Effects of Capillary Discontinuities on Water Flow Retention in Layered Snow covers

Abstract

The effect of capillary barriers in layered snowcovers has been examined through use of a numerical mass and energy balance model, laboratory tests and field tests. The degree of suction within the layers has been related to capillary rise and in turn to snow porosity and grain size. The relative importance of permeability and capillary tension on liquid water levels has been examined and it was concluded that capillary discontinuities play a dominant role. It has been shown both theoretically and experimentally that high-over-low suction transitions lead to interruption of water flow vertically and to horizontal movement along discontinuities. Infiltration rates predicted by the numerical model are low because of the omission of finger flow. A more realistic rendering would require a three-dimensional model or incorporate the empirical approach of Marsh and Woo.