Evaluating the spatial and temporal distribution of snow accumulation, snowmelts and discharge in a multi basin scale: An application to the Tohoku Region, Japan

The main aim of this study is to discuss the temporal and spatial distributions of the snow water equivalent, snowmelt and discharge in a multibasin scale (Tohoku Region, Japan; covering about 77000 km²), using the heat budget model with the help of remote sensing (satellite images and meteorological radar). The calculated distributions of snow water equivalent were similar to that of the snow map obtained from the satellite images. At the same time, the seasonal variation of discharge in the three basins investigated (Yuda, covering 583 km², Shichikasyuku, 237 km² and Okutadami, 426 km²) was in good agreement with the observed one at the dam. Moreover, we conducted sensitivity tests for increasing solar radiation and air temperature by adding 10 W/m² to the solar radiation and I degree to air temperature, respectively. The peaks of the snow cover area did not change so much, although the area in the snowmelt season decreased in these cases. The snow water equivalent in both cases became smaller than the control, particularly in the case of a 1 degree increase in air temperature. The snowmelt and discharge increased in the first half of the snowmelt period but were less than the control in the latter half. The model suggested in this study will be able to estimate changes in the hydrological elements related to snow, if a scenario of the climate change is provided.