HR: 1340h
AN: H23C-1436    [Abstracts]
TI: Seasonal Snowpack Dynamics and Runoff in a Maritime Forested Basin, Niigata, Japan
AU: * Whitaker, A C
EM: whitaker@cc.niigata-u.ac.jp
AF: Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata, 950-2181 Japan
AU: Sugiyama, H
EM: hydsugi@cc.niigata-u.ac.jp
AF: Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata, 950-2181 Japan
AB: Seasonal snowpack dynamics are described through field measurements under contrasting canopy conditions for a mountainous catchment in the Japan Sea region. Microclimatic data, snow accumulation, albedo and lysimeter runoff is given through three complete winter seasons 2002-05 in: (1) mature cedar stand, (2) larch stand, and (3) regenerating cedar stand or opening. The accumulation and melt of seasonal snowpack strongly influences streamflow runoff during December to May, including winter base-flow, mid-winter melt, rain-on-snow, and diurnal peaks driven by radiation melt in spring. Lysimeter runoff at all sites is characterised by constant ground melt of 0.8-1.0 mm/day. Rapid response to mid-winter melt or rainfall shows that the snowpack remains in a ripe or near-ripe condition throughout the snowcover season. Hourly and daily lysimeter discharge was greatest during rain-on-snow with the majority of runoff due to rainfall passing through the snowpack as opposed to snowmelt. For both rain-on-snow and radiation melt events lysimeter discharge was generally greatest at the open site, although there were exceptions such as during interception melt events. During radiation melt instantaneous discharge was up to 4.0 times greater in the opening compared to the mature cedar, and 48-hour discharge was up to 2.5 times greater. Perhaps characteristic of maritime climates, forest interception melt is shown to be important in addition to sublimation in reducing snow accumulation beneath dense canopies. While sublimation represents a loss from the catchment water balance, interception melt percolates through the snowpack and contributes to soil moisture during the winter season. Strong differences in microclimate and snowpack albedo persisted between cedar, larch and open sites, and it is suggested further work is needed to account for this in hydrological simulation models.
DE: 1854 Precipitation (3354)
DE: 1860 Streamflow
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: Fall Meeting 2005