Assimilation of EO based data into LSM to compute the contribution of snowmelt to discharge in the High Mountainous Region.

The cryosphere is an important component of the Earth’s climate system and is exceptionally sensitive to global warming. Studies have shown the decline in the ice and snow cover with increasing temperatures in the Himalayan Mountainous Region (HMR), the third-largest deposit of ice and snow. The melting of ice and snow contributes to the discharge and affects the availability of water in the downstream areas. The introduction of satellite-based observations in conjunction with land surface modelling is paramount as the scarcity of ground data in the mountainous region limits the study.

The study focuses on the snowmelt contribution of the HMR to the discharge of Ganga Basin. An integrative approach of NASA Land Information System Framework (LISF)-NOAH Land Surface Model and Runoff Routing Model is used to estimate the snowmelt contribution to discharge. The snowmelt contribution has been compared for the period 2008-2018 based on two model runs, i.e., control with experiment run wherein satellite-based snow cover observations (MODIS) has been assimilated in the model based on Direct Assimilation (DA). Assimilation of snow cover data helps to model the snowmelt efficiently as compared to control run which is then used to simulate discharge and snowmelt contribution to discharge.

The simulated DA mode results are more congruous with the station observed data and is helpful in producing a snowmelt baseline for the HMR. The snowmelt baseline can be used for comparing future snowmelt contributions to discharge in the context of environmental change.