UBC Theses and Dissertations

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UBC Theses and Dissertations

Modification and evaluation of a computer nitrogen management model for the Fraser Valley of British Columbia Willetts, Shawn E.


In an effort to better predict both soil water flow and soil nitrogen processes at sites within the Fraser Valley, the simplistic soil water algorithms of the Bulley and Cappelaere (1978) nitrogen management model were replaced by the more accurate algorithms of Richard (1988). The modified model was then calibrated using field-measured water table levels for 1992. A sensitivity analysis was performed and model simulations were run for November and December 1991 and January through September 1993. Results from the modified and unmodified models were compared to field nitrogen and soil moisture data collected at two sites in the Lower Fraser Valley. Incorporation of the Richard (1988) soil water algorithms in the Bulley and Cap pelaere (1978) nitrogen management model improved model representation of soil water regimes, but did not improve simulated soil nitrogen processes. Discrepancies between model predicted and field-measured values were attributed to spatial variability in field data, lack of field-measured parameters for use as model input, and poor model descrip tions of soil nitrogen processes.

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