2011 Volume 117 Pages 11-21
Frozen soil layer sometimes impedes the snowmelt infiltration into deep soil layer, which decreases the amount of soil water recharge and delay the transporta-tion of nitric acid to deep soil layer. To investigate the rela-tionship between soil frost and snowmelt infiltration, three years field observation was conducted at the arable fieldlocated in Tokachi region in northernmost island of Japan. Two plots were prepared and snow on the one plot was re-moved for approximately one month to enhance the soil freezing. As a result, soil frost depths at the beginning of snowmelt period were ranged between 0.1 and 0.5 m. The amount of infiltrated water into below 0.5 m depth during snowmelt period was calculated from the field data. The strong relationship between the frost depth and the ratio of snowmelt infiltration to the available snowmelt water (in-filtration ratio) was obtained, whereas there were no clear relationships between the infiltration ratio and soil temper-ature at 0.05 m depth just before the beginning of snowmelt period. Thus, the frost depth is one of the most important factors to estimate the amount of snowmelt infiltration into deep soil layer when the frost depth is relatively shallow. We explained the process of the decrease in the snowmelt infiltration with the increase in the soil frost depth using a conceptual model.
