Soil frost effects on soil water and runoff dynamics along a boreal transect: 2. Simulations

A physically based SVAT-model was rested with soil and snow physical measur ements, as well as runoff data fr om an 8600 m(2) catchment in northern Swe den in order to quantify the influence of soil frost on spring snowmelt run off in a moderately sloped, boreal forest. The model was run as an array of connected profiles cascading to the brook. For three winter seasons (1995- 98) it was able to predict the onset and total accumulation of the runoff w ith satisfactory accuracy. Surface runoff was identified as only a minor fr action of the total runoff occurring during short periods in connection wit h ice blocking of the water-conducting pores. Little surface runoff, though , does not mean that soil frost is unimportant for spring runoff. Simulatio ns without frost routines systematically underestimated the total accumulat ed runoff. The possibility of major frost effects appearing in response to specific combinations of weather conditions were also tested. Different sce narios of critical initial conditions for the winter, e.g, high water satur ation and delayed snow accumulation leading to an increased frost penetrati on, were tested. These showed that under special circumstances there is pot ential for increased spring runoff due to soil frost. Copyright (C) 2001 Jo hn Wiley & Sons, Ltd.