HR: 0800h
AN: C51B-1045    [Abstracts]
TI: Using Stable Oxygen Isotopes to Partition Seasonal Precipitation Inputs in the Kolyma River.
AU: * Welp, L R
EM: welp@caltech.edu
AF: Environmental Science and Engineering, California Institute of Technology, MC 100-23, 1200 E California Blvd, Pasadena, CA 91125 United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: Earth System Sceince Department, University of California, Irvine, 3212 Croul Hall, University of California, Irvine, Irvine, CA 92697 United States
AU: Zimova, G M
AF: Northeast Science Station, Russian Academy of Sciences, PO Box 18, Cherskii,, Sakha Russian Federation
AU: Davydova, A I
AF: Northeast Science Station, Russian Academy of Sciences, PO Box 18, Cherskii,, Sakha Russian Federation
AU: Davydov, S P
AF: Northeast Science Station, Russian Academy of Sciences, PO Box 18, Cherskii,, Sakha Russian Federation
AU: Zimov, S A
EM: tneh@mail.sakha.ru
AF: Northeast Science Station, Russian Academy of Sciences, PO Box 18, Cherskii,, Sakha Russian Federation
AB: The Kolyma River in northeastern Siberia is one of the five largest in Russia, with an annual discharge into the Arctic Ocean of 123 km$^{3}$, of which 90% occurs in the summer. It is unique among Eurasian rivers because the entire watershed area is underlain by continuous permafrost. Also, it has experienced the smallest increase of discharge over the last several decades. On average, the Kolyma river basin receives 300 to 500 mm of precipitation, of which, approximately 50% occurs in the summer. We analyzed Kolyma river water collected near the Northeast Science Station in Cherskii, Russia, from August 2002 through October 2003 for stable oxygen isotopic composition ($\delta^{18}$O) in order to partition the river flow into summer and winter precipitation inputs. The $\delta^{18}$O of the summer precipitation end-member was characterized by sampling 31 rain events at Cherskii during 2002 and 2003. Winter precipitation $\delta^{18}$O was estimated by a spatial survey of snow samples from 25 locations (within 300 km of Cherskii), collected from the top and bottom of the snowpack, prior to snowmelt on April 8-19, 2003. Inputs and standard deviations to a two end-member mixing model were -16 $\pm$ 5 $\permil$ (VSMOW) for summer and -26 $\pm$ 5 $\permil$ for winter. Throughout the ice-free season of river flow, the contribution from snow inputs to the Kolyma was approximately 55% with a standard error of 8%. (Error does not include bias based on restricted spatial sampling of precipitation in the watershed region.) During spring snowmelt (at the peak of the discharge pulse), snow inputs reached 84%. Weighting the fractions of rain/snow by discharge data from the Kolymskoye gauging station 160 km upstream of the collection site, for an entire year from October 2003 to 2004, yielded percent seasonal contributions to the total annual discharge of 38% summer rain and 63% winter snow with a standard error of 8%.
DE: 1655 Water cycles (1836)
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting