Estimation of mass and energy balance of glaciers using a distributed energy balance model over the Chandra river basin (Western Himalaya)

The ongoing glacier shrinking in the Himalayan region causes a significant threat to freshwater sustainability and associated future runoff. However, data on the spatial climatic contribution of glacier retreat is scanty in this region. To investigate the spatially distributed glacier surface energy and mass fluxes, a two-dimensional mass balance model was developed and applied to the selected glaciers of the Chandra basin, in the Upper Indus Basin, Western Himalaya. This model is driven by the remote sensing data and meteorological variables measured in the vicinity of the Chandra basin for six hydrological years (October 2013 to September 2019). The modelled variables were calibrated/validated with the in-situ observation from the Himansh station in the Chandra basin. We have derived air temperature (T-a) spatially using the multivariate statistical approach, which indicates a relative error of 0.02-0.05 degrees C with the observed data. Additionally, the relative error between the modelled and observed radiation fluxes was a(-1) for the six hydrological years. Results illustrated that the mean surface melt rate of the selected glaciers ranged from -5.1 to -2.5 m w.e. a(-1) that lies between 4500 and 5000 m a.s.l. The study revealed that the net radiation (R-N) contributes ~75% in total energy (F-M) during the melt season while sensible heat (H-S), latent heat (H-l), and ground heat (H-G) fluxes shared 15%, 8%, and 2%, respectively. Sensitivity analysis of the energy balance components suggested that the mass balance is highly sensitive to albedo and surface radiations in the study area. Overall, the proposed model performed well for glacier-wide energy and mass balance estimation and confirms the utility of remote sensing data, which may help in reducing data scarcity in the upper reaches of the Himalayan region.

Automated summary

The study developed a two-dimensional mass balance model to investigate the spatially distributed glacier surface energy and mass fluxes in the Western Himalaya. Results showed that net radiation is the major contributor to total energy during the melt season, while sensible heat, latent heat, and ground heat fluxes have smaller contributions. Sensitivity analysis indicated that albedo and surface radiations are highly sensitive factors affecting glacier mass balance in the study area.