Future projection of cryospheric and hydrologic regimes in Koshi River basin, Central Himalaya, using coupled glacier dynamics and glacio-hydrological models

• Published in: Journal of Glaciology
• Main Authors: Mira Khadka, Rijan Bhakta Kayastha, Rakesh Kayastha
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2020
• Subjects: Climatic variability; glacier dynamics modelling; glacio-hydrological modelling; Koshi River basin; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2020.51; https://doaj.org/article/863517e8c9144ab5b363261df7169e68

Climate-induced cryospheric changes can have a significant impact on the downstream water availability. In this study, the Open Global Glacier Model (OGGM) and the Glacio-hydrological Degree-day Model (GDM) are integrated to project the response of cryospheric and hydrological systems to climate change until 2100. The study area comprises six sub-basins of glacierized Koshi River basin covering Nepalese and Chinese territories. The output from OGGM is provided as input to GDM along with the spatial and hydro-meteorological data. The average glacier area change in all the sub-basins from 2021 to 2100 is estimated as 65 and 85% decrease and the average glacier volume change is estimated as 76 and 86% decrease for RCP 4.5 and 8.5 scenarios, respectively. The future simulated discharge shows an increasing trend in pre-monsoon and monsoon seasons and a decreasing trend in post-monsoon and winter seasons after 2060 in all the sub-basins, which can lead to wetter wet seasons and drier dry seasons in the far future. A shift in peak flow is observed from August to July in most of the sub-basins. The coupled modelling technique used in this study can largely improve our understanding of glacio-hydrological dynamics in the Himalayan region.