ИСТИНА

In general, Caucasus glaciers lost approximately one-third of the area and half of the volume during the 20th century. Prediction of their further degradation in changing environment is a challenging task because rivers fed by glacier melt water provide up to 70% of the total river run-off in the adjacent piedmont territories. Therefore accurate assessment of future glacial run-off is a key problem of sustainable development in the regions where hydrological regime is dependent on glacial run-off. The problem is solved by dynamical modeling of mountain glaciers. Because of lack of regular observations, it is feasible to focus on several reference glaciers in the region and to further extrapolate modeling results on the whole glaciated area. We employ a 3D higher-order ice flow model coupled with a surface mass-balance model to perform prognostic numerical experiments aimed at simulation of future dynamics of Djankuat Glacier. It is a typical valley glacier on the northern slope of the main Caucasus chain. Djankuat is one of the most well studied glaciers in Russia (and, perhaps, in the World) which has been continuously monitored during the last fifty years. Considerable parts of the ablation zones of Djankuat are covered with debris. Heat and physical properties of the debris layer are very different from those of ice. Debris layer determines ablation rate and ice run-off regime. Dependently on thickness, it can accelerate ablation or totally isolate ice cover from melting. To correctly describe ablation rate, we incorporated an algorithm for calculation of ablation rate under the layer of debris. To validate the model, we utilize observations from the nearest weather stations (Terskol and Mestia), as well as flow velocity, radio echo-sounding, accumulation and ablation measurements. In the prognostic numerical experiments, we simulated possible Djankuat evolution until the year 2100.