Abstract
The hydrological conditions have been observed in the Yanagatani Experimental Catchment (70.0ha) located in Shiga Prefecture to the west of Lake Biwa, in hilly mountains consisting of Paraeozoic. The catchment is covered with forest canopies; Fagus crenata, Quercus mongolica, Cryptomeria japonica. The water-gauge station is composed of concrete weir with a rectangular notch. For measuring precipitation, two automatic recording gauges of a 0.5mm tipping-bucket type are installed. One of the rain gauge is equipped a electric heater for melting snow.
The annual mean temperature is 13.1℃. Snow lies from late December to early March every year. A maximum snow depth is 96cm, recorded in February 1980.
The direct runoff ratio is small in Yanagatani. The direct runoff is composed of only the surface flow from 30percent of the catchment. It is not composed of the quick subsurface flow. It is concluded that the small value of the direct runoff ratio comes from the lack of this component by the kinematic wave method using a model with two different slopes.
The annual evapotranspiration from this catchment is estimated at 600 mm by annual water budget.
