ABSTRACT
Glaciers in the Hindu Kush Himalaya (HKH) are important freshwater resources. Glacier recession may lead to a significant decrease in summer runoff. This study focuses on Afghanistan in the western Himalayas with an arid to semi-arid climate, where, despite strong societal and ecosystem dependance upon mountain water resources, the contribution of glacier melt is poorly known. This study used a new conceptual precipitation and ice melt-runoff model to assess current and future streamflow, taking into account the effects of debris-covered ice. Three catchments with varying glacier cover are considered: Sust (4,609 km2, 15.6% glacier cover) in eastern Afghanistan; the Taqchakhana (264.4 km2 area, 2.8% glacier cover) in northern Afghanistan; and the Bamyan (325.3 km2, 0.7% glacier cover) in central Afghanistan. Results identified different annual hydrological regimes, with glacier runoff dominating Sust (76%), rain and snow runoff dominating Taqchakhana (50%), and baseflow dominating Bamyan (61%). Future climate scenarios under RCP 2.6 predict an increase in mean annual glacier runoff until 2050, followed by a decline due to temperature stabilization and cooling in Sust and Taqchakhana. Meanwhile, Bamyan's runoff is predicted to decrease throughout the 21st century. Under RCP 8.5, a more pronounced glacier runoff increase is projected in Sust and Taqchakhana.
HIGHLIGHTS
Applies a new ice melt-runoff model including a debris-covered ice representation.
Shows glaciers' influence on summer streamflow for data-scarce catchments.
Suggests climate change impacts water availability in diverse glacier-sized catchments.
Illustrates debris-covered ice impact on glacier runoff.