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United States Department of Agriculture

Agricultural Research Service

Research Project: Understanding Snow and Hydrologic Processes in Mountainous Terrain with a Changing Climate

Location: Northwest Watershed Management Research

Title: Snow distribution, melt and surface water inputs to the soil in the mountain rain-snow transition zone

Authors
item Kormos, Patrick -
item Marks, Daniel
item Mcnamara, Jim -
item Marshall, Hp -
item Winstral, Adam
item Flores, Alejandro -

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2014
Publication Date: June 28, 2014
Citation: Kormos, P., Marks, D.G., Mcnamara, J., Marshall, H., Winstral, A.H., Flores, A.N. 2014. Snow distribution, melt and surface water inputs to the soil in the mountain rain-snow transition zone. Journal of Hydrology. DOI: 10.1016.j.jhydrol.2014.06.051.

Interpretive Summary: The timing, magnitude, and spatial distribution of snow cover and the resulting surface water inputs (SWI) are quantified for a catchment in the rain-snow transition zone. Southwest facing slopes receive smaller and more frequent SWI from mid winter snowmelt, while the northeast slope receives more SWI during the spring. Four emergent surface water input patterns emerge through the melt season: 1) near uniform, 2) controlled by topographic differences in energy fluxes, 3) transitional, and 4) controlled by precipitation distribution. Differences in surface water inputs between hillslopes were less than expected during rain-on-snow events. Turbulent fluxes dominated the snowpack energetics in four of the seven rain-on-snow events. Net radiation fluxes dominate spring melt events. Variations in the method used to distribute precipitation may result in large differences in total precipitation to the basin.

Technical Abstract: The timing, magnitude, and spatial distribution of snow cover and the resulting surface water inputs (SWI) are quantified for a catchment in the rain-snow transition zone. Although the timing of melt events are similar across the basin, southwest facing slopes receive smaller and more frequent SWI from mid winter snowmelt, while the northeast slope receives more SWI during the spring. Three spatial patterns are observed in modeled SWI time series: 1) uniform, 2) majority of SWI on south facing slopes, and 3) majority of SWI on north facing slopes. Although any of these three spatial patterns can occur at any time in the snow season, four emergent surface water input patterns emerge through the melt season: 1) near uniform, 2) controlled by topographic differences in energy fluxes, 3) transitional, and 4) controlled by precipitation distribution. Differences in surface water inputs between hillslopes were less than expected during rain-on-snow events. Turbulent fluxes dominated the snowpack energetics in four of the seven rain-on-snow events. Advective fluxes are greater than 17% during the first 2 rain-on-snow events in December and January. Net radiation fluxes dominate spring melt events. Variations in the method used to distribute precipitation may result in large differences in total precipitation to the basin.

Last Modified: 10/22/2014
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