| Popis: |
A three phase temperature - density model was developed to simulate the temperature patterns of a snowpack and generate snowmelt. This one dimensional model is based on the heat flow equation with air and ground temperature as the two boundary conditions. With four measured input variables the model permits the computation of the temperature patterns, density, heat flux and sublimation of snow over specified time intervals.;The model was applied to the Medway drainage basin near London, Ontario. Six snow courses were operated for the winter of 1977-78 to collect information on snow temperature, density and water equivalent at various depths in the snowpack. The model was tested on fifty five sampling points of which six were randomly selected, one from each snow course to present the results. The results indicate that: (1) The model can simulate the temperature - density patterns in a snowpack with a high degree of accuracy. (2) It is possible to identify different kinds of metamorphism in the snowpack. (3) That the computed heat flux is a good indication of the thermal budget of a snowpack over time. (4) A negative heat flux increases density in the top layers of a snowpack. The reverse is true for a positive heat flux except for cases where melt is produced at the top layers. Under such circumstances, especially during the spring melt season, phase transition of water is more important and active than transference of heat by conduction. (5) Sublimation is a function of the temperature gradients in the snowpack and can be estimated quantitatively. (6) There is a high correlation between measured and simulated runoff volumes. (7) Over shorter time intervals, as for the spring runoff period, March 16 - April 15, the melt predicting capability of the model is dependent on the characteristic temperature. (8) The model is not unique in terms of geographical location and can be easily tested in any drainage basin. (9) To improve the efficiency and accuracy of the model it is suggested that the role of other variables be considered. |
