The Shirakawa dam basin, the upper reach of the Mogami River, is one of the heaviest snowfall areas in Japan and has sometimes caused snowmelt flood.A method using satellite data and ground data on snow depth is developed to evaluate the snowmelt runoff.Snow covered area is obtained by comparing NOAA/AVHRR data with the ground data that also gives snowmelt rate.Addition of snowmelt discharge calculated from the area, melt rate, and the density and the rainfall discharge is compared with the observed discharge flowing into the dam.