Understanding the Role of Controls on the Timing of Daily Streamflow Peak and its Seasonal Variation

Abstract:

Understanding and prediction of snowmelt generated streamflow at sub-daily time scales is important for reservoir scheduling and climate change characterization. This is particularly important in the Western U.S. where over 50 - 70% of water supply is provided by snowmelt during the melting period. Previous studies reported that daily peak flow timing might shift earlier in some basins, but later in others during the melt season. This shift of peak flow timing was attributed to three crucial processes: translation time of liquid water flux through snowpack, translation time from the base of snowpacks to river channels, and translation time in the river channels to stream gage stations. Here we evaluate our ability to simulate the sub-daily streamflow peak time and quantitatively explore the relative contribution from each individual factor. Our analysis shows that the timing of the daily peak is dominantly controlled by melt translation time from the bottom of snowpack to the river channel, while the seasonal variation in daily peak is influenced the most by translation time through the snow pack. An additional factor, the increasing trend of temperature and radiation in melt season, is also contributing to the timing of peak streamflow and its variations.