Basin division and snowmelt discharge in an alpine basin

An alpine basin in the Colorado Front Range was divided into topographically different grid squares in an attempt to define areas within the basin with similar snow and energy environments. The 188 grids were separated into 10 groups. A t-test between groups, of snowcover present June 23, indicates no significant difference in snowcover for that date. However, the same topographic characteristics (elevation, slope, aspect and angle) were more successful predicting ablation. Modifications in grid size and further statistical analysis are suggested. Three expansion rates for the isothermal snowpack (exponential, linear, and a growth curve) from the beginning of snowmelt to peak snowmelt runoff were tested. The exponential and linear models underestimated discharge by 33% and 14%, respectively, while the growth curve overestimated discharge by 10.5%. The 10.55% overestimate (89.5% basin efficiency) agrees well with Carroll's (1976) estimated basin efficiency of 90% for the same basin.