Analysis of Modern Changes in the Runoff of Mountain Rivers in the Permafrost Zone (on the Example of the Upper Kolyma)

Abstract

The purpose is to assess the peculiarities of formation of the surface component of the runoff of mountain rivers of the permafrost zone under the infl uence of modern anthropogenic and climatic impacts. Materials and methods. For watercourses of diff erent sizes and degree of disturbance in the Upper Kolyma valleys, the mean discharge for 30-year periods (months VI - IX) before and after the active warming phase was calculated. The analysis of changes in river water content with regard to permafrost and hydrogeological conditions and anthropogenic disturbances in their valleys was carried out. The infl uence of climatic and anthropogenic factors on river runoff was traced, taking into account the thickness of well-permeable alluvium in fl oodplains. Results and discussion. For the period of the active phase of climate change, a stable connection between the intensifi cation of melting of perennial ice on catchments and river runoff has been revealed. The role of the process of talik expansion in the reduction of the surface component of the runoff of rivers with undisturbed and technogenesis-disturbed valleys has been established. The role of the infl uence of the thickness of well-permeable gravel deposits and anthropogenic disturbances in fl oodplains on the surface component of runoff has been traced. Conclusions. The geo-ecological substantiation of the diff erent response of river runoff to the active phase of global climate change is given on the example of rivers in the upper Kolyma River basin. For this period, the important role in the formation of the surface component of runoff of the opposite in its orientation processes of activation of melting of perennial ice at catchments and expansion of taliks in river valleys has been established.