Runoff modeling of debris-covered Gangotri glacier System, Himalaya using ERA5 data since 1979

Abstract

The present study describes the hydrological characteristics of the Gangotri Glacier System, which is one of the largest glacier systems in the Bhagirathi Basin, located in the Garhwal range of the central Himalaya in the Uttarakhand state of India. Snow melt, ice melt and rainfall-runoff were reconstructed over 1979–2020 for the Gangotri Glacier catchment (India) applying a glacio-hydrological model. The model was calibrated against available geodetic MBs over the period 2006-2014. Model validation was done using field-observed runoff for the period 1999–2000. The mean annual catchment-wide runoff is 12.94 𝑚 over 1979–2020. Snow melt 3/𝑠 contribution was the maximum with a value of 33%, while debris covered ice melt, rainfall and clean ice melt contributed 31%, 21% and 15%, respectively to the total runoff over this period. The whole Gangotri Glacier System shows the maximum annual runoff of 15.65 𝑚 in the 3 𝑠−1 year 1994 and the minimum annual runoff of 10.26 𝑚 in the year 1989. The model is most 3 𝑠−1 sensitive to the threshold temperature for melt.