Observation of snow water equivalent in the North catchment area of Lake Biwa

Field investigations were carried out during the winters of 2001 through 2008 to investigate the annual fluctuation of the snow water equivalent (SWE) in the north catchment area of Lake Biwa in the northeast region of Shiga Prefecture, also in the southern part of the heavy snowfall area of Japan. On the basis of the observations from this study, the SWE model was developed that can simulate temporal changes in the SWE in this region. This model can calculate the SWE, using an empirical parameter specific to the Shiga Prefecture. The model was developed to include snow accumulation and snowmelt processes, using only precipitation and temperature. It was used to estimate the annual SWE over every 1‐h interval at a catchment area in Yogo, Shiga Prefecture, Japan. The accumulation process involves separation of snowfall and rainfall at different temperatures by using an empirical formula. For the snowmelt process, the degree‐hour method is employed. The performance of the degree‐hour method depends on a region’s accumulated temperature. The model was applied to data collected during the winters of 2001 and 2008, and the results compared to the observed SWE in Yogo. The observed and calculated results for 2001 are in good agreement, whereas they are not in good agreement for 2008. Thus, this model can be used to simulate different scenarios specified in the IPCC guidelines, for different temperature and precipitation values, only for the winter of 2001.