Assessment of the Water Balance of the Glacierized Issyk-Kul Basin in Kyrgyzstan under Climate Change

The impacts of climate change and glacier retreat are changing the hydrology of high mountain river systems, with critical implications for water management. In regions such as Central Asia, where resources and data availability are limited, accessible modeling tools are essential to support informed decision-making.
We apply MATILDA, an open-source glacio-hydrological modeling toolkit, to assess the water balance of the endorheic Issyk-Kul basin in Kyrgyzstan under changing climate conditions from 1982 to 2100. Using a semi-distributed approach, the study simulates hydrological dynamics for the tributaries of Issyk-Kul on a catchment basis. The calibration includes snow water equivalent reanalysis data, glacier mass balance observations and 31 historical discharge records, mainly from the Soviet era.
To estimate historical and future glacier evolution of the more than 800 glaciers in the basin, MATILDA is coupled with the advanced Global Glacier Evolution Model (GloGEM). This approach allows to improve the representation of glacier changes in the simulations compared to simplified glacier routines and to evaluate their suitability for hydrological modeling in high mountain catchments. The presented results of the first phase of the study focus on climate change impacts on the general water balance, runoff contributions from the cryosphere, and the resulting lake level.
By integrating public data and open source routines, the study demonstrates the potential of MATILDA to support water management in glacierized basins facing climate change.