Aufeises of the Siberian permafrost zone and increase of the river channel nets

Abstract

Aufeises (surface icings) formed by groundwater outflows are widespread on the territory of East Siberia and Far East. By their number, sizes, and the channel-forming role they considerably exceed the “classical” (sedimentary-metamorphic) form of glaciations. Relative coverage of territory by aufeises estimated with regard for parameters of more than 10 000 ice fields is 0.66% (50 000 km 2 ). On rivers which lengths are shorter 500 km, the aufeis sizes depend on waterflow orders. The largest quantity of giant groundwater aufeises is formed in river valleys of 3–4 orders. Cumulative channel-forming effect of the aufeis phenomena is expressed by a value of increase of the river channel net relative to its characteristics higher and lower an aufeis glade. This value is well-correlating with the aufeis coverage of river basins as well as with morphostructure, permafrost, and hydro-geological conditions of these territories. Increase of the net with respect to one aufeis changes from 3.5 km in mountains in south of East Siberia up to 23 km in the Verkhoyansk-Kolyma mountain area and on the Chukchi Peninsula. On the average, increase of a channel net with respect to one large groundwater aufeis amounts to 12.2 km while in areas of both continuous and discontinuous permafrost (total area F = 7.6 million km 2 ) the total increase is estimated as 690 thousand km. Our calculations testify extremely great role of the aufeises in transformation of river channel nets and structures of valley landscapes as a whole. It is possible to see in mountains that small and middle rivers are characterized by a system of many channels caused by the aufeis influence, and such system can exist continuously for tens km along a river course. For further understanding of regulations of formation and spreading of aufeises and the aufeis channel-forming processes future long-term investigations are needed and they should be performed with use of large-scale aerial and space surveys as well as regular observations on special aufeis sites.