Northern Research Basins Water Balance (Proceedings of a workshop held at Victoria, Canada, March 2004). IAHS Publ. 290, 2004, 13–27

Abstract Eleven years of water balance data were analysed in a snowy, mountainous watershed in Moshiri, Hokkaido, Japan. The average annual mean precipitation, discharge, evapotranspiration, and storage change were 1670 mm, 1375 mm, 370 mm, and –75 mm, respectively. The variation in annual mean precipitation was the largest among these components. Meanwhile, variation in evapotranspiration was small. Storage in the watershed reached its annual minimum in July, when precipitation was small and evapotranspiration was large in the summer drought period. Storage increased in September, reflecting the increase in rainfall, and then increased drastically with the start of snowfall. Winter storage was several times larger than summer storage, indicating that snow storage is important for the annual water balance. The pre-melt SWE showed a large inter-annual variation, ranging from 400 mm to 800 mm. Those variations reflect the total precipitation during winter and the rain/snow discrimination in the early winter and the melting season.

Key words annual water balance; Hokkaido, Japan; interannual variation; snowy and mountainous watershed; snow storage