Submitted to: Trans American Geophysical Union
Publication Type: Abstract only
Publication Acceptance Date: 11/7/2005
Publication Date: 12/15/2005
Citation: Seyfried, M., Grant, L., and Marks, D. 2005. Vadose zone effects on snowmelt generated streamflow, abstract C21A-1070, Eos, Transactions of the American Geophysical Union, 86(52):F431 Interpretive Summary:
Technical Abstract: Processes of evaporation, transpiration and absorption of water within the rood one constitute a secondary control on the amount and timing of snowmelt-generated streamflow. Even in relatively small watersheds the timing and amount of snowmelt inputs to the root zone may be highly variable due to uneven snow distribution and melt dynamics related to topographic and vegetative influences. Since most streamflow from snowmelt results from subsurface flow, a complete characterization of streamflow generation processes requires knowledge of subsurface hydraulic properties, which is rare even in small watersheds. We investigate the potential for estimating root zone impacts on streamflow generation using a spatially distributed, one dimensional modeling approach, thus accounting for variability of inputs and root zone processes, but regarding the watershed as highly “connected” in the subsurface. We combine a snowmelt model that accounts for input variability with a simple soil water balance model that accounts for plant uptake, evaporation and drainage. The approach was tested on the 0.36 km2 Reynolds Mountain experimental watershed in Idaho. We found that the one-dimensional modeling approach accurately captured the dynamics of streamflow initiation and reduction, indicating a high degree of subsurface connectivity. The amount of runoff estimated from one-dimensional deep drainage, however, was substantially over estimated. This appears to be due to transpiration of subsurface water that reemerges in the root zone down slope from the input. Subsequent simulations, accounting for this are consistent with this explanation.