HR: 0830h
AN: C21B-0819    [PDF]
TI: Low runoff response to permafrost dynamic within the Lena River watershed
AU: * Berezovskaya, S
EM: ffslb2@uaf.edu
AF: Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanana Drive, Fairbanks, AK 99775-5860 United States
AU: Yang, D
EM: ffdy@uaf.edu
AF: Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanana Drive, Fairbanks, AK 99775-5860 United States
AU: Romanovksy, V
EM: ffver@uaf.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775-7320 United States
AU: Sazonova, T
EM: ftts1@uaf.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775-7320 United States
AB: River runoff formation, particularly during low flow season, is one of the most sensitive processes to permafrost thawing and degradation. Historical data on river discharge, precipitation, air temperature and modeling results on active layer thickness and soil temperature are processed to study the response of river stream flow on changes in ground conditions. Analysis of the permafrost dynamics along the Lena River watershed for the past century shows that under the impact of air temperature variability significant changes occurred in the mean annual ground temperatures (ñ3-4 C) and active layer thickness (ñ1 m). It was found that air temperature rise produced additional thawing of active layer of 0.5-2.0 m everywhere within the transect. The permafrost dynamic is highly pronounced at the southern mountain region of the Lena basin. Analysis of the river discharge time series in that region (Chulman River) over the period 1936-1990 suggests the alternation in the water regime of autumn and winter natural runoff. Along with runoff alternation precipitation sum over the warm period (June-September) in that region is characterized by tendency to increase during 1964 - 1984. Air temperature in October is always below zero and ground surface freezes preventing penetration of any precipitation water. The river discharge in October tends to decrease since the beginning of 1960s whereas winter runoff is raised over this period. Increase of active layer thickness and spread of taliks suggest the subsurface capacity increase, which tends to accumulate more water within, thus, decreasing the autumn (October) and increasing the winter (November - April) discharge. It should be noted, that this pattern is not widespread along the Lena River watershed. It persists locally at the southern part of the basin.
DE: 1823 Frozen ground
DE: 1860 Runoff and streamflow
SC: Cryosphere [C]
MN: 2003 Fall Meeting