Differential release of water from Arizona snowpacks.

Abstract

The opportunity to increase water yield from snowpacks in Arizona is in part dependent on optimizing melt from sites of varying forest overstories. Since snowpack water equivalent varies with vegetation density, optimum melt may be defined as highest melt per inch of water equivalent on the ground. Identification of optimum sites for melt water yield in terms of forest overstories would provide a guide toward minimizing the ratio of vapor to liquid water loss from snowpacks. Eight modified snow melt lysimeters were installed in Arizona. Measurements of season melt, melt rates, timing, and efficiency were used to evaluate the lysimeter and characterize a snowpack in Arizona. Also, site differences in snowpack melt efficiency were assessed. The volumetric snow melt lysimeter performed well. No differences in those snowpack parameters studied were found among four sites, both open and forested. Season melt outflow for all sites was 9.8 inches, while average daily and maximum average daily melt rates for weekly periods were 0.2 and 0.4 inches per day, respectively. Methods used to simulate the forest floor-snowpack interface affected the magnitude of snow melt measurements. No site differences in snowpack melt efficiency were detected.