An estimation of winter precipitation on mountain areas deduced from dam-inflow data

Abstract

The estimation of precipitation at high elevations has rarely been carried out because of the lack of an adequate observation system. The dam inflow suggests that the high-altitude precipitation in winter must be several times as much as that in summer. To obtain a satisfactory estimate of the high-altitude precipitation, three rivers were selected : Uchinokura, Kasahori, and Kamiichigawa, each of which rises from a separate mountain area. Each drainage area is divided into several zones according to altitude, and the precipitation in every divided zone was calculated from the dam-inflow data. The total of the precipitations thus calculated is the whole precipitation in the drainage area. A formula relating air temperature and snowmelt was induced, and the estimated total amount of the snowmelt was compared with the amount of dam-inflow. The results proves the validity of the calculated high-altitude precipitation.