The Influence of Snow Cover Conditions on the Hydrological Cycle in a Mountain Watershed

Abstract

Hydrological variables in an experimental watershed (A=19.45 km²) set up in a snowy mountain region have been observed and measured in detail from Sep. 2000. In this paper we discuss and evaluate the effect of different snow cover conditions such as snow water equivalent (SWE) on the hydrological cycle by using these observed records and hydrological information estimated with a snowmelt model. The results of this study indicate that the ratioof discharge during the cold season (Dec. to May) to precipitation is about 90% every water year without beingaffected by the amount of precipitation during the cold season. It is also presented that the ratio of total snowmelt discharge during cold season to annual discharge is 50 to 57%, and this large ratio means snowpack and snowmelt playan important role in river recharge. Indicators of snow cover condition such as maximum SWE and starting date for snowmelt season are correlated with the occurrence of droughty events. Additionally, the validity of an improved temperature index snowmelt model is shown.