Contributions of snow to the annual water balance in Moshiri watershed, northern Hokkaido, Japan

Abstract

Characteristics of the water balance were investigated in an experimental watershed where there is a seasonal snow cover. To estimate the basin-wide snowmelt by the heat balance method, seven observation sites were established in the watershed and the dependencies of meteorological parameters on elevation, slope, and forest density were examined. In the snowmelt season, the net radiation and sensible heat flux increased with elevation because of the decrease in forest density, an increase in wind speed, and the temperature inversion phenomenon, which resulted in an increase in the snowmelt rate with elevation. The solid precipitation accounted for 53% of the annual precipitation and snowmelt runoff accounted for 45% of the annual runoff. The runoff/precipitation ratio was 0.75 in the snowmelt season. Evaporation was negligibly small during the winter season, but it increased during the snow-free period. The total water loss due to evaporation was about a quarter of the annual precipitation.