HR: 0800h
AN: C21B-0474    [Abstracts]
TI: Lateral Water Movement in a Melting Snowcover: Implications for Hydrologic Modeling
AU: * Whitson, M D
EM: mikewhitson@mail.boisestate.edu
AF: Department of Geosciences, Boise State University, Boise, ID 83725, United States
AU: McNamara, J P
EM: jmcnamar@boisestate.edu
AF: Department of Geosciences, Boise State University, Boise, ID 83725, United States
AB: Catchments convert vertical inputs of precipitation to lateral fluxes. Quantifying the integral processes of moisture redistribution within a catchment is a key challenge for hydrologic modelers, yet the lateral movement of meltwater within a snowpack is commonly ignored. We present data that suggests that the processes governing lateral redistribution of meltwater routing in the snowpack during a snowmelt event are important to the total flux of water out of a watershed. Initial dye tracer field studies near Mores Creek Summit, Idaho, have shown that meltwater movement on moderate angle slopes (<35°) through a ripe, melting snowpack is highly mobile with flow directions that are largely dependant on snowpack characteristics. These experiments have shown considerable downslope movement of meltwater with a dependance on diurnal cycles. Due to the spatial variability of snowpack stratigraphy, there is also a resultant variability in meltwater volume movement over small areas. The experiments showed the dye tracer infiltrated vertically through the snowpack until it reached a stratigraphic boundary, where it began to accumulate and move laterally downslope. These layers within the snowpack stratigraphy were signified by an increase in liquid water content, grain size, and density. The tracer moved large distances laterally along these boundaries, unless conditions allowed for it to resume vertical infiltration. Initial dye emplacement experiments showed a downslope water movement velocity on the order of 1 m h^-1. The results presented here are preliminary observations from field work performed during the spring 2007 snowmelt event.
DE: 0740 Snowmelt
SC: Cryosphere [C]
MN: 2007 Fall Meeting