Hydrograph Characteristics In Relation To Low, Normal And High Snowpacks In Utah – A Water Management Tool

Long term (\u3e30 year) daily snow water equivalent (SWE) observations enable researchers to establish relationships between various SWE and hydrograph characteristics. The shape and magnitude of snowmelt hydrographs in Utah depend predominantly on the magnitude of the snowpack being melted. As observed elsewhere, years with low snowpacks melt out earlier, have lower peak flows and lower total flow volume than average or high snowpack years, and vice versa for high snowpack years. However, in relation to melt-out dates at SNOTEL sites, a higher proportion of the annual April-July flow in low years is shifted toward the end of the hydrograph, whereas a larger proportion of flow occurs prior to melt-out in higher snowpack years. This paper examines the timing of peak flow and the proportion and distribution of flow relative to the timing of snowpack melt out at selected watersheds and SNOTEL stations across the state of Utah. The ability to predict the temporal distribution of streamflow based only on the magnitude of snowpack and the melt out date at specific SNOTEL sites could improve water management, especially where limited or no seasonal water supply forecasts are available. (KEYWORDS: SNOTEL, Snow Survey, SWE, hydrograph, peak flow