Northern Research Basins Water Balance (Proceedings of a workshop held at Victoria, Canada, March 2004). IAHS Publ. 290, 2004, 50–64

1 Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan

2 Frontier Observational Research System for Global Change, Yokohama 236-0001, Japan

Abstract To clarify the summer water balance of an Arctic tundra watershed in eastern Siberia, hydrological and meteorological observations were made during three summer seasons from 1997 to 1999. The weather conditions in these summers were considerably different from year to year: wet in 1997, dry in 1998, and first dry then wet in 1999. Both summer rainfall and snowmelt amount were major input components, and they showed considerable interannual variability. Stream runoff was substantial as the output component, and its high inter-annual variability, depended on that of input components. The area of rocky terrain with lichen occupied 36% of the whole watershed, and evapotranspiration from there was quite small. This led to the relatively small amount of basin-averaged evapotranspiration compared with other components. Change in storage within the thaw layer was small, because its thickness was thin and soil moisture was kept in a nearly saturated condition during the summer.

Key words Arctic tundra; basin water balance; eastern Siberia; evapotranspiration; runoff