Functioning of glacierized catchments in Monsoon and Alpine regimes of Himalaya

Glacier mass balance (MB) and runoff relationship is poorly explored in the Himalaya due to limited in-situ data. A simplified glacio-hydrological model is used to reconstruct the long-term MB and runoff on Dokriani Bamak Glacier (DBG) in the Monsoon regime and Chhota Shigri Glacier (CSG) catchments in the Alpine regime of the Himalaya. Since 1950, DBG and CSG show limited mass wastage with mean annual glacier-wide MB of -0.09 +/- 0.35 m w.e. a(-1) and -0.12 +/- 0.28 m w.e. a(-1), respectively. The mean annual catchment-wide runoff are also almost similar 0.13 +/- 0.01 106 m(3) a(-1) and 0.14 +/- 0.01 106 m(3) a(-1) from DBG and CSG catchments, respectively over 1950-2020. Available in-situ short-term MB and runoff data from eight glacierized catchments do not show any significant MB-runoff relationship, except for CSG. The long-term modelled MB and runoff data on both DBG and CSG catchments suggest that the higher catchment-wide runoff corresponds to more negative MB, and vice versa. This is in contrast to the previously suggested MB-runoff relationship on DBG catchment. Present detailed analysis also indicates that the hydrology of the DBG catchment is mainly dominated by the summer precipi-tation, while in CSG catchment, it is mainly controlled by the glacier-wide annual MB. In dry years, the corre-sponding negative annual MB on both the glaciers provides additional glacier-degraded runoff to the catchment streams that can be as high as 13% and 38% of total runoff on DBG and CSG catchments, respectively.

Automated summary

The relationship between glacier mass balance (MB) and runoff in the Himalaya has been poorly studied due to limited data. This study used a simplified glacio-hydrological model to reconstruct the long-term MB and runoff on two glaciers in different regimes of the Himalaya. The results show that the glaciers have experienced limited mass wastage and the catchment-wide runoff is correlated with the glacier mass balance.