.2024.175028DOI Listing

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