HR: 0800h
AN: U41A-0808    [Abstracts]
TI: Analysis of variability in spring maximum discharge across Arctic drainage basin of Eurasia
AU: * Shiklomanov, A
EM: alex.shiklomanov@unh.edu
AF: Water Systems Analysis Group, CSRC Morse Hall, University of New Hampshire, Durham, NH 03824 United States
AU: Rawlins, M
EM: rawlins@eos.sr.unh.edu
AF: Water Systems Analysis Group, CSRC Morse Hall, University of New Hampshire, Durham, NH 03824 United States
AU: Lammers, R
EM: richard.lammers@unh.edu
AF: Water Systems Analysis Group, CSRC Morse Hall, University of New Hampshire, Durham, NH 03824 United States
AU: Vorosmarty, C
EM: charles.vorosmarty@unh.edu
AF: Water Systems Analysis Group, CSRC Morse Hall, University of New Hampshire, Durham, NH 03824 United States
AB: Many Siberian and Northern European rivers have experienced catastrophic flooding during last 10-15 years. These floods are associated mainly with spring flow peak formed as a result of snow melting. Analysis of these extreme events over the extensive territory of the Eurasian pan-Arctic is difficult due to a lack of published daily stage data for the region. In most cases the severe floods are related with high discharge. Given recent evidence of significant change in the arctic hydrological cycle, analysis of maximum discharge is important to better understand the effects of climate variability on these extreme flooding events.
Our analysis uses newly available daily discharge data for 98 Russian gauges in the Eurasian pan-Arctic with drainage areas from 1000 to 50000 km² and minimal human impact. We investigate trends in maximum spring daily discharge and the date of its appearance. All rivers were predominantly snow melt dominated, that is, 50-80% of total runoff occurs during spring. The hydrographs show clear spring peaks and high flows during summer-fall due to rainfall. In some rivers, summer-fall flood discharge occasionally exceeds the maximum spring discharge.
Analysis of the magnitudes and timing of maximum river discharge showed the tendency toward earlier peak flow with higher maximum discharge. Maximum discharge values have increased 3-20% for 80% of the gauges over the last 50 years. Trends toward earlier spring peak flow were found for 90% of the gauges and most of them correspond to positive trends in the discharge values. Therefore the greatest positive trends in magnitude of maximum discharge are associated with the earliest appearance of the maximum. We can hypothesize that earlier snow melt leads to reduced water losses and therefore to increases in spring discharge. To have a more complete picture of spring river discharge response to changes in climate drivers we will analyze the daily air temperature and precipitation data from newly distributed NCDC dataset for former USSR.
DE: 1655 Water cycles (1836)
DE: 1807 Climate impacts
DE: 1817 Extreme events
DE: 1833 Hydroclimatology
DE: 1872 Time series analysis (3270, 4277, 4475)
SC: Union [U]
MN: Fall Meeting 2005