Earth’s Cryosphere, 2009, Vol. XIII, No. 1, p. 55-64

ESTIMATION OF THE INFLUENCE OF CLIMATIC CHANGES ON A SURFACE-WATER DRAIN BY SIMULATION OF THERMAL INTERACTION BETWEEN GROUND WATER AND PERMAFROST (ON THE EXAMPLE OF THE UPPER LENA RIVER WATERSHED)

N.N. Romanovskiy, S.N. Buldovich, G.S. Tipenko*, D.O. Sergeev*, M.V. Kasymskaya, A.V. Gavrilov

Lomonosov Moscow State University, Faculty of Geology, 119991, Moscow, Vorobyovy Gory, Russia, nromanovsky@rambler.ru
* Institute of Environmental Geoscience, 101000, Moscow, Ulansky per., 13, build. 2, P/O box 145, Russia, cryo@geoenv.ru

Nowadays the research problem of the dynamics of a river run-off of large river basins in permafrost area is actual owing to climatic changes. Study of the influence of change climatic and geocryological conditions on hydrological characteristics of the river basin of permafrost region was carried out for conditions of Southern Yakutia (the Lena River watershed), using two-dimensional conjugated groundwater flow-heat problem.
By means of mathematical simulation it has been determined that permafrost becomes colder under the influence of the descending cold infiltration water in comparison with pure conductive geothermal heat flux case. The convective open talik in the river valley becomes stable. The basic conclusion of the modeling is that even at great depths the temperature fields and the permafrost shape are sensible to the water precipitation infiltration in thawed areas. As a result of permafrost degradation, the areas of groundwater feeding and the reservoir capacity of fissured rock increase and the river discharge changes.
The proposed approach makes it possible to clarify peculiarities of temperature field of convective taliks in the area of discontinuous permafrost and also explains the specific characteristics of water discharge tributaries of the Lena.

Key words: Permafrost, underground water, river run-off, climate change, numerical simulation.