Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

Variability of thaw depth depending on surface micro-undulation and vegetation cover in the Siberian tundra

Kunio Watanabe (1), Tadataka Ezaki (2), Kazunari Fukumura (3), Masaru Mizoguchi (4), Hideki Kiyosawa (1)

Arctic tundra is characterized by permafrost overlaid by an active layer. The active layer is a thin layer of surface soil that experiences annual freezing and thawing. The runoff and subsurface storage in the arctic tundra watershed may be controlled by variation of the thaw depth in the active layer. Ground thawing is affected not only by the physical properties of soil of the active layer, but also by the surface energy balance and by water movement through the active layer, which are spatially variable due to undulations and vegetation cover of ground surface. Therefore, it is important to know the spatial variation of thaw depth and to clarify its relationship with the micro-undulations and vegetation cover of the ground surface. The survey was carried out in the summer of 1999. A 10 m observation grid was set up in a 100 ´ 100 m area selected in a typical tundra watershed near Tiksi, Siberia. The ground surface level, groundwater level and thaw depth were investigated at each intersection of the grid. The vegetation cover in each 10 m square grid was classified by the dominant species observed. The thaw depth varied spatially within a range of 0.3 to 1 m throughout the observation grid. The direction of runoff on the active layer was shown by analyzing micro-undulations in the ground surface. The ground thawed to a smaller depth on long slopes, and thawed to a greater depth at or near water-filled micro-depressions. The thaw depth also varied with the vegetation cover; the thaw was shallower in moss-covered areas and deeper near frost boils. The influences of micro-undulation and vegetation cover on the spatial variation of thaw depth are discussed. Our results imply that the spatial variation of thaw depth in a tundra watershed can be estimated using surface information, such as topography and vegetation.

Submittal Information

Name : Date :
    Kunio Watanabe
    08-Jun-01-15:10:28
Organization : Theme :
    Faculty of Bioresources, Mie university
    Theme 1
Address : Presentation :
    1515 Kamihama, Tsu, 514-8507
    Poster or oral
Country : Abstract ID :
    Japan
    T1KW08Jun01151028
Phone : Fax :
    +81-59-231-9573
    +81-59-231-9571
E-mail :
    kunio@dobokuPc4.bio.mie-u.ac.jp