Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Changes in River Runoff over the East-Siberian Sea Basin
Sveta Berezovskaya1
1Water and Environmental Research Center, University of Alaska Fairbanks, PO Box 755860, Fairbanks, AK, 99775-5860, USA, Phone 907-474-2783, Fax 907-474-7979, ffslb2@uaf.edu
The main rivers flowing to the East-Siberian Sea (ESS) are the Kolyma, Indigirka and Alazeya Rivers. All together those rivers bring 151 km3 of fresh water per year to the East-Siberian Sea. A sparse network of hydrological stations is mainly located in the upper and middle basins of the Indigirka and Kolyma rivers. The interfluves and the eastern part of the ESS basin are practically ignored in the runoff observations.
The Kolyma River in the upper and middle reach drains mainly mountain terrain, flowing along the Kolyma lowland in downstream. The Indigirka River’s watershed covers both mountainous and lowland territories, whereas the Alaseya River primarily drains the near shore lowland (Kolyma Lowland) containing plenty of thermokarst lakes and swamps. It causes the significant difference in their water regimes. The Kolyma River is characterized by pronounced spring-summer (May-June) flooding with the summer-autumn short-term floods, whereas at the Alazeya and Indigirka outlet stations, the flooding wave is more flat and smoothly passes the period of summer-autumn floods. The autumn runoff (September-October) significantly increased in recent decades at the Indigirka and Alazeya Rivers. The average change in autumn runoff at the Voronzovo station (Indigirka River outlet station) comprises 61 % from 1937 to 1994. However, analysis of long-term precipitation in September along the Indigirka River shows the decreasing trend in recent decades (1973-1993). In order to understand the reasons of autumn runoff increase, the roles of aufeis impact, thermokarst lakes and permafrost dymanics have been analyzed.
The runoff increase during the winter season is strongly pronounced at middle and low reach of the Kolyma River from 1980. This increase is associated with the dam and Kolymskoe reservoir construction at the section of Sinegorye station. The Indigirka and Alazeya Rivers don’t reflect any significant change in the winter discharge in recent decades implying the strong winter runoff increase is due to dam establishment.
Abstract Categories: Changes on Land
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