Assessment of runoff sources in glaciated catchments of Inner Tien-Shan, Kyrgyzstan

<p>Water resources problems are more burning than ever in the region of Central Asia. Glacier degradation followed by a decrease in the average river flow creates vulnerability for the population living, particularly in the high-mountain areas. The study of small glaciated basins with complex topography is difficult due to the inaccessibility and lack of in-situ measurements. Recently with an improvement in monitoring network and reanalysis data, glaciohydrological modeling of water resources with an assessment of water balance components has become more achievable. In this study, we used land surface model SiBUC (Simple Biosphere including Urban Canopy) paired with GLIMB (GLacIer energy Mass Balance) model to assess the seasonal distribution of runoff and its sources in three basins of the Central Tien-Shan: Djuuku (area of 558 km², 8.3% glaciated), Kichi-Kyzyl-Suu (99 km², 1.8% glaciated) and Chon-Kyzyl-Suu (298 km², 11.4% glaciated). The incoming solar radiation was corrected considering the complex topography and cloud effect. The results of glacier mass balance were compared with the WGMS data on 5 glaciers located in the study region. Thus, depending on the area of glaciation and precipitation regime, glaciers can contribute to annual runoff from 2.4 % in basins with less glaciation up to 31.2% in highly glaciated basins. Another important point is the relationship between the contribution of glaciers and the amount of precipitation. Therefore, in dry years, glaciers can significantly reduce the intensity of droughts, but the disappearance of glaciers can break this pattern.</p>