Runoff System Model in Snow Accumulation and Melting Seasons

Abstract

The model making in the snow accumulation and melting seasons may be dealt with with the series of the following system. Snowfall→Transformation System I→Snowpack→Transformation System II→Snowmelt→Tranformation System III→Streamflow. The snowmelt and runoff system models developed in this study are primarily concerned with considering the above processes on as physical a basis as possible and at the same time best representing those processes in light of practical modelling considerations according to available data. As for the snowfall and the transformation system I, firstly, the observed data of depth of snow are directly introduced into the model. As for the transformation system II, in addition to the temperature index method the heat budget considerations are partly introduced into the model. And moreover the behaviour through the snowpack of the water melted or frozen by the heat transfer is introduced on a physical basis in order to make the model more rational. As for the transformation system III, the statistical unit hydrograph method proposed previously is expanded to the snow accumulation and melting seasons with some modifications. Lastly the above models are applied to the Kuzuryu River, in particular. For the very heavy snowfall of 1981 the sequence of inflow into the dam up the river are estimated.