ACCURACY OF SNOWMELT RUNOFF FORECAST BASED ON WEATHER FORECAST

Abstract

This paper discusses the accuracy of snowmelt runoff estimated from weather forecasts. The study was conducted for the basin of the Hoheikyo Dam (134 km²), a dam on the Toyohira River of the Ishikari River System. Snowmelt runoff is estimated for the snowmelt seasons of 2006 and 2007. So that estimation would be practical to conduct, we set the estimation procedure as follows: 1) obtain weather forecast data online; 2) use that data to estimate hourly snowmelt and runoff volumes for the upcoming 24 hours; and 3) calculate the estimation accuracy by comparing the estimated snowmelt runoff volume to measured snowmelt runoff volume.

Of the various types of weather data used for estimation, the accuracy of rainfall estimation had the greatest influence on the accuracy of snowmelt runoff estimation. Also, the longer was the lead-time for estimation, the greater was the margin of error. It was found that snowmelt runoff can be accurately estimated for lead times of up to 6 hours.