HR: 0800h
AN: H11F-0359    [Abstracts]
TI: Simulation of Spring Snowmelt Runoff by Considering Effect of Local Topography on Snow Cover and Freezing/Thawing Soil Layer in Kushiro Mire
AU: * Nakayama, T
EM: nakat@nies.go.jp
AF: Watershed Environment Management Team, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Watanabe, M
EM: masawata@nies.go.jp
AF: Division of Water and Soil Environment, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: The NIES Integrated Catchment-based Eco-hydrology (NICE) model [Nakayama and Watanabe, 2004] was expanded to consider the effect of the snow layer and the freezing/thawing soil layer on spring snowmelt runoff in the Kushiro River catchment, Japan (NICE-2). Snow/freezing model was expanded including the effect of local topography and meteorology, and surface runoff mode was expanded to two-layer model of freezing/thawing soil layers. The NICE-2 reproduced well the measured values of snow depth, soil moisture, soil temperature, groundwater level, and river flow discharge throughout the year, showing that this model achieves high accuracy and that the mechanism of spring snowmelt runoff is related to changes in soil structure, soil temperature, soil moisture, and groundwater level. In particular, soil frost alters the hydraulic character of soil by restricting infiltration in the coldest part of winter, increasing pore size after the thawing process, and creating macropores and desiccation cracks in the soil. The effect of the spring snowmelt runoff on sediment-load influx and nutrient infiltration is very important because the spring snowmelt runoff is a significant component of the water balance in this catchment and the soil structure changes dramatically during this period. The drying phenomenon in the Kushiro Mire is closely related with the increased influx of sediments from the surrounding area, where agricultural development, reclamation, and channelization of the river occurred [Nakayama and Watanabe, 2004]. In future work, the NICE-2 can simulate the relation between water and sediment influx to the mire by including the mass transfer process, which will be very important in protecting the sediment loads from riparian forests, and in predicting the recovery of a mire ecosystem by re-meandering the channelized rivers. [Reference] Nakayama, T., and M. Watanabe, Simulation of drying phenomena associated with vegetation change caused by invasion of alder (Alnus japonica) in Kushiro Mire, Water Resour. Res., Vol.40, No.8, W08402, 2004.
DE: 1836 Hydrologic budget (1655)
DE: 1878 Water/energy interactions
DE: 1890 Wetlands
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting