Melt Runoff Characteristics and Hydro-Meteorological Assessment of East Rathong Glacier in Sikkim Himalaya, India

Hydro-meteorological records of glacier meltwater are very limited in the Indian Himalayan region, especially in the Sikkim Himalaya. Hydrological data coupled with meteorological parameters (temperature, rainfall and humidity) of a catchment facilitate in understanding the dynamics of glacier’s meltwater generation at a local scale. Sikkim Himalaya, an integral part of eastern Himalaya lacks the hydro-meteorological assessment of glacier’s meltwater stream. Therefore, hydro-meteorological analysis of East Rathong Glacier was conducted for three consecutive ablation seasons (June – September) from 2013 to 2015. The data record a maximum runoff during the peak ablation month of July and August (~ 69%), reflecting the seasonal evolution of hydrologic conduits and the expansion of subglacial channels, and the rest runoff observed during June (~ 10%) and September (~ 21%). During the study period, the maximum ( Q max ) and minimum runoff ( Q min ) of 15.71 and 1.46 m 3 s −1 , respectively were recorded at 17:30 and 9:30 h. The maximum monthly variability in meltwater discharge was recorded in June (C v = 0.29) and September (C v = 0.37), which reflects the role of the large extent of seasonal snowfall during early ablation and the seasonal evolution of sub-glacial internal drainage networks in the glacier, respectively. We found that the variability in mean ( T mean ) and maximum temperatures ( T max ) has been increased over the subsequent months during the progress of the ablation season with the highest variability in minimum temperature ( T min ) during the end of the ablation season. The correlation matrix analysis shows significant hydro-meteorological relationships of glacier’s meltwater discharge (Q) with the minimum temperature ( R 2 = 0.43), maximum temperature ( R 2 = 0.93), mean temperature ( R 2 = 0.93), Rainfall ( R 2 = 0.99) and Relative humidity ( R 2 = 0.77), suggesting the substantial meteorological influences in producing meltwater discharge at monthly scale. The present in-situ observation on hydro-meteorological characteristics of East Rathong Glacier can be used effectively for the hydrological modelling of freshwater resources (Glaciers) which further contribute to the freshwater management under a changing climate.