The primary objective of this study is to develop a definitive set of observations of spatial and temporal heterogeneity of: 1) surface structure of a snowpack during melt, 2) internal flow paths, and 3) delivery of water at the snowpack base. From these data we will the define the spatial statistics of meltwater flow through snow. Modeling and additional field efforts will build on this empirical data base to extend our understanding of meltwater pathways through snow to the small basin scale (8 ha). We concentrate in this proposal on observations which will characterize and quantify the detailed processes which determine infiltration and runoff. This more detailed knowledge of the physics of snow hydrology will make possible more reliable modeling and prediction of snowmelt runoff.
We propose to quantify the spatial and temporal variation of meltwater
flow through snow using an extensive array of 116 snow lysimeters
that will determine
i) the characteristic correlation
lengths of snowmelt runoff;
ii) the spatial variance of meltwater flow; and
iii) effective hydraulic conductivity of the snowpack.
Aerial photographs using near-IR wavelengths will be used to
provide a specific method for inferring
the onset and degree of heterogeneous infiltration from remote sensing
and to more accurately predict the discharge hydrograph of a ripening
snowpack, again from remote sensing measurements.
The evolution of internal flowpaths will be constructed
from non-destructive temperature and conductance probes
and from destructive measurements of snowpack stratigraphy
and dye tracers.
The information on snow physical characteristics will
be used to parameterize an existing meltwater infiltration
model coupled with the development of a second model
that explicitly includes the dynamics of preferential
Plot and modeling efforts will then be scaled to the
8 ha Martinelli basin to
evaluate the importance of spatial and temporal variations of
meltwater infiltration at the catchment scale.