HR: 0800h
AN: U41C-0624    [Abstracts]
TI: Rising minimum flows in northern Eurasian rivers suggest a growing influence of groundwater in the high-latitude water cycle
AU: * Smith, L C
EM: lsmith@geog.ucla.edu
AF: University of California, Los Angeles, Department of Geography, Los Angeles, CA 90095- 1524, United States
AU: Pavelsky, T M
EM: pavelsky@ucla.edu
AF: University of California, Los Angeles, Department of Geography, Los Angeles, CA 90095- 1524, United States
AU: MacDonald, G M
EM: macdonal@geog.ucla.edu
AF: University of California, Los Angeles, Department of Geography, Los Angeles, CA 90095- 1524, United States
AU: Shiklomanov, A I
EM: alex.shiklomanov@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Durham, NH 03824, United States
AU: Lammers, R B
EM: richard.lammers@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Durham, NH 03824, United States
AB: A first analysis of new daily discharge data for 111 northern rivers from 1936-1999 and 1958-1989 finds an overall pattern of increasing minimum daily flows (low-flows) throughout Russia. The increases are generally more ubiquitous than are increases in mean flow, occur in summer as well as winter, and occur in non-permafrost as well as permafrost terrain. A subset of 12 unusually complete river discharge records from 1935-2002 suggests that the most recent minimum-flow increases since 1985 are largely unprecedented in the historical record, at least for this small group of stations. Hydrograph baseflow separations were not performed. However, if minimum-flows are presumed at least correlative with groundwater and unsaturated zone inputs to river discharge, then the data suggest a broad-scale mobilization of such water sources in the late 20th century. It is unknown whether this phenomenon simply reflects increased precipitation throughput, or indicates that some other process is at play; what is known is that low-flows are rising in many watersheds across Russia. We speculate that reduced intensity of seasonal ground freezing, together with precipitation increases, could drive much of the +7 percent late twentieth-century increases in Eurasian river discharge to the Arctic Ocean
UR: http://lena.sscnet.ucla.edu
DE: 0702 Permafrost (0475)
DE: 0704 Seasonally frozen ground
DE: 0744 Rivers (0483, 1856)
DE: 1621 Cryospheric change (0776)
DE: 1833 Hydroclimatology
SC: Union [U]
MN: 2007 Fall Meeting