An Elaboration Of Two Methods To Investigate Unfrozen Water Movement In A Snow-Soil Environment (Tdr, Instrumentation, Heat)

Abstract

Hydrologic research of processes related to snow and to frozen soil have generally been regarded as separate entities. The unknowns involved in these fields were so numerous, that few attempted to examine snow-soil interactions. Better tools (mathematical models and field equipment) are needed to study unfrozen-water movement in snow-soil systems and to understand and test theories of water movement in frozen media. The overall thesis objective is to see if Anderson's snow model can be modified to include soil heat and mass transfer to provide good simulations of these processes in a snow-soil environment. The first part of this thesis deals with the elaboration of the time domain reflectometry method to continuously measure the unfrozen water content of soil and snow in the field. The continuous monitoring, over a one-year period, of unfrozen water content at different soil depths was successful. The application of the same method to snow, was quite promising, but requires the addition of snow density. The second part of the thesis deals with the application of an energy and mass balance model to a snow cover and soil. The snow model satisfactorily simulated snow cover density, snow water equivalent, snow depth, time of disappearance, snow temperature and snowmelt runoff for the one accumulation and two snowmelt periods. The boundary from the soil surface was lowered to a certain soil depth to include detailed processes of heat and mass transfer occurring in the soil. The output values of the new model were compared with the data of one snowmelt period. It was found that instead of modifying Anderson's snowmelt model, it would be better to develop an entirely new model that would have two unknowns in the soil and the snow and only two boundaries: the snow-air interface and the soil at a certain depth in the ground.