Snow Melt and Capture


Efficient capture of snow water has two features: catching the snow and capturing the melt water. Because snow often is accompanied by wind, the principles of snow catch are similar to those used in protecting soil against erosion by wind. Standing crop residue, shelter belts, strip cropping, and artificial barriers have all been used to maximize snow-catch. Standing crop residues conserved 37 percent of the overwinter precipitation, while fields with no standing residues conserved only 9 percent. The proportion of the land area covered by standing crop residues in a field obviously affects snow catch. Raising the cutting height of sunflower stalks increased stored soil water from snow in another study. With any kind of residue, the greater the height, the greater the potential snow capture.

Snowfall capture is the simplest part of capturing the snow water resource. Unfortunately, getting snowmelt water into the soil is far less predictable and manageable due to soil freezing. Infiltration rates for frozen soils are determined by two factors: soil frost structure (i.e., small granulated units versus massive concrete-like units) and soil water content at the time of freezing. Soils frozen at low water content do not impede infiltration because they granulate, leaving adequate open pore space for infiltration. In contrast, soils frozen at high water contents freeze into dense, massive, concrete-like structures that are nearly impermeable to water. Rapid warming accompanied by rainfall on such frozen soils can cause major runoff and erosion.