Snowfall interception is particularly important to the hydrology of forested cold regions. Unloading of intercepted snow controls the snow available for interception loss due to sublimation from that held in the canopy. This thesis seeks to determine the factors that affect the magnitude and timing of unloading at the forest-stand scale. A field program was established that measured interception and unloading at a forest-stand scale using a series of hanging lysimeters and a 7 m tall spruce tree suspended, in-situ, on a load-cell.<p>
Meteorological conditions including snowfall, wind speed, air temperature, and incoming radiation were recorded above and below the forest canopy. Unloading did not behave as described by current unloading models. It was observed to be triggered by occurrences of wind gusts or melt conditions within the canopy but no trends were found in the measurements that could be used to predict the onset of unloading from gusts or air temperature alone. An association between intercepted snow sublimation and unloading was found and this relationship was further found to be an exponential function of air temperature. An expression based on this empirical model can be used to calculate unloading as a function of sublimation rate in hydrological models or to calculate unloading directly as a function of canopy snow load and air temperature.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-09302010-145706 |
| Date | 30 September 2010 |
| Creators | MacDonald, James P |
| Contributors | Pomeroy, John, Spence, Chris, Westbrooke, Cherie, Maule, Charles, Aitken, Alec |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-09302010-145706/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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